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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2005-05-05 16:15:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-05-05 16:36:40 -0700 |
| commit | f3ddbdc6267c32223035ea9bb8456a2d86f65ba1 (patch) | |
| tree | bc11ca9a8bc1f1ebdc70e59bb28e8e328346f7bb /fs/buffer.c | |
| parent | 3c8fad1829cc33e903500b41d989fa50ab196378 (diff) | |
| download | lwn-f3ddbdc6267c32223035ea9bb8456a2d86f65ba1.tar.gz lwn-f3ddbdc6267c32223035ea9bb8456a2d86f65ba1.zip | |
[PATCH] fix race in __block_prepare_write
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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 6ed59497fd4d..af7c51ded2e1 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1953,7 +1953,7 @@ static int __block_prepare_write(struct inode *inode, struct page *page, if (!buffer_mapped(bh)) { err = get_block(inode, block, bh, 1); if (err) - goto out; + break; if (buffer_new(bh)) { clear_buffer_new(bh); unmap_underlying_metadata(bh->b_bdev, @@ -1995,10 +1995,12 @@ static int __block_prepare_write(struct inode *inode, struct page *page, while(wait_bh > wait) { wait_on_buffer(*--wait_bh); if (!buffer_uptodate(*wait_bh)) - return -EIO; + err = -EIO; } - return 0; -out: + if (!err) + return err; + + /* Error case: */ /* * Zero out any newly allocated blocks to avoid exposing stale * data. If BH_New is set, we know that the block was newly |