Messages in this thread Patch in this message | | | Subject | [patch] fix race in __block_prepare_write | From | Nick Piggin <> | Date | Thu, 21 Apr 2005 16:11:34 +1000 |
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Questions? Comments?
-- SUSE Labs, Novell Inc. Fix a race where __block_prepare_write can leak out an in-flight read against a bh if get_block returns an error. This can lead to the page becoming unlocked while the buffer is locked and the read still in flight. __mpage_writepage BUGs on this condition.
BUG sighted on a 2-way Itanium2 system with 16K PAGE_SIZE running
fsstress -v -d $DIR/tmp -n 1000 -p 1000 -l 2
where $DIR is a new ext2 filesystem with 4K blocks that is quite small (causing get_block to fail often with -ENOSPC).
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Index: linux-2.6/fs/buffer.c =================================================================== --- linux-2.6.orig/fs/buffer.c 2005-04-21 11:55:17.549614278 +1000 +++ linux-2.6/fs/buffer.c 2005-04-21 15:55:41.483826075 +1000 @@ -1988,6 +1988,7 @@ *wait_bh++=bh; } } +out: /* * If we issued read requests - let them complete. */ @@ -1996,8 +1997,9 @@ if (!buffer_uptodate(*wait_bh)) return -EIO; } - return 0; -out: + if (!err) + return err; + /* * Zero out any newly allocated blocks to avoid exposing stale * data. If BH_New is set, we know that the block was newly | |