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| author | Jan Kara <jack@suse.cz> | 2017-08-06 00:43:24 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-11 19:30:13 +0300 |
| commit | 8a3a235bac007057f1ca51206899287019b88369 (patch) | |
| tree | df2de6d84cb32cdc3ca72896f9ca17b8433fd175 /fs | |
| parent | e6c7308ec57d6ee9936cd021873ff7b5d4e7be5b (diff) | |
| download | linux-8a3a235bac007057f1ca51206899287019b88369.tar.xz | |
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>
Diffstat (limited to 'fs')
| -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 ed2a57a3bb50..9dfb324de119 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -340,6 +340,8 @@ 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) @@ -354,6 +356,7 @@ 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); |