[PATCH 5.4 55/80] NFS: LOOKUP_DIRECTORY is also ok with symlinks

Greg Kroah-Hartman
2022-02-21T09:14:04Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

commit e0caaf75d443e02e55e146fd75fe2efc8aed5540 upstream.

Commit ac795161c936 (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: Paul Menzel <pmenzel@molgen.mpg.de>
Fixes: ac795161c936 ("NFSv4: Handle case where the lookup of a directory fails")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Tested-by: Donald Buczek <buczek@molgen.mpg.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/dir.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1641,14 +1641,14 @@ no_open:
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)) {