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lvm2/driver/device-mapper/dm.c
2001-09-27 10:15:02 +00:00

921 lines
17 KiB
C

/*
* device-mapper.c
*
* Copyright (C) 2001 Sistina Software
*
* This software is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2, or (at
* your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Changelog
*
* 14/08/2001 - First Version [Joe Thornber]
*/
#include "dm.h"
/* defines for blk.h */
#define MAJOR_NR DM_BLK_MAJOR
#define DEVICE_NR(device) MINOR(device) /* has no partition bits */
#define DEVICE_NAME "device-mapper" /* name for messaging */
#define DEVICE_NO_RANDOM /* no entropy to contribute */
#define DEVICE_OFF(d) /* do-nothing */
#include <linux/blk.h>
#include <linux/blkpg.h>
/* we only need this for the lv_bmap struct definition, not happy */
#include <linux/lvm.h>
#define MAX_DEVICES 64
#define DEFAULT_READ_AHEAD 64
const char *_name = "device-mapper";
int _version[3] = {0, 1, 0};
struct io_hook {
struct mapped_device *md;
struct target *target;
int rw;
void (*end_io)(struct buffer_head * bh, int uptodate);
void *context;
};
kmem_cache_t *_io_hook_cache;
#define rl down_read(&_dev_lock)
#define ru up_read(&_dev_lock)
#define wl down_write(&_dev_lock)
#define wu up_write(&_dev_lock)
struct rw_semaphore _dev_lock;
static struct mapped_device *_devs[MAX_DEVICES];
/* block device arrays */
static int _block_size[MAX_DEVICES];
static int _blksize_size[MAX_DEVICES];
static int _hardsect_size[MAX_DEVICES];
const char *_fs_dir = "device-mapper";
static devfs_handle_t _dev_dir;
static int request(request_queue_t *q, int rw, struct buffer_head *bh);
static int dm_user_bmap(struct inode *inode, struct lv_bmap *lvb);
/*
* setup and teardown the driver
*/
static int dm_init(void)
{
int ret;
init_rwsem(&_dev_lock);
if (!_io_hook_cache)
_io_hook_cache = kmem_cache_create("dm io hooks",
sizeof(struct io_hook),
0, 0, NULL, NULL);
if (!_io_hook_cache)
return -ENOMEM;
if ((ret = dm_fs_init()) || (ret = dm_target_init()))
return ret;
/* set up the arrays */
read_ahead[MAJOR_NR] = DEFAULT_READ_AHEAD;
blk_size[MAJOR_NR] = _block_size;
blksize_size[MAJOR_NR] = _blksize_size;
hardsect_size[MAJOR_NR] = _hardsect_size;
if (devfs_register_blkdev(MAJOR_NR, _name, &dm_blk_dops) < 0) {
printk(KERN_ERR "%s -- register_blkdev failed\n", _name);
return -EIO;
}
blk_queue_make_request(BLK_DEFAULT_QUEUE(MAJOR_NR), request);
_dev_dir = devfs_mk_dir(0, _fs_dir, NULL);
printk(KERN_INFO "%s %d.%d.%d initialised\n", _name,
_version[0], _version[1], _version[2]);
return 0;
}
static void dm_exit(void)
{
if (kmem_cache_destroy(_io_hook_cache))
WARN("it looks like there are still some io_hooks allocated");
_io_hook_cache = 0;
dm_fs_exit();
if (devfs_unregister_blkdev(MAJOR_NR, _name) < 0)
printk(KERN_ERR "%s -- unregister_blkdev failed\n", _name);
read_ahead[MAJOR_NR] = 0;
blk_size[MAJOR_NR] = 0;
blksize_size[MAJOR_NR] = 0;
hardsect_size[MAJOR_NR] = 0;
printk(KERN_INFO "%s %d.%d.%d cleaned up\n", _name,
_version[0], _version[1], _version[2]);
}
/*
* block device functions
*/
static int dm_blk_open(struct inode *inode, struct file *file)
{
int minor = MINOR(inode->i_rdev);
struct mapped_device *md;
if (minor >= MAX_DEVICES)
return -ENXIO;
wl;
md = _devs[minor];
if (!md || !is_active(md)) {
wu;
return -ENXIO;
}
md->use_count++;
wu;
MOD_INC_USE_COUNT;
return 0;
}
static int dm_blk_close(struct inode *inode, struct file *file)
{
int minor = MINOR(inode->i_rdev);
struct mapped_device *md;
if (minor >= MAX_DEVICES)
return -ENXIO;
wl;
md = _devs[minor];
if (!md || md->use_count < 1) {
WARN("reference count in mapped_device incorrect");
wu;
return -ENXIO;
}
md->use_count--;
wu;
MOD_DEC_USE_COUNT;
return 0;
}
/* In 512-byte units */
#define VOLUME_SIZE(minor) (_block_size[(minor)] >> 1)
static int dm_blk_ioctl(struct inode *inode, struct file *file,
uint command, ulong a)
{
int minor = MINOR(inode->i_rdev);
long size;
if (minor >= MAX_DEVICES)
return -ENXIO;
switch (command) {
case BLKSSZGET:
case BLKROGET:
case BLKROSET:
#if 0
case BLKELVSET:
case BLKELVGET:
#endif
return blk_ioctl(inode->i_dev, command, a);
break;
case BLKGETSIZE:
size = VOLUME_SIZE(minor);
if (copy_to_user((void *) a, &size, sizeof (long)))
return -EFAULT;
break;
case BLKFLSBUF:
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
fsync_dev(inode->i_rdev);
invalidate_buffers(inode->i_rdev);
return 0;
case BLKRAGET:
if (copy_to_user
((void *) a, &read_ahead[MAJOR(inode->i_rdev)],
sizeof (long)))
return -EFAULT;
return 0;
case BLKRASET:
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
read_ahead[MAJOR(inode->i_rdev)] = a;
return 0;
case BLKRRPART:
return -EINVAL;
case LV_BMAP:
return dm_user_bmap(inode, (struct lv_bmap *) a);
default:
WARN("unknown block ioctl %d", command);
return -EINVAL;
}
return 0;
}
static inline struct io_hook *alloc_io_hook(void)
{
return kmem_cache_alloc(_io_hook_cache, GFP_NOIO);
}
static inline void free_io_hook(struct io_hook *ih)
{
kmem_cache_free(_io_hook_cache, ih);
}
/*
* FIXME: need to decide if deferred_io's need
* their own slab, I say no for now since they are
* only used when the device is suspended.
*/
static inline struct deferred_io *alloc_deferred(void)
{
return kmalloc(sizeof(struct deferred_io), GFP_NOIO);
}
static inline void free_deferred(struct deferred_io *di)
{
kfree(di);
}
/*
* call a targets optional error function if
* an io failed.
*/
static inline int call_err_fn(struct io_hook *ih, struct buffer_head *bh)
{
dm_err_fn err = ih->target->type->err;
if (err)
return err(bh, ih->rw, ih->target->private);
return 0;
}
/*
* bh->b_end_io routine that decrements the
* pending count and then calls the original
* bh->b_end_io fn.
*/
static void dec_pending(struct buffer_head *bh, int uptodate)
{
struct io_hook *ih = bh->b_private;
if (!uptodate && call_err_fn(ih, bh))
return;
if (atomic_dec_and_test(&ih->md->pending))
/* nudge anyone waiting on suspend queue */
wake_up(&ih->md->wait);
bh->b_end_io = ih->end_io;
bh->b_private = ih->context;
free_io_hook(ih);
bh->b_end_io(bh, uptodate);
}
/*
* add the bh to the list of deferred io.
*/
static int queue_io(struct mapped_device *md, struct buffer_head *bh, int rw)
{
struct deferred_io *di = alloc_deferred();
if (!di)
return -ENOMEM;
wl;
if (test_bit(DM_ACTIVE, &md->state)) {
wu;
return 0;
}
di->bh = bh;
di->rw = rw;
di->next = md->deferred;
md->deferred = di;
wu;
return 1;
}
/*
* do the bh mapping for a given leaf
*/
static inline int __map_buffer(struct mapped_device *md,
struct buffer_head *bh, int rw, int leaf)
{
int r;
dm_map_fn fn;
void *context;
struct io_hook *ih = NULL;
struct target *ti = md->map->targets + leaf;
fn = ti->type->map;
context = ti->private;
ih = alloc_io_hook();
if (!ih)
return 0;
ih->md = md;
ih->rw = rw;
ih->target = ti;
ih->end_io = bh->b_end_io;
ih->context = bh->b_private;
r = fn(bh, rw, context);
if (r > 0) {
/* hook the end io request fn */
atomic_inc(&md->pending);
bh->b_end_io = dec_pending;
bh->b_private = ih;
} else if (r == 0)
/* we don't need to hook */
free_io_hook(ih);
else if (r < 0) {
free_io_hook(ih);
return 0;
}
return 1;
}
/*
* search the btree for the correct target.
*/
static inline int __find_node(struct dm_table *t, struct buffer_head *bh)
{
int l, n = 0, k = 0;
offset_t *node;
for (l = 0; l < t->depth; l++) {
n = get_child(n, k);
node = get_node(t, l, n);
for (k = 0; k < KEYS_PER_NODE; k++)
if (node[k] >= bh->b_rsector)
break;
}
return (KEYS_PER_NODE * n) + k;
}
static int request(request_queue_t *q, int rw, struct buffer_head *bh)
{
struct mapped_device *md;
int r, minor = MINOR(bh->b_rdev);
if (minor >= MAX_DEVICES)
goto bad_no_lock;
rl;
md = _devs[minor];
if (!md || !md->map)
goto bad;
/* if we're suspended we have to queue this io for later */
if (!test_bit(DM_ACTIVE, &md->state)) {
ru;
r = queue_io(md, bh, rw);
if (r < 0)
goto bad_no_lock;
else if (r > 0)
return 0; /* deferred successfully */
rl; /* FIXME: there's still a race here */
}
if (!__map_buffer(md, bh, rw, __find_node(md->map, bh)))
goto bad;
ru;
return 1;
bad:
ru;
bad_no_lock:
buffer_IO_error(bh);
return 0;
}
static int check_dev_size(int minor, unsigned long block)
{
/* FIXME: check this */
unsigned long max_sector = (_block_size[minor] << 1) + 1;
unsigned long sector = (block + 1) * (_blksize_size[minor] >> 9);
return (sector > max_sector) ? 0 : 1;
}
/*
* creates a dummy buffer head and maps it (for lilo).
*/
static int do_bmap(kdev_t dev, unsigned long block,
kdev_t *r_dev, unsigned long *r_block)
{
struct mapped_device *md;
struct buffer_head bh;
int minor = MINOR(dev), r;
struct target *t;
rl;
if ((minor >= MAX_DEVICES) || !(md = _devs[minor]) ||
!test_bit(DM_ACTIVE, &md->state)) {
r = -ENXIO;
goto out;
}
if (!check_dev_size(minor, block)) {
r = -EINVAL;
goto out;
}
/* setup dummy bh */
memset(&bh, 0, sizeof(bh));
bh.b_blocknr = block;
bh.b_dev = bh.b_rdev = dev;
bh.b_size = _blksize_size[minor];
bh.b_rsector = block * (bh.b_size >> 9);
/* find target */
t = md->map->targets + __find_node(md->map, &bh);
/* do the mapping */
r = t->type->map(&bh, READ, t->private);
*r_dev = bh.b_rdev;
*r_block = bh.b_rsector / (bh.b_size >> 9);
out:
ru;
return r;
}
/*
* marshals arguments and results between user and
* kernel space.
*/
static int dm_user_bmap(struct inode *inode, struct lv_bmap *lvb)
{
unsigned long block, r_block;
kdev_t r_dev;
int r;
if (get_user(block, &lvb->lv_block))
return -EFAULT;
if ((r = do_bmap(inode->i_rdev, block, &r_dev, &r_block)))
return r;
if (put_user(kdev_t_to_nr(r_dev), &lvb->lv_dev) ||
put_user(r_block, &lvb->lv_block))
return -EFAULT;
return 0;
}
/*
* see if the device with a specific minor # is
* free.
*/
static inline int __specific_dev(int minor)
{
if (minor > MAX_DEVICES) {
WARN("request for a mapped_device > than MAX_DEVICES");
return 0;
}
if (!_devs[minor])
return minor;
return -1;
}
/*
* find the first free device.
*/
static inline int __any_old_dev(void)
{
int i;
for (i = 0; i < MAX_DEVICES; i++)
if (!_devs[i])
return i;
return -1;
}
/*
* allocate and initialise a blank device.
*/
static struct mapped_device *alloc_dev(int minor)
{
struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
if (!md)
return 0;
memset(md, 0, sizeof (*md));
wl;
minor = (minor < 0) ? __any_old_dev() : __specific_dev(minor);
if (minor < 0) {
WARN("no free devices available");
wu;
kfree(md);
return 0;
}
md->dev = MKDEV(DM_BLK_MAJOR, minor);
md->name[0] = '\0';
md->state = 0;
init_waitqueue_head(&md->wait);
_devs[minor] = md;
wu;
return md;
}
/*
* open a device so we can use it as a map
* destination.
*/
static int open_dev(struct dm_dev *d)
{
int err;
if (d->bd)
BUG();
if (!(d->bd = bdget(kdev_t_to_nr(d->dev))))
return -ENOMEM;
if ((err = blkdev_get(d->bd, FMODE_READ|FMODE_WRITE, 0, BDEV_FILE))) {
bdput(d->bd);
return err;
}
return 0;
}
/*
* close a device that we've been using.
*/
static void close_dev(struct dm_dev *d)
{
if (!d->bd)
return;
blkdev_put(d->bd, BDEV_FILE);
bdput(d->bd);
d->bd = 0;
}
/*
* Close a list of devices.
*/
static void close_devices(struct list_head *devices)
{
struct list_head *tmp;
for (tmp = devices->next; tmp != devices; tmp = tmp->next) {
struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
close_dev(dd);
}
}
/*
* Open a list of devices.
*/
static int open_devices(struct list_head *devices)
{
int r = 0;
struct list_head *tmp;
for (tmp = devices->next; tmp != devices; tmp = tmp->next) {
struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
if ((r = open_dev(dd)))
goto bad;
}
return 0;
bad:
close_devices(devices);
return r;
}
struct mapped_device *dm_find_by_minor(int minor)
{
struct mapped_device *md;
rl;
md = _devs[minor];
ru;
return md;
}
static int register_device(struct mapped_device *md)
{
md->devfs_entry =
devfs_register(_dev_dir, md->name, DEVFS_FL_CURRENT_OWNER,
MAJOR(md->dev), MINOR(md->dev),
S_IFBLK | S_IRUSR | S_IWUSR | S_IRGRP,
&dm_blk_dops, NULL);
if (!md->devfs_entry)
return -ENOMEM;
return 0;
}
static int unregister_device(struct mapped_device *md)
{
devfs_unregister(md->devfs_entry);
return 0;
}
/*
* constructor for a new device
*/
struct mapped_device *dm_create(const char *name, int minor)
{
int r;
struct mapped_device *md;
if (minor >= MAX_DEVICES)
return ERR_PTR(-ENXIO);
if (!(md = alloc_dev(minor)))
return ERR_PTR(-ENXIO);
wl;
strcpy(md->name, name);
_devs[minor] = md;
if ((r = register_device(md))) {
wu;
return ERR_PTR(r);
}
wu;
return md;
}
/*
* destructor for the device. md->map is
* deliberately not destroyed, dm-fs should manage
* table objects.
*/
int dm_remove(struct mapped_device *md)
{
int minor, r;
wl;
if (md->use_count) {
wu;
return -EPERM;
}
if ((r = unregister_device(md))) {
wu;
return r;
}
minor = MINOR(md->dev);
_devs[minor] = 0;
wu;
kfree(md);
return 0;
}
/*
* the hardsect size for a mapped device is the
* smallest hard sect size from the devices it
* maps onto.
*/
static int __find_hardsect_size(struct list_head *devices)
{
int result = INT_MAX, size;
struct list_head *tmp;
for (tmp = devices->next; tmp != devices; tmp = tmp->next) {
struct dm_dev *dd = list_entry(tmp, struct dm_dev, list);
size = get_hardsect_size(dd->dev);
if (size < result)
result = size;
}
return result;
}
/*
* Bind a table to the device.
*/
void __bind(struct mapped_device *md, struct dm_table *t)
{
int minor = MINOR(md->dev);
md->map = t;
/* in k */
_block_size[minor] = (t->highs[t->num_targets - 1] + 1) >> 1;
_blksize_size[minor] = BLOCK_SIZE;
_hardsect_size[minor] = __find_hardsect_size(&t->devices);
register_disk(NULL, md->dev, 1, &dm_blk_dops, _block_size[minor]);
}
/*
* requeue the deferred buffer_heads by calling
* generic_make_request.
*/
static void __flush_deferred_io(struct mapped_device *md)
{
struct deferred_io *c, *n;
for (c = md->deferred, md->deferred = 0; c; c = n) {
n = c->next;
generic_make_request(c->rw, c->bh);
free_deferred(c);
}
}
/*
* make the device available for use, if was
* previously suspended rather than newly created
* then all queued io is flushed
*/
int dm_activate(struct mapped_device *md, struct dm_table *table)
{
int r;
/* check that the mapping has at least been loaded. */
if (!table->num_targets)
return -EINVAL;
wl;
/* you must be deactivated first */
if (is_active(md)) {
wu;
return -EPERM;
}
__bind(md, table);
if ((r = open_devices(&md->map->devices))) {
wu;
return r;
}
set_bit(DM_ACTIVE, &md->state);
__flush_deferred_io(md);
wu;
return 0;
}
/*
* Deactivate the device, the device must not be
* opened by anyone.
*/
int dm_deactivate(struct mapped_device *md)
{
rl;
if (md->use_count) {
ru;
return -EPERM;
}
fsync_dev(md->dev);
ru;
wl;
if (md->use_count) {
/* drat, somebody got in quick ... */
wu;
return -EPERM;
}
close_devices(&md->map->devices);
md->map = 0;
clear_bit(DM_ACTIVE, &md->state);
wu;
return 0;
}
/*
* We need to be able to change a mapping table
* under a mounted filesystem. for example we
* might want to move some data in the background.
* Before the table can be swapped with
* dm_bind_table, dm_suspend must be called to
* flush any in flight buffer_heads and ensure
* that any further io gets deferred.
*/
void dm_suspend(struct mapped_device *md)
{
DECLARE_WAITQUEUE(wait, current);
wl;
if (!is_active(md)) {
wu;
return;
}
clear_bit(DM_ACTIVE, &md->state);
wu;
/* wait for all the pending io to flush */
add_wait_queue(&md->wait, &wait);
current->state = TASK_UNINTERRUPTIBLE;
do {
wl;
if (!atomic_read(&md->pending))
break;
wu;
schedule();
} while (1);
current->state = TASK_RUNNING;
remove_wait_queue(&md->wait, &wait);
close_devices(&md->map->devices);
md->map = 0;
wu;
}
struct block_device_operations dm_blk_dops = {
open: dm_blk_open,
release: dm_blk_close,
ioctl: dm_blk_ioctl
};
/*
* module hooks
*/
module_init(dm_init);
module_exit(dm_exit);
MODULE_DESCRIPTION("device-mapper driver");
MODULE_AUTHOR("Joe Thornber <thornber@btconnect.com>");
/*
* Local variables:
* c-file-style: "linux"
* End:
*/