[PATCH AUTOSEL 4.4 8/8] tmpfs: make lseek(SEEK_DATA/SEK_HOLE) return ENXIO with a negative offset

Sasha Levin
2018-11-22T19:57:52Z

From: Yufen Yu <yuyufen@huawei.com>

[ Upstream commit 1a413646931cb14442065cfc17561e50f5b5bb44 ]

Other filesystems such as ext4, f2fs and ubifs all return ENXIO when
lseek (SEEK_DATA or SEEK_HOLE) requests a negative offset.

man 2 lseek says

: EINVAL whence is not valid. Or: the resulting file offset would be
: negative, or beyond the end of a seekable device.
:
: ENXIO whence is SEEK_DATA or SEEK_HOLE, and the file offset is beyond
: the end of the file.

Make tmpfs return ENXIO under these circumstances as well. After this,
tmpfs also passes xfstests's generic/448.

[akpm@linux-foundation.org: rewrite changelog]
Link: http://lkml.kernel.org/r/1540434176-14349-1-git-send-email-yuyufen@huawei.com
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/shmem.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 8e506a45a6ef..d902b413941a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1818,9 +1818,7 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
mutex_lock(&inode->i_mutex);
/* We're holding i_mutex so we can access i_size directly */

- if (offset < 0)
- offset = -EINVAL;
- else if (offset >= inode->i_size)
+ if (offset < 0 || offset >= inode->i_size)
offset = -ENXIO;
else {
start = offset >> PAGE_CACHE_SHIFT;
--
2.17.1