The patch titled
introduce write_begin write_end aops important fix
has been added to the -mm tree. Its filename is
introduce-write_begin-write_end-aops-important-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: introduce write_begin write_end aops important fix
From: Nick Piggin <npiggin@xxxxxxx>
Credit for these next 4 patches goes to Hugh. He found and fixed the
problem, I just split them up and added a bit of a changelog and
hopefully no new bugs.
When running kbuild stress testing, it data corruptions on ext2 were
noticed occasionally.
The page being written to by write(2) was being unlocked in generic_write_end
before updating i_size, and that renders an extending-write vulnerable to have
its newly written data zeroed out if writepage comes at the wrong time and
finds the page unlocked but i_size is not yet updated.
Fortunately ext3 wasn't affected by this bug, but ext2 and others using
generic_write_end would be.
Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx>
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/buffer.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff -puN fs/buffer.c~introduce-write_begin-write_end-aops-important-fix fs/buffer.c
--- a/fs/buffer.c~introduce-write_begin-write_end-aops-important-fix
+++ a/fs/buffer.c
@@ -2028,19 +2028,22 @@ int generic_write_end(struct file *file,
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
- unlock_page(page);
- mark_page_accessed(page); /* XXX: put this in caller? */
- page_cache_release(page);
-
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold i_mutex.
+ *
+ * But it's important to update i_size while still holding page lock:
+ * page writeout could otherwise come in and zero beyond i_size.
*/
if (pos+copied > inode->i_size) {
i_size_write(inode, pos+copied);
mark_inode_dirty(inode);
}
+ unlock_page(page);
+ mark_page_accessed(page);
+ page_cache_release(page);
+
return copied;
}
EXPORT_SYMBOL(generic_write_end);
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
origin.patch
mm-fix-fault-vs-invalidate-race-for-linear-mappings.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear.patch
mm-fault-feedback-1.patch
mm-fault-feedback-2.patch
mm-fault-feedback-2-fix.patch
mm-fault-feedback-2-fix-2.patch
mm-fix-clear_page_dirty_for_io-vs-fault-race.patch
mm-revert-kernel_ds-buffered-write-optimisation.patch
revert-81b0c8713385ce1b1b9058e916edcf9561ad76d6.patch
revert-6527c2bdf1f833cc18e8f42bd97973d583e4aa83.patch
mm-clean-up-buffered-write-code.patch
mm-debug-write-deadlocks.patch
mm-trim-more-holes.patch
mm-buffered-write-cleanup.patch
mm-write-iovec-cleanup.patch
mm-fix-pagecache-write-deadlocks.patch
mm-buffered-write-iterator.patch
fs-fix-data-loss-on-error.patch
fs-introduce-write_begin-write_end-and-perform_write-aops.patch
introduce-write_begin-write_end-aops-important-fix.patch
mm-restore-kernel_ds-optimisations.patch
implement-simple-fs-aops.patch
block_dev-convert-to-new-aops.patch
ext2-convert-to-new-aops.patch
ext3-convert-to-new-aops.patch
ext3-convert-to-new-aops-fix.patch
ext4-convert-to-new-aops.patch
ext4-convert-to-new-aops-fix.patch
xfs-convert-to-new-aops.patch
fs-new-cont-helpers.patch
fat-convert-to-new-aops.patch
hfs-convert-to-new-aops.patch
hfsplus-convert-to-new-aops.patch
hpfs-convert-to-new-aops.patch
bfs-convert-to-new-aops.patch
qnx4-convert-to-new-aops.patch
reiserfs-use-generic-write.patch
reiserfs-convert-to-new-aops.patch
reiserfs-convert-to-new-aops-fix.patch
reiserfs-use-generic_cont_expand_simple.patch
with-reiserfs-no-longer-using-the-weird-generic_cont_expand-remove-it-completely.patch
nfs-convert-to-new-aops.patch
smb-convert-to-new-aops.patch
fuse-convert-to-new-aops.patch
hostfs-convert-to-new-aops.patch
hostfs-convert-to-new-aops-fix.patch
jffs2-convert-to-new-aops.patch
ufs-convert-to-new-aops.patch
udf-convert-to-new-aops.patch
udf-convert-to-new-aops-fix.patch
sysv-convert-to-new-aops.patch
minix-convert-to-new-aops.patch
jfs-convert-to-new-aops.patch
fs-adfs-convert-to-new-aops.patch
fs-affs-convert-to-new-aops.patch
affs-convert-to-new-aops-fix.patch
ocfs2-convert-to-new-aops.patch
fs-remove-some-aop_truncated_page.patch
fs-reiserfs-cleanups.patch
fs-introduce-write_begin-write_end-and-perform_write-aops-revoke.patch
reiser4-fix-for-new-aops-patches.patch
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