Commit 1cc127b5 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Add a thread pool just for submit_bio 



If a bio submission is after a lock holder waiting for the bio
on the work queue, it is possible to deadlock.  Move the bios
into their own pool.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent df5b5520

fs/btrfs/ctree.h

+4 −0
Original line number Diff line number Diff line
@@ -529,9 +529,13 @@ struct btrfs_fs_info { 
	 * can run with FS locks held, and the writers may be waiting for

	 * those locks.  We don't want ordering in the pending list to cause

	 * deadlocks, and so the two are serviced separately.

	 *

	 * A third pool does submit_bio to avoid deadlocking with the other

	 * two

	 */

	struct btrfs_workers workers;

	struct btrfs_workers endio_workers;

	struct btrfs_workers submit_workers;

	int thread_pool_size;



#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)

fs/btrfs/disk-io.c

+4 −0
Original line number Diff line number Diff line
@@ -1233,8 +1233,10 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	 * cannot dynamically grow.

	 */

	btrfs_init_workers(&fs_info->workers, fs_info->thread_pool_size);

	btrfs_init_workers(&fs_info->submit_workers, fs_info->thread_pool_size);

	btrfs_init_workers(&fs_info->endio_workers, fs_info->thread_pool_size);

	btrfs_start_workers(&fs_info->workers, 1);

	btrfs_start_workers(&fs_info->submit_workers, 1);

	btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
@@ -1343,6 +1345,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, 
	extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);

	btrfs_stop_workers(&fs_info->workers);

	btrfs_stop_workers(&fs_info->endio_workers);

	btrfs_stop_workers(&fs_info->submit_workers);

fail_iput:

	iput(fs_info->btree_inode);

fail:
@@ -1597,6 +1600,7 @@ int close_ctree(struct btrfs_root *root) 


	btrfs_stop_workers(&fs_info->workers);

	btrfs_stop_workers(&fs_info->endio_workers);

	btrfs_stop_workers(&fs_info->submit_workers);



	iput(fs_info->btree_inode);

#if 0

fs/btrfs/volumes.c

+2 −1
Original line number Diff line number Diff line
@@ -2112,7 +2112,8 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device, 
	spin_unlock(&device->io_lock);



	if (should_queue)

		btrfs_queue_worker(&root->fs_info->workers, &device->work);

		btrfs_queue_worker(&root->fs_info->submit_workers,

				   &device->work);

	return 0;

}