1 files changed, 28 insertions, 9 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 4aca7475fd82..1d7ddd664c0d 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -153,9 +153,10 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
 	struct btrfs_ordered_extent *entry;
 	int ret;
 	u64 qgroup_rsv = 0;
+	const bool is_nocow = (flags &
+	       ((1U << BTRFS_ORDERED_NOCOW) | (1U << BTRFS_ORDERED_PREALLOC)));
 
-	if (flags &
-	    ((1 << BTRFS_ORDERED_NOCOW) | (1 << BTRFS_ORDERED_PREALLOC))) {
+	if (is_nocow) {
 		/* For nocow write, we can release the qgroup rsv right now */
 		ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes, &qgroup_rsv);
 		if (ret < 0)
@@ -170,8 +171,13 @@ static struct btrfs_ordered_extent *alloc_ordered_extent(
 			return ERR_PTR(ret);
 	}
 	entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
-	if (!entry)
+	if (!entry) {
+		if (!is_nocow)
+			btrfs_qgroup_free_refroot(inode->root->fs_info,
+						  btrfs_root_id(inode->root),
+						  qgroup_rsv, BTRFS_QGROUP_RSV_DATA);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	entry->file_offset = file_offset;
 	entry->num_bytes = num_bytes;
@@ -253,7 +259,7 @@ static void insert_ordered_extent(struct btrfs_ordered_extent *entry)
  * @disk_bytenr:     Offset of extent on disk.
  * @disk_num_bytes:  Size of extent on disk.
  * @offset:          Offset into unencoded data where file data starts.
- * @flags:           Flags specifying type of extent (1 << BTRFS_ORDERED_*).
+ * @flags:           Flags specifying type of extent (1U << BTRFS_ORDERED_*).
  * @compress_type:   Compression algorithm used for data.
  *
  * Most of these parameters correspond to &struct btrfs_file_extent_item. The
@@ -842,10 +848,12 @@ void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
 /*
  * Start IO and wait for a given ordered extent to finish.
  *
- * Wait on page writeback for all the pages in the extent and the IO completion
- * code to insert metadata into the btree corresponding to the extent.
+ * Wait on page writeback for all the pages in the extent but not in
+ * [@nowriteback_start, @nowriteback_start + @nowriteback_len) and the
+ * IO completion code to insert metadata into the btree corresponding to the extent.
  */
-void btrfs_start_ordered_extent(struct btrfs_ordered_extent *entry)
+void btrfs_start_ordered_extent_nowriteback(struct btrfs_ordered_extent *entry,
+					    u64 nowriteback_start, u32 nowriteback_len)
 {
 	u64 start = entry->file_offset;
 	u64 end = start + entry->num_bytes - 1;
@@ -865,8 +873,19 @@ void btrfs_start_ordered_extent(struct btrfs_ordered_extent *entry)
 	 * start IO on any dirty ones so the wait doesn't stall waiting
 	 * for the flusher thread to find them
 	 */
-	if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
-		filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start, end);
+	if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags)) {
+		if (!nowriteback_len) {
+			filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start, end);
+		} else {
+			if (start < nowriteback_start)
+				filemap_fdatawrite_range(inode->vfs_inode.i_mapping, start,
+							 nowriteback_start - 1);
+			if (nowriteback_start + nowriteback_len < end)
+				filemap_fdatawrite_range(inode->vfs_inode.i_mapping,
+							 nowriteback_start + nowriteback_len,
+							 end);
+		}
+	}
 
 	if (!freespace_inode)
 		btrfs_might_wait_for_event(inode->root->fs_info, btrfs_ordered_extent);