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authorMike Snitzer <snitzer@redhat.com>2011-01-13 19:53:46 +0000
committerAlasdair G Kergon <agk@redhat.com>2011-01-13 19:53:46 +0000
commitc217649bf2d60ac119afd71d938278cffd55962b (patch)
tree5addf2130d59f9fab614d852ac8fe7724ef78c9f /drivers/md
parent581548db3b3c0f6e25b500329eb02e3c72e7acbe (diff)
downloadop-kernel-dev-c217649bf2d60ac119afd71d938278cffd55962b.zip
op-kernel-dev-c217649bf2d60ac119afd71d938278cffd55962b.tar.gz
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
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f48a2f3..4ef066a 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);
}
/*
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