linux/block/genhd.c

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/*
* gendisk handling
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/kdev_t.h>
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/kobj_map.h>
#include <linux/mutex.h>
#include <linux/idr.h>
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
#include <linux/log2.h>
#include "blk.h"
static DEFINE_MUTEX(block_class_lock);
struct kobject *block_depr;
/* for extended dynamic devt allocation, currently only one major is used */
#define MAX_EXT_DEVT (1 << MINORBITS)
/* For extended devt allocation. ext_devt_mutex prevents look up
* results from going away underneath its user.
*/
static DEFINE_MUTEX(ext_devt_mutex);
static DEFINE_IDR(ext_devt_idr);
static struct device_type disk_type;
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
static void disk_alloc_events(struct gendisk *disk);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
static void disk_add_events(struct gendisk *disk);
static void disk_del_events(struct gendisk *disk);
static void disk_release_events(struct gendisk *disk);
/**
* disk_get_part - get partition
* @disk: disk to look partition from
* @partno: partition number
*
* Look for partition @partno from @disk. If found, increment
* reference count and return it.
*
* CONTEXT:
* Don't care.
*
* RETURNS:
* Pointer to the found partition on success, NULL if not found.
*/
struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
{
struct hd_struct *part = NULL;
struct disk_part_tbl *ptbl;
if (unlikely(partno < 0))
return NULL;
rcu_read_lock();
ptbl = rcu_dereference(disk->part_tbl);
if (likely(partno < ptbl->len)) {
part = rcu_dereference(ptbl->part[partno]);
if (part)
get_device(part_to_dev(part));
}
rcu_read_unlock();
return part;
}
EXPORT_SYMBOL_GPL(disk_get_part);
/**
* disk_part_iter_init - initialize partition iterator
* @piter: iterator to initialize
* @disk: disk to iterate over
* @flags: DISK_PITER_* flags
*
* Initialize @piter so that it iterates over partitions of @disk.
*
* CONTEXT:
* Don't care.
*/
void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
unsigned int flags)
{
struct disk_part_tbl *ptbl;
rcu_read_lock();
ptbl = rcu_dereference(disk->part_tbl);
piter->disk = disk;
piter->part = NULL;
if (flags & DISK_PITER_REVERSE)
piter->idx = ptbl->len - 1;
else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
piter->idx = 0;
else
piter->idx = 1;
piter->flags = flags;
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(disk_part_iter_init);
/**
* disk_part_iter_next - proceed iterator to the next partition and return it
* @piter: iterator of interest
*
* Proceed @piter to the next partition and return it.
*
* CONTEXT:
* Don't care.
*/
struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
{
struct disk_part_tbl *ptbl;
int inc, end;
/* put the last partition */
disk_put_part(piter->part);
piter->part = NULL;
/* get part_tbl */
rcu_read_lock();
ptbl = rcu_dereference(piter->disk->part_tbl);
/* determine iteration parameters */
if (piter->flags & DISK_PITER_REVERSE) {
inc = -1;
if (piter->flags & (DISK_PITER_INCL_PART0 |
DISK_PITER_INCL_EMPTY_PART0))
end = -1;
else
end = 0;
} else {
inc = 1;
end = ptbl->len;
}
/* iterate to the next partition */
for (; piter->idx != end; piter->idx += inc) {
struct hd_struct *part;
part = rcu_dereference(ptbl->part[piter->idx]);
if (!part)
continue;
if (!part_nr_sects_read(part) &&
!(piter->flags & DISK_PITER_INCL_EMPTY) &&
!(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
piter->idx == 0))
continue;
get_device(part_to_dev(part));
piter->part = part;
piter->idx += inc;
break;
}
rcu_read_unlock();
return piter->part;
}
EXPORT_SYMBOL_GPL(disk_part_iter_next);
/**
* disk_part_iter_exit - finish up partition iteration
* @piter: iter of interest
*
* Called when iteration is over. Cleans up @piter.
*
* CONTEXT:
* Don't care.
*/
void disk_part_iter_exit(struct disk_part_iter *piter)
{
disk_put_part(piter->part);
piter->part = NULL;
}
EXPORT_SYMBOL_GPL(disk_part_iter_exit);
static inline int sector_in_part(struct hd_struct *part, sector_t sector)
{
return part->start_sect <= sector &&
sector < part->start_sect + part_nr_sects_read(part);
}
/**
* disk_map_sector_rcu - map sector to partition
* @disk: gendisk of interest
* @sector: sector to map
*
* Find out which partition @sector maps to on @disk. This is
* primarily used for stats accounting.
*
* CONTEXT:
* RCU read locked. The returned partition pointer is valid only
* while preemption is disabled.
*
* RETURNS:
* Found partition on success, part0 is returned if no partition matches
*/
struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector)
{
struct disk_part_tbl *ptbl;
struct hd_struct *part;
int i;
ptbl = rcu_dereference(disk->part_tbl);
part = rcu_dereference(ptbl->last_lookup);
if (part && sector_in_part(part, sector))
return part;
for (i = 1; i < ptbl->len; i++) {
part = rcu_dereference(ptbl->part[i]);
if (part && sector_in_part(part, sector)) {
rcu_assign_pointer(ptbl->last_lookup, part);
return part;
}
}
return &disk->part0;
}
EXPORT_SYMBOL_GPL(disk_map_sector_rcu);
/*
* Can be deleted altogether. Later.
*
*/
static struct blk_major_name {
struct blk_major_name *next;
int major;
char name[16];
} *major_names[BLKDEV_MAJOR_HASH_SIZE];
/* index in the above - for now: assume no multimajor ranges */
static inline int major_to_index(unsigned major)
{
return major % BLKDEV_MAJOR_HASH_SIZE;
}
#ifdef CONFIG_PROC_FS
void blkdev_show(struct seq_file *seqf, off_t offset)
{
struct blk_major_name *dp;
if (offset < BLKDEV_MAJOR_HASH_SIZE) {
mutex_lock(&block_class_lock);
for (dp = major_names[offset]; dp; dp = dp->next)
seq_printf(seqf, "%3d %s\n", dp->major, dp->name);
mutex_unlock(&block_class_lock);
}
}
#endif /* CONFIG_PROC_FS */
/**
* register_blkdev - register a new block device
*
* @major: the requested major device number [1..255]. If @major=0, try to
* allocate any unused major number.
* @name: the name of the new block device as a zero terminated string
*
* The @name must be unique within the system.
*
* The return value depends on the @major input parameter.
* - if a major device number was requested in range [1..255] then the
* function returns zero on success, or a negative error code
* - if any unused major number was requested with @major=0 parameter
* then the return value is the allocated major number in range
* [1..255] or a negative error code otherwise
*/
int register_blkdev(unsigned int major, const char *name)
{
struct blk_major_name **n, *p;
int index, ret = 0;
mutex_lock(&block_class_lock);
/* temporary */
if (major == 0) {
for (index = ARRAY_SIZE(major_names)-1; index > 0; index--) {
if (major_names[index] == NULL)
break;
}
if (index == 0) {
printk("register_blkdev: failed to get major for %s\n",
name);
ret = -EBUSY;
goto out;
}
major = index;
ret = major;
}
p = kmalloc(sizeof(struct blk_major_name), GFP_KERNEL);
if (p == NULL) {
ret = -ENOMEM;
goto out;
}
p->major = major;
strlcpy(p->name, name, sizeof(p->name));
p->next = NULL;
index = major_to_index(major);
for (n = &major_names[index]; *n; n = &(*n)->next) {
if ((*n)->major == major)
break;
}
if (!*n)
*n = p;
else
ret = -EBUSY;
if (ret < 0) {
printk("register_blkdev: cannot get major %d for %s\n",
major, name);
kfree(p);
}
out:
mutex_unlock(&block_class_lock);
return ret;
}
EXPORT_SYMBOL(register_blkdev);
void unregister_blkdev(unsigned int major, const char *name)
{
struct blk_major_name **n;
struct blk_major_name *p = NULL;
int index = major_to_index(major);
mutex_lock(&block_class_lock);
for (n = &major_names[index]; *n; n = &(*n)->next)
if ((*n)->major == major)
break;
if (!*n || strcmp((*n)->name, name)) {
WARN_ON(1);
} else {
p = *n;
*n = p->next;
}
mutex_unlock(&block_class_lock);
kfree(p);
}
EXPORT_SYMBOL(unregister_blkdev);
static struct kobj_map *bdev_map;
/**
* blk_mangle_minor - scatter minor numbers apart
* @minor: minor number to mangle
*
* Scatter consecutively allocated @minor number apart if MANGLE_DEVT
* is enabled. Mangling twice gives the original value.
*
* RETURNS:
* Mangled value.
*
* CONTEXT:
* Don't care.
*/
static int blk_mangle_minor(int minor)
{
#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
int i;
for (i = 0; i < MINORBITS / 2; i++) {
int low = minor & (1 << i);
int high = minor & (1 << (MINORBITS - 1 - i));
int distance = MINORBITS - 1 - 2 * i;
minor ^= low | high; /* clear both bits */
low <<= distance; /* swap the positions */
high >>= distance;
minor |= low | high; /* and set */
}
#endif
return minor;
}
/**
* blk_alloc_devt - allocate a dev_t for a partition
* @part: partition to allocate dev_t for
* @devt: out parameter for resulting dev_t
*
* Allocate a dev_t for block device.
*
* RETURNS:
* 0 on success, allocated dev_t is returned in *@devt. -errno on
* failure.
*
* CONTEXT:
* Might sleep.
*/
int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
{
struct gendisk *disk = part_to_disk(part);
int idx, rc;
/* in consecutive minor range? */
if (part->partno < disk->minors) {
*devt = MKDEV(disk->major, disk->first_minor + part->partno);
return 0;
}
/* allocate ext devt */
do {
if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
return -ENOMEM;
rc = idr_get_new(&ext_devt_idr, part, &idx);
} while (rc == -EAGAIN);
if (rc)
return rc;
if (idx > MAX_EXT_DEVT) {
idr_remove(&ext_devt_idr, idx);
return -EBUSY;
}
*devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
return 0;
}
/**
* blk_free_devt - free a dev_t
* @devt: dev_t to free
*
* Free @devt which was allocated using blk_alloc_devt().
*
* CONTEXT:
* Might sleep.
*/
void blk_free_devt(dev_t devt)
{
might_sleep();
if (devt == MKDEV(0, 0))
return;
if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
mutex_lock(&ext_devt_mutex);
idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
mutex_unlock(&ext_devt_mutex);
}
}
static char *bdevt_str(dev_t devt, char *buf)
{
if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
char tbuf[BDEVT_SIZE];
snprintf(tbuf, BDEVT_SIZE, "%02x%02x", MAJOR(devt), MINOR(devt));
snprintf(buf, BDEVT_SIZE, "%-9s", tbuf);
} else
snprintf(buf, BDEVT_SIZE, "%03x:%05x", MAJOR(devt), MINOR(devt));
return buf;
}
/*
* Register device numbers dev..(dev+range-1)
* range must be nonzero
* The hash chain is sorted on range, so that subranges can override.
*/
void blk_register_region(dev_t devt, unsigned long range, struct module *module,
struct kobject *(*probe)(dev_t, int *, void *),
int (*lock)(dev_t, void *), void *data)
{
kobj_map(bdev_map, devt, range, module, probe, lock, data);
}
EXPORT_SYMBOL(blk_register_region);
void blk_unregister_region(dev_t devt, unsigned long range)
{
kobj_unmap(bdev_map, devt, range);
}
EXPORT_SYMBOL(blk_unregister_region);
static struct kobject *exact_match(dev_t devt, int *partno, void *data)
{
struct gendisk *p = data;
return &disk_to_dev(p)->kobj;
}
static int exact_lock(dev_t devt, void *data)
{
struct gendisk *p = data;
if (!get_disk(p))
return -1;
return 0;
}
static void register_disk(struct gendisk *disk)
{
struct device *ddev = disk_to_dev(disk);
struct block_device *bdev;
struct disk_part_iter piter;
struct hd_struct *part;
int err;
ddev->parent = disk->driverfs_dev;
dev_set_name(ddev, disk->disk_name);
/* delay uevents, until we scanned partition table */
dev_set_uevent_suppress(ddev, 1);
if (device_add(ddev))
return;
if (!sysfs_deprecated) {
err = sysfs_create_link(block_depr, &ddev->kobj,
kobject_name(&ddev->kobj));
if (err) {
device_del(ddev);
return;
}
}
disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
/* No minors to use for partitions */
if (!disk_part_scan_enabled(disk))
goto exit;
/* No such device (e.g., media were just removed) */
if (!get_capacity(disk))
goto exit;
bdev = bdget_disk(disk, 0);
if (!bdev)
goto exit;
bdev->bd_invalidated = 1;
err = blkdev_get(bdev, FMODE_READ, NULL);
if (err < 0)
goto exit;
blkdev_put(bdev, FMODE_READ);
exit:
/* announce disk after possible partitions are created */
dev_set_uevent_suppress(ddev, 0);
kobject_uevent(&ddev->kobj, KOBJ_ADD);
/* announce possible partitions */
disk_part_iter_init(&piter, disk, 0);
while ((part = disk_part_iter_next(&piter)))
kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
disk_part_iter_exit(&piter);
}
/**
* add_disk - add partitioning information to kernel list
* @disk: per-device partitioning information
*
* This function registers the partitioning information in @disk
* with the kernel.
*
* FIXME: error handling
*/
void add_disk(struct gendisk *disk)
{
struct backing_dev_info *bdi;
dev_t devt;
int retval;
/* minors == 0 indicates to use ext devt from part0 and should
* be accompanied with EXT_DEVT flag. Make sure all
* parameters make sense.
*/
WARN_ON(disk->minors && !(disk->major || disk->first_minor));
WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
disk->flags |= GENHD_FL_UP;
retval = blk_alloc_devt(&disk->part0, &devt);
if (retval) {
WARN_ON(1);
return;
}
disk_to_dev(disk)->devt = devt;
/* ->major and ->first_minor aren't supposed to be
* dereferenced from here on, but set them just in case.
*/
disk->major = MAJOR(devt);
disk->first_minor = MINOR(devt);
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
disk_alloc_events(disk);
/* Register BDI before referencing it from bdev */
bdi = &disk->queue->backing_dev_info;
bdi_register_dev(bdi, disk_devt(disk));
blk_register_region(disk_devt(disk), disk->minors, NULL,
exact_match, exact_lock, disk);
register_disk(disk);
blk_register_queue(disk);
block: make gendisk hold a reference to its queue The following command sequence triggers an oops. # mount /dev/sdb1 /mnt # echo 1 > /sys/class/scsi_device/0\:0\:1\:0/device/delete # umount /mnt general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 791, comm: umount Not tainted 3.1.0-rc3-work+ #8 Bochs Bochs RIP: 0010:[<ffffffff810d0879>] [<ffffffff810d0879>] __lock_acquire+0x389/0x1d60 ... Call Trace: [<ffffffff810d2845>] lock_acquire+0x95/0x140 [<ffffffff81aed87b>] _raw_spin_lock+0x3b/0x50 [<ffffffff811573bc>] bdi_lock_two+0x5c/0x70 [<ffffffff811c2f6c>] bdev_inode_switch_bdi+0x4c/0xf0 [<ffffffff811c3fcb>] __blkdev_put+0x11b/0x1d0 [<ffffffff811c4010>] __blkdev_put+0x160/0x1d0 [<ffffffff811c40df>] blkdev_put+0x5f/0x190 [<ffffffff8118f18d>] kill_block_super+0x4d/0x80 [<ffffffff8118f4a5>] deactivate_locked_super+0x45/0x70 [<ffffffff8119003a>] deactivate_super+0x4a/0x70 [<ffffffff811ac4ad>] mntput_no_expire+0xed/0x130 [<ffffffff811acf2e>] sys_umount+0x7e/0x3a0 [<ffffffff81aeeeab>] system_call_fastpath+0x16/0x1b This is because bdev holds on to disk but disk doesn't pin the associated queue. If a SCSI device is removed while the device is still open, the sdev puts the base reference to the queue on release. When the bdev is finally released, the associated queue is already gone along with the bdi and bdev_inode_switch_bdi() ends up dereferencing already freed bdi. Even if it were not for this bug, disk not holding onto the associated queue is very unusual and error-prone. Fix it by making add_disk() take an extra reference to its queue and put it on disk_release() and ensuring that disk and its fops owner are put in that order after all accesses to the disk and queue are complete. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-19 16:31:07 +04:00
/*
* Take an extra ref on queue which will be put on disk_release()
* so that it sticks around as long as @disk is there.
*/
WARN_ON_ONCE(!blk_get_queue(disk->queue));
block: make gendisk hold a reference to its queue The following command sequence triggers an oops. # mount /dev/sdb1 /mnt # echo 1 > /sys/class/scsi_device/0\:0\:1\:0/device/delete # umount /mnt general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 791, comm: umount Not tainted 3.1.0-rc3-work+ #8 Bochs Bochs RIP: 0010:[<ffffffff810d0879>] [<ffffffff810d0879>] __lock_acquire+0x389/0x1d60 ... Call Trace: [<ffffffff810d2845>] lock_acquire+0x95/0x140 [<ffffffff81aed87b>] _raw_spin_lock+0x3b/0x50 [<ffffffff811573bc>] bdi_lock_two+0x5c/0x70 [<ffffffff811c2f6c>] bdev_inode_switch_bdi+0x4c/0xf0 [<ffffffff811c3fcb>] __blkdev_put+0x11b/0x1d0 [<ffffffff811c4010>] __blkdev_put+0x160/0x1d0 [<ffffffff811c40df>] blkdev_put+0x5f/0x190 [<ffffffff8118f18d>] kill_block_super+0x4d/0x80 [<ffffffff8118f4a5>] deactivate_locked_super+0x45/0x70 [<ffffffff8119003a>] deactivate_super+0x4a/0x70 [<ffffffff811ac4ad>] mntput_no_expire+0xed/0x130 [<ffffffff811acf2e>] sys_umount+0x7e/0x3a0 [<ffffffff81aeeeab>] system_call_fastpath+0x16/0x1b This is because bdev holds on to disk but disk doesn't pin the associated queue. If a SCSI device is removed while the device is still open, the sdev puts the base reference to the queue on release. When the bdev is finally released, the associated queue is already gone along with the bdi and bdev_inode_switch_bdi() ends up dereferencing already freed bdi. Even if it were not for this bug, disk not holding onto the associated queue is very unusual and error-prone. Fix it by making add_disk() take an extra reference to its queue and put it on disk_release() and ensuring that disk and its fops owner are put in that order after all accesses to the disk and queue are complete. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-19 16:31:07 +04:00
retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
"bdi");
WARN_ON(retval);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
disk_add_events(disk);
}
EXPORT_SYMBOL(add_disk);
void del_gendisk(struct gendisk *disk)
{
struct disk_part_iter piter;
struct hd_struct *part;
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
disk_del_events(disk);
/* invalidate stuff */
disk_part_iter_init(&piter, disk,
DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
while ((part = disk_part_iter_next(&piter))) {
invalidate_partition(disk, part->partno);
delete_partition(disk, part->partno);
}
disk_part_iter_exit(&piter);
invalidate_partition(disk, 0);
blk_free_devt(disk_to_dev(disk)->devt);
set_capacity(disk, 0);
disk->flags &= ~GENHD_FL_UP;
sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
bdi_unregister(&disk->queue->backing_dev_info);
blk_unregister_queue(disk);
blk_unregister_region(disk_devt(disk), disk->minors);
part_stat_set_all(&disk->part0, 0);
disk->part0.stamp = 0;
kobject_put(disk->part0.holder_dir);
kobject_put(disk->slave_dir);
disk->driverfs_dev = NULL;
if (!sysfs_deprecated)
sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
device_del(disk_to_dev(disk));
}
EXPORT_SYMBOL(del_gendisk);
/**
* get_gendisk - get partitioning information for a given device
* @devt: device to get partitioning information for
* @partno: returned partition index
*
* This function gets the structure containing partitioning
* information for the given device @devt.
*/
struct gendisk *get_gendisk(dev_t devt, int *partno)
{
struct gendisk *disk = NULL;
if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
struct kobject *kobj;
kobj = kobj_lookup(bdev_map, devt, partno);
if (kobj)
disk = dev_to_disk(kobj_to_dev(kobj));
} else {
struct hd_struct *part;
mutex_lock(&ext_devt_mutex);
part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
if (part && get_disk(part_to_disk(part))) {
*partno = part->partno;
disk = part_to_disk(part);
}
mutex_unlock(&ext_devt_mutex);
}
return disk;
}
EXPORT_SYMBOL(get_gendisk);
/**
* bdget_disk - do bdget() by gendisk and partition number
* @disk: gendisk of interest
* @partno: partition number
*
* Find partition @partno from @disk, do bdget() on it.
*
* CONTEXT:
* Don't care.
*
* RETURNS:
* Resulting block_device on success, NULL on failure.
*/
struct block_device *bdget_disk(struct gendisk *disk, int partno)
{
struct hd_struct *part;
struct block_device *bdev = NULL;
part = disk_get_part(disk, partno);
if (part)
bdev = bdget(part_devt(part));
disk_put_part(part);
return bdev;
}
EXPORT_SYMBOL(bdget_disk);
/*
* print a full list of all partitions - intended for places where the root
* filesystem can't be mounted and thus to give the victim some idea of what
* went wrong
*/
void __init printk_all_partitions(void)
{
struct class_dev_iter iter;
struct device *dev;
class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
while ((dev = class_dev_iter_next(&iter))) {
struct gendisk *disk = dev_to_disk(dev);
struct disk_part_iter piter;
struct hd_struct *part;
char name_buf[BDEVNAME_SIZE];
char devt_buf[BDEVT_SIZE];
/*
* Don't show empty devices or things that have been
* suppressed
*/
if (get_capacity(disk) == 0 ||
(disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
continue;
/*
* Note, unlike /proc/partitions, I am showing the
* numbers in hex - the same format as the root=
* option takes.
*/
disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
while ((part = disk_part_iter_next(&piter))) {
bool is_part0 = part == &disk->part0;
printk("%s%s %10llu %s %s", is_part0 ? "" : " ",
bdevt_str(part_devt(part), devt_buf),
(unsigned long long)part_nr_sects_read(part) >> 1
, disk_name(disk, part->partno, name_buf),
part->info ? part->info->uuid : "");
if (is_part0) {
if (disk->driverfs_dev != NULL &&
disk->driverfs_dev->driver != NULL)
printk(" driver: %s\n",
disk->driverfs_dev->driver->name);
else
printk(" (driver?)\n");
} else
printk("\n");
}
disk_part_iter_exit(&piter);
}
class_dev_iter_exit(&iter);
}
#ifdef CONFIG_PROC_FS
/* iterator */
static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
{
loff_t skip = *pos;
struct class_dev_iter *iter;
struct device *dev;
iter = kmalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return ERR_PTR(-ENOMEM);
seqf->private = iter;
class_dev_iter_init(iter, &block_class, NULL, &disk_type);
do {
dev = class_dev_iter_next(iter);
if (!dev)
return NULL;
} while (skip--);
return dev_to_disk(dev);
}
static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
{
struct device *dev;
(*pos)++;
dev = class_dev_iter_next(seqf->private);
if (dev)
return dev_to_disk(dev);
return NULL;
}
static void disk_seqf_stop(struct seq_file *seqf, void *v)
{
struct class_dev_iter *iter = seqf->private;
/* stop is called even after start failed :-( */
if (iter) {
class_dev_iter_exit(iter);
kfree(iter);
}
}
static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
{
void *p;
p = disk_seqf_start(seqf, pos);
if (!IS_ERR_OR_NULL(p) && !*pos)
seq_puts(seqf, "major minor #blocks name\n\n");
return p;
}
static int show_partition(struct seq_file *seqf, void *v)
{
struct gendisk *sgp = v;
struct disk_part_iter piter;
struct hd_struct *part;
char buf[BDEVNAME_SIZE];
/* Don't show non-partitionable removeable devices or empty devices */
if (!get_capacity(sgp) || (!disk_max_parts(sgp) &&
(sgp->flags & GENHD_FL_REMOVABLE)))
return 0;
if (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)
return 0;
/* show the full disk and all non-0 size partitions of it */
disk_part_iter_init(&piter, sgp, DISK_PITER_INCL_PART0);
while ((part = disk_part_iter_next(&piter)))
seq_printf(seqf, "%4d %7d %10llu %s\n",
MAJOR(part_devt(part)), MINOR(part_devt(part)),
(unsigned long long)part_nr_sects_read(part) >> 1,
disk_name(sgp, part->partno, buf));
disk_part_iter_exit(&piter);
return 0;
}
static const struct seq_operations partitions_op = {
.start = show_partition_start,
.next = disk_seqf_next,
.stop = disk_seqf_stop,
.show = show_partition
};
static int partitions_open(struct inode *inode, struct file *file)
{
return seq_open(file, &partitions_op);
}
static const struct file_operations proc_partitions_operations = {
.open = partitions_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
#endif
static struct kobject *base_probe(dev_t devt, int *partno, void *data)
{
if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
/* Make old-style 2.4 aliases work */
request_module("block-major-%d", MAJOR(devt));
return NULL;
}
static int __init genhd_device_init(void)
{
int error;
block_class.dev_kobj = sysfs_dev_block_kobj;
error = class_register(&block_class);
if (unlikely(error))
return error;
bdev_map = kobj_map_init(base_probe, &block_class_lock);
blk_dev_init();
block: fix boot failure with CONFIG_DEBUG_BLOCK_EXT_DEVT=y and nash We run into system boot failure with kernel 2.6.28-rc. We found it on a couple of machines, including T61 notebook, nehalem machine, and another HPC NX6325 notebook. All the machines use FedoraCore 8 or FedoraCore 9. With kernel prior to 2.6.28-rc, system boot doesn't fail. I debug it and locate the root cause. Pls. see http://bugzilla.kernel.org/show_bug.cgi?id=11899 https://bugzilla.redhat.com/show_bug.cgi?id=471517 As a matter of fact, there are 2 bugs. 1)root=/dev/sda1, system boot randomly fails. Mostly, boot for 5 times and fails once. nash has a bug. Some of its functions misuse return value 0. Sometimes, 0 means timeout and no uevent available. Sometimes, 0 means nash gets an uevent, but the uevent isn't block-related (for exmaple, usb). If by coincidence, kernel tells nash that uevents are available, but kernel also set timeout, nash might stops collecting other uevents in queue if current uevent isn't block-related. I work out a patch for nash to fix it. http://bugzilla.kernel.org/attachment.cgi?id=18858 2) root=LABEL=/, system always can't boot. initrd init reports switchroot fails. Here is an executation branch of nash when booting: (1) nash read /sys/block/sda/dev; Assume major is 8 (on my desktop) (2) nash query /proc/devices with the major number; It found line "8 sd"; (3) nash use 'sd' to search its own probe table to find device (DISK) type for the device and add it to its own list; (4) Later on, it probes all devices in its list to get filesystem labels; scsi register "8 sd" always. When major is 259, nash fails to find the device(DISK) type. I enables CONFIG_DEBUG_BLOCK_EXT_DEVT=y when compiling kernel, so 259 is picked up for device /dev/sda1, which causes nash to fail to find device (DISK) type. To fixing issue 2), I create a patch for nash and another patch for kernel. http://bugzilla.kernel.org/attachment.cgi?id=18859 http://bugzilla.kernel.org/attachment.cgi?id=18837 Below is the patch for kernel 2.6.28-rc4. It registers blkext, a new block device in proc/devices. With 2 patches on nash and 1 patch on kernel, I boot my machines for dozens of times without failure. Signed-off-by Zhang Yanmin <yanmin.zhang@linux.intel.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-11-14 10:26:30 +03:00
register_blkdev(BLOCK_EXT_MAJOR, "blkext");
/* create top-level block dir */
if (!sysfs_deprecated)
block_depr = kobject_create_and_add("block", NULL);
return 0;
}
subsys_initcall(genhd_device_init);
static ssize_t disk_range_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n", disk->minors);
}
static ssize_t disk_ext_range_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n", disk_max_parts(disk));
}
static ssize_t disk_removable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n",
(disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
}
static ssize_t disk_ro_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n", get_disk_ro(disk) ? 1 : 0);
}
static ssize_t disk_capability_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%x\n", disk->flags);
}
static ssize_t disk_alignment_offset_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n", queue_alignment_offset(disk->queue));
}
static ssize_t disk_discard_alignment_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n", queue_discard_alignment(disk->queue));
}
static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
static DEVICE_ATTR(discard_alignment, S_IRUGO, disk_discard_alignment_show,
NULL);
static DEVICE_ATTR(capability, S_IRUGO, disk_capability_show, NULL);
static DEVICE_ATTR(stat, S_IRUGO, part_stat_show, NULL);
static DEVICE_ATTR(inflight, S_IRUGO, part_inflight_show, NULL);
#ifdef CONFIG_FAIL_MAKE_REQUEST
static struct device_attribute dev_attr_fail =
__ATTR(make-it-fail, S_IRUGO|S_IWUSR, part_fail_show, part_fail_store);
#endif
#ifdef CONFIG_FAIL_IO_TIMEOUT
static struct device_attribute dev_attr_fail_timeout =
__ATTR(io-timeout-fail, S_IRUGO|S_IWUSR, part_timeout_show,
part_timeout_store);
#endif
static struct attribute *disk_attrs[] = {
&dev_attr_range.attr,
&dev_attr_ext_range.attr,
&dev_attr_removable.attr,
&dev_attr_ro.attr,
&dev_attr_size.attr,
&dev_attr_alignment_offset.attr,
&dev_attr_discard_alignment.attr,
&dev_attr_capability.attr,
&dev_attr_stat.attr,
&dev_attr_inflight.attr,
#ifdef CONFIG_FAIL_MAKE_REQUEST
&dev_attr_fail.attr,
#endif
#ifdef CONFIG_FAIL_IO_TIMEOUT
&dev_attr_fail_timeout.attr,
#endif
NULL
};
static struct attribute_group disk_attr_group = {
.attrs = disk_attrs,
};
static const struct attribute_group *disk_attr_groups[] = {
&disk_attr_group,
NULL
};
/**
* disk_replace_part_tbl - replace disk->part_tbl in RCU-safe way
* @disk: disk to replace part_tbl for
* @new_ptbl: new part_tbl to install
*
* Replace disk->part_tbl with @new_ptbl in RCU-safe way. The
* original ptbl is freed using RCU callback.
*
* LOCKING:
* Matching bd_mutx locked.
*/
static void disk_replace_part_tbl(struct gendisk *disk,
struct disk_part_tbl *new_ptbl)
{
struct disk_part_tbl *old_ptbl = disk->part_tbl;
rcu_assign_pointer(disk->part_tbl, new_ptbl);
if (old_ptbl) {
rcu_assign_pointer(old_ptbl->last_lookup, NULL);
kfree_rcu(old_ptbl, rcu_head);
}
}
/**
* disk_expand_part_tbl - expand disk->part_tbl
* @disk: disk to expand part_tbl for
* @partno: expand such that this partno can fit in
*
* Expand disk->part_tbl such that @partno can fit in. disk->part_tbl
* uses RCU to allow unlocked dereferencing for stats and other stuff.
*
* LOCKING:
* Matching bd_mutex locked, might sleep.
*
* RETURNS:
* 0 on success, -errno on failure.
*/
int disk_expand_part_tbl(struct gendisk *disk, int partno)
{
struct disk_part_tbl *old_ptbl = disk->part_tbl;
struct disk_part_tbl *new_ptbl;
int len = old_ptbl ? old_ptbl->len : 0;
int target = partno + 1;
size_t size;
int i;
/* disk_max_parts() is zero during initialization, ignore if so */
if (disk_max_parts(disk) && target > disk_max_parts(disk))
return -EINVAL;
if (target <= len)
return 0;
size = sizeof(*new_ptbl) + target * sizeof(new_ptbl->part[0]);
new_ptbl = kzalloc_node(size, GFP_KERNEL, disk->node_id);
if (!new_ptbl)
return -ENOMEM;
new_ptbl->len = target;
for (i = 0; i < len; i++)
rcu_assign_pointer(new_ptbl->part[i], old_ptbl->part[i]);
disk_replace_part_tbl(disk, new_ptbl);
return 0;
}
static void disk_release(struct device *dev)
{
struct gendisk *disk = dev_to_disk(dev);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
disk_release_events(disk);
kfree(disk->random);
disk_replace_part_tbl(disk, NULL);
free_part_stats(&disk->part0);
free_part_info(&disk->part0);
block: make gendisk hold a reference to its queue The following command sequence triggers an oops. # mount /dev/sdb1 /mnt # echo 1 > /sys/class/scsi_device/0\:0\:1\:0/device/delete # umount /mnt general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 791, comm: umount Not tainted 3.1.0-rc3-work+ #8 Bochs Bochs RIP: 0010:[<ffffffff810d0879>] [<ffffffff810d0879>] __lock_acquire+0x389/0x1d60 ... Call Trace: [<ffffffff810d2845>] lock_acquire+0x95/0x140 [<ffffffff81aed87b>] _raw_spin_lock+0x3b/0x50 [<ffffffff811573bc>] bdi_lock_two+0x5c/0x70 [<ffffffff811c2f6c>] bdev_inode_switch_bdi+0x4c/0xf0 [<ffffffff811c3fcb>] __blkdev_put+0x11b/0x1d0 [<ffffffff811c4010>] __blkdev_put+0x160/0x1d0 [<ffffffff811c40df>] blkdev_put+0x5f/0x190 [<ffffffff8118f18d>] kill_block_super+0x4d/0x80 [<ffffffff8118f4a5>] deactivate_locked_super+0x45/0x70 [<ffffffff8119003a>] deactivate_super+0x4a/0x70 [<ffffffff811ac4ad>] mntput_no_expire+0xed/0x130 [<ffffffff811acf2e>] sys_umount+0x7e/0x3a0 [<ffffffff81aeeeab>] system_call_fastpath+0x16/0x1b This is because bdev holds on to disk but disk doesn't pin the associated queue. If a SCSI device is removed while the device is still open, the sdev puts the base reference to the queue on release. When the bdev is finally released, the associated queue is already gone along with the bdi and bdev_inode_switch_bdi() ends up dereferencing already freed bdi. Even if it were not for this bug, disk not holding onto the associated queue is very unusual and error-prone. Fix it by making add_disk() take an extra reference to its queue and put it on disk_release() and ensuring that disk and its fops owner are put in that order after all accesses to the disk and queue are complete. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2011-10-19 16:31:07 +04:00
if (disk->queue)
blk_put_queue(disk->queue);
kfree(disk);
}
struct class block_class = {
.name = "block",
};
static char *block_devnode(struct device *dev, umode_t *mode)
{
struct gendisk *disk = dev_to_disk(dev);
if (disk->devnode)
return disk->devnode(disk, mode);
return NULL;
}
static struct device_type disk_type = {
.name = "disk",
.groups = disk_attr_groups,
.release = disk_release,
.devnode = block_devnode,
};
#ifdef CONFIG_PROC_FS
/*
* aggregate disk stat collector. Uses the same stats that the sysfs
* entries do, above, but makes them available through one seq_file.
*
* The output looks suspiciously like /proc/partitions with a bunch of
* extra fields.
*/
static int diskstats_show(struct seq_file *seqf, void *v)
{
struct gendisk *gp = v;
struct disk_part_iter piter;
struct hd_struct *hd;
char buf[BDEVNAME_SIZE];
int cpu;
/*
if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
seq_puts(seqf, "major minor name"
" rio rmerge rsect ruse wio wmerge "
"wsect wuse running use aveq"
"\n\n");
*/
disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
while ((hd = disk_part_iter_next(&piter))) {
cpu = part_stat_lock();
part_round_stats(cpu, hd);
part_stat_unlock();
seq_printf(seqf, "%4d %7d %s %lu %lu %lu "
"%u %lu %lu %lu %u %u %u %u\n",
MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
disk_name(gp, hd->partno, buf),
part_stat_read(hd, ios[READ]),
part_stat_read(hd, merges[READ]),
part_stat_read(hd, sectors[READ]),
jiffies_to_msecs(part_stat_read(hd, ticks[READ])),
part_stat_read(hd, ios[WRITE]),
part_stat_read(hd, merges[WRITE]),
part_stat_read(hd, sectors[WRITE]),
jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])),
part_in_flight(hd),
jiffies_to_msecs(part_stat_read(hd, io_ticks)),
jiffies_to_msecs(part_stat_read(hd, time_in_queue))
);
}
disk_part_iter_exit(&piter);
return 0;
}
static const struct seq_operations diskstats_op = {
.start = disk_seqf_start,
.next = disk_seqf_next,
.stop = disk_seqf_stop,
.show = diskstats_show
};
static int diskstats_open(struct inode *inode, struct file *file)
{
return seq_open(file, &diskstats_op);
}
static const struct file_operations proc_diskstats_operations = {
.open = diskstats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init proc_genhd_init(void)
{
proc_create("diskstats", 0, NULL, &proc_diskstats_operations);
proc_create("partitions", 0, NULL, &proc_partitions_operations);
return 0;
}
module_init(proc_genhd_init);
#endif /* CONFIG_PROC_FS */
dev_t blk_lookup_devt(const char *name, int partno)
{
dev_t devt = MKDEV(0, 0);
struct class_dev_iter iter;
struct device *dev;
class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
while ((dev = class_dev_iter_next(&iter))) {
struct gendisk *disk = dev_to_disk(dev);
struct hd_struct *part;
if (strcmp(dev_name(dev), name))
continue;
if (partno < disk->minors) {
/* We need to return the right devno, even
* if the partition doesn't exist yet.
*/
devt = MKDEV(MAJOR(dev->devt),
MINOR(dev->devt) + partno);
break;
}
part = disk_get_part(disk, partno);
if (part) {
devt = part_devt(part);
disk_put_part(part);
break;
}
disk_put_part(part);
}
class_dev_iter_exit(&iter);
return devt;
}
EXPORT_SYMBOL(blk_lookup_devt);
struct gendisk *alloc_disk(int minors)
{
return alloc_disk_node(minors, NUMA_NO_NODE);
}
EXPORT_SYMBOL(alloc_disk);
struct gendisk *alloc_disk_node(int minors, int node_id)
{
struct gendisk *disk;
disk = kmalloc_node(sizeof(struct gendisk),
GFP_KERNEL | __GFP_ZERO, node_id);
if (disk) {
if (!init_part_stats(&disk->part0)) {
kfree(disk);
return NULL;
}
disk->node_id = node_id;
if (disk_expand_part_tbl(disk, 0)) {
free_part_stats(&disk->part0);
kfree(disk);
return NULL;
}
disk->part_tbl->part[0] = &disk->part0;
/*
* set_capacity() and get_capacity() currently don't use
* seqcounter to read/update the part0->nr_sects. Still init
* the counter as we can read the sectors in IO submission
* patch using seqence counters.
*
* TODO: Ideally set_capacity() and get_capacity() should be
* converted to make use of bd_mutex and sequence counters.
*/
seqcount_init(&disk->part0.nr_sects_seq);
hd_ref_init(&disk->part0);
disk->minors = minors;
rand_initialize_disk(disk);
disk_to_dev(disk)->class = &block_class;
disk_to_dev(disk)->type = &disk_type;
device_initialize(disk_to_dev(disk));
}
return disk;
}
EXPORT_SYMBOL(alloc_disk_node);
struct kobject *get_disk(struct gendisk *disk)
{
struct module *owner;
struct kobject *kobj;
if (!disk->fops)
return NULL;
owner = disk->fops->owner;
if (owner && !try_module_get(owner))
return NULL;
kobj = kobject_get(&disk_to_dev(disk)->kobj);
if (kobj == NULL) {
module_put(owner);
return NULL;
}
return kobj;
}
EXPORT_SYMBOL(get_disk);
void put_disk(struct gendisk *disk)
{
if (disk)
kobject_put(&disk_to_dev(disk)->kobj);
}
EXPORT_SYMBOL(put_disk);
static void set_disk_ro_uevent(struct gendisk *gd, int ro)
{
char event[] = "DISK_RO=1";
char *envp[] = { event, NULL };
if (!ro)
event[8] = '0';
kobject_uevent_env(&disk_to_dev(gd)->kobj, KOBJ_CHANGE, envp);
}
void set_device_ro(struct block_device *bdev, int flag)
{
bdev->bd_part->policy = flag;
}
EXPORT_SYMBOL(set_device_ro);
void set_disk_ro(struct gendisk *disk, int flag)
{
struct disk_part_iter piter;
struct hd_struct *part;
if (disk->part0.policy != flag) {
set_disk_ro_uevent(disk, flag);
disk->part0.policy = flag;
}
disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
while ((part = disk_part_iter_next(&piter)))
part->policy = flag;
disk_part_iter_exit(&piter);
}
EXPORT_SYMBOL(set_disk_ro);
int bdev_read_only(struct block_device *bdev)
{
if (!bdev)
return 0;
return bdev->bd_part->policy;
}
EXPORT_SYMBOL(bdev_read_only);
int invalidate_partition(struct gendisk *disk, int partno)
{
int res = 0;
struct block_device *bdev = bdget_disk(disk, partno);
if (bdev) {
fsync_bdev(bdev);
Fix over-zealous flush_disk when changing device size. There are two cases when we call flush_disk. In one, the device has disappeared (check_disk_change) so any data will hold becomes irrelevant. In the oter, the device has changed size (check_disk_size_change) so data we hold may be irrelevant. In both cases it makes sense to discard any 'clean' buffers, so they will be read back from the device if needed. In the former case it makes sense to discard 'dirty' buffers as there will never be anywhere safe to write the data. In the second case it *does*not* make sense to discard dirty buffers as that will lead to file system corruption when you simply enlarge the containing devices. flush_disk calls __invalidate_devices. __invalidate_device calls both invalidate_inodes and invalidate_bdev. invalidate_inodes *does* discard I_DIRTY inodes and this does lead to fs corruption. invalidate_bev *does*not* discard dirty pages, but I don't really care about that at present. So this patch adds a flag to __invalidate_device (calling it __invalidate_device2) to indicate whether dirty buffers should be killed, and this is passed to invalidate_inodes which can choose to skip dirty inodes. flusk_disk then passes true from check_disk_change and false from check_disk_size_change. dm avoids tripping over this problem by calling i_size_write directly rathher than using check_disk_size_change. md does use check_disk_size_change and so is affected. This regression was introduced by commit 608aeef17a which causes check_disk_size_change to call flush_disk, so it is suitable for any kernel since 2.6.27. Cc: stable@kernel.org Acked-by: Jeff Moyer <jmoyer@redhat.com> Cc: Andrew Patterson <andrew.patterson@hp.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: NeilBrown <neilb@suse.de>
2011-02-24 09:25:47 +03:00
res = __invalidate_device(bdev, true);
bdput(bdev);
}
return res;
}
EXPORT_SYMBOL(invalidate_partition);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
/*
* Disk events - monitor disk events like media change and eject request.
*/
struct disk_events {
struct list_head node; /* all disk_event's */
struct gendisk *disk; /* the associated disk */
spinlock_t lock;
struct mutex block_mutex; /* protects blocking */
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
int block; /* event blocking depth */
unsigned int pending; /* events already sent out */
unsigned int clearing; /* events being cleared */
long poll_msecs; /* interval, -1 for default */
struct delayed_work dwork;
};
static const char *disk_events_strs[] = {
[ilog2(DISK_EVENT_MEDIA_CHANGE)] = "media_change",
[ilog2(DISK_EVENT_EJECT_REQUEST)] = "eject_request",
};
static char *disk_uevents[] = {
[ilog2(DISK_EVENT_MEDIA_CHANGE)] = "DISK_MEDIA_CHANGE=1",
[ilog2(DISK_EVENT_EJECT_REQUEST)] = "DISK_EJECT_REQUEST=1",
};
/* list of all disk_events */
static DEFINE_MUTEX(disk_events_mutex);
static LIST_HEAD(disk_events);
/* disable in-kernel polling by default */
static unsigned long disk_events_dfl_poll_msecs = 0;
static unsigned long disk_events_poll_jiffies(struct gendisk *disk)
{
struct disk_events *ev = disk->ev;
long intv_msecs = 0;
/*
* If device-specific poll interval is set, always use it. If
* the default is being used, poll iff there are events which
* can't be monitored asynchronously.
*/
if (ev->poll_msecs >= 0)
intv_msecs = ev->poll_msecs;
else if (disk->events & ~disk->async_events)
intv_msecs = disk_events_dfl_poll_msecs;
return msecs_to_jiffies(intv_msecs);
}
/**
* disk_block_events - block and flush disk event checking
* @disk: disk to block events for
*
* On return from this function, it is guaranteed that event checking
* isn't in progress and won't happen until unblocked by
* disk_unblock_events(). Events blocking is counted and the actual
* unblocking happens after the matching number of unblocks are done.
*
* Note that this intentionally does not block event checking from
* disk_clear_events().
*
* CONTEXT:
* Might sleep.
*/
void disk_block_events(struct gendisk *disk)
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
{
struct disk_events *ev = disk->ev;
unsigned long flags;
bool cancel;
if (!ev)
return;
/*
* Outer mutex ensures that the first blocker completes canceling
* the event work before further blockers are allowed to finish.
*/
mutex_lock(&ev->block_mutex);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
spin_lock_irqsave(&ev->lock, flags);
cancel = !ev->block++;
spin_unlock_irqrestore(&ev->lock, flags);
if (cancel)
cancel_delayed_work_sync(&disk->ev->dwork);
mutex_unlock(&ev->block_mutex);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
}
static void __disk_unblock_events(struct gendisk *disk, bool check_now)
{
struct disk_events *ev = disk->ev;
unsigned long intv;
unsigned long flags;
spin_lock_irqsave(&ev->lock, flags);
if (WARN_ON_ONCE(ev->block <= 0))
goto out_unlock;
if (--ev->block)
goto out_unlock;
/*
* Not exactly a latency critical operation, set poll timer
* slack to 25% and kick event check.
*/
intv = disk_events_poll_jiffies(disk);
set_timer_slack(&ev->dwork.timer, intv / 4);
if (check_now)
queue_delayed_work(system_freezable_wq, &ev->dwork, 0);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
else if (intv)
queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
out_unlock:
spin_unlock_irqrestore(&ev->lock, flags);
}
/**
* disk_unblock_events - unblock disk event checking
* @disk: disk to unblock events for
*
* Undo disk_block_events(). When the block count reaches zero, it
* starts events polling if configured.
*
* CONTEXT:
* Don't care. Safe to call from irq context.
*/
void disk_unblock_events(struct gendisk *disk)
{
if (disk->ev)
__disk_unblock_events(disk, false);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
}
/**
2011-07-01 18:17:47 +04:00
* disk_flush_events - schedule immediate event checking and flushing
* @disk: disk to check and flush events for
* @mask: events to flush
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
*
2011-07-01 18:17:47 +04:00
* Schedule immediate event checking on @disk if not blocked. Events in
* @mask are scheduled to be cleared from the driver. Note that this
* doesn't clear the events from @disk->ev.
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
*
* CONTEXT:
2011-07-01 18:17:47 +04:00
* If @mask is non-zero must be called with bdev->bd_mutex held.
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
*/
2011-07-01 18:17:47 +04:00
void disk_flush_events(struct gendisk *disk, unsigned int mask)
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
{
block: don't use non-syncing event blocking in disk_check_events() This patch is part of fix for triggering of WARN_ON_ONCE() in disk_clear_events() reported in bug#34662. https://bugzilla.kernel.org/show_bug.cgi?id=34662 disk_clear_events() blocks events, schedules and flushes the event work. It expects the work to have started execution on schedule and finished on return from flush. WARN_ON_ONCE() triggers if the event work hasn't executed as expected. This problem happens because __disk_block_events() fails to guarantee that the event work item is not in flight on return from the function in race-free manner. The problem is two-fold and this patch addresses one of them. When __disk_block_events() is called with @sync == %false, it bumps event block count, calls cancel_delayed_work() and return. This makes it impossible to guarantee that event polling is not in flight on return from syncing __disk_block_events() - if the first blocker was non-syncing, polling could still be in progress and later syncing ones would assume that the first blocker already canceled it. Making __disk_block_events() cancel_sync regardless of block count isn't feasible either as it may race with forced event checking in disk_clear_events(). As disk_check_events() is the only user of non-syncing __disk_block_events(), updating it to directly cancel and schedule event work is the easiest way to solve the issue. Note that there's another bug in __disk_block_events() and this patch doesn't fix the issue completely. Later patch will fix the other bug. Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com> Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com> Reported-by: Borislav Petkov <bp@alien8.de> Reported-by: Meelis Roos <mroos@linux.ee> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-06-09 22:43:54 +04:00
struct disk_events *ev = disk->ev;
if (!ev)
return;
2011-07-01 18:17:47 +04:00
spin_lock_irq(&ev->lock);
ev->clearing |= mask;
workqueue: use mod_delayed_work() instead of cancel + queue Convert delayed_work users doing cancel_delayed_work() followed by queue_delayed_work() to mod_delayed_work(). Most conversions are straight-forward. Ones worth mentioning are, * drivers/edac/edac_mc.c: edac_mc_workq_setup() converted to always use mod_delayed_work() and cancel loop in edac_mc_reset_delay_period() is dropped. * drivers/platform/x86/thinkpad_acpi.c: No need to remember whether watchdog is active or not. @fan_watchdog_active and related code dropped. * drivers/power/charger-manager.c: Seemingly a lot of delayed_work_pending() abuse going on here. [delayed_]work_pending() are unsynchronized and racy when used like this. I converted one instance in fullbatt_handler(). Please conver the rest so that it invokes workqueue APIs for the intended target state rather than trying to game work item pending state transitions. e.g. if timer should be modified - call mod_delayed_work(), canceled - call cancel_delayed_work[_sync](). * drivers/thermal/thermal_sys.c: thermal_zone_device_set_polling() simplified. Note that round_jiffies() calls in this function are meaningless. round_jiffies() work on absolute jiffies not delta delay used by delayed_work. v2: Tomi pointed out that __cancel_delayed_work() users can't be safely converted to mod_delayed_work(). They could be calling it from irq context and if that happens while delayed_work_timer_fn() is running, it could deadlock. __cancel_delayed_work() users are dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Acked-by: Anton Vorontsov <cbouatmailru@gmail.com> Acked-by: David Howells <dhowells@redhat.com> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Doug Thompson <dougthompson@xmission.com> Cc: David Airlie <airlied@linux.ie> Cc: Roland Dreier <roland@kernel.org> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Len Brown <len.brown@intel.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Johannes Berg <johannes@sipsolutions.net>
2012-08-03 21:30:47 +04:00
if (!ev->block)
mod_delayed_work(system_freezable_wq, &ev->dwork, 0);
2011-07-01 18:17:47 +04:00
spin_unlock_irq(&ev->lock);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
}
/**
* disk_clear_events - synchronously check, clear and return pending events
* @disk: disk to fetch and clear events from
* @mask: mask of events to be fetched and clearted
*
* Disk events are synchronously checked and pending events in @mask
* are cleared and returned. This ignores the block count.
*
* CONTEXT:
* Might sleep.
*/
unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
{
const struct block_device_operations *bdops = disk->fops;
struct disk_events *ev = disk->ev;
unsigned int pending;
if (!ev) {
/* for drivers still using the old ->media_changed method */
if ((mask & DISK_EVENT_MEDIA_CHANGE) &&
bdops->media_changed && bdops->media_changed(disk))
return DISK_EVENT_MEDIA_CHANGE;
return 0;
}
/* tell the workfn about the events being cleared */
spin_lock_irq(&ev->lock);
ev->clearing |= mask;
spin_unlock_irq(&ev->lock);
/* uncondtionally schedule event check and wait for it to finish */
disk_block_events(disk);
/*
* We need to put the work on system_nrt_wq here since there is a
* deadlock that happens while probing a usb device while suspending. If
* we put work on a freezable workqueue here, a usb probe will wait here
* until the workqueue is unfrozen during suspend. Since suspend waits
* on all probes to complete, we have a deadlock
*/
queue_delayed_work(system_nrt_wq, &ev->dwork, 0);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
flush_delayed_work(&ev->dwork);
__disk_unblock_events(disk, false);
/* then, fetch and clear pending events */
spin_lock_irq(&ev->lock);
WARN_ON_ONCE(ev->clearing & mask); /* cleared by workfn */
pending = ev->pending & mask;
ev->pending &= ~mask;
spin_unlock_irq(&ev->lock);
return pending;
}
static void disk_events_workfn(struct work_struct *work)
{
struct delayed_work *dwork = to_delayed_work(work);
struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
struct gendisk *disk = ev->disk;
char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
unsigned int clearing = ev->clearing;
unsigned int events;
unsigned long intv;
int nr_events = 0, i;
/* check events */
events = disk->fops->check_events(disk, clearing);
/* accumulate pending events and schedule next poll if necessary */
spin_lock_irq(&ev->lock);
events &= ~ev->pending;
ev->pending |= events;
ev->clearing &= ~clearing;
intv = disk_events_poll_jiffies(disk);
if (!ev->block && intv)
queue_delayed_work(system_freezable_wq, &ev->dwork, intv);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
spin_unlock_irq(&ev->lock);
/*
* Tell userland about new events. Only the events listed in
* @disk->events are reported. Unlisted events are processed the
* same internally but never get reported to userland.
*/
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
for (i = 0; i < ARRAY_SIZE(disk_uevents); i++)
if (events & disk->events & (1 << i))
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
envp[nr_events++] = disk_uevents[i];
if (nr_events)
kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
}
/*
* A disk events enabled device has the following sysfs nodes under
* its /sys/block/X/ directory.
*
* events : list of all supported events
* events_async : list of events which can be detected w/o polling
* events_poll_msecs : polling interval, 0: disable, -1: system default
*/
static ssize_t __disk_events_show(unsigned int events, char *buf)
{
const char *delim = "";
ssize_t pos = 0;
int i;
for (i = 0; i < ARRAY_SIZE(disk_events_strs); i++)
if (events & (1 << i)) {
pos += sprintf(buf + pos, "%s%s",
delim, disk_events_strs[i]);
delim = " ";
}
if (pos)
pos += sprintf(buf + pos, "\n");
return pos;
}
static ssize_t disk_events_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return __disk_events_show(disk->events, buf);
}
static ssize_t disk_events_async_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return __disk_events_show(disk->async_events, buf);
}
static ssize_t disk_events_poll_msecs_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%ld\n", disk->ev->poll_msecs);
}
static ssize_t disk_events_poll_msecs_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct gendisk *disk = dev_to_disk(dev);
long intv;
if (!count || !sscanf(buf, "%ld", &intv))
return -EINVAL;
if (intv < 0 && intv != -1)
return -EINVAL;
disk_block_events(disk);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
disk->ev->poll_msecs = intv;
__disk_unblock_events(disk, true);
return count;
}
static const DEVICE_ATTR(events, S_IRUGO, disk_events_show, NULL);
static const DEVICE_ATTR(events_async, S_IRUGO, disk_events_async_show, NULL);
static const DEVICE_ATTR(events_poll_msecs, S_IRUGO|S_IWUSR,
disk_events_poll_msecs_show,
disk_events_poll_msecs_store);
static const struct attribute *disk_events_attrs[] = {
&dev_attr_events.attr,
&dev_attr_events_async.attr,
&dev_attr_events_poll_msecs.attr,
NULL,
};
/*
* The default polling interval can be specified by the kernel
* parameter block.events_dfl_poll_msecs which defaults to 0
* (disable). This can also be modified runtime by writing to
* /sys/module/block/events_dfl_poll_msecs.
*/
static int disk_events_set_dfl_poll_msecs(const char *val,
const struct kernel_param *kp)
{
struct disk_events *ev;
int ret;
ret = param_set_ulong(val, kp);
if (ret < 0)
return ret;
mutex_lock(&disk_events_mutex);
list_for_each_entry(ev, &disk_events, node)
2011-07-01 18:17:47 +04:00
disk_flush_events(ev->disk, 0);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
mutex_unlock(&disk_events_mutex);
return 0;
}
static const struct kernel_param_ops disk_events_dfl_poll_msecs_param_ops = {
.set = disk_events_set_dfl_poll_msecs,
.get = param_get_ulong,
};
#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "block."
module_param_cb(events_dfl_poll_msecs, &disk_events_dfl_poll_msecs_param_ops,
&disk_events_dfl_poll_msecs, 0644);
/*
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
* disk_{alloc|add|del|release}_events - initialize and destroy disk_events.
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
*/
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
static void disk_alloc_events(struct gendisk *disk)
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
{
struct disk_events *ev;
if (!disk->fops->check_events)
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
return;
ev = kzalloc(sizeof(*ev), GFP_KERNEL);
if (!ev) {
pr_warn("%s: failed to initialize events\n", disk->disk_name);
return;
}
INIT_LIST_HEAD(&ev->node);
ev->disk = disk;
spin_lock_init(&ev->lock);
mutex_init(&ev->block_mutex);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
ev->block = 1;
ev->poll_msecs = -1;
INIT_DELAYED_WORK(&ev->dwork, disk_events_workfn);
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
disk->ev = ev;
}
static void disk_add_events(struct gendisk *disk)
{
if (!disk->ev)
return;
/* FIXME: error handling */
if (sysfs_create_files(&disk_to_dev(disk)->kobj, disk_events_attrs) < 0)
pr_warn("%s: failed to create sysfs files for events\n",
disk->disk_name);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
mutex_lock(&disk_events_mutex);
block: fix __blkdev_get and add_disk race condition The following situation might occur: __blkdev_get: add_disk: register_disk() get_gendisk() disk_block_events() disk->ev == NULL disk_add_events() __disk_unblock_events() disk->ev != NULL --ev->block Then we unblock events, when they are suppose to be blocked. This can trigger events related block/genhd.c warnings, but also can crash in sd_check_events() or other places. I'm able to reproduce crashes with the following scripts (with connected usb dongle as sdb disk). <snip> DEV=/dev/sdb ENABLE=/sys/bus/usb/devices/1-2/bConfigurationValue function stop_me() { for i in `jobs -p` ; do kill $i 2> /dev/null ; done exit } trap stop_me SIGHUP SIGINT SIGTERM for ((i = 0; i < 10; i++)) ; do while true; do fdisk -l $DEV 2>&1 > /dev/null ; done & done while true ; do echo 1 > $ENABLE sleep 1 echo 0 > $ENABLE done </snip> I use the script to verify patch fixing oops in sd_revalidate_disk http://marc.info/?l=linux-scsi&m=132935572512352&w=2 Without Jun'ichi Nomura patch titled "Fix NULL pointer dereference in sd_revalidate_disk" or this one, script easily crash kernel within a few seconds. With both patches applied I do not observe crash. Unfortunately after some time (dozen of minutes), script will hung in: [ 1563.906432] [<c08354f5>] schedule_timeout_uninterruptible+0x15/0x20 [ 1563.906437] [<c04532d5>] msleep+0x15/0x20 [ 1563.906443] [<c05d60b2>] blk_drain_queue+0x32/0xd0 [ 1563.906447] [<c05d6e00>] blk_cleanup_queue+0xd0/0x170 [ 1563.906454] [<c06d278f>] scsi_free_queue+0x3f/0x60 [ 1563.906459] [<c06d7e6e>] __scsi_remove_device+0x6e/0xb0 [ 1563.906463] [<c06d4aff>] scsi_forget_host+0x4f/0x60 [ 1563.906468] [<c06cd84a>] scsi_remove_host+0x5a/0xf0 [ 1563.906482] [<f7f030fb>] quiesce_and_remove_host+0x5b/0xa0 [usb_storage] [ 1563.906490] [<f7f03203>] usb_stor_disconnect+0x13/0x20 [usb_storage] Anyway I think this patch is some step forward. As drawback, I do not teardown on sysfs file create error, because I do not know how to nullify disk->ev (since it can be used). However add_disk error handling practically does not exist too, and things will work without this sysfs file, except events will not be exported to user space. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-02 13:43:28 +04:00
list_add_tail(&disk->ev->node, &disk_events);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
mutex_unlock(&disk_events_mutex);
/*
* Block count is initialized to 1 and the following initial
* unblock kicks it into action.
*/
__disk_unblock_events(disk, true);
}
static void disk_del_events(struct gendisk *disk)
{
if (!disk->ev)
return;
disk_block_events(disk);
implement in-kernel gendisk events handling Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 22:57:37 +03:00
mutex_lock(&disk_events_mutex);
list_del_init(&disk->ev->node);
mutex_unlock(&disk_events_mutex);
sysfs_remove_files(&disk_to_dev(disk)->kobj, disk_events_attrs);
}
static void disk_release_events(struct gendisk *disk)
{
/* the block count should be 1 from disk_del_events() */
WARN_ON_ONCE(disk->ev && disk->ev->block != 1);
kfree(disk->ev);
}