Btrfs: New data=ordered implementation

The old data=ordered code would force commit to wait until
all the data extents from the transaction were fully on disk.  This
introduced large latencies into the commit and stalled new writers
in the transaction for a long time.

The new code changes the way data allocations and extents work:

* When delayed allocation is filled, data extents are reserved, and
  the extent bit EXTENT_ORDERED is set on the entire range of the extent.
  A struct btrfs_ordered_extent is allocated an inserted into a per-inode
  rbtree to track the pending extents.

* As each page is written EXTENT_ORDERED is cleared on the bytes corresponding
  to that page.

* When all of the bytes corresponding to a single struct btrfs_ordered_extent
  are written, The previously reserved extent is inserted into the FS
  btree and into the extent allocation trees.  The checksums for the file
  data are also updated.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f3783db..ceebc05 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -25,6 +25,7 @@
 #include <linux/fs.h>
 #include <linux/completion.h>
 #include <linux/backing-dev.h>
+#include <linux/wait.h>
 #include <asm/kmap_types.h>
 #include "bit-radix.h"
 #include "extent_io.h"
@@ -37,6 +38,7 @@ extern struct kmem_cache *btrfs_trans_handle_cachep;
 extern struct kmem_cache *btrfs_transaction_cachep;
 extern struct kmem_cache *btrfs_bit_radix_cachep;
 extern struct kmem_cache *btrfs_path_cachep;
+struct btrfs_ordered_sum;
 
 #define BTRFS_MAGIC "_B5RfS_M"
 
@@ -510,6 +512,7 @@ struct btrfs_fs_info {
 	u64 max_inline;
 	u64 alloc_start;
 	struct btrfs_transaction *running_transaction;
+	wait_queue_head_t transaction_throttle;
 	struct btrfs_super_block super_copy;
 	struct btrfs_super_block super_for_commit;
 	struct block_device *__bdev;
@@ -541,6 +544,7 @@ struct btrfs_fs_info {
 	 */
 	struct btrfs_workers workers;
 	struct btrfs_workers endio_workers;
+	struct btrfs_workers endio_write_workers;
 	struct btrfs_workers submit_workers;
 	struct task_struct *transaction_kthread;
 	struct task_struct *cleaner_kthread;
@@ -1384,6 +1388,17 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
 		       u64 owner, u64 owner_offset,
 		       u64 empty_size, u64 hint_byte,
 		       u64 search_end, struct btrfs_key *ins, u64 data);
+int btrfs_alloc_reserved_extent(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				u64 root_objectid, u64 ref_generation,
+				u64 owner, u64 owner_offset,
+				struct btrfs_key *ins);
+int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  u64 num_bytes, u64 min_alloc_size,
+				  u64 empty_size, u64 hint_byte,
+				  u64 search_end, struct btrfs_key *ins,
+				  u64 data);
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		  struct extent_buffer *buf);
 int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
@@ -1556,9 +1571,9 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 			     u64 bytenr, int mod);
 int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 			   struct btrfs_root *root, struct inode *inode,
-			   struct bio *bio, char *sums);
+			   struct btrfs_ordered_sum *sums);
 int btrfs_csum_one_bio(struct btrfs_root *root,
-		       struct bio *bio, char **sums_ret);
+		       struct bio *bio, struct btrfs_ordered_sum **sums_ret);
 struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 					  struct btrfs_root *root,
 					  struct btrfs_path *path,