bcachefs: Kill bch2_dev_bkey_exists() in backpointer code

Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/alloc_foreground.c

@@ -342,7 +342,7 @@ static struct open_bucket *try_alloc_bucket(struct btree_trans *trans, struct bc
 		struct bch_backpointer bp;
 		struct bpos bp_pos = POS_MIN;
 
-		ret = bch2_get_next_backpointer(trans, POS(ca->dev_idx, b), -1,
+		ret = bch2_get_next_backpointer(trans, ca, POS(ca->dev_idx, b), -1,
 						&bp_pos, &bp,
 						BTREE_ITER_nopreserve);
 		if (ret) {

fs/bcachefs/backpointers.c

@@ -23,20 +23,26 @@ static bool extent_matches_bp(struct bch_fs *c,
 	const union bch_extent_entry *entry;
 	struct extent_ptr_decoded p;
 
+	rcu_read_lock();
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 		struct bpos bucket2;
 		struct bch_backpointer bp2;
 
 		if (p.ptr.cached)
 			continue;
 
-		struct bch_dev *ca = bch2_dev_bkey_exists(c, p.ptr.dev);
+		struct bch_dev *ca = bch2_dev_rcu(c, p.ptr.dev);
+		if (!ca)
+			continue;
 
 		bch2_extent_ptr_to_bp(c, ca, btree_id, level, k, p, entry, &bucket2, &bp2);
 		if (bpos_eq(bucket, bucket2) &&
-		    !memcmp(&bp, &bp2, sizeof(bp)))
+		    !memcmp(&bp, &bp2, sizeof(bp))) {
+			rcu_read_unlock();
 			return true;
+		}
 	}
+	rcu_read_unlock();
 
 	return false;
 }
@@ -47,16 +53,21 @@ int bch2_backpointer_invalid(struct bch_fs *c, struct bkey_s_c k,
 {
 	struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
 
-	/* these will be caught by fsck */
-	if (!bch2_dev_exists(c, bp.k->p.inode))
+	rcu_read_lock();
+	struct bch_dev *ca = bch2_dev_rcu(c, bp.k->p.inode);
+	if (!ca) {
+		/* these will be caught by fsck */
+		rcu_read_unlock();
 		return 0;
+	}
 
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, bp.k->p.inode);
-	struct bpos bucket = bp_pos_to_bucket(c, bp.k->p);
+	struct bpos bucket = bp_pos_to_bucket(ca, bp.k->p);
+	struct bpos bp_pos = bucket_pos_to_bp_noerror(ca, bucket, bp.v->bucket_offset);
+	rcu_read_unlock();
 	int ret = 0;
 
 	bkey_fsck_err_on((bp.v->bucket_offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT) >= ca->mi.bucket_size ||
-			 !bpos_eq(bp.k->p, bucket_pos_to_bp_noerror(ca, bucket, bp.v->bucket_offset)),
+			 !bpos_eq(bp.k->p, bp_pos),
 			 c, err,
 			 backpointer_bucket_offset_wrong,
 			 "backpointer bucket_offset wrong");
@@ -77,10 +88,16 @@ void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer
 
 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 {
-	if (bch2_dev_exists(c, k.k->p.inode)) {
+	rcu_read_lock();
+	struct bch_dev *ca = bch2_dev_rcu(c, k.k->p.inode);
+	if (ca) {
+		struct bpos bucket = bp_pos_to_bucket(ca, k.k->p);
+		rcu_read_unlock();
 		prt_str(out, "bucket=");
-		bch2_bpos_to_text(out, bp_pos_to_bucket(c, k.k->p));
+		bch2_bpos_to_text(out, bucket);
 		prt_str(out, " ");
+	} else {
+		rcu_read_unlock();
 	}
 
 	bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
@@ -146,6 +163,7 @@ static noinline int backpointer_mod_err(struct btree_trans *trans,
 }
 
 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
+				struct bch_dev *ca,
 				struct bpos bucket,
 				struct bch_backpointer bp,
 				struct bkey_s_c orig_k,
@@ -162,7 +180,7 @@ int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 		return ret;
 
 	bkey_backpointer_init(&bp_k->k_i);
-	bp_k->k.p = bucket_pos_to_bp(trans->c, bucket, bp.bucket_offset);
+	bp_k->k.p = bucket_pos_to_bp(ca, bucket, bp.bucket_offset);
 	bp_k->v = bp;
 
 	if (!insert) {
@@ -198,13 +216,13 @@ int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
  * Find the next backpointer >= *bp_offset:
  */
 int bch2_get_next_backpointer(struct btree_trans *trans,
+			      struct bch_dev *ca,
 			      struct bpos bucket, int gen,
 			      struct bpos *bp_pos,
 			      struct bch_backpointer *bp,
 			      unsigned iter_flags)
 {
-	struct bch_fs *c = trans->c;
-	struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
+	struct bpos bp_end_pos = bucket_pos_to_bp(ca, bpos_nosnap_successor(bucket), 0);
 	struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 	struct bkey_s_c k;
 	int ret = 0;
@@ -224,7 +242,7 @@ int bch2_get_next_backpointer(struct btree_trans *trans,
 			goto done;
 	}
 
-	*bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
+	*bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(ca, bucket, 0));
 
 	for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
 				     *bp_pos, iter_flags, k, ret) {
@@ -250,7 +268,6 @@ static void backpointer_not_found(struct btree_trans *trans,
 {
 	struct bch_fs *c = trans->c;
 	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
@@ -260,6 +277,10 @@ static void backpointer_not_found(struct btree_trans *trans,
 	if (likely(!bch2_backpointers_no_use_write_buffer))
 		return;
 
+	struct bpos bucket;
+	if (!bp_pos_to_bucket_nodev(c, bp_pos, &bucket))
+		return;
+
 	prt_printf(&buf, "backpointer doesn't match %s it points to:\n  ",
 		   bp.level ? "btree node" : "extent");
 	prt_printf(&buf, "bucket: ");
@@ -289,15 +310,17 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 {
 	if (likely(!bp.level)) {
 		struct bch_fs *c = trans->c;
-		struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
-		struct bkey_s_c k;
+
+		struct bpos bucket;
+		if (!bp_pos_to_bucket_nodev(c, bp_pos, &bucket))
+			return bkey_s_c_err(-EIO);
 
 		bch2_trans_node_iter_init(trans, iter,
 					  bp.btree_id,
 					  bp.pos,
 					  0, 0,
 					  iter_flags);
-		k = bch2_btree_iter_peek_slot(iter);
+		struct bkey_s_c k = bch2_btree_iter_peek_slot(iter);
 		if (bkey_err(k)) {
 			bch2_trans_iter_exit(trans, iter);
 			return k;
@@ -326,18 +349,20 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 					struct bch_backpointer bp)
 {
 	struct bch_fs *c = trans->c;
-	struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
-	struct btree *b;
 
 	BUG_ON(!bp.level);
 
+	struct bpos bucket;
+	if (!bp_pos_to_bucket_nodev(c, bp_pos, &bucket))
+		return ERR_PTR(-EIO);
+
 	bch2_trans_node_iter_init(trans, iter,
 				  bp.btree_id,
 				  bp.pos,
 				  0,
 				  bp.level - 1,
 				  0);
-	b = bch2_btree_iter_peek_node(iter);
+	struct btree *b = bch2_btree_iter_peek_node(iter);
 	if (IS_ERR_OR_NULL(b))
 		goto err;
 
@@ -368,16 +393,16 @@ static int bch2_check_btree_backpointer(struct btree_trans *trans, struct btree_
 	struct printbuf buf = PRINTBUF;
 	int ret = 0;
 
-	if (fsck_err_on(!bch2_dev_exists(c, k.k->p.inode), c,
-			backpointer_to_missing_device,
-			"backpointer for missing device:\n%s",
-			(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
-		ret = bch2_btree_delete_at(trans, bp_iter, 0);
+	struct bpos bucket;
+	if (!bp_pos_to_bucket_nodev_noerror(c, k.k->p, &bucket)) {
+		if (fsck_err(c, backpointer_to_missing_device,
+			     "backpointer for missing device:\n%s",
+			     (bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
+			ret = bch2_btree_delete_at(trans, bp_iter, 0);
 		goto out;
 	}
 
-	alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc,
-				     bp_pos_to_bucket(c, k.k->p), 0);
+	alloc_k = bch2_bkey_get_iter(trans, &alloc_iter, BTREE_ID_alloc, bucket, 0);
 	ret = bkey_err(alloc_k);
 	if (ret)
 		goto out;
@@ -512,25 +537,27 @@ static int check_bp_exists(struct btree_trans *trans,
 	struct printbuf buf = PRINTBUF;
 	struct bkey_s_c bp_k;
 	struct bkey_buf tmp;
-	int ret;
+	int ret = 0;
 
 	bch2_bkey_buf_init(&tmp);
 
-	if (!bch2_dev_bucket_exists(c, bucket)) {
+	struct bch_dev *ca = bch2_dev_bucket_tryget(c, bucket);
+	if (!ca) {
 		prt_str(&buf, "extent for nonexistent device:bucket ");
 		bch2_bpos_to_text(&buf, bucket);
 		prt_str(&buf, "\n  ");
 		bch2_bkey_val_to_text(&buf, c, orig_k);
 		bch_err(c, "%s", buf.buf);
-		return -BCH_ERR_fsck_repair_unimplemented;
+		ret = -BCH_ERR_fsck_repair_unimplemented;
+		goto err;
 	}
 
 	if (bpos_lt(bucket, s->bucket_start) ||
 	    bpos_gt(bucket, s->bucket_end))
-		return 0;
+		goto out;
 
 	bp_k = bch2_bkey_get_iter(trans, &bp_iter, BTREE_ID_backpointers,
-				  bucket_pos_to_bp(c, bucket, bp.bucket_offset),
+				  bucket_pos_to_bp(ca, bucket, bp.bucket_offset),
 				  0);
 	ret = bkey_err(bp_k);
 	if (ret)
@@ -563,6 +590,7 @@ static int check_bp_exists(struct btree_trans *trans,
 	bch2_trans_iter_exit(trans, &other_extent_iter);
 	bch2_trans_iter_exit(trans, &bp_iter);
 	bch2_bkey_buf_exit(&tmp, c);
+	bch2_dev_put(ca);
 	printbuf_exit(&buf);
 	return ret;
 check_existing_bp:
@@ -638,13 +666,13 @@ static int check_bp_exists(struct btree_trans *trans,
 
 	struct bkey_i_backpointer n_bp_k;
 	bkey_backpointer_init(&n_bp_k.k_i);
-	n_bp_k.k.p = bucket_pos_to_bp(trans->c, bucket, bp.bucket_offset);
+	n_bp_k.k.p = bucket_pos_to_bp(ca, bucket, bp.bucket_offset);
 	n_bp_k.v = bp;
 	prt_printf(&buf, "\n  want:  ");
 	bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&n_bp_k.k_i));
 
 	if (fsck_err(c, ptr_to_missing_backpointer, "%s", buf.buf))
-		ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
+		ret = bch2_bucket_backpointer_mod(trans, ca, bucket, bp, orig_k, true);
 
 	goto out;
 }
@@ -668,8 +696,14 @@ static int check_extent_to_backpointers(struct btree_trans *trans,
 		if (p.ptr.cached)
 			continue;
 
-		struct bch_dev *ca = bch2_dev_bkey_exists(c, p.ptr.dev);
-		bch2_extent_ptr_to_bp(c, ca, btree, level, k, p, entry, &bucket_pos, &bp);
+		rcu_read_lock();
+		struct bch_dev *ca = bch2_dev_rcu(c, p.ptr.dev);
+		if (ca)
+			bch2_extent_ptr_to_bp(c, ca, btree, level, k, p, entry, &bucket_pos, &bp);
+		rcu_read_unlock();
+
+		if (!ca)
+			continue;
 
 		ret = check_bp_exists(trans, s, bucket_pos, bp, k);
 		if (ret)

fs/bcachefs/backpointers.h

@@ -6,6 +6,7 @@
 #include "btree_iter.h"
 #include "btree_update.h"
 #include "buckets.h"
+#include "error.h"
 #include "super.h"
 
 static inline u64 swab40(u64 x)
@@ -36,15 +37,29 @@ void bch2_backpointer_swab(struct bkey_s);
  * Convert from pos in backpointer btree to pos of corresponding bucket in alloc
  * btree:
  */
-static inline struct bpos bp_pos_to_bucket(const struct bch_fs *c,
-					   struct bpos bp_pos)
+static inline struct bpos bp_pos_to_bucket(const struct bch_dev *ca, struct bpos bp_pos)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, bp_pos.inode);
 	u64 bucket_sector = bp_pos.offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT;
 
 	return POS(bp_pos.inode, sector_to_bucket(ca, bucket_sector));
 }
 
+static inline bool bp_pos_to_bucket_nodev_noerror(struct bch_fs *c, struct bpos bp_pos, struct bpos *bucket)
+{
+	rcu_read_lock();
+	struct bch_dev *ca = bch2_dev_rcu(c, bp_pos.inode);
+	if (ca)
+		*bucket = bp_pos_to_bucket(ca, bp_pos);
+	rcu_read_unlock();
+	return ca != NULL;
+}
+
+static inline bool bp_pos_to_bucket_nodev(struct bch_fs *c, struct bpos bp_pos, struct bpos *bucket)
+{
+	return !bch2_fs_inconsistent_on(!bp_pos_to_bucket_nodev_noerror(c, bp_pos, bucket),
+					c, "backpointer for missing device %llu", bp_pos.inode);
+}
+
 static inline struct bpos bucket_pos_to_bp_noerror(const struct bch_dev *ca,
 						   struct bpos bucket,
 						   u64 bucket_offset)
@@ -57,32 +72,32 @@ static inline struct bpos bucket_pos_to_bp_noerror(const struct bch_dev *ca,
 /*
  * Convert from pos in alloc btree + bucket offset to pos in backpointer btree:
  */
-static inline struct bpos bucket_pos_to_bp(const struct bch_fs *c,
+static inline struct bpos bucket_pos_to_bp(const struct bch_dev *ca,
 					   struct bpos bucket,
 					   u64 bucket_offset)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, bucket.inode);
 	struct bpos ret = bucket_pos_to_bp_noerror(ca, bucket, bucket_offset);
-	EBUG_ON(!bkey_eq(bucket, bp_pos_to_bucket(c, ret)));
+	EBUG_ON(!bkey_eq(bucket, bp_pos_to_bucket(ca, ret)));
 	return ret;
 }
 
-int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *, struct bpos bucket,
-				struct bch_backpointer, struct bkey_s_c, bool);
+int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *, struct bch_dev *,
+				struct bpos bucket, struct bch_backpointer, struct bkey_s_c, bool);
 
 static inline int bch2_bucket_backpointer_mod(struct btree_trans *trans,
+				struct bch_dev *ca,
 				struct bpos bucket,
 				struct bch_backpointer bp,
 				struct bkey_s_c orig_k,
 				bool insert)
 {
 	if (unlikely(bch2_backpointers_no_use_write_buffer))
-		return bch2_bucket_backpointer_mod_nowritebuffer(trans, bucket, bp, orig_k, insert);
+		return bch2_bucket_backpointer_mod_nowritebuffer(trans, ca, bucket, bp, orig_k, insert);
 
 	struct bkey_i_backpointer bp_k;
 
 	bkey_backpointer_init(&bp_k.k_i);
-	bp_k.k.p = bucket_pos_to_bp(trans->c, bucket, bp.bucket_offset);
+	bp_k.k.p = bucket_pos_to_bp(ca, bucket, bp.bucket_offset);
 	bp_k.v = bp;
 
 	if (!insert) {
@@ -142,7 +157,7 @@ static inline void bch2_extent_ptr_to_bp(struct bch_fs *c, struct bch_dev *ca,
 	};
 }
 
-int bch2_get_next_backpointer(struct btree_trans *, struct bpos, int,
+int bch2_get_next_backpointer(struct btree_trans *, struct bch_dev *ca, struct bpos, int,
 			      struct bpos *, struct bch_backpointer *, unsigned);
 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *, struct btree_iter *,
 					 struct bpos, struct bch_backpointer,

fs/bcachefs/buckets.c

@@ -988,7 +988,7 @@ static int bch2_trigger_pointer(struct btree_trans *trans,
 			goto err;
 
 		if (!p.ptr.cached) {
-			ret = bch2_bucket_backpointer_mod(trans, bucket, bp, k, insert);
+			ret = bch2_bucket_backpointer_mod(trans, ca, bucket, bp, k, insert);
 			if (ret)
 				goto err;
 		}