fs: do not drop inode_lock in dispose_list

Despite the comment above it we can not safely drop the lock here.
invalidate_list is called from many other places that just umount.
Also switch to proper list macros now that we never drop the lock.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/inode.c

@@ -482,26 +482,10 @@ static void dispose_list(struct list_head *head)
  */
 static int invalidate_list(struct list_head *head, struct list_head *dispose)
 {
-	struct list_head *next;
+	struct inode *inode, *next;
 	int busy = 0;
 
-	next = head->next;
-	for (;;) {
-		struct list_head *tmp = next;
-		struct inode *inode;
-
-		/*
-		 * We can reschedule here without worrying about the list's
-		 * consistency because the per-sb list of inodes must not
-		 * change during umount anymore, and because iprune_sem keeps
-		 * shrink_icache_memory() away.
-		 */
-		cond_resched_lock(&inode_lock);
-
-		next = next->next;
-		if (tmp == head)
-			break;
-		inode = list_entry(tmp, struct inode, i_sb_list);
+	list_for_each_entry_safe(inode, next, head, i_sb_list) {
 		if (inode->i_state & I_NEW)
 			continue;
 		if (atomic_read(&inode->i_count)) {