1 files changed, 74 insertions, 46 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 6c24b69e2d0a..a9778a91511e 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -160,14 +160,16 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
  * @compress_type:   Compression algorithm used for data.
  *
  * Most of these parameters correspond to &struct btrfs_file_extent_item. The
- * tree is given a single reference on the ordered extent that was inserted.
+ * tree is given a single reference on the ordered extent that was inserted, and
+ * the returned pointer is given a second reference.
  *
- * Return: 0 or -ENOMEM.
+ * Return: the new ordered extent or error pointer.
  */
-int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
-			     u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
-			     u64 disk_num_bytes, u64 offset, unsigned flags,
-			     int compress_type)
+struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
+			struct btrfs_inode *inode, u64 file_offset,
+			u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+			u64 disk_num_bytes, u64 offset, unsigned long flags,
+			int compress_type)
 {
 	struct btrfs_root *root = inode->root;
 	struct btrfs_fs_info *fs_info = root->fs_info;
@@ -181,7 +183,7 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
 		/* For nocow write, we can release the qgroup rsv right now */
 		ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes);
 		if (ret < 0)
-			return ret;
+			return ERR_PTR(ret);
 		ret = 0;
 	} else {
 		/*
@@ -190,11 +192,11 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
 		 */
 		ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes);
 		if (ret < 0)
-			return ret;
+			return ERR_PTR(ret);
 	}
 	entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
 	if (!entry)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	entry->file_offset = file_offset;
 	entry->num_bytes = num_bytes;
@@ -256,6 +258,32 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
 	btrfs_mod_outstanding_extents(inode, 1);
 	spin_unlock(&inode->lock);
 
+	/* One ref for the returned entry to match semantics of lookup. */
+	refcount_inc(&entry->refs);
+
+	return entry;
+}
+
+/*
+ * Add a new btrfs_ordered_extent for the range, but drop the reference instead
+ * of returning it to the caller.
+ */
+int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
+			     u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+			     u64 disk_num_bytes, u64 offset, unsigned long flags,
+			     int compress_type)
+{
+	struct btrfs_ordered_extent *ordered;
+
+	ordered = btrfs_alloc_ordered_extent(inode, file_offset, num_bytes,
+					     ram_bytes, disk_bytenr,
+					     disk_num_bytes, offset, flags,
+					     compress_type);
+
+	if (IS_ERR(ordered))
+		return PTR_ERR(ordered);
+	btrfs_put_ordered_extent(ordered);
+
 	return 0;
 }
 
@@ -1088,39 +1116,37 @@ bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end,
 	return false;
 }
 
-
-static int clone_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pos,
-				u64 len)
-{
-	struct inode *inode = ordered->inode;
-	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
-	u64 file_offset = ordered->file_offset + pos;
-	u64 disk_bytenr = ordered->disk_bytenr + pos;
-	unsigned long flags = ordered->flags & BTRFS_ORDERED_TYPE_FLAGS;
-
-	/*
-	 * The splitting extent is already counted and will be added again in
-	 * btrfs_add_ordered_extent_*(). Subtract len to avoid double counting.
-	 */
-	percpu_counter_add_batch(&fs_info->ordered_bytes, -len,
-				 fs_info->delalloc_batch);
-	WARN_ON_ONCE(flags & (1 << BTRFS_ORDERED_COMPRESSED));
-	return btrfs_add_ordered_extent(BTRFS_I(inode), file_offset, len, len,
-					disk_bytenr, len, 0, flags,
-					ordered->compress_type);
-}
-
-int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pre,
-				u64 post)
+/* Split out a new ordered extent for this first @len bytes of @ordered. */
+int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 len)
 {
 	struct inode *inode = ordered->inode;
 	struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
-	struct rb_node *node;
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
-	int ret = 0;
+	u64 file_offset = ordered->file_offset;
+	u64 disk_bytenr = ordered->disk_bytenr;
+	unsigned long flags = ordered->flags & BTRFS_ORDERED_TYPE_FLAGS;
+	struct rb_node *node;
 
 	trace_btrfs_ordered_extent_split(BTRFS_I(inode), ordered);
 
+	ASSERT(!(flags & (1U << BTRFS_ORDERED_COMPRESSED)));
+
+	/*
+	 * The entire bio must be covered by the ordered extent, but we can't
+	 * reduce the original extent to a zero length either.
+	 */
+	if (WARN_ON_ONCE(len >= ordered->num_bytes))
+		return -EINVAL;
+	/* We cannot split once ordered extent is past end_bio. */
+	if (WARN_ON_ONCE(ordered->bytes_left != ordered->disk_num_bytes))
+		return -EINVAL;
+	/* We cannot split a compressed ordered extent. */
+	if (WARN_ON_ONCE(ordered->disk_num_bytes != ordered->num_bytes))
+		return -EINVAL;
+	/* Checksum list should be empty. */
+	if (WARN_ON_ONCE(!list_empty(&ordered->list)))
+		return -EINVAL;
+
 	spin_lock_irq(&tree->lock);
 	/* Remove from tree once */
 	node = &ordered->rb_node;
@@ -1129,11 +1155,11 @@ int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pre,
 	if (tree->last == node)
 		tree->last = NULL;
 
-	ordered->file_offset += pre;
-	ordered->disk_bytenr += pre;
-	ordered->num_bytes -= (pre + post);
-	ordered->disk_num_bytes -= (pre + post);
-	ordered->bytes_left -= (pre + post);
+	ordered->file_offset += len;
+	ordered->disk_bytenr += len;
+	ordered->num_bytes -= len;
+	ordered->disk_num_bytes -= len;
+	ordered->bytes_left -= len;
 
 	/* Re-insert the node */
 	node = tree_insert(&tree->tree, ordered->file_offset, &ordered->rb_node);
@@ -1144,13 +1170,15 @@ int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pre,
 
 	spin_unlock_irq(&tree->lock);
 
-	if (pre)
-		ret = clone_ordered_extent(ordered, 0, pre);
-	if (ret == 0 && post)
-		ret = clone_ordered_extent(ordered, pre + ordered->disk_num_bytes,
-					   post);
+	/*
+	 * The splitting extent is already counted and will be added again in
+	 * btrfs_add_ordered_extent(). Subtract len to avoid double counting.
+	 */
+	percpu_counter_add_batch(&fs_info->ordered_bytes, -len, fs_info->delalloc_batch);
 
-	return ret;
+	return btrfs_add_ordered_extent(BTRFS_I(inode), file_offset, len, len,
+					disk_bytenr, len, 0, flags,
+					ordered->compress_type);
 }
 
 int __init ordered_data_init(void)