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[PATCH] dm: add DMF_FREEING 

There is a chicken and egg problem between the block layer and dm in which the
gendisk associated with a mapping keeps a reference-less pointer to the
mapped_device.

This patch uses a new flag DMF_FREEING to indicate when the mapped_device is
no longer valid.  This is checked to prevent any attempt to open the device
from succeeding while the device is being destroyed.

[akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled]

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
hifive-unleashed-5.1
Jeff Mahoney 2006-06-26 00:27:23 -07:00 committed by Linus Torvalds
parent f32c10b099
commit fba9f90e56
1 changed files with 30 additions and 2 deletions
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32
drivers/md/dm.c
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@ -63,6 +63,7 @@ union map_info *dm_get_mapinfo(struct bio *bio)
#define DMF_BLOCK_IO 0
#define DMF_SUSPENDED 1
#define DMF_FROZEN 2
#define DMF_FREEING 3
struct mapped_device {
struct rw_semaphore io_lock;
@ -221,9 +222,23 @@ static int dm_blk_open(struct inode *inode, struct file *file)
{
struct mapped_device *md;
spin_lock(&_minor_lock);
md = inode->i_bdev->bd_disk->private_data;
if (!md)
goto out;
if (test_bit(DMF_FREEING, &md->flags)) {
md = NULL;
goto out;
}
dm_get(md);
return 0;
out:
spin_unlock(&_minor_lock);
return md ? 0 : -ENXIO;
}
static int dm_blk_close(struct inode *inode, struct file *file)
@ -919,6 +934,11 @@ static void free_dev(struct mapped_device *md)
mempool_destroy(md->io_pool);
del_gendisk(md->disk);
free_minor(minor);
spin_lock(&_minor_lock);
md->disk->private_data = NULL;
spin_unlock(&_minor_lock);
put_disk(md->disk);
blk_cleanup_queue(md->queue);
kfree(md);
@ -1023,9 +1043,14 @@ static struct mapped_device *dm_find_md(dev_t dev)
spin_lock(&_minor_lock);
md = idr_find(&_minor_idr, minor);
if (md && (md == MINOR_ALLOCED || (dm_disk(md)->first_minor != minor)))
if (md && (md == MINOR_ALLOCED ||
(dm_disk(md)->first_minor != minor) ||
test_bit(DMF_FREEING, &md->flags))) {
md = NULL;
goto out;
}
out:
spin_unlock(&_minor_lock);
return md;
@ -1060,9 +1085,12 @@ void dm_put(struct mapped_device *md)
{
struct dm_table *map;
BUG_ON(test_bit(DMF_FREEING, &md->flags));
if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
map = dm_get_table(md);
idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);
if (!dm_suspended(md)) {
dm_table_presuspend_targets(map);