Merge branch 'for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
"A couple of small fixes"

* 'for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: check prepare_uptodate_page() error code earlier
Btrfs: check for empty bitmap list in setup_cluster_bitmaps
btrfs: fix misleading warning when space cache failed to load
Btrfs: fix transaction handle leak in balance
Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list

fs/btrfs/extent-tree.c

···
 		 * until transaction commit to do the actual discard.
 		 */
 		if (trimming) {
-			WARN_ON(!list_empty(&block_group->bg_list));
-			spin_lock(&trans->transaction->deleted_bgs_lock);
+			spin_lock(&fs_info->unused_bgs_lock);
+			/*
+			 * A concurrent scrub might have added us to the list
+			 * fs_info->unused_bgs, so use a list_move operation
+			 * to add the block group to the deleted_bgs list.
+			 */
 			list_move(&block_group->bg_list,
 				  &trans->transaction->deleted_bgs);
-			spin_unlock(&trans->transaction->deleted_bgs_lock);
+			spin_unlock(&fs_info->unused_bgs_lock);
 			btrfs_get_block_group(block_group);
 		}
 end_trans:

fs/btrfs/file.c

···
  * on error we return an unlocked page and the error value
  * on success we return a locked page and 0
  */
-static int prepare_uptodate_page(struct page *page, u64 pos,
+static int prepare_uptodate_page(struct inode *inode,
+				 struct page *page, u64 pos,
 				 bool force_uptodate)
 {
 	int ret = 0;
···
 		if (!PageUptodate(page)) {
 			unlock_page(page);
 			return -EIO;
+		}
+		if (page->mapping != inode->i_mapping) {
+			unlock_page(page);
+			return -EAGAIN;
 		}
 	}
 	return 0;
···
 	int faili;
 
 	for (i = 0; i < num_pages; i++) {
+again:
 		pages[i] = find_or_create_page(inode->i_mapping, index + i,
 					       mask | __GFP_WRITE);
 		if (!pages[i]) {
···
 		}
 
 		if (i == 0)
-			err = prepare_uptodate_page(pages[i], pos,
+			err = prepare_uptodate_page(inode, pages[i], pos,
 						    force_uptodate);
-		if (i == num_pages - 1)
-			err = prepare_uptodate_page(pages[i],
+		if (!err && i == num_pages - 1)
+			err = prepare_uptodate_page(inode, pages[i],
 						    pos + write_bytes, false);
 		if (err) {
 			page_cache_release(pages[i]);
+			if (err == -EAGAIN) {
+				err = 0;
+				goto again;
+			}
 			faili = i - 1;
 			goto fail;
 		}

fs/btrfs/free-space-cache.c

···
 		spin_unlock(&block_group->lock);
 		ret = 0;
 
-		btrfs_warn(fs_info, "failed to load free space cache for block group %llu, rebuild it now",
+		btrfs_warn(fs_info, "failed to load free space cache for block group %llu, rebuilding it now",
 			block_group->key.objectid);
 	}
 
···
 		     u64 cont1_bytes, u64 min_bytes)
 {
 	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
-	struct btrfs_free_space *entry;
+	struct btrfs_free_space *entry = NULL;
 	int ret = -ENOSPC;
 	u64 bitmap_offset = offset_to_bitmap(ctl, offset);
 
···
 	 * The bitmap that covers offset won't be in the list unless offset
 	 * is just its start offset.
 	 */
-	entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
-	if (entry->offset != bitmap_offset) {
+	if (!list_empty(bitmaps))
+		entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
+
+	if (!entry || entry->offset != bitmap_offset) {
 		entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
 		if (entry && list_empty(&entry->list))
 			list_add(&entry->list, bitmaps);

fs/btrfs/transaction.c

···
 	cur_trans->num_dirty_bgs = 0;
 	spin_lock_init(&cur_trans->dirty_bgs_lock);
 	INIT_LIST_HEAD(&cur_trans->deleted_bgs);
-	spin_lock_init(&cur_trans->deleted_bgs_lock);
 	spin_lock_init(&cur_trans->dropped_roots_lock);
 	list_add_tail(&cur_trans->list, &fs_info->trans_list);
 	extent_io_tree_init(&cur_trans->dirty_pages,

fs/btrfs/transaction.h

···
 	 */
 	struct mutex cache_write_mutex;
 	spinlock_t dirty_bgs_lock;
+	/* Protected by spin lock fs_info->unused_bgs_lock. */
 	struct list_head deleted_bgs;
-	spinlock_t deleted_bgs_lock;
 	spinlock_t dropped_roots_lock;
 	struct btrfs_delayed_ref_root delayed_refs;
 	int aborted;

fs/btrfs/volumes.c

···
 
 			ret = btrfs_force_chunk_alloc(trans, chunk_root,
 						      BTRFS_BLOCK_GROUP_DATA);
+			btrfs_end_transaction(trans, chunk_root);
 			if (ret < 0) {
 				mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 				goto error;
 			}
-
-			btrfs_end_transaction(trans, chunk_root);
 			chunk_reserved = 1;
 		}