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Commit 00361589 authored by Josef Bacik's avatar Josef Bacik Committed by Chris Mason
Browse files

Btrfs: avoid starting a transaction in the write path 



I noticed while looking at a deadlock that we are always starting a transaction
in cow_file_range().  This isn't really needed since we only need a transaction
if we are doing an inline extent, or if the allocator needs to allocate a chunk.
So push down all the transaction start stuff to be closer to where we actually
need a transaction in all of these cases.  This will hopefully reduce our write
latency when we are committing often.  Thanks,

Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
Signed-off-by: default avatarChris Mason <chris.mason@fusionio.com>
parent 9ffba8cd

fs/btrfs/ctree.h

+4 −7
Original line number Diff line number Diff line
@@ -3165,10 +3165,8 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans, 
				   struct btrfs_root *root,

				   u64 root_objectid, u64 owner, u64 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,

int btrfs_reserve_extent(struct btrfs_root *root, u64 num_bytes,

			 u64 min_alloc_size, u64 empty_size, u64 hint_byte,

			 struct btrfs_key *ins, int is_data);

int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,

		  struct extent_buffer *buf, int full_backref, int for_cow);
@@ -3612,8 +3610,7 @@ void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work); 
struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *page,

					   size_t pg_offset, u64 start, u64 len,

					   int create);

noinline int can_nocow_extent(struct btrfs_trans_handle *trans,

			      struct inode *inode, u64 offset, u64 *len,

noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,

			      u64 *orig_start, u64 *orig_block_len,

			      u64 *ram_bytes);

fs/btrfs/extent-tree.c

+22 −13
Original line number Diff line number Diff line
@@ -6121,8 +6121,7 @@ enum btrfs_loop_type { 
 * ins->offset == number of blocks

 * Any available blocks before search_start are skipped.

 */

static noinline int find_free_extent(struct btrfs_trans_handle *trans,

				     struct btrfs_root *orig_root,

static noinline int find_free_extent(struct btrfs_root *orig_root,

				     u64 num_bytes, u64 empty_size,

				     u64 hint_byte, struct btrfs_key *ins,

				     u64 flags)
@@ -6345,9 +6344,9 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans, 
					      block_group->full_stripe_len);



			/* allocate a cluster in this block group */

			ret = btrfs_find_space_cluster(trans, root,

					       block_group, last_ptr,

					       search_start, num_bytes,

			ret = btrfs_find_space_cluster(root, block_group,

						       last_ptr, search_start,

						       num_bytes,

						       aligned_cluster);

			if (ret == 0) {

				/*
@@ -6479,18 +6478,29 @@ static noinline int find_free_extent(struct btrfs_trans_handle *trans, 
		index = 0;

		loop++;

		if (loop == LOOP_ALLOC_CHUNK) {

			struct btrfs_trans_handle *trans;



			trans = btrfs_join_transaction(root);

			if (IS_ERR(trans)) {

				ret = PTR_ERR(trans);

				goto out;

			}



			ret = do_chunk_alloc(trans, root, flags,

					     CHUNK_ALLOC_FORCE);

			/*

			 * Do not bail out on ENOSPC since we

			 * can do more things.

			 */

			if (ret < 0 && ret != -ENOSPC) {

			if (ret < 0 && ret != -ENOSPC)

				btrfs_abort_transaction(trans,

							root, ret);

			else

				ret = 0;

			btrfs_end_transaction(trans, root);

			if (ret)

				goto out;

		}

		}



		if (loop == LOOP_NO_EMPTY_SIZE) {

			empty_size = 0;
@@ -6553,8 +6563,7 @@ static void dump_space_info(struct btrfs_space_info *info, u64 bytes, 
	up_read(&info->groups_sem);

}



int btrfs_reserve_extent(struct btrfs_trans_handle *trans,

			 struct btrfs_root *root,

int btrfs_reserve_extent(struct btrfs_root *root,

			 u64 num_bytes, u64 min_alloc_size,

			 u64 empty_size, u64 hint_byte,

			 struct btrfs_key *ins, int is_data)
@@ -6566,8 +6575,8 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans, 
	flags = btrfs_get_alloc_profile(root, is_data);

again:

	WARN_ON(num_bytes < root->sectorsize);

	ret = find_free_extent(trans, root, num_bytes, empty_size,

			       hint_byte, ins, flags);

	ret = find_free_extent(root, num_bytes, empty_size, hint_byte, ins,

			       flags);



	if (ret == -ENOSPC) {

		if (!final_tried) {
@@ -6955,7 +6964,7 @@ struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans, 
	if (IS_ERR(block_rsv))

		return ERR_CAST(block_rsv);



	ret = btrfs_reserve_extent(trans, root, blocksize, blocksize,

	ret = btrfs_reserve_extent(root, blocksize, blocksize,

				   empty_size, hint, &ins, 0);

	if (ret) {

		unuse_block_rsv(root->fs_info, block_rsv, blocksize);

fs/btrfs/file.c

+1 −10
Original line number Diff line number Diff line
@@ -1339,7 +1339,6 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file, 
static noinline int check_can_nocow(struct inode *inode, loff_t pos,

				    size_t *write_bytes)

{

	struct btrfs_trans_handle *trans;

	struct btrfs_root *root = BTRFS_I(inode)->root;

	struct btrfs_ordered_extent *ordered;

	u64 lockstart, lockend;
@@ -1361,16 +1360,8 @@ static noinline int check_can_nocow(struct inode *inode, loff_t pos, 
		btrfs_put_ordered_extent(ordered);

	}



	trans = btrfs_join_transaction(root);

	if (IS_ERR(trans)) {

		unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);

		return PTR_ERR(trans);

	}



	num_bytes = lockend - lockstart + 1;

	ret = can_nocow_extent(trans, inode, lockstart, &num_bytes, NULL, NULL,

			       NULL);

	btrfs_end_transaction(trans, root);

	ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);

	if (ret <= 0) {

		ret = 0;

	} else {

fs/btrfs/free-space-cache.c

+1 −2
Original line number Diff line number Diff line
@@ -2525,8 +2525,7 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, 
 * returns zero and sets up cluster if things worked out, otherwise

 * it returns -enospc

 */

int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,

			     struct btrfs_root *root,

int btrfs_find_space_cluster(struct btrfs_root *root,

			     struct btrfs_block_group_cache *block_group,

			     struct btrfs_free_cluster *cluster,

			     u64 offset, u64 bytes, u64 empty_size)

fs/btrfs/free-space-cache.h

+1 −2
Original line number Diff line number Diff line
@@ -98,8 +98,7 @@ u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group, 
u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root);

void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,

			   u64 bytes);

int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,

			     struct btrfs_root *root,

int btrfs_find_space_cluster(struct btrfs_root *root,

			     struct btrfs_block_group_cache *block_group,

			     struct btrfs_free_cluster *cluster,

			     u64 offset, u64 bytes, u64 empty_size);