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author | Filipe Manana <fdmanana@suse.com> | 2015-09-28 09:56:26 +0100 |
---|---|---|
committer | Chris Mason <clm@fb.com> | 2015-10-05 16:56:27 -0700 |
commit | 808f80b46790f27e145c72112189d6a3be2bc884 (patch) | |
tree | d4fed13bcd51297693ec319a9901dacc53dd44c2 /fs/btrfs/extent_io.c | |
parent | b786f16ac3c5d4f7a5fd136656b6a1301b29b73b (diff) | |
download | op-kernel-dev-808f80b46790f27e145c72112189d6a3be2bc884.zip op-kernel-dev-808f80b46790f27e145c72112189d6a3be2bc884.tar.gz |
Btrfs: update fix for read corruption of compressed and shared extents
My previous fix in commit 005efedf2c7d ("Btrfs: fix read corruption of
compressed and shared extents") was effective only if the compressed
extents cover a file range with a length that is not a multiple of 16
pages. That's because the detection of when we reached a different range
of the file that shares the same compressed extent as the previously
processed range was done at extent_io.c:__do_contiguous_readpages(),
which covers subranges with a length up to 16 pages, because
extent_readpages() groups the pages in clusters no larger than 16 pages.
So fix this by tracking the start of the previously processed file
range's extent map at extent_readpages().
The following test case for fstests reproduces the issue:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15
_cleanup()
{
rm -f $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
# real QA test starts here
_need_to_be_root
_supported_fs btrfs
_supported_os Linux
_require_scratch
_require_cloner
rm -f $seqres.full
test_clone_and_read_compressed_extent()
{
local mount_opts=$1
_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount $mount_opts
# Create our test file with a single extent of 64Kb that is going to
# be compressed no matter which compression algo is used (zlib/lzo).
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0K 64K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Now clone the compressed extent into an adjacent file offset.
$CLONER_PROG -s 0 -d $((64 * 1024)) -l $((64 * 1024)) \
$SCRATCH_MNT/foo $SCRATCH_MNT/foo
echo "File digest before unmount:"
md5sum $SCRATCH_MNT/foo | _filter_scratch
# Remount the fs or clear the page cache to trigger the bug in
# btrfs. Because the extent has an uncompressed length that is a
# multiple of 16 pages, all the pages belonging to the second range
# of the file (64K to 128K), which points to the same extent as the
# first range (0K to 64K), had their contents full of zeroes instead
# of the byte 0xaa. This was a bug exclusively in the read path of
# compressed extents, the correct data was stored on disk, btrfs
# just failed to fill in the pages correctly.
_scratch_remount
echo "File digest after remount:"
# Must match the digest we got before.
md5sum $SCRATCH_MNT/foo | _filter_scratch
}
echo -e "\nTesting with zlib compression..."
test_clone_and_read_compressed_extent "-o compress=zlib"
_scratch_unmount
echo -e "\nTesting with lzo compression..."
test_clone_and_read_compressed_extent "-o compress=lzo"
status=0
exit
Cc: stable@vger.kernel.org
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Tested-by: Timofey Titovets <nefelim4ag@gmail.com>
Diffstat (limited to 'fs/btrfs/extent_io.c')
-rw-r--r-- | fs/btrfs/extent_io.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 11aa8f7..363726b 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3144,12 +3144,12 @@ static inline void __do_contiguous_readpages(struct extent_io_tree *tree, get_extent_t *get_extent, struct extent_map **em_cached, struct bio **bio, int mirror_num, - unsigned long *bio_flags, int rw) + unsigned long *bio_flags, int rw, + u64 *prev_em_start) { struct inode *inode; struct btrfs_ordered_extent *ordered; int index; - u64 prev_em_start = (u64)-1; inode = pages[0]->mapping->host; while (1) { @@ -3165,7 +3165,7 @@ static inline void __do_contiguous_readpages(struct extent_io_tree *tree, for (index = 0; index < nr_pages; index++) { __do_readpage(tree, pages[index], get_extent, em_cached, bio, - mirror_num, bio_flags, rw, &prev_em_start); + mirror_num, bio_flags, rw, prev_em_start); page_cache_release(pages[index]); } } @@ -3175,7 +3175,8 @@ static void __extent_readpages(struct extent_io_tree *tree, int nr_pages, get_extent_t *get_extent, struct extent_map **em_cached, struct bio **bio, int mirror_num, - unsigned long *bio_flags, int rw) + unsigned long *bio_flags, int rw, + u64 *prev_em_start) { u64 start = 0; u64 end = 0; @@ -3196,7 +3197,7 @@ static void __extent_readpages(struct extent_io_tree *tree, index - first_index, start, end, get_extent, em_cached, bio, mirror_num, bio_flags, - rw); + rw, prev_em_start); start = page_start; end = start + PAGE_CACHE_SIZE - 1; first_index = index; @@ -3207,7 +3208,8 @@ static void __extent_readpages(struct extent_io_tree *tree, __do_contiguous_readpages(tree, &pages[first_index], index - first_index, start, end, get_extent, em_cached, bio, - mirror_num, bio_flags, rw); + mirror_num, bio_flags, rw, + prev_em_start); } static int __extent_read_full_page(struct extent_io_tree *tree, @@ -4218,6 +4220,7 @@ int extent_readpages(struct extent_io_tree *tree, struct page *page; struct extent_map *em_cached = NULL; int nr = 0; + u64 prev_em_start = (u64)-1; for (page_idx = 0; page_idx < nr_pages; page_idx++) { page = list_entry(pages->prev, struct page, lru); @@ -4234,12 +4237,12 @@ int extent_readpages(struct extent_io_tree *tree, if (nr < ARRAY_SIZE(pagepool)) continue; __extent_readpages(tree, pagepool, nr, get_extent, &em_cached, - &bio, 0, &bio_flags, READ); + &bio, 0, &bio_flags, READ, &prev_em_start); nr = 0; } if (nr) __extent_readpages(tree, pagepool, nr, get_extent, &em_cached, - &bio, 0, &bio_flags, READ); + &bio, 0, &bio_flags, READ, &prev_em_start); if (em_cached) free_extent_map(em_cached); |