vfs: add d_is_dir()

Add d_is_dir(dentry) helper which is analogous to S_ISDIR().

To avoid confusion, rename d_is_directory() to d_can_lookup().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/namei.c b/fs/namei.c
index 4b491b4..e987ea7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1796,7 +1796,7 @@
 			if (err)
 				return err;
 		}
-		if (!d_is_directory(nd->path.dentry)) {
+		if (!d_can_lookup(nd->path.dentry)) {
 			err = -ENOTDIR; 
 			break;
 		}
@@ -1817,7 +1817,7 @@
 		struct dentry *root = nd->root.dentry;
 		struct inode *inode = root->d_inode;
 		if (*name) {
-			if (!d_is_directory(root))
+			if (!d_can_lookup(root))
 				return -ENOTDIR;
 			retval = inode_permission(inode, MAY_EXEC);
 			if (retval)
@@ -1873,7 +1873,7 @@
 		dentry = f.file->f_path.dentry;
 
 		if (*name) {
-			if (!d_is_directory(dentry)) {
+			if (!d_can_lookup(dentry)) {
 				fdput(f);
 				return -ENOTDIR;
 			}
@@ -1955,7 +1955,7 @@
 		err = complete_walk(nd);
 
 	if (!err && nd->flags & LOOKUP_DIRECTORY) {
-		if (!d_is_directory(nd->path.dentry)) {
+		if (!d_can_lookup(nd->path.dentry)) {
 			path_put(&nd->path);
 			err = -ENOTDIR;
 		}
@@ -2414,11 +2414,11 @@
 	    IS_IMMUTABLE(inode) || IS_SWAPFILE(inode))
 		return -EPERM;
 	if (isdir) {
-		if (!d_is_directory(victim) && !d_is_autodir(victim))
+		if (!d_is_dir(victim))
 			return -ENOTDIR;
 		if (IS_ROOT(victim))
 			return -EBUSY;
-	} else if (d_is_directory(victim) || d_is_autodir(victim))
+	} else if (d_is_dir(victim))
 		return -EISDIR;
 	if (IS_DEADDIR(dir))
 		return -ENOENT;
@@ -3016,11 +3016,10 @@
 	}
 	audit_inode(name, nd->path.dentry, 0);
 	error = -EISDIR;
-	if ((open_flag & O_CREAT) &&
-	    (d_is_directory(nd->path.dentry) || d_is_autodir(nd->path.dentry)))
+	if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
 		goto out;
 	error = -ENOTDIR;
-	if ((nd->flags & LOOKUP_DIRECTORY) && !d_is_directory(nd->path.dentry))
+	if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
 		goto out;
 	if (!S_ISREG(nd->inode->i_mode))
 		will_truncate = false;
@@ -3744,7 +3743,7 @@
 slashes:
 	if (d_is_negative(dentry))
 		error = -ENOENT;
-	else if (d_is_directory(dentry) || d_is_autodir(dentry))
+	else if (d_is_dir(dentry))
 		error = -EISDIR;
 	else
 		error = -ENOTDIR;
@@ -4123,7 +4122,7 @@
 	       struct inode **delegated_inode)
 {
 	int error;
-	int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry);
+	int is_dir = d_is_dir(old_dentry);
 	const unsigned char *old_name;
 
 	if (old_dentry->d_inode == new_dentry->d_inode)
@@ -4216,7 +4215,7 @@
 	if (d_is_negative(old_dentry))
 		goto exit4;
 	/* unless the source is a directory trailing slashes give -ENOTDIR */
-	if (!d_is_directory(old_dentry) && !d_is_autodir(old_dentry)) {
+	if (!d_is_dir(old_dentry)) {
 		error = -ENOTDIR;
 		if (oldnd.last.name[oldnd.last.len])
 			goto exit4;