diff options
| author | Mike Snitzer <snitzer@redhat.com> | 2011-01-13 19:53:46 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2011-01-13 19:53:46 +0000 |
| commit | c217649bf2d60ac119afd71d938278cffd55962b (patch) | |
| tree | 5addf2130d59f9fab614d852ac8fe7724ef78c9f | |
| parent | 581548db3b3c0f6e25b500329eb02e3c72e7acbe (diff) | |
dm: dont take i_mutex to change device size
No longer needlessly hold md->bdev->bd_inode->i_mutex when changing the
size of a DM device. This additional locking is unnecessary because
i_size_write() is already protected by the existing critical section in
dm_swap_table(). DM already has a reference on md->bdev so the
associated bd_inode may be changed without lifetime concerns.
A negative side-effect of having held md->bdev->bd_inode->i_mutex was
that a concurrent DM device resize and flush (via fsync) would deadlock.
Dropping md->bdev->bd_inode->i_mutex eliminates this potential for
deadlock. The following reproducer no longer deadlocks:
https://www.redhat.com/archives/dm-devel/2009-July/msg00284.html
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: stable@kernel.org
| -rw-r--r-- | drivers/md/dm.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index f48a2f359ac..4ef066a3090 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1992,13 +1992,14 @@ static void event_callback(void *context) wake_up(&md->eventq); } +/* + * Protected by md->suspend_lock obtained by dm_swap_table(). + */ static void __set_size(struct mapped_device *md, sector_t size) { set_capacity(md->disk, size); - mutex_lock(&md->bdev->bd_inode->i_mutex); i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT); - mutex_unlock(&md->bdev->bd_inode->i_mutex); } /* |