smbfs: use dget_parent

Use dget_parent instead of opencoding it.  This simplifies the code, but
more importanly prepares for the more complicated locking for a parent
dget in the dcache scale patch series.

Note that the d_time assignment in smb_renew_times moves out of d_lock,
but it's a single atomic 32-bit value, and that's what other sites
setting it do already.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/smbfs/dir.c

@@ -406,21 +406,15 @@ void
 smb_renew_times(struct dentry * dentry)
 {
 	dget(dentry);
-	spin_lock(&dentry->d_lock);
-	for (;;) {
-		struct dentry *parent;
+	dentry->d_time = jiffies;
 
-		dentry->d_time = jiffies;
-		if (IS_ROOT(dentry))
-			break;
-		parent = dentry->d_parent;
-		dget(parent);
-		spin_unlock(&dentry->d_lock);
+	while (!IS_ROOT(dentry)) {
+		struct dentry *parent = dget_parent(dentry);
 		dput(dentry);
 		dentry = parent;
-		spin_lock(&dentry->d_lock);
+
+		dentry->d_time = jiffies;
 	}
-	spin_unlock(&dentry->d_lock);
 	dput(dentry);
 }
 

fs/smbfs/proc.c

@@ -332,16 +332,15 @@ static int smb_build_path(struct smb_sb_info *server, unsigned char *buf,
 	 * and store it in reversed order [see reverse_string()]
 	 */
 	dget(entry);
-	spin_lock(&entry->d_lock);
 	while (!IS_ROOT(entry)) {
 		struct dentry *parent;
 
 		if (maxlen < (3<<unicode)) {
-			spin_unlock(&entry->d_lock);
 			dput(entry);
 			return -ENAMETOOLONG;
 		}
 
+		spin_lock(&entry->d_lock);
 		len = server->ops->convert(path, maxlen-2, 
 				      entry->d_name.name, entry->d_name.len,
 				      server->local_nls, server->remote_nls);
@@ -359,15 +358,12 @@ static int smb_build_path(struct smb_sb_info *server, unsigned char *buf,
 		}
 		*path++ = '\\';
 		maxlen -= len+1;
-
-		parent = entry->d_parent;
-		dget(parent);
 		spin_unlock(&entry->d_lock);
+
+		parent = dget_parent(entry);
 		dput(entry);
 		entry = parent;
-		spin_lock(&entry->d_lock);
 	}
-	spin_unlock(&entry->d_lock);
 	dput(entry);
 	reverse_string(buf, path-buf);