On Fri, May 15, 2009 at 07:03:14AM +0930, Kevin Shanahan wrote: > On Thu, May 14, 2009 at 05:23:25PM -0400, Theodore Tso wrote: > > On Fri, May 15, 2009 at 06:32:45AM +0930, Kevin Shanahan wrote: > > > Okay, so now I've booted into 2.6.29.3 + check_block_validity patch + > > > short circuit i_cached_extent patch, mounted the fs without > > > nodelalloc. I was able to run the full exchange backup without > > > triggering the check_block_validity error. > > > > Great! > > > > So here's the final fix (it replaces the short circuit i_cached_extent > > patch) which I plan to push to Linus. It should be much less of a > > performance hit than simply short-circuiting i_cached_extent... > > > > Thanks so much for helping to find track this down!!! If ever someone > > deserved an "Ext4 Baker Street Irregulars" T-shirt, it would be > > you.... > > Hehe, no problem. Will do the final testing shortly (ran out of time > this morning, users are back on the system now). Just one little > correction to your patch below: > > > commit 039ed7a483fdcb2dbbc29f00cd0d74c101ab14c5 > > Author: Theodore Ts'o <tytso@xxxxxxx> > > Date: Thu May 14 17:09:37 2009 -0400 > > > > ext4: Fix race in ext4_inode_info.i_cached_extent > > > > If one CPU is reading from a file while another CPU is writing to the > > same file different locations, there is nothing protecting the > > i_cached_extent structure from being used and updated at the same > > time. This could potentially cause the wrong location on disk to be > > read or written to, including potentially causing the corruption of > > the block group descriptors and/or inode table. > > > > Many thanks to Ken Shannah for helping to track down this problem. > ^^^^^^^^^^^ Tested-by: Kevin Shanahan <kmshanah@xxxxxxxxxxx> Yes, this patch seems to have fixed the issue. I ran my "exchange backup to samba share" test on 2.6.29.3 + check_block_validity patch + the fix race patch with no problems. Cheers, Kevin. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
