diff options
| author | Jan Kara <jack@suse.cz> | 2017-08-05 17:43:24 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-11 08:49:30 -0700 |
| commit | 0814c3a9447ba284ef91b2d27755bf5a4514ca64 (patch) | |
| tree | 350d0b62cc50cd2f482c6951b1244008afb7b00c | |
| parent | b680e22fca767103ea4f86e21a8cca927f9d1ca7 (diff) | |
ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize
commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 9e77c089e8cb..d17d12ed6f73 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -469,6 +469,8 @@ 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) @@ -483,6 +485,7 @@ 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); |