bcachefs: Kill opts.buckets_nouse

Now explicitly allocate and free the buckets_nouse bitmap - this is
going to be used for online fsck.

To go RW when we haven't check allocations, we'll do a much slimmed down
version that just initializes the buckets_nouse bitmaps.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/buckets.c

@@ -1519,6 +1519,31 @@ int __bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res,
 
 /* Startup/shutdown: */
 
+void bch2_buckets_nouse_free(struct bch_fs *c)
+{
+	for_each_member_device(c, ca) {
+		kvfree_rcu_mightsleep(ca->buckets_nouse);
+		ca->buckets_nouse = NULL;
+	}
+}
+
+int bch2_buckets_nouse_alloc(struct bch_fs *c)
+{
+	for_each_member_device(c, ca) {
+		BUG_ON(ca->buckets_nouse);
+
+		ca->buckets_nouse = kvmalloc(BITS_TO_LONGS(ca->mi.nbuckets) *
+					    sizeof(unsigned long),
+					    GFP_KERNEL|__GFP_ZERO);
+		if (!ca->buckets_nouse) {
+			percpu_ref_put(&ca->ref);
+			return -BCH_ERR_ENOMEM_buckets_nouse;
+		}
+	}
+
+	return 0;
+}
+
 static void bucket_gens_free_rcu(struct rcu_head *rcu)
 {
 	struct bucket_gens *buckets =
@@ -1530,24 +1555,17 @@ static void bucket_gens_free_rcu(struct rcu_head *rcu)
 int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 {
 	struct bucket_gens *bucket_gens = NULL, *old_bucket_gens = NULL;
-	unsigned long *buckets_nouse = NULL;
 	bool resize = ca->bucket_gens != NULL;
 	int ret;
 
+	BUG_ON(resize && ca->buckets_nouse);
+
 	if (!(bucket_gens	= kvmalloc(sizeof(struct bucket_gens) + nbuckets,
 					   GFP_KERNEL|__GFP_ZERO))) {
 		ret = -BCH_ERR_ENOMEM_bucket_gens;
 		goto err;
 	}
 
-	if ((c->opts.buckets_nouse &&
-	     !(buckets_nouse	= kvmalloc(BITS_TO_LONGS(nbuckets) *
-					   sizeof(unsigned long),
-					   GFP_KERNEL|__GFP_ZERO)))) {
-		ret = -BCH_ERR_ENOMEM_buckets_nouse;
-		goto err;
-	}
-
 	bucket_gens->first_bucket = ca->mi.first_bucket;
 	bucket_gens->nbuckets	= nbuckets;
 
@@ -1565,17 +1583,11 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 		memcpy(bucket_gens->b,
 		       old_bucket_gens->b,
 		       n);
-		if (buckets_nouse)
-			memcpy(buckets_nouse,
-			       ca->buckets_nouse,
-			       BITS_TO_LONGS(n) * sizeof(unsigned long));
 	}
 
 	rcu_assign_pointer(ca->bucket_gens, bucket_gens);
 	bucket_gens	= old_bucket_gens;
 
-	swap(ca->buckets_nouse, buckets_nouse);
-
 	nbuckets = ca->mi.nbuckets;
 
 	if (resize) {
@@ -1586,7 +1598,6 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 
 	ret = 0;
 err:
-	kvfree(buckets_nouse);
 	if (bucket_gens)
 		call_rcu(&bucket_gens->rcu, bucket_gens_free_rcu);
 

fs/bcachefs/buckets.h

@@ -472,6 +472,9 @@ static inline u64 avail_factor(u64 r)
 	return div_u64(r << RESERVE_FACTOR, (1 << RESERVE_FACTOR) + 1);
 }
 
+void bch2_buckets_nouse_free(struct bch_fs *);
+int bch2_buckets_nouse_alloc(struct bch_fs *);
+
 int bch2_dev_buckets_resize(struct bch_fs *, struct bch_dev *, u64);
 void bch2_dev_buckets_free(struct bch_dev *);
 int bch2_dev_buckets_alloc(struct bch_fs *, struct bch_dev *);

fs/bcachefs/opts.h

@@ -426,11 +426,6 @@ enum fsck_err_opts {
 	  BCH_SB_VERSION_UPGRADE,	BCH_VERSION_UPGRADE_compatible,	\
 	  NULL,		"Set superblock to latest version,\n"		\
 			"allowing any new features to be used")		\
-	x(buckets_nouse,		u8,				\
-	  0,								\
-	  OPT_BOOL(),							\
-	  BCH2_NO_SB_OPT,		false,				\
-	  NULL,		"Allocate the buckets_nouse bitmap")		\
 	x(stdio,			u64,				\
 	  0,								\
 	  OPT_UINT(0, S64_MAX),						\

fs/bcachefs/super.c

@@ -531,9 +531,7 @@ int bch2_fs_read_write_early(struct bch_fs *c)
 
 static void __bch2_fs_free(struct bch_fs *c)
 {
-	unsigned i;
-
-	for (i = 0; i < BCH_TIME_STAT_NR; i++)
+	for (unsigned i = 0; i < BCH_TIME_STAT_NR; i++)
 		bch2_time_stats_exit(&c->times[i]);
 
 	bch2_find_btree_nodes_exit(&c->found_btree_nodes);
@@ -1189,6 +1187,7 @@ static void bch2_dev_free(struct bch_dev *ca)
 	if (ca->kobj.state_in_sysfs)
 		kobject_del(&ca->kobj);
 
+	kfree(ca->buckets_nouse);
 	bch2_free_super(&ca->disk_sb);
 	bch2_dev_journal_exit(ca);