autofs4: factor should_expire() out of autofs4_expire_indirect.

Future patch will potentially call this twice, so make it separate.
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Ian Kent <raven@themaw.net>
Tested-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/autofs4/expire.c

@@ -339,39 +339,24 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 	return NULL;
 }
 
-/*
- * Find an eligible tree to time-out
- * A tree is eligible if :-
- *  - it is unused by any user process
- *  - it has been unused for exp_timeout time
+/* Check if 'dentry' should expire, or return a nearby
+ * dentry that is suitable.
+ * If returned dentry is different from arg dentry,
+ * then a dget() reference was taken, else not.
  */
-struct dentry *autofs4_expire_indirect(struct super_block *sb,
+static struct dentry *should_expire(struct dentry *dentry,
 				    struct vfsmount *mnt,
-				       struct autofs_sb_info *sbi,
+				    unsigned long timeout,
 				    int how)
 {
-	unsigned long timeout;
-	struct dentry *root = sb->s_root;
-	struct dentry *dentry;
-	struct dentry *expired = NULL;
 	int do_now = how & AUTOFS_EXP_IMMEDIATE;
 	int exp_leaves = how & AUTOFS_EXP_LEAVES;
-	struct autofs_info *ino;
+	struct autofs_info *ino = autofs4_dentry_ino(dentry);
 	unsigned int ino_count;
 
-	if (!root)
-		return NULL;
-
-	now = jiffies;
-	timeout = sbi->exp_timeout;
-
-	dentry = NULL;
-	while ((dentry = get_next_positive_subdir(dentry, root))) {
-		spin_lock(&sbi->fs_lock);
-		ino = autofs4_dentry_ino(dentry);
 	/* No point expiring a pending mount */
 	if (ino->flags & AUTOFS_INF_PENDING)
-			goto next;
+		return NULL;
 
 	/*
 	 * Case 1: (i) indirect mount or top level pseudo direct mount
@@ -385,14 +370,12 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 
 		/* Can we umount this guy */
 		if (autofs4_mount_busy(mnt, dentry))
-				goto next;
+			return NULL;
 
 		/* Can we expire this guy */
-			if (autofs4_can_expire(dentry, timeout, do_now)) {
-				expired = dentry;
-				goto found;
-			}
-			goto next;
+		if (autofs4_can_expire(dentry, timeout, do_now))
+			return dentry;
+		return NULL;
 	}
 
 	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)) {
@@ -402,44 +385,75 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
 		 * A symlink can't be "busy" in the usual sense so
 		 * just check last used for expire timeout.
 		 */
-			if (autofs4_can_expire(dentry, timeout, do_now)) {
-				expired = dentry;
-				goto found;
-			}
-			goto next;
+		if (autofs4_can_expire(dentry, timeout, do_now))
+			return dentry;
+		return NULL;
 	}
 
 	if (simple_empty(dentry))
-			goto next;
+		return NULL;
 
 	/* Case 2: tree mount, expire iff entire tree is not busy */
 	if (!exp_leaves) {
 		/* Path walk currently on this dentry? */
 		ino_count = atomic_read(&ino->count) + 1;
 		if (d_count(dentry) > ino_count)
-				goto next;
+			return NULL;
 
-			if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
-				expired = dentry;
-				goto found;
-			}
+		if (!autofs4_tree_busy(mnt, dentry, timeout, do_now))
+			return dentry;
 	/*
 	 * Case 3: pseudo direct mount, expire individual leaves
 	 *	   (autofs-4.1).
 	 */
 	} else {
 		/* Path walk currently on this dentry? */
+		struct dentry *expired;
 		ino_count = atomic_read(&ino->count) + 1;
 		if (d_count(dentry) > ino_count)
-				goto next;
+			return NULL;
 
 		expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
 		if (expired) {
+			if (expired == dentry)
 				dput(dentry);
-				goto found;
+			return expired;
 		}
 	}
-next:
+	return NULL;
+}
+/*
+ * Find an eligible tree to time-out
+ * A tree is eligible if :-
+ *  - it is unused by any user process
+ *  - it has been unused for exp_timeout time
+ */
+struct dentry *autofs4_expire_indirect(struct super_block *sb,
+				       struct vfsmount *mnt,
+				       struct autofs_sb_info *sbi,
+				       int how)
+{
+	unsigned long timeout;
+	struct dentry *root = sb->s_root;
+	struct dentry *dentry;
+	struct dentry *expired;
+	struct autofs_info *ino;
+
+	if (!root)
+		return NULL;
+
+	now = jiffies;
+	timeout = sbi->exp_timeout;
+
+	dentry = NULL;
+	while ((dentry = get_next_positive_subdir(dentry, root))) {
+		spin_lock(&sbi->fs_lock);
+		expired = should_expire(dentry, mnt, timeout, how);
+		if (expired) {
+			if (expired != dentry)
+				dput(dentry);
+			goto found;
+		}
 		spin_unlock(&sbi->fs_lock);
 	}
 	return NULL;