[PATCH] ufs: handle truncated pages

ufs_get_locked_page is called twice in ufs code, one time in ufs_truncate
path(we allocated last block), and another time when fragments are
reallocated.  In ideal world in the second case on allocation/free block
layer we should not know that things like `truncate' exists, but now with
such crutch like ufs_get_locked_page we can (or should?) skip truncated
pages.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/ufs/balloc.c

@@ -248,7 +248,7 @@ static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk,
 
 		if (likely(cur_index != index)) {
 			page = ufs_get_locked_page(mapping, index);
-			if (IS_ERR(page))
+			if (!page || IS_ERR(page)) /* it was truncated or EIO */
 				continue;
 		} else
 			page = locked_page;

fs/ufs/util.c

@@ -251,7 +251,6 @@ struct page *ufs_get_locked_page(struct address_space *mapping,
 {
 	struct page *page;
 
-try_again:
 	page = find_lock_page(mapping, index);
 	if (!page) {
 		page = read_cache_page(mapping, index,
@@ -271,7 +270,8 @@ try_again:
 			/* Truncate got there first */
 			unlock_page(page);
 			page_cache_release(page);
-			goto try_again;
+			page = NULL;
+			goto out;
 		}
 
 		if (!PageUptodate(page) || PageError(page)) {