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Revert "loop: Get rid of loop_index_mutex"

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This reverts commit 6a8f1d8d701462937ce01a3f2219af5435372af7 which is
commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

It does not work properly in the 4.9.y tree and causes more problems
than it fixes, so revert it.

Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Reported-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2019-02-27 15:00:55 +01:00
parent 86af0f992e
commit c6ae51ad49
1 changed files with 19 additions and 20 deletions
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39
drivers/block/loop.c
View File

@ -81,6 +81,7 @@
#include <asm/uaccess.h>
static DEFINE_IDR(loop_index_idr);
static DEFINE_MUTEX(loop_index_mutex);
static DEFINE_MUTEX(loop_ctl_mutex);
static int max_part;
@ -1559,11 +1560,9 @@ static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
static int lo_open(struct block_device *bdev, fmode_t mode)
{
struct loop_device *lo;
int err;
int err = 0;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
return err;
mutex_lock(&loop_index_mutex);
lo = bdev->bd_disk->private_data;
if (!lo) {
err = -ENXIO;
@ -1572,7 +1571,7 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
atomic_inc(&lo->lo_refcnt);
out:
mutex_unlock(&loop_ctl_mutex);
mutex_unlock(&loop_index_mutex);
return err;
}
@ -1581,11 +1580,12 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
struct loop_device *lo;
int err;
mutex_lock(&loop_ctl_mutex);
mutex_lock(&loop_index_mutex);
lo = disk->private_data;
if (atomic_dec_return(&lo->lo_refcnt))
goto out_unlock;
goto unlock_index;
mutex_lock(&loop_ctl_mutex);
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
/*
* In autoclear mode, stop the loop thread
@ -1593,7 +1593,7 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
*/
err = loop_clr_fd(lo);
if (!err)
return;
goto unlock_index;
} else {
/*
* Otherwise keep thread (if running) and config,
@ -1602,8 +1602,9 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
loop_flush(lo);
}
out_unlock:
mutex_unlock(&loop_ctl_mutex);
unlock_index:
mutex_unlock(&loop_index_mutex);
}
static const struct block_device_operations lo_fops = {
@ -1889,7 +1890,7 @@ static struct kobject *loop_probe(dev_t dev, int *part, void *data)
struct kobject *kobj;
int err;
mutex_lock(&loop_ctl_mutex);
mutex_lock(&loop_index_mutex);
err = loop_lookup(&lo, MINOR(dev) >> part_shift);
if (err < 0)
err = loop_add(&lo, MINOR(dev) >> part_shift);
@ -1897,7 +1898,7 @@ static struct kobject *loop_probe(dev_t dev, int *part, void *data)
kobj = NULL;
else
kobj = get_disk(lo->lo_disk);
mutex_unlock(&loop_ctl_mutex);
mutex_unlock(&loop_index_mutex);
*part = 0;
return kobj;
@ -1907,13 +1908,9 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
unsigned long parm)
{
struct loop_device *lo;
int ret;
int ret = -ENOSYS;
ret = mutex_lock_killable(&loop_ctl_mutex);
if (ret)
return ret;
ret = -ENOSYS;
mutex_lock(&loop_index_mutex);
switch (cmd) {
case LOOP_CTL_ADD:
ret = loop_lookup(&lo, parm);
@ -1927,6 +1924,7 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
ret = loop_lookup(&lo, parm);
if (ret < 0)
break;
mutex_lock(&loop_ctl_mutex);
if (lo->lo_state != Lo_unbound) {
ret = -EBUSY;
mutex_unlock(&loop_ctl_mutex);
@ -1938,6 +1936,7 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
break;
}
lo->lo_disk->private_data = NULL;
mutex_unlock(&loop_ctl_mutex);
idr_remove(&loop_index_idr, lo->lo_number);
loop_remove(lo);
break;
@ -1947,7 +1946,7 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
break;
ret = loop_add(&lo, -1);
}
mutex_unlock(&loop_ctl_mutex);
mutex_unlock(&loop_index_mutex);
return ret;
}
@ -2030,10 +2029,10 @@ static int __init loop_init(void)
THIS_MODULE, loop_probe, NULL, NULL);
/* pre-create number of devices given by config or max_loop */
mutex_lock(&loop_ctl_mutex);
mutex_lock(&loop_index_mutex);
for (i = 0; i < nr; i++)
loop_add(&lo, i);
mutex_unlock(&loop_ctl_mutex);
mutex_unlock(&loop_index_mutex);
printk(KERN_INFO "loop: module loaded\n");
return 0;