NFS: LOOKUP_DIRECTORY is also ok with symlinks

stable inclusion
from linux-4.19.231
commit 67552482aee7a139ed957595db8668d28ddc2c42

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

commit e0caaf75 upstream.

Commit ac795161 (NFSv4: Handle case where the lookup of a directory
fails) [1], part of Linux since 5.17-rc2, introduced a regression, where
a symbolic link on an NFS mount to a directory on another NFS does not
resolve(?) the first time it is accessed:
Reported-by: NPaul Menzel <pmenzel@molgen.mpg.de>
Fixes: ac795161 ("NFSv4: Handle case where the lookup of a directory fails")
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Tested-by: NDonald Buczek <buczek@molgen.mpg.de>
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>
Signed-off-by: NLaibin Qiu <qiulaibin@huawei.com>

fs/nfs/dir.c

@@ -1640,14 +1640,14 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	if (!res) {
 		inode = d_inode(dentry);
 		if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
-		    !S_ISDIR(inode->i_mode))
+		    !(S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)))
 			res = ERR_PTR(-ENOTDIR);
 		else if (inode && S_ISREG(inode->i_mode))
 			res = ERR_PTR(-EOPENSTALE);
 	} else if (!IS_ERR(res)) {
 		inode = d_inode(res);
 		if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
-		    !S_ISDIR(inode->i_mode)) {
+		    !(S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))) {
 			dput(res);
 			res = ERR_PTR(-ENOTDIR);
 		} else if (inode && S_ISREG(inode->i_mode)) {