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authorJan Kara <jack@suse.cz>2017-08-05 17:43:24 -0400
committerTheodore Ts'o <tytso@mit.edu>2017-08-05 17:43:24 -0400
commitfcf5ea10992fbac3c7473a1db33d56a139333cd1 (patch)
tree6d34847e81c3b949606546a24627ae82a422b50c /fs/ext4/file.c
parente45105772db41c5318b2a7ec1c420183183414e3 (diff)
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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+
Diffstat (limited to 'fs/ext4/file.c')
-rw-r--r--fs/ext4/file.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 58294c9a7e1d..0d7cf0cc9b87 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -537,6 +537,8 @@ 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)
@@ -551,6 +553,7 @@ 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);