[dm-devel] [PATCH] ext4: fix freeze deadlock under IO

Ted Ts'o tytso at mit.edu
Sun Aug 1 21:41:32 UTC 2010


On Wed, Jun 23, 2010 at 02:37:27PM -0500, Eric Sandeen wrote:
> Commit 6b0310fbf087ad6 caused a regression resulting in deadlocks
> when freezing a filesystem which had active IO; the vfs_check_frozen
> level (SB_FREEZE_WRITE) did not let the freeze-related IO syncing
> through.  Duh.
> 
> Changing the test to FREEZE_TRANS should let the normal freeze
> syncing get through the fs, but still block any transactions from
> starting once the fs is completely frozen.
> 
> I tested this by running fsstress in the background while periodically
> snapshotting the fs and running fsck on the result.  I ran into
> occasional deadlocks, but different ones.  I think this is a
> fine fix for the problem at hand, and the other deadlocky things
> will need more investigation.
> 
> Reported-by: Phillip Susi <psusi at cfl.rr.com>
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>

Applied to the ext4 patch queue.  Sorry for missing this earier.

	       	    	  	  	    - Ted




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