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From 1a413646931cb14442065cfc17561e50f5b5bb44 Mon Sep 17 00:00:00 2001
From: Yufen Yu <yuyufen@huawei.com>
Date: Fri, 16 Nov 2018 15:08:39 -0800
Subject: [PATCH] tmpfs: make lseek(SEEK_DATA/SEK_HOLE) return ENXIO with a negative offset
Git-commit: 1a413646931cb14442065cfc17561e50f5b5bb44
Patch-mainline: v4.20-rc3
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 mm/shmem.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index ea26d7a0342d..d44991ea5ed4 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2563,9 +2563,7 @@ static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
 	inode_lock(inode);
 	/* 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_SHIFT;
-- 
2.19.2