3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

[ 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.

[[email protected]: rewrite changelog]
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Yufen Yu <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: William Kucharski <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 mm/shmem.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 371d5eca80ed..64c33e3dbe69 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1805,9 +1805,7 @@ 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



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