ovl: do not fail because of O_NOATIME

mainline inclusion
from mainline-v5.11-rc1
commit b6650dab
category: bugfix
bugzilla: 187815, https://gitee.com/openeuler/kernel/issues/I5WLBD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b6650dab404c701d7fe08a108b746542a934da84

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

In case the file cannot be opened with O_NOATIME because of lack of
capabilities, then clear O_NOATIME instead of failing.

Remove WARN_ON(), since it would now trigger if O_NOATIME was cleared.
Noticed by Amir Goldstein.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: NZhang Yi <yi.zhang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/overlayfs/file.c

@@ -54,9 +54,10 @@ static struct file *ovl_open_realfile(const struct file *file,
 	err = inode_permission(realinode, MAY_OPEN | acc_mode);
 	if (err) {
 		realfile = ERR_PTR(err);
-	} else if (!inode_owner_or_capable(realinode)) {
-		realfile = ERR_PTR(-EPERM);
 	} else {
+		if (!inode_owner_or_capable(realinode))
+			flags &= ~O_NOATIME;
+
 		realfile = open_with_fake_path(&file->f_path, flags, realinode,
 					       current_cred());
 	}
@@ -76,12 +77,6 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
 	struct inode *inode = file_inode(file);
 	int err;
 
-	flags |= OVL_OPEN_FLAGS;
-
-	/* If some flag changed that cannot be changed then something's amiss */
-	if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
-		return -EIO;
-
 	flags &= OVL_SETFL_MASK;
 
 	if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))