ceph_d_revalidate(): use stable parent inode passed by caller

No need to mess with the boilerplate for obtaining what we already
have.  Note that ceph is one of the "will want a path from filesystem
root if we want to talk to server" cases, so the name of the last
component is of little use - it is passed to fscrypt_d_revalidate()
and it's used to deal with (also crypt-related) case in request
marshalling, when encrypted name turns out to be too long.  The former
is not a problem, but the latter is racy; that part will be handled
in the next commit.

Reviewed-by: Jeff Layton <[email protected]>
Reviewed-by: Viacheslav Dubeyko <[email protected]>
Signed-off-by: Al Viro <[email protected]>

Author: Al Viro

fs/ceph/dir.c

@@ -1940,30 +1940,19 @@ static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry,
 /*
  * Check if cached dentry can be trusted.
  */
-static int ceph_d_revalidate(struct inode *parent_dir, const struct qstr *name,
+static int ceph_d_revalidate(struct inode *dir, const struct qstr *name,
 			     struct dentry *dentry, unsigned int flags)
 {
 	struct ceph_mds_client *mdsc = ceph_sb_to_fs_client(dentry->d_sb)->mdsc;
 	struct ceph_client *cl = mdsc->fsc->client;
 	int valid = 0;
-	struct dentry *parent;
-	struct inode *dir, *inode;
+	struct inode *inode;
 
-	valid = fscrypt_d_revalidate(parent_dir, name, dentry, flags);
+	valid = fscrypt_d_revalidate(dir, name, dentry, flags);
 	if (valid <= 0)
 		return valid;
 
-	if (flags & LOOKUP_RCU) {
-		parent = READ_ONCE(dentry->d_parent);
-		dir = d_inode_rcu(parent);
-		if (!dir)
-			return -ECHILD;
-		inode = d_inode_rcu(dentry);
-	} else {
-		parent = dget_parent(dentry);
-		dir = d_inode(parent);
-		inode = d_inode(dentry);
-	}
+	inode = d_inode_rcu(dentry);
 
 	doutc(cl, "%p '%pd' inode %p offset 0x%llx nokey %d\n",
 	      dentry, dentry, inode, ceph_dentry(dentry)->offset,
@@ -2039,9 +2028,6 @@ static int ceph_d_revalidate(struct inode *parent_dir, const struct qstr *name,
 	doutc(cl, "%p '%pd' %s\n", dentry, dentry, valid ? "valid" : "invalid");
 	if (!valid)
 		ceph_dir_clear_complete(dir);
-
-	if (!(flags & LOOKUP_RCU))
-		dput(parent);
 	return valid;
 }