Merge tag 'fscache-fixes-20140917' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fs-cache fixes from David Howells:

 - Put a timeout in releasepage() to deal with a recursive hang between
   the memory allocator, writeback, ext4 and fscache under memory
   pressure.

 - Fix a pair of refcount bugs in the fscache error handling.

 - Remove a couple of unused pagevecs.

 - The cachefiles requirement that the base directory support rename
   should permit rename2 as an alternative - otherwise certain
   filesystems cannot now be used as backing stores (such as ext4).

* tag 'fscache-fixes-20140917' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  CacheFiles: Handle rename2
  cachefiles: remove two unused pagevecs.
  FS-Cache: refcount becomes corrupt under vma pressure.
  FS-Cache: Reduce cookie ref count if submit fails.
  FS-Cache: Timeout for releasepage()

fs/cachefiles/namei.c

@@ -779,7 +779,8 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 	    !subdir->d_inode->i_op->lookup ||
 	    !subdir->d_inode->i_op->mkdir ||
 	    !subdir->d_inode->i_op->create ||
-	    !subdir->d_inode->i_op->rename ||
+	    (!subdir->d_inode->i_op->rename &&
+	     !subdir->d_inode->i_op->rename2) ||
 	    !subdir->d_inode->i_op->rmdir ||
 	    !subdir->d_inode->i_op->unlink)
 		goto check_error;

fs/cachefiles/rdwr.c

@@ -151,7 +151,6 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
 	struct cachefiles_one_read *monitor;
 	struct cachefiles_object *object;
 	struct fscache_retrieval *op;
-	struct pagevec pagevec;
 	int error, max;
 
 	op = container_of(_op, struct fscache_retrieval, op);
@@ -160,8 +159,6 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
 
 	_enter("{ino=%lu}", object->backer->d_inode->i_ino);
 
-	pagevec_init(&pagevec, 0);
-
 	max = 8;
 	spin_lock_irq(&object->work_lock);
 
@@ -396,7 +393,6 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 {
 	struct cachefiles_object *object;
 	struct cachefiles_cache *cache;
-	struct pagevec pagevec;
 	struct inode *inode;
 	sector_t block0, block;
 	unsigned shift;
@@ -427,8 +423,6 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 	op->op.flags |= FSCACHE_OP_ASYNC;
 	op->op.processor = cachefiles_read_copier;
 
-	pagevec_init(&pagevec, 0);
-
 	/* we assume the absence or presence of the first block is a good
 	 * enough indication for the page as a whole
 	 * - TODO: don't use bmap() for this as it is _not_ actually good

fs/fscache/object.c

@@ -982,6 +982,7 @@ nomem:
 submit_op_failed:
 	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
 	spin_unlock(&cookie->lock);
+	fscache_unuse_cookie(object);
 	kfree(op);
 	_leave(" [EIO]");
 	return transit_to(KILL_OBJECT);

fs/fscache/page.c

@@ -43,6 +43,19 @@ void __fscache_wait_on_page_write(struct fscache_cookie *cookie, struct page *pa
 }
 EXPORT_SYMBOL(__fscache_wait_on_page_write);
 
+/*
+ * wait for a page to finish being written to the cache. Put a timeout here
+ * since we might be called recursively via parent fs.
+ */
+static
+bool release_page_wait_timeout(struct fscache_cookie *cookie, struct page *page)
+{
+	wait_queue_head_t *wq = bit_waitqueue(&cookie->flags, 0);
+
+	return wait_event_timeout(*wq, !__fscache_check_page_write(cookie, page),
+				  HZ);
+}
+
 /*
  * decide whether a page can be released, possibly by cancelling a store to it
  * - we're allowed to sleep if __GFP_WAIT is flagged
@@ -115,7 +128,10 @@ page_busy:
 	}
 
 	fscache_stat(&fscache_n_store_vmscan_wait);
-	__fscache_wait_on_page_write(cookie, page);
+	if (!release_page_wait_timeout(cookie, page))
+		_debug("fscache writeout timeout page: %p{%lx}",
+			page, page->index);
+
 	gfp &= ~__GFP_WAIT;
 	goto try_again;
 }
@@ -182,7 +198,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
 {
 	struct fscache_operation *op;
 	struct fscache_object *object;
-	bool wake_cookie;
+	bool wake_cookie = false;
 
 	_enter("%p", cookie);
 
@@ -212,15 +228,16 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
 
 	__fscache_use_cookie(cookie);
 	if (fscache_submit_exclusive_op(object, op) < 0)
-		goto nobufs;
+		goto nobufs_dec;
 	spin_unlock(&cookie->lock);
 	fscache_stat(&fscache_n_attr_changed_ok);
 	fscache_put_operation(op);
 	_leave(" = 0");
 	return 0;
 
-nobufs:
+nobufs_dec:
 	wake_cookie = __fscache_unuse_cookie(cookie);
+nobufs:
 	spin_unlock(&cookie->lock);
 	kfree(op);
 	if (wake_cookie)