diff options
| author | Jan Kara <jack@suse.cz> | 2017-08-05 17:43:24 -0400 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2017-08-12 12:17:26 +0200 |
| commit | 0658f0dd3e372bedd7af683ada6ee7d0fba29f1e (patch) | |
| tree | 5c00c1e782e9df0a299bd7d377828729b4523805 | |
| parent | dd729e9ccc6e2b7ef4b65338f72cf161ef5869e9 (diff) | |
ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize
ext4_find_unwritten_pgoff() does not properly handle a situation when
starting index is in the middle of a page and blocksize < pagesize. The
following command shows the bug on filesystem with 1k blocksize:
xfs_io -f -c "falloc 0 4k" \
-c "pwrite 1k 1k" \
-c "pwrite 3k 1k" \
-c "seek -a -r 0" foo
In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048,
SEEK_DATA) will return the correct result.
Fix the problem by neglecting buffers in a page before starting offset.
Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
CC: stable@vger.kernel.org # 3.8+
| -rw-r--r-- | fs/ext4/file.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index bae48a0de..4b99a8786 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -515,6 +515,8 @@ static int ext4_find_unwritten_pgoff(struct inode *inode, lastoff = page_offset(page); bh = head = page_buffers(page); do { + if (lastoff + bh->b_size <= startoff) + goto next; if (buffer_uptodate(bh) || buffer_unwritten(bh)) { if (whence == SEEK_DATA) @@ -529,6 +531,7 @@ static int ext4_find_unwritten_pgoff(struct inode *inode, unlock_page(page); goto out; } +next: lastoff += bh->b_size; bh = bh->b_this_page; } while (bh != head); |