Commit 853960d0 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Simplify, fix bch2_backpointer_get_key() 



 - backpointer_not_found() checks backpointers_no_use_write_buffer, no
   need to do it inbackpointer_get_key().

 - always use backpointer_get_node() for pointers to nodes:
   backpointer_get_key() was sometimes returning the key from the root
   node unlocked.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent daba90f2

fs/bcachefs/backpointers.c

+33 −44
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include "backpointers.h"

#include "btree_cache.h"

#include "btree_update.h"

#include "btree_update_interior.h"

#include "btree_write_buffer.h"

#include "error.h"
@@ -226,6 +227,11 @@ static void backpointer_not_found(struct btree_trans *trans, 
	struct printbuf buf = PRINTBUF;

	struct bpos bucket = bp_pos_to_bucket(c, bp_pos);



	/*

	 * If we're using the btree write buffer, the backpointer we were

	 * looking at may have already been deleted - failure to find what it

	 * pointed to is not an error:

	 */

	if (likely(!bch2_backpointers_no_use_write_buffer))

		return;
@@ -256,16 +262,15 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans, 
					 struct bch_backpointer bp,

					 unsigned iter_flags)

{

	if (likely(!bp.level)) {

		struct bch_fs *c = trans->c;

	struct btree_root *r = bch2_btree_id_root(c, bp.btree_id);

		struct bpos bucket = bp_pos_to_bucket(c, bp_pos);

		struct bkey_s_c k;



		bch2_trans_node_iter_init(trans, iter,

					  bp.btree_id,

					  bp.pos,

				  0,

				  min(bp.level, r->level),

					  0, 0,

					  iter_flags);

		k = bch2_btree_iter_peek_slot(iter);

		if (bkey_err(k)) {
@@ -273,39 +278,21 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans, 
			return k;

		}



	if (bp.level == r->level + 1)

		k = bkey_i_to_s_c(&r->key);



		if (k.k && extent_matches_bp(c, bp.btree_id, bp.level, k, bucket, bp))

			return k;



		bch2_trans_iter_exit(trans, iter);

		backpointer_not_found(trans, bp_pos, bp, k);

		return bkey_s_c_null;

	} else {

		struct btree *b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);



	if (unlikely(bch2_backpointers_no_use_write_buffer)) {

		if (bp.level) {

			struct btree *b;



			/*

			 * If a backpointer for a btree node wasn't found, it may be

			 * because it was overwritten by a new btree node that hasn't

			 * been written out yet - backpointer_get_node() checks for

			 * this:

			 */

			b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);

			if (!IS_ERR_OR_NULL(b))

				return bkey_i_to_s_c(&b->key);



		if (IS_ERR_OR_NULL(b)) {

			bch2_trans_iter_exit(trans, iter);



			if (IS_ERR(b))

				return bkey_s_c_err(PTR_ERR(b));

			return bkey_s_c_null;

			return IS_ERR(b) ? bkey_s_c_err(PTR_ERR(b)) : bkey_s_c_null;

		}



		backpointer_not_found(trans, bp_pos, bp, k);

		return bkey_i_to_s_c(&b->key);

	}



	return bkey_s_c_null;

}



struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
@@ -329,6 +316,8 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans, 
	if (IS_ERR(b))

		goto err;



	BUG_ON(b->c.level != bp.level - 1);



	if (b && extent_matches_bp(c, bp.btree_id, bp.level,

				   bkey_i_to_s_c(&b->key),

				   bucket, bp))