From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 30 Jan 2010 21:11:21 +0000 (-0500)
Subject: fix NFS4 handling of mountpoint stat
X-Git-Tag: firefly_0821_release~10186^2~1793
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=839f573c0438d44d1df1df96963150668d5846c9;p=firefly-linux-kernel-4.4.55.git

fix NFS4 handling of mountpoint stat

commit 462d60577a997aa87c935ae4521bd303733a9f2b upstream.

RFC says we need to follow the chain of mounts if there's more
than one stacked on that point.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 0fbd50cee1f6..c598ab948211 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2129,9 +2129,15 @@ out_acl:
 		 * and this is the root of a cross-mounted filesystem.
 		 */
 		if (ignore_crossmnt == 0 &&
-		    exp->ex_path.mnt->mnt_root->d_inode == dentry->d_inode) {
-			err = vfs_getattr(exp->ex_path.mnt->mnt_parent,
-				exp->ex_path.mnt->mnt_mountpoint, &stat);
+		    dentry == exp->ex_path.mnt->mnt_root) {
+			struct path path = exp->ex_path;
+			path_get(&path);
+			while (follow_up(&path)) {
+				if (path.dentry != path.mnt->mnt_root)
+					break;
+			}
+			err = vfs_getattr(path.mnt, path.dentry, &stat);
+			path_put(&path);
 			if (err)
 				goto out_nfserr;
 		}