Btrfs: two stage dirty block group writeout

Block group cache writeout is currently waiting on the pages for each
block group cache before moving on to writing the next one.  This commit
switches things around to send down all the caches and then wait on them
in batches.

The end result is much faster, since we're keeping the disk pipeline
full.

Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/btrfs/free-space-cache.h b/fs/btrfs/free-space-cache.h
index 88b2238a0aed..c4339863af05 100644
--- a/fs/btrfs/free-space-cache.h
+++ b/fs/btrfs/free-space-cache.h
@@ -48,6 +48,8 @@ struct btrfs_free_space_op {
                            struct btrfs_free_space *info);
 };
 
+struct btrfs_io_ctl;
+
 struct inode *lookup_free_space_inode(struct btrfs_root *root,
                                       struct btrfs_block_group_cache
                                       *block_group, struct btrfs_path *path);
@@ -63,11 +65,15 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
                                     struct inode *inode);
 int load_free_space_cache(struct btrfs_fs_info *fs_info,
                           struct btrfs_block_group_cache *block_group);
+int btrfs_wait_cache_io(struct btrfs_root *root,
+                        struct btrfs_trans_handle *trans,
+                        struct btrfs_block_group_cache *block_group,
+                        struct btrfs_io_ctl *io_ctl,
+                        struct btrfs_path *path, u64 offset);
 int btrfs_write_out_cache(struct btrfs_root *root,
                           struct btrfs_trans_handle *trans,
                           struct btrfs_block_group_cache *block_group,
                           struct btrfs_path *path);
-
 struct inode *lookup_free_ino_inode(struct btrfs_root *root,
                                     struct btrfs_path *path);
 int create_free_ino_inode(struct btrfs_root *root,