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Commit e7261386 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: Factor out loop processing all refs of a head 



This patch introduces a new helper encompassing the implicit inner loop
in __btrfs_run_delayed_refs which processes all the refs for a given
head. The code is mostly copy/paste, the only difference is that if we
detect a newer reference then -EAGAIN is returned so that callers can
react correctly.

Also, at the end of the loop the head is relocked and
btrfs_merge_delayed_refs is run again to retain the pre-refactoring
semantics.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b1cdbcb5

fs/btrfs/extent-tree.c

+77 −0
Original line number Diff line number Diff line
@@ -2535,6 +2535,83 @@ static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head( 
	return head;

}



static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,

				    struct btrfs_delayed_ref_head *locked_ref,

				    unsigned long *run_refs)

{

	struct btrfs_fs_info *fs_info = trans->fs_info;

	struct btrfs_delayed_ref_root *delayed_refs;

	struct btrfs_delayed_extent_op *extent_op;

	struct btrfs_delayed_ref_node *ref;

	int must_insert_reserved = 0;

	int ret;



	delayed_refs = &trans->transaction->delayed_refs;



	while ((ref = select_delayed_ref(locked_ref))) {

		if (ref->seq &&

		    btrfs_check_delayed_seq(fs_info, ref->seq)) {

			spin_unlock(&locked_ref->lock);

			unselect_delayed_ref_head(delayed_refs, locked_ref);

			return -EAGAIN;

		}



		(*run_refs)++;

		ref->in_tree = 0;

		rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);

		RB_CLEAR_NODE(&ref->ref_node);

		if (!list_empty(&ref->add_list))

			list_del(&ref->add_list);

		/*

		 * When we play the delayed ref, also correct the ref_mod on

		 * head

		 */

		switch (ref->action) {

		case BTRFS_ADD_DELAYED_REF:

		case BTRFS_ADD_DELAYED_EXTENT:

			locked_ref->ref_mod -= ref->ref_mod;

			break;

		case BTRFS_DROP_DELAYED_REF:

			locked_ref->ref_mod += ref->ref_mod;

			break;

		default:

			WARN_ON(1);

		}

		atomic_dec(&delayed_refs->num_entries);



		/*

		 * Record the must_insert_reserved flag before we drop the

		 * spin lock.

		 */

		must_insert_reserved = locked_ref->must_insert_reserved;

		locked_ref->must_insert_reserved = 0;



		extent_op = locked_ref->extent_op;

		locked_ref->extent_op = NULL;

		spin_unlock(&locked_ref->lock);



		ret = run_one_delayed_ref(trans, ref, extent_op,

					  must_insert_reserved);



		btrfs_free_delayed_extent_op(extent_op);

		if (ret) {

			unselect_delayed_ref_head(delayed_refs, locked_ref);

			btrfs_put_delayed_ref(ref);

			btrfs_debug(fs_info, "run_one_delayed_ref returned %d",

				    ret);

			return ret;

		}



		btrfs_put_delayed_ref(ref);

		cond_resched();



		spin_lock(&locked_ref->lock);

		btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);

	}



	return 0;

}



/*

 * Returns 0 on success or if called with an already aborted transaction.

 * Returns -ENOMEM or -EIO on failure and will abort the transaction.