Commit 53863232 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Lower contention on the csum mutex 



This takes the csum mutex deeper in the call chain and releases it
more often.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4854ddd0

fs/btrfs/async-thread.c

+2 −1
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ struct btrfs_worker_thread { 


	/* number of things on the pending list */

	atomic_t num_pending;



	unsigned long sequence;



	/* protects the pending list. */
@@ -242,7 +243,7 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers) 
	worker = list_entry(next, struct btrfs_worker_thread, worker_list);

	atomic_inc(&worker->num_pending);

	worker->sequence++;

	if (worker->sequence % 4 == 0)

	if (worker->sequence % workers->idle_thresh == 0)

		list_move_tail(next, &workers->worker_list);

	return worker;

}

fs/btrfs/disk-io.c

+8 −1
Original line number Diff line number Diff line
@@ -1386,7 +1386,14 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	 * devices

	 */

	fs_info->submit_workers.idle_thresh = 64;

	fs_info->workers.idle_thresh = 32;



	/* fs_info->workers is responsible for checksumming file data

	 * blocks and metadata.  Using a larger idle thresh allows each

	 * worker thread to operate on things in roughly the order they

	 * were sent by the writeback daemons, improving overall locality

	 * of the IO going down the pipe.

	 */

	fs_info->workers.idle_thresh = 128;



	btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);

	btrfs_init_workers(&fs_info->endio_workers, "endio",

fs/btrfs/file-item.c

+12 −4
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans, 
	file_key.offset = offset;

	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);



	mutex_lock(&BTRFS_I(inode)->csum_mutex);

	item = btrfs_lookup_csum(trans, root, path, objectid, offset, 1);

	if (!IS_ERR(item)) {

		leaf = path->nodes[0];
@@ -367,7 +368,7 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans, 
	ret = btrfs_search_slot(trans, root, &file_key, path,

				BTRFS_CRC32_SIZE, 1);

	if (ret < 0)

		goto fail;

		goto fail_unlock;

	if (ret == 0) {

		BUG();

	}
@@ -411,10 +412,10 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans, 
	ret = btrfs_insert_empty_item(trans, root, path, &file_key,

				      ins_size);

	if (ret < 0)

		goto fail;

		goto fail_unlock;

	if (ret != 0) {

		WARN_ON(1);

		goto fail;

		goto fail_unlock;

	}

csum:

	leaf = path->nodes[0];
@@ -427,6 +428,8 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans, 
	item_end = (struct btrfs_csum_item *)((unsigned char *)item_end +

				      btrfs_item_size_nr(leaf, path->slots[0]));

	eb_token = NULL;

	mutex_unlock(&BTRFS_I(inode)->csum_mutex);

	cond_resched();

next_sector:



	if (!eb_token ||
@@ -467,13 +470,18 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans, 
		eb_token = NULL;

	}

	btrfs_mark_buffer_dirty(path->nodes[0]);

	cond_resched();

	if (total_bytes < sums->len) {

		btrfs_release_path(root, path);

		goto again;

	}

fail:

out:

	btrfs_free_path(path);

	return ret;



fail_unlock:

	mutex_unlock(&BTRFS_I(inode)->csum_mutex);

	goto out;

}



int btrfs_csum_truncate(struct btrfs_trans_handle *trans,

fs/btrfs/inode.c

+0 −2
Original line number Diff line number Diff line
@@ -415,10 +415,8 @@ static noinline int add_pending_csums(struct btrfs_trans_handle *trans, 
	btrfs_set_trans_block_group(trans, inode);

	list_for_each(cur, list) {

		sum = list_entry(cur, struct btrfs_ordered_sum, list);

		mutex_lock(&BTRFS_I(inode)->csum_mutex);

		btrfs_csum_file_blocks(trans, BTRFS_I(inode)->root,

				       inode, sum);

		mutex_unlock(&BTRFS_I(inode)->csum_mutex);

	}

	return 0;

}