Commit a98048e1 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: simplify obtaining a delayed ref head 



Instead of doing it in two steps outside of delayed-ref.c, leaking low
level details such as locking, move the logic entirely to delayed-ref.c
under btrfs_select_ref_head(), reducing code and making things simpler
for the caller.

Reviewed-by: default avatarBoris Burkov <boris@bur.io>
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 7ef36048

fs/btrfs/delayed-ref.c

+22 −5
Original line number Diff line number Diff line
@@ -431,7 +431,7 @@ static struct btrfs_delayed_ref_head *find_ref_head( 
	return NULL;

}



bool btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,

static bool btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,

				   struct btrfs_delayed_ref_head *head)

{

	lockdep_assert_held(&delayed_refs->lock);
@@ -561,8 +561,9 @@ struct btrfs_delayed_ref_head *btrfs_select_ref_head( 
		struct btrfs_delayed_ref_root *delayed_refs)

{

	struct btrfs_delayed_ref_head *head;

	bool locked;



	lockdep_assert_held(&delayed_refs->lock);

	spin_lock(&delayed_refs->lock);

again:

	head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,

			     true);
@@ -570,16 +571,20 @@ struct btrfs_delayed_ref_head *btrfs_select_ref_head( 
		delayed_refs->run_delayed_start = 0;

		head = find_first_ref_head(delayed_refs);

	}

	if (!head)

	if (!head) {

		spin_unlock(&delayed_refs->lock);

		return NULL;

	}



	while (head->processing) {

		struct rb_node *node;



		node = rb_next(&head->href_node);

		if (!node) {

			if (delayed_refs->run_delayed_start == 0)

			if (delayed_refs->run_delayed_start == 0) {

				spin_unlock(&delayed_refs->lock);

				return NULL;

			}

			delayed_refs->run_delayed_start = 0;

			goto again;

		}
@@ -592,6 +597,18 @@ struct btrfs_delayed_ref_head *btrfs_select_ref_head( 
	delayed_refs->num_heads_ready--;

	delayed_refs->run_delayed_start = head->bytenr +

		head->num_bytes;



	locked = btrfs_delayed_ref_lock(delayed_refs, head);

	spin_unlock(&delayed_refs->lock);



	/*

	 * We may have dropped the spin lock to get the head mutex lock, and

	 * that might have given someone else time to free the head.  If that's

	 * true, it has been removed from our list and we can move on.

	 */

	if (!locked)

		return ERR_PTR(-EAGAIN);



	return head;

}

fs/btrfs/delayed-ref.h

+0 −2
Original line number Diff line number Diff line
@@ -369,8 +369,6 @@ void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info, 
struct btrfs_delayed_ref_head *

btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,

			    u64 bytenr);

bool btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,

			    struct btrfs_delayed_ref_head *head);

static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)

{

	mutex_unlock(&head->mutex);

fs/btrfs/extent-tree.c

+1 −34
Original line number Diff line number Diff line
@@ -1953,39 +1953,6 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans, 
	return ret;

}



static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(

					struct btrfs_trans_handle *trans)

{

	struct btrfs_delayed_ref_root *delayed_refs =

		&trans->transaction->delayed_refs;

	struct btrfs_delayed_ref_head *head = NULL;

	bool locked;



	spin_lock(&delayed_refs->lock);

	head = btrfs_select_ref_head(delayed_refs);

	if (!head) {

		spin_unlock(&delayed_refs->lock);

		return head;

	}



	/*

	 * Grab the lock that says we are going to process all the refs for

	 * this head

	 */

	locked = btrfs_delayed_ref_lock(delayed_refs, head);

	spin_unlock(&delayed_refs->lock);



	/*

	 * We may have dropped the spin lock to get the head mutex lock, and

	 * that might have given someone else time to free the head.  If that's

	 * true, it has been removed from our list and we can move on.

	 */

	if (!locked)

		head = ERR_PTR(-EAGAIN);



	return head;

}



static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,

					   struct btrfs_delayed_ref_head *locked_ref,

					   u64 *bytes_released)
@@ -2092,7 +2059,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, 


	do {

		if (!locked_ref) {

			locked_ref = btrfs_obtain_ref_head(trans);

			locked_ref = btrfs_select_ref_head(delayed_refs);

			if (IS_ERR_OR_NULL(locked_ref)) {

				if (PTR_ERR(locked_ref) == -EAGAIN) {

					continue;