namei: get rid of nameidata->base

we can do fdput() under rcu_read_lock() just fine; all we need to take
care of is fetching nd->inode value first.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -503,7 +503,6 @@ struct nameidata {
 	int		last_type;
 	unsigned	depth;
 	int		total_link_count;
-	struct file	*base;
 	struct saved {
 		struct path link;
 		void *cookie;
@@ -1872,7 +1871,6 @@ static int path_init(int dfd, const struct filename *name, unsigned int flags,
 	nd->last_type = LAST_ROOT; /* if there are only slashes... */
 	nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
 	nd->depth = 0;
-	nd->base = NULL;
 	if (flags & LOOKUP_ROOT) {
 		struct dentry *root = nd->root.dentry;
 		struct inode *inode = root->d_inode;
@@ -1941,14 +1939,15 @@ static int path_init(int dfd, const struct filename *name, unsigned int flags,
 
 		nd->path = f.file->f_path;
 		if (flags & LOOKUP_RCU) {
-			if (f.flags & FDPUT_FPUT)
-				nd->base = f.file;
-			nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
 			rcu_read_lock();
+			nd->inode = nd->path.dentry->d_inode;
+			nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
 		} else {
 			path_get(&nd->path);
-			fdput(f);
+			nd->inode = nd->path.dentry->d_inode;
 		}
+		fdput(f);
+		goto done;
 	}
 
 	nd->inode = nd->path.dentry->d_inode;
@@ -1971,8 +1970,6 @@ static void path_cleanup(struct nameidata *nd)
 		path_put(&nd->root);
 		nd->root.mnt = NULL;
 	}
-	if (unlikely(nd->base))
-		fput(nd->base);
 }
 
 static int trailing_symlink(struct nameidata *nd)