This is a note to let you know that I've just added the patch titled
dm: dont take i_mutex to change device size
to the 2.6.37-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-dont-take-i_mutex-to-change-device-size.patch
and it can be found in the queue-2.6.37 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From c217649bf2d60ac119afd71d938278cffd55962b Mon Sep 17 00:00:00 2001
From: Mike Snitzer <[email protected]>
Date: Thu, 13 Jan 2011 19:53:46 +0000
Subject: dm: dont take i_mutex to change device size
From: Mike Snitzer <[email protected]>
commit c217649bf2d60ac119afd71d938278cffd55962b upstream.
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 <[email protected]>
Signed-off-by: Mikulas Patocka <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/md/dm.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- 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);
}
/*
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.37/dm-mpath-disable-blk_abort_queue.patch
queue-2.6.37/dm-dont-take-i_mutex-to-change-device-size.patch
_______________________________________________
stable mailing list
[email protected]
http://linux.kernel.org/mailman/listinfo/stable
