bcachefs: for_each_member_device() now declares loop iter

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

14 files changed, 158 insertions, 243 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index f202082ffe82..138dbda49f3e 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1788,16 +1788,14 @@ err:
 static void bch2_do_invalidates_work(struct work_struct *work)
 {
 	struct bch_fs *c = container_of(work, struct bch_fs, invalidate_work);
-	struct bch_dev *ca;
 	struct btree_trans *trans = bch2_trans_get(c);
-	unsigned i;
 	int ret = 0;
 
 	ret = bch2_btree_write_buffer_tryflush(trans);
 	if (ret)
 		goto err;
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		s64 nr_to_invalidate =
 			should_invalidate_buckets(ca, bch2_dev_usage_read(ca));
 
@@ -1926,8 +1924,6 @@ bkey_err:
 
 int bch2_fs_freespace_init(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
 	int ret = 0;
 	bool doing_init = false;
 
@@ -1936,7 +1932,7 @@ int bch2_fs_freespace_init(struct bch_fs *c)
 	 * every mount:
 	 */
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		if (ca->mi.freespace_initialized)
 			continue;
 
@@ -1996,15 +1992,13 @@ out:
 
 void bch2_recalc_capacity(struct bch_fs *c)
 {
-	struct bch_dev *ca;
 	u64 capacity = 0, reserved_sectors = 0, gc_reserve;
 	unsigned bucket_size_max = 0;
 	unsigned long ra_pages = 0;
-	unsigned i;
 
 	lockdep_assert_held(&c->state_lock);
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		struct backing_dev_info *bdi = ca->disk_sb.bdev->bd_disk->bdi;
 
 		ra_pages += bdi->ra_pages;
@@ -2012,7 +2006,7 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
 	bch2_set_ra_pages(c, ra_pages);
 
-	for_each_rw_member(ca, c, i) {
+	for_each_rw_member(c, ca) {
 		u64 dev_reserve = 0;
 
 		/*
@@ -2068,11 +2062,9 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
 u64 bch2_min_rw_member_capacity(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
 	u64 ret = U64_MAX;
 
-	for_each_rw_member(ca, c, i)
+	for_each_rw_member(c, ca)
 		ret = min(ret, ca->mi.nbuckets * ca->mi.bucket_size);
 	return ret;
 }
diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c
index d5c5cc4282db..ea1d0ed70f50 100644
--- a/fs/bcachefs/btree_gc.c
+++ b/fs/bcachefs/btree_gc.c
@@ -1153,13 +1153,10 @@ static void bch2_mark_dev_superblock(struct bch_fs *c, struct bch_dev *ca,
 
 static void bch2_mark_superblocks(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
 	mutex_lock(&c->sb_lock);
 	gc_pos_set(c, gc_phase(GC_PHASE_SB));
 
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		bch2_mark_dev_superblock(c, ca, BTREE_TRIGGER_GC);
 	mutex_unlock(&c->sb_lock);
 }
@@ -1184,13 +1181,10 @@ static void bch2_mark_pending_btree_node_frees(struct bch_fs *c)
 
 static void bch2_gc_free(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
 	genradix_free(&c->reflink_gc_table);
 	genradix_free(&c->gc_stripes);
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		kvpfree(rcu_dereference_protected(ca->buckets_gc, 1),
 			sizeof(struct bucket_array) +
 			ca->mi.nbuckets * sizeof(struct bucket));
@@ -1212,7 +1206,7 @@ static int bch2_gc_done(struct bch_fs *c,
 	bool verify = !metadata_only &&
 		!c->opts.reconstruct_alloc &&
 		(!initial || (c->sb.compat & (1ULL << BCH_COMPAT_alloc_info)));
-	unsigned i, dev;
+	unsigned i;
 	int ret = 0;
 
 	percpu_down_write(&c->mark_lock);
@@ -1224,14 +1218,14 @@ static int bch2_gc_done(struct bch_fs *c,
 		      , ##__VA_ARGS__, dst->_f, src->_f)))		\
 		dst->_f = src->_f
 #define copy_dev_field(_err, _f, _msg, ...)				\
-	copy_field(_err, _f, "dev %u has wrong " _msg, dev, ##__VA_ARGS__)
+	copy_field(_err, _f, "dev %u has wrong " _msg, ca->dev_idx, ##__VA_ARGS__)
 #define copy_fs_field(_err, _f, _msg, ...)				\
 	copy_field(_err, _f, "fs has wrong " _msg, ##__VA_ARGS__)
 
 	for (i = 0; i < ARRAY_SIZE(c->usage); i++)
 		bch2_fs_usage_acc_to_base(c, i);
 
-	for_each_member_device(ca, c, dev) {
+	__for_each_member_device(c, ca) {
 		struct bch_dev_usage *dst = ca->usage_base;
 		struct bch_dev_usage *src = (void *)
 			bch2_acc_percpu_u64s((u64 __percpu *) ca->usage_gc,
@@ -1307,9 +1301,6 @@ fsck_err:
 
 static int bch2_gc_start(struct bch_fs *c)
 {
-	struct bch_dev *ca = NULL;
-	unsigned i;
-
 	BUG_ON(c->usage_gc);
 
 	c->usage_gc = __alloc_percpu_gfp(fs_usage_u64s(c) * sizeof(u64),
@@ -1319,7 +1310,7 @@ static int bch2_gc_start(struct bch_fs *c)
 		return -BCH_ERR_ENOMEM_gc_start;
 	}
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		BUG_ON(ca->usage_gc);
 
 		ca->usage_gc = alloc_percpu(struct bch_dev_usage);
@@ -1338,10 +1329,7 @@ static int bch2_gc_start(struct bch_fs *c)
 
 static int bch2_gc_reset(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		free_percpu(ca->usage_gc);
 		ca->usage_gc = NULL;
 	}
@@ -1379,9 +1367,6 @@ static int bch2_alloc_write_key(struct btree_trans *trans,
 	enum bch_data_type type;
 	int ret;
 
-	if (bkey_ge(iter->pos, POS(ca->dev_idx, ca->mi.nbuckets)))
-		return 1;
-
 	old = bch2_alloc_to_v4(k, &old_convert);
 	new = *old;
 
@@ -1478,48 +1463,36 @@ fsck_err:
 
 static int bch2_gc_alloc_done(struct bch_fs *c, bool metadata_only)
 {
-	struct btree_trans *trans = bch2_trans_get(c);
-	struct bch_dev *ca;
-	unsigned i;
 	int ret = 0;
 
-	for_each_member_device(ca, c, i) {
-		ret = for_each_btree_key_commit(trans, iter, BTREE_ID_alloc,
-				POS(ca->dev_idx, ca->mi.first_bucket),
-				BTREE_ITER_SLOTS|BTREE_ITER_PREFETCH, k,
-				NULL, NULL, BCH_TRANS_COMMIT_lazy_rw,
-			bch2_alloc_write_key(trans, &iter, k, metadata_only));
-
-		if (ret < 0) {
-			bch_err_fn(c, ret);
+	for_each_member_device(c, ca) {
+		ret = bch2_trans_run(c,
+			for_each_btree_key_upto_commit(trans, iter, BTREE_ID_alloc,
+					POS(ca->dev_idx, ca->mi.first_bucket),
+					POS(ca->dev_idx, ca->mi.nbuckets - 1),
+					BTREE_ITER_SLOTS|BTREE_ITER_PREFETCH, k,
+					NULL, NULL, BCH_TRANS_COMMIT_lazy_rw,
+				bch2_alloc_write_key(trans, &iter, k, metadata_only)));
+		if (ret) {
 			percpu_ref_put(&ca->ref);
 			break;
 		}
 	}
 
-	bch2_trans_put(trans);
-	return ret < 0 ? ret : 0;
+	bch_err_fn(c, ret);
+	return ret;
 }
 
 static int bch2_gc_alloc_start(struct bch_fs *c, bool metadata_only)
 {
-	struct bch_dev *ca;
-	struct btree_trans *trans = bch2_trans_get(c);
-	struct bucket *g;
-	struct bch_alloc_v4 a_convert;
-	const struct bch_alloc_v4 *a;
-	unsigned i;
-	int ret;
-
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		struct bucket_array *buckets = kvpmalloc(sizeof(struct bucket_array) +
 				ca->mi.nbuckets * sizeof(struct bucket),
 				GFP_KERNEL|__GFP_ZERO);
 		if (!buckets) {
 			percpu_ref_put(&ca->ref);
 			bch_err(c, "error allocating ca->buckets[gc]");
-			ret = -BCH_ERR_ENOMEM_gc_alloc_start;
-			goto err;
+			return -BCH_ERR_ENOMEM_gc_alloc_start;
 		}
 
 		buckets->first_bucket	= ca->mi.first_bucket;
@@ -1527,41 +1500,38 @@ static int bch2_gc_alloc_start(struct bch_fs *c, bool metadata_only)
 		rcu_assign_pointer(ca->buckets_gc, buckets);
 	}
 
-	ret = for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
-				 BTREE_ITER_PREFETCH, k, ({
-		ca = bch_dev_bkey_exists(c, k.k->p.inode);
-		g = gc_bucket(ca, k.k->p.offset);
-
-		a = bch2_alloc_to_v4(k, &a_convert);
-
-		g->gen_valid	= 1;
-		g->gen		= a->gen;
-
-		if (metadata_only &&
-		    (a->data_type == BCH_DATA_user ||
-		     a->data_type == BCH_DATA_cached ||
-		     a->data_type == BCH_DATA_parity)) {
-			g->data_type		= a->data_type;
-			g->dirty_sectors	= a->dirty_sectors;
-			g->cached_sectors	= a->cached_sectors;
-			g->stripe		= a->stripe;
-			g->stripe_redundancy	= a->stripe_redundancy;
-		}
+	int ret = bch2_trans_run(c,
+		for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
+					 BTREE_ITER_PREFETCH, k, ({
+			struct bch_dev *ca = bch_dev_bkey_exists(c, k.k->p.inode);
+			struct bucket *g = gc_bucket(ca, k.k->p.offset);
 
-		0;
-	}));
-err:
-	bch2_trans_put(trans);
+			struct bch_alloc_v4 a_convert;
+			const struct bch_alloc_v4 *a = bch2_alloc_to_v4(k, &a_convert);
+
+			g->gen_valid	= 1;
+			g->gen		= a->gen;
+
+			if (metadata_only &&
+			    (a->data_type == BCH_DATA_user ||
+			     a->data_type == BCH_DATA_cached ||
+			     a->data_type == BCH_DATA_parity)) {
+				g->data_type		= a->data_type;
+				g->dirty_sectors	= a->dirty_sectors;
+				g->cached_sectors	= a->cached_sectors;
+				g->stripe		= a->stripe;
+				g->stripe_redundancy	= a->stripe_redundancy;
+			}
+
+			0;
+		})));
 	bch_err_fn(c, ret);
 	return ret;
 }
 
 static void bch2_gc_alloc_reset(struct bch_fs *c, bool metadata_only)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		struct bucket_array *buckets = gc_bucket_array(ca);
 		struct bucket *g;
 
@@ -1932,10 +1902,7 @@ static int bch2_alloc_write_oldest_gen(struct btree_trans *trans, struct btree_i
 
 int bch2_gc_gens(struct bch_fs *c)
 {
-	struct btree_trans *trans;
-	struct bch_dev *ca;
 	u64 b, start_time = local_clock();
-	unsigned i;
 	int ret;
 
 	/*
@@ -1948,9 +1915,8 @@ int bch2_gc_gens(struct bch_fs *c)
 
 	trace_and_count(c, gc_gens_start, c);
 	down_read(&c->gc_lock);
-	trans = bch2_trans_get(c);
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		struct bucket_gens *gens = bucket_gens(ca);
 
 		BUG_ON(ca->oldest_gen);
@@ -1967,33 +1933,31 @@ int bch2_gc_gens(struct bch_fs *c)
 			ca->oldest_gen[b] = gens->b[b];
 	}
 
-	for (i = 0; i < BTREE_ID_NR; i++)
+	for (unsigned i = 0; i < BTREE_ID_NR; i++)
 		if (btree_type_has_ptrs(i)) {
 			c->gc_gens_btree = i;
 			c->gc_gens_pos = POS_MIN;
 
-			ret = for_each_btree_key_commit(trans, iter, i,
-					POS_MIN,
-					BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
-					k,
-					NULL, NULL,
-					BCH_TRANS_COMMIT_no_enospc,
-				gc_btree_gens_key(trans, &iter, k));
-			if (!bch2_err_matches(ret, EROFS))
-				bch_err_fn(c, ret);
+			ret = bch2_trans_run(c,
+				for_each_btree_key_commit(trans, iter, i,
+						POS_MIN,
+						BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS,
+						k,
+						NULL, NULL,
+						BCH_TRANS_COMMIT_no_enospc,
+					gc_btree_gens_key(trans, &iter, k)));
 			if (ret)
 				goto err;
 		}
 
-	ret = for_each_btree_key_commit(trans, iter, BTREE_ID_alloc,
-			POS_MIN,
-			BTREE_ITER_PREFETCH,
-			k,
-			NULL, NULL,
-			BCH_TRANS_COMMIT_no_enospc,
-		bch2_alloc_write_oldest_gen(trans, &iter, k));
-	if (!bch2_err_matches(ret, EROFS))
-		bch_err_fn(c, ret);
+	ret = bch2_trans_run(c,
+		for_each_btree_key_commit(trans, iter, BTREE_ID_alloc,
+				POS_MIN,
+				BTREE_ITER_PREFETCH,
+				k,
+				NULL, NULL,
+				BCH_TRANS_COMMIT_no_enospc,
+			bch2_alloc_write_oldest_gen(trans, &iter, k)));
 	if (ret)
 		goto err;
 
@@ -2005,14 +1969,15 @@ int bch2_gc_gens(struct bch_fs *c)
 	bch2_time_stats_update(&c->times[BCH_TIME_btree_gc], start_time);
 	trace_and_count(c, gc_gens_end, c);
 err:
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		kvfree(ca->oldest_gen);
 		ca->oldest_gen = NULL;
 	}
 
-	bch2_trans_put(trans);
 	up_read(&c->gc_lock);
 	mutex_unlock(&c->gc_gens_lock);
+	if (!bch2_err_matches(ret, EROFS))
+		bch_err_fn(c, ret);
 	return ret;
 }
 
diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index 31b7f0ba7d9e..29a6e2b17e48 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -47,27 +47,23 @@ static inline void fs_usage_data_type_to_base(struct bch_fs_usage *fs_usage,
 
 void bch2_fs_usage_initialize(struct bch_fs *c)
 {
-	struct bch_fs_usage *usage;
-	struct bch_dev *ca;
-	unsigned i;
-
 	percpu_down_write(&c->mark_lock);
-	usage = c->usage_base;
+	struct bch_fs_usage *usage = c->usage_base;
 
-	for (i = 0; i < ARRAY_SIZE(c->usage); i++)
+	for (unsigned i = 0; i < ARRAY_SIZE(c->usage); i++)
 		bch2_fs_usage_acc_to_base(c, i);
 
-	for (i = 0; i < BCH_REPLICAS_MAX; i++)
+	for (unsigned i = 0; i < BCH_REPLICAS_MAX; i++)
 		usage->reserved += usage->persistent_reserved[i];
 
-	for (i = 0; i < c->replicas.nr; i++) {
+	for (unsigned i = 0; i < c->replicas.nr; i++) {
 		struct bch_replicas_entry_v1 *e =
 			cpu_replicas_entry(&c->replicas, i);
 
 		fs_usage_data_type_to_base(usage, e->data_type, usage->replicas[i]);
 	}
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		struct bch_dev_usage dev = bch2_dev_usage_read(ca);
 
 		usage->hidden += (dev.d[BCH_DATA_sb].buckets +
@@ -1766,10 +1762,7 @@ int bch2_trans_mark_dev_sb(struct bch_fs *c, struct bch_dev *ca)
 
 int bch2_trans_mark_dev_sbs(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		int ret = bch2_trans_mark_dev_sb(c, ca);
 		if (ret) {
 			percpu_ref_put(&ca->ref);
diff --git a/fs/bcachefs/chardev.c b/fs/bcachefs/chardev.c
index 08922f7e380a..304ea619a888 100644
--- a/fs/bcachefs/chardev.c
+++ b/fs/bcachefs/chardev.c
@@ -865,8 +865,6 @@ static long bch2_ioctl_disk_get_idx(struct bch_fs *c,
 				    struct bch_ioctl_disk_get_idx arg)
 {
 	dev_t dev = huge_decode_dev(arg.dev);
-	struct bch_dev *ca;
-	unsigned i;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
@@ -874,10 +872,10 @@ static long bch2_ioctl_disk_get_idx(struct bch_fs *c,
 	if (!dev)
 		return -EINVAL;
 
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		if (ca->dev == dev) {
 			percpu_ref_put(&ca->io_ref);
-			return i;
+			return ca->dev_idx;
 		}
 
 	return -BCH_ERR_ENOENT_dev_idx_not_found;
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index 409c957a0549..bc280a0a957d 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -1666,11 +1666,9 @@ err:
 static int bch2_show_devname(struct seq_file *seq, struct dentry *root)
 {
 	struct bch_fs *c = root->d_sb->s_fs_info;
-	struct bch_dev *ca;
-	unsigned i;
 	bool first = true;
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		if (!first)
 			seq_putc(seq, ':');
 		first = false;
@@ -1794,13 +1792,12 @@ static struct dentry *bch2_mount(struct file_system_type *fs_type,
 				 int flags, const char *dev_name, void *data)
 {
 	struct bch_fs *c;
-	struct bch_dev *ca;
 	struct super_block *sb;
 	struct inode *vinode;
 	struct bch_opts opts = bch2_opts_empty();
 	char **devs;
 	struct bch_fs **devs_to_fs = NULL;
-	unsigned i, nr_devs;
+	unsigned nr_devs;
 	int ret;
 
 	opt_set(opts, read_only, (flags & SB_RDONLY) != 0);
@@ -1822,7 +1819,7 @@ static struct dentry *bch2_mount(struct file_system_type *fs_type,
 		goto got_sb;
 	}
 
-	for (i = 0; i < nr_devs; i++)
+	for (unsigned i = 0; i < nr_devs; i++)
 		devs_to_fs[i] = bch2_path_to_fs(devs[i]);
 
 	sb = sget(fs_type, bch2_test_super, bch2_noset_super,
@@ -1893,7 +1890,7 @@ got_sb:
 
 	sb->s_bdi->ra_pages		= VM_READAHEAD_PAGES;
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		struct block_device *bdev = ca->disk_sb.bdev;
 
 		/* XXX: create an anonymous device for multi device filesystems */
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 5883fc38b4f5..f9cd24113920 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -1029,10 +1029,7 @@ err:
 
 int bch2_fs_journal_alloc(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		if (ca->journal.nr)
 			continue;
 
diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c
index 6db821c86551..364aca3b78fe 100644
--- a/fs/bcachefs/journal_io.c
+++ b/fs/bcachefs/journal_io.c
@@ -1171,8 +1171,6 @@ int bch2_journal_read(struct bch_fs *c,
 	struct journal_list jlist;
 	struct journal_replay *i, **_i, *prev = NULL;
 	struct genradix_iter radix_iter;
-	struct bch_dev *ca;
-	unsigned iter;
 	struct printbuf buf = PRINTBUF;
 	bool degraded = false, last_write_torn = false;
 	u64 seq;
@@ -1183,7 +1181,7 @@ int bch2_journal_read(struct bch_fs *c,
 	jlist.last_seq = 0;
 	jlist.ret = 0;
 
-	for_each_member_device(ca, c, iter) {
+	for_each_member_device(c, ca) {
 		if (!c->opts.fsck &&
 		    !(bch2_dev_has_data(c, ca) & (1 << BCH_DATA_journal)))
 			continue;
@@ -1349,7 +1347,7 @@ int bch2_journal_read(struct bch_fs *c,
 			continue;
 
 		for (ptr = 0; ptr < i->nr_ptrs; ptr++) {
-			ca = bch_dev_bkey_exists(c, i->ptrs[ptr].dev);
+			struct bch_dev *ca = bch_dev_bkey_exists(c, i->ptrs[ptr].dev);
 
 			if (!i->ptrs[ptr].csum_good)
 				bch_err_dev_offset(ca, i->ptrs[ptr].sector,
@@ -1893,12 +1891,11 @@ CLOSURE_CALLBACK(bch2_journal_write)
 {
 	closure_type(j, struct journal, io);
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
-	struct bch_dev *ca;
 	struct journal_buf *w = journal_last_unwritten_buf(j);
 	struct bch_replicas_padded replicas;
 	struct bio *bio;
 	struct printbuf journal_debug_buf = PRINTBUF;
-	unsigned i, nr_rw_members = 0;
+	unsigned nr_rw_members = 0;
 	int ret;
 
 	BUG_ON(BCH_SB_CLEAN(c->disk_sb.sb));
@@ -1958,7 +1955,7 @@ CLOSURE_CALLBACK(bch2_journal_write)
 	if (c->opts.nochanges)
 		goto no_io;
 
-	for_each_rw_member(ca, c, i)
+	for_each_rw_member(c, ca)
 		nr_rw_members++;
 
 	if (nr_rw_members > 1)
@@ -1975,7 +1972,7 @@ CLOSURE_CALLBACK(bch2_journal_write)
 		goto err;
 
 	if (!JSET_NO_FLUSH(w->data) && w->separate_flush) {
-		for_each_rw_member(ca, c, i) {
+		for_each_rw_member(c, ca) {
 			percpu_ref_get(&ca->io_ref);
 
 			bio = ca->journal.bio;
diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c
index 794c10ec01b6..ef8f7e537f9f 100644
--- a/fs/bcachefs/journal_reclaim.c
+++ b/fs/bcachefs/journal_reclaim.c
@@ -263,12 +263,10 @@ static bool should_discard_bucket(struct journal *j, struct journal_device *ja)
 void bch2_journal_do_discards(struct journal *j)
 {
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
-	struct bch_dev *ca;
-	unsigned iter;
 
 	mutex_lock(&j->discard_lock);
 
-	for_each_rw_member(ca, c, iter) {
+	for_each_rw_member(c, ca) {
 		struct journal_device *ja = &ca->journal;
 
 		while (should_discard_bucket(j, ja)) {
@@ -583,13 +581,11 @@ static size_t journal_flush_pins(struct journal *j,
 static u64 journal_seq_to_flush(struct journal *j)
 {
 	struct bch_fs *c = container_of(j, struct bch_fs, journal);
-	struct bch_dev *ca;
 	u64 seq_to_flush = 0;
-	unsigned iter;
 
 	spin_lock(&j->lock);
 
-	for_each_rw_member(ca, c, iter) {
+	for_each_rw_member(c, ca) {
 		struct journal_device *ja = &ca->journal;
 		unsigned nr_buckets, bucket_to_flush;
 
diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
index 8aa212685b3f..69e06a84dad4 100644
--- a/fs/bcachefs/movinggc.c
+++ b/fs/bcachefs/movinggc.c
@@ -267,19 +267,16 @@ err:
  */
 unsigned long bch2_copygc_wait_amount(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned dev_idx;
 	s64 wait = S64_MAX, fragmented_allowed, fragmented;
-	unsigned i;
 
-	for_each_rw_member(ca, c, dev_idx) {
+	for_each_rw_member(c, ca) {
 		struct bch_dev_usage usage = bch2_dev_usage_read(ca);
 
 		fragmented_allowed = ((__dev_buckets_available(ca, usage, BCH_WATERMARK_stripe) *
 				       ca->mi.bucket_size) >> 1);
 		fragmented = 0;
 
-		for (i = 0; i < BCH_DATA_NR; i++)
+		for (unsigned i = 0; i < BCH_DATA_NR; i++)
 			if (data_type_movable(i))
 				fragmented += usage.d[i].fragmented;
 
diff --git a/fs/bcachefs/recovery.c b/fs/bcachefs/recovery.c
index 837816263983..4f29b9d69c6a 100644
--- a/fs/bcachefs/recovery.c
+++ b/fs/bcachefs/recovery.c
@@ -1000,8 +1000,6 @@ int bch2_fs_initialize(struct bch_fs *c)
 	struct bch_inode_unpacked root_inode, lostfound_inode;
 	struct bkey_inode_buf packed_inode;
 	struct qstr lostfound = QSTR("lost+found");
-	struct bch_dev *ca;
-	unsigned i;
 	int ret;
 
 	bch_notice(c, "initializing new filesystem");
@@ -1023,10 +1021,10 @@ int bch2_fs_initialize(struct bch_fs *c)
 	set_bit(BCH_FS_may_go_rw, &c->flags);
 	set_bit(BCH_FS_fsck_done, &c->flags);
 
-	for (i = 0; i < BTREE_ID_NR; i++)
+	for (unsigned i = 0; i < BTREE_ID_NR; i++)
 		bch2_btree_root_alloc(c, i);
 
-	for_each_member_device(ca, c, i)
+	for_each_member_device(c, ca)
 		bch2_dev_usage_init(ca);
 
 	ret = bch2_fs_journal_alloc(c);
@@ -1054,7 +1052,7 @@ int bch2_fs_initialize(struct bch_fs *c)
 	if (ret)
 		goto err;
 
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		ca->new_fs_bucket_idx = 0;
 
 	ret = bch2_fs_freespace_init(c);
@@ -1117,6 +1115,6 @@ int bch2_fs_initialize(struct bch_fs *c)
 
 	return 0;
 err:
-	bch_err_fn(ca, ret);
+	bch_err_fn(c, ret);
 	return ret;
 }
diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
index 8dc0e3db1f03..ca14f86fb2a9 100644
--- a/fs/bcachefs/sb-clean.c
+++ b/fs/bcachefs/sb-clean.c
@@ -191,13 +191,10 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 					   struct jset_entry **end,
 					   u64 journal_seq)
 {
-	struct bch_dev *ca;
-	unsigned i, dev;
-
 	percpu_down_read(&c->mark_lock);
 
 	if (!journal_seq) {
-		for (i = 0; i < ARRAY_SIZE(c->usage); i++)
+		for (unsigned i = 0; i < ARRAY_SIZE(c->usage); i++)
 			bch2_fs_usage_acc_to_base(c, i);
 	} else {
 		bch2_fs_usage_acc_to_base(c, journal_seq & JOURNAL_BUF_MASK);
@@ -223,7 +220,7 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 		u->v		= cpu_to_le64(atomic64_read(&c->key_version));
 	}
 
-	for (i = 0; i < BCH_REPLICAS_MAX; i++) {
+	for (unsigned i = 0; i < BCH_REPLICAS_MAX; i++) {
 		struct jset_entry_usage *u =
 			container_of(jset_entry_init(end, sizeof(*u)),
 				     struct jset_entry_usage, entry);
@@ -234,7 +231,7 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 		u->v		= cpu_to_le64(c->usage_base->persistent_reserved[i]);
 	}
 
-	for (i = 0; i < c->replicas.nr; i++) {
+	for (unsigned i = 0; i < c->replicas.nr; i++) {
 		struct bch_replicas_entry_v1 *e =
 			cpu_replicas_entry(&c->replicas, i);
 		struct jset_entry_data_usage *u =
@@ -247,7 +244,7 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 			      "embedded variable length struct");
 	}
 
-	for_each_member_device(ca, c, dev) {
+	for_each_member_device(c, ca) {
 		unsigned b = sizeof(struct jset_entry_dev_usage) +
 			sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR;
 		struct jset_entry_dev_usage *u =
@@ -255,9 +252,9 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 				     struct jset_entry_dev_usage, entry);
 
 		u->entry.type = BCH_JSET_ENTRY_dev_usage;
-		u->dev = cpu_to_le32(dev);
+		u->dev = cpu_to_le32(ca->dev_idx);
 
-		for (i = 0; i < BCH_DATA_NR; i++) {
+		for (unsigned i = 0; i < BCH_DATA_NR; i++) {
 			u->d[i].buckets = cpu_to_le64(ca->usage_base->d[i].buckets);
 			u->d[i].sectors	= cpu_to_le64(ca->usage_base->d[i].sectors);
 			u->d[i].fragmented = cpu_to_le64(ca->usage_base->d[i].fragmented);
@@ -266,7 +263,7 @@ void bch2_journal_super_entries_add_common(struct bch_fs *c,
 
 	percpu_up_read(&c->mark_lock);
 
-	for (i = 0; i < 2; i++) {
+	for (unsigned i = 0; i < 2; i++) {
 		struct jset_entry_clock *clock =
 			container_of(jset_entry_init(end, sizeof(*clock)),
 				     struct jset_entry_clock, entry);
diff --git a/fs/bcachefs/sb-members.h b/fs/bcachefs/sb-members.h
index 03613e3eb8e3..6443c802a375 100644
--- a/fs/bcachefs/sb-members.h
+++ b/fs/bcachefs/sb-members.h
@@ -100,12 +100,15 @@ static inline struct bch_dev *__bch2_next_dev(struct bch_fs *c, unsigned *iter,
 #define for_each_member_device_rcu(ca, c, iter, mask)			\
 	for ((iter) = 0; ((ca) = __bch2_next_dev((c), &(iter), mask)); (iter)++)
 
-static inline struct bch_dev *bch2_get_next_dev(struct bch_fs *c, unsigned *iter)
+static inline struct bch_dev *bch2_get_next_dev(struct bch_fs *c, struct bch_dev *ca)
 {
-	struct bch_dev *ca;
+	unsigned idx = ca ? ca->dev_idx + 1 : 0;
+
+	if (ca)
+		percpu_ref_put(&ca->ref);
 
 	rcu_read_lock();
-	if ((ca = __bch2_next_dev(c, iter, NULL)))
+	if ((ca = __bch2_next_dev(c, &idx, NULL)))
 		percpu_ref_get(&ca->ref);
 	rcu_read_unlock();
 
@@ -115,41 +118,44 @@ static inline struct bch_dev *bch2_get_next_dev(struct bch_fs *c, unsigned *iter
 /*
  * If you break early, you must drop your ref on the current device
  */
-#define for_each_member_device(ca, c, iter)				\
-	for ((iter) = 0;						\
-	     (ca = bch2_get_next_dev(c, &(iter)));			\
-	     percpu_ref_put(&ca->ref), (iter)++)
+#define __for_each_member_device(_c, _ca)				\
+	for (;	(_ca = bch2_get_next_dev(_c, _ca));)
+
+#define for_each_member_device(_c, _ca)					\
+	for (struct bch_dev *_ca = NULL;				\
+	     (_ca = bch2_get_next_dev(_c, _ca));)
 
 static inline struct bch_dev *bch2_get_next_online_dev(struct bch_fs *c,
-						      unsigned *iter,
-						      int state_mask)
+						       struct bch_dev *ca,
+						       unsigned state_mask)
 {
-	struct bch_dev *ca;
+	unsigned idx = ca ? ca->dev_idx + 1 : 0;
+
+	if (ca)
+		percpu_ref_put(&ca->io_ref);
 
 	rcu_read_lock();
-	while ((ca = __bch2_next_dev(c, iter, NULL)) &&
+	while ((ca = __bch2_next_dev(c, &idx, NULL)) &&
 	       (!((1 << ca->mi.state) & state_mask) ||
 		!percpu_ref_tryget(&ca->io_ref)))
-		(*iter)++;
+		idx++;
 	rcu_read_unlock();
 
 	return ca;
 }
 
-#define __for_each_online_member(ca, c, iter, state_mask)		\
-	for ((iter) = 0;						\
-	     (ca = bch2_get_next_online_dev(c, &(iter), state_mask));	\
-	     percpu_ref_put(&ca->io_ref), (iter)++)
+#define __for_each_online_member(_c, _ca, state_mask)			\
+	for (struct bch_dev *_ca = NULL;				\
+	     (_ca = bch2_get_next_online_dev(_c, _ca, state_mask));)
 
-#define for_each_online_member(ca, c, iter)				\
-	__for_each_online_member(ca, c, iter, ~0)
+#define for_each_online_member(c, ca)					\
+	__for_each_online_member(c, ca, ~0)
 
-#define for_each_rw_member(ca, c, iter)					\
-	__for_each_online_member(ca, c, iter, 1 << BCH_MEMBER_STATE_rw)
+#define for_each_rw_member(c, ca)					\
+	__for_each_online_member(c, ca, BIT(BCH_MEMBER_STATE_rw))
 
-#define for_each_readable_member(ca, c, iter)				\
-	__for_each_online_member(ca, c, iter,				\
-		(1 << BCH_MEMBER_STATE_rw)|(1 << BCH_MEMBER_STATE_ro))
+#define for_each_readable_member(c, ca)				\
+	__for_each_online_member(c, ca,	BIT( BCH_MEMBER_STATE_rw)|BIT(BCH_MEMBER_STATE_ro))
 
 /*
  * If a key exists that references a device, the device won't be going away and
@@ -175,11 +181,9 @@ static inline struct bch_dev *bch_dev_locked(struct bch_fs *c, unsigned idx)
 static inline struct bch_devs_mask bch2_online_devs(struct bch_fs *c)
 {
 	struct bch_devs_mask devs;
-	struct bch_dev *ca;
-	unsigned i;
 
 	memset(&devs, 0, sizeof(devs));
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		__set_bit(ca->dev_idx, devs.d);
 	return devs;
 }
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index 136c01403c95..b9669059f64b 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -240,14 +240,12 @@ struct bch_sb_field *bch2_sb_field_resize_id(struct bch_sb_handle *sb,
 
 	if (sb->fs_sb) {
 		struct bch_fs *c = container_of(sb, struct bch_fs, disk_sb);
-		struct bch_dev *ca;
-		unsigned i;
 
 		lockdep_assert_held(&c->sb_lock);
 
 		/* XXX: we're not checking that offline device have enough space */
 
-		for_each_online_member(ca, c, i) {
+		for_each_online_member(c, ca) {
 			struct bch_sb_handle *dev_sb = &ca->disk_sb;
 
 			if (bch2_sb_realloc(dev_sb, le32_to_cpu(dev_sb->sb->u64s) + d)) {
@@ -487,8 +485,6 @@ static int bch2_sb_validate(struct bch_sb_handle *disk_sb, struct printbuf *out,
 static void bch2_sb_update(struct bch_fs *c)
 {
 	struct bch_sb *src = c->disk_sb.sb;
-	struct bch_dev *ca;
-	unsigned i;
 
 	lockdep_assert_held(&c->sb_lock);
 
@@ -512,8 +508,8 @@ static void bch2_sb_update(struct bch_fs *c)
 	c->sb.features		= le64_to_cpu(src->features[0]);
 	c->sb.compat		= le64_to_cpu(src->compat[0]);
 
-	for_each_member_device(ca, c, i) {
-		struct bch_member m = bch2_sb_member_get(src, i);
+	for_each_member_device(c, ca) {
+		struct bch_member m = bch2_sb_member_get(src, ca->dev_idx);
 		ca->mi = bch2_mi_to_cpu(&m);
 	}
 }
@@ -892,9 +888,8 @@ static void write_one_super(struct bch_fs *c, struct bch_dev *ca, unsigned idx)
 int bch2_write_super(struct bch_fs *c)
 {
 	struct closure *cl = &c->sb_write;
-	struct bch_dev *ca;
 	struct printbuf err = PRINTBUF;
-	unsigned i, sb = 0, nr_wrote;
+	unsigned sb = 0, nr_wrote;
 	struct bch_devs_mask sb_written;
 	bool wrote, can_mount_without_written, can_mount_with_written;
 	unsigned degraded_flags = BCH_FORCE_IF_DEGRADED;
@@ -928,10 +923,10 @@ int bch2_write_super(struct bch_fs *c)
 	bch2_sb_members_cpy_v2_v1(&c->disk_sb);
 	bch2_sb_errors_from_cpu(c);
 
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		bch2_sb_from_fs(c, ca);
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		printbuf_reset(&err);
 
 		ret = bch2_sb_validate(&ca->disk_sb, &err, WRITE);
@@ -952,16 +947,16 @@ int bch2_write_super(struct bch_fs *c)
 	if (!BCH_SB_INITIALIZED(c->disk_sb.sb))
 		goto out;
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		__set_bit(ca->dev_idx, sb_written.d);
 		ca->sb_write_error = 0;
 	}
 
-	for_each_online_member(ca, c, i)
+	for_each_online_member(c, ca)
 		read_back_super(c, ca);
 	closure_sync(cl);
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		if (ca->sb_write_error)
 			continue;
 
@@ -988,7 +983,7 @@ int bch2_write_super(struct bch_fs *c)
 
 	do {
 		wrote = false;
-		for_each_online_member(ca, c, i)
+		for_each_online_member(c, ca)
 			if (!ca->sb_write_error &&
 			    sb < ca->disk_sb.sb->layout.nr_superblocks) {
 				write_one_super(c, ca, sb);
@@ -998,7 +993,7 @@ int bch2_write_super(struct bch_fs *c)
 		sb++;
 	} while (wrote);
 
-	for_each_online_member(ca, c, i) {
+	for_each_online_member(c, ca) {
 		if (ca->sb_write_error)
 			__clear_bit(ca->dev_idx, sb_written.d);
 		else
@@ -1010,7 +1005,7 @@ int bch2_write_super(struct bch_fs *c)
 	can_mount_with_written =
 		bch2_have_enough_devs(c, sb_written, degraded_flags, false);
 
-	for (i = 0; i < ARRAY_SIZE(sb_written.d); i++)
+	for (unsigned i = 0; i < ARRAY_SIZE(sb_written.d); i++)
 		sb_written.d[i] = ~sb_written.d[i];
 
 	can_mount_without_written =
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 5cc09b4b50af..d534df3b653a 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -249,8 +249,7 @@ static void bch2_dev_usage_journal_reserve(struct bch_fs *c)
 
 static void __bch2_fs_read_only(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i, clean_passes = 0;
+	unsigned clean_passes = 0;
 	u64 seq = 0;
 
 	bch2_fs_ec_stop(c);
@@ -286,7 +285,7 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 	/*
 	 * After stopping journal:
 	 */
-	for_each_member_device(ca, c, i)
+	for_each_member_device(c, ca)
 		bch2_dev_allocator_remove(c, ca);
 }
 
@@ -427,8 +426,6 @@ static int bch2_fs_read_write_late(struct bch_fs *c)
 
 static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 {
-	struct bch_dev *ca;
-	unsigned i;
 	int ret;
 
 	if (test_bit(BCH_FS_initial_gc_unfixed, &c->flags)) {
@@ -469,7 +466,7 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 	 */
 	set_bit(JOURNAL_NEED_FLUSH_WRITE, &c->journal.flags);
 
-	for_each_rw_member(ca, c, i)
+	for_each_rw_member(c, ca)
 		bch2_dev_allocator_add(c, ca);
 	bch2_recalc_capacity(c);
 
@@ -479,7 +476,7 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 #ifndef BCH_WRITE_REF_DEBUG
 	percpu_ref_reinit(&c->writes);
 #else
-	for (i = 0; i < BCH_WRITE_REF_NR; i++) {
+	for (unsigned i = 0; i < BCH_WRITE_REF_NR; i++) {
 		BUG_ON(atomic_long_read(&c->writes[i]));
 		atomic_long_inc(&c->writes[i]);
 	}
@@ -602,9 +599,6 @@ static void bch2_fs_release(struct kobject *kobj)
 
 void __bch2_fs_stop(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
-
 	bch_verbose(c, "shutting down");
 
 	set_bit(BCH_FS_stopping, &c->flags);
@@ -615,7 +609,7 @@ void __bch2_fs_stop(struct bch_fs *c)
 	bch2_fs_read_only(c);
 	up_write(&c->state_lock);
 
-	for_each_member_device(ca, c, i)
+	for_each_member_device(c, ca)
 		if (ca->kobj.state_in_sysfs &&
 		    ca->disk_sb.bdev)
 			sysfs_remove_link(bdev_kobj(ca->disk_sb.bdev), "bcachefs");
@@ -637,7 +631,7 @@ void __bch2_fs_stop(struct bch_fs *c)
 	/* btree prefetch might have kicked off reads in the background: */
 	bch2_btree_flush_all_reads(c);
 
-	for_each_member_device(ca, c, i)
+	for_each_member_device(c, ca)
 		cancel_work_sync(&ca->io_error_work);
 
 	cancel_work_sync(&c->read_only_work);
@@ -676,8 +670,6 @@ void bch2_fs_stop(struct bch_fs *c)
 
 static int bch2_fs_online(struct bch_fs *c)
 {
-	struct bch_dev *ca;
-	unsigned i;
 	int ret = 0;
 
 	lockdep_assert_held(&bch_fs_list_lock);
@@ -710,7 +702,7 @@ static int bch2_fs_online(struct bch_fs *c)
 
 	down_write(&c->state_lock);
 
-	for_each_member_device(ca, c, i) {
+	for_each_member_device(c, ca) {
 		ret = bch2_dev_sysfs_online(c, ca);
 		if (ret) {
 			bch_err(c, "error creating sysfs objects");
@@ -1000,9 +992,7 @@ static void print_mount_opts(struct bch_fs *c)
 
 int bch2_fs_start(struct bch_fs *c)
 {
-	struct bch_dev *ca;
 	time64_t now = ktime_get_real_seconds();
-	unsigned i;
 	int ret;
 
 	print_mount_opts(c);
@@ -1019,12 +1009,12 @@ int bch2_fs_start(struct bch_fs *c)
 		goto err;
 	}
 
-	for_each_online_member(ca, c, i)
-		bch2_members_v2_get_mut(c->disk_sb.sb, i)->last_mount = cpu_to_le64(now);
+	for_each_online_member(c, ca)
+		bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx)->last_mount = cpu_to_le64(now);
 
 	mutex_unlock(&c->sb_lock);
 
-	for_each_rw_member(ca, c, i)
+	for_each_rw_member(c, ca)
 		bch2_dev_allocator_add(c, ca);
 	bch2_recalc_capacity(c);
 
@@ -1361,8 +1351,7 @@ bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
 			    enum bch_member_state new_state, int flags)
 {
 	struct bch_devs_mask new_online_devs;
-	struct bch_dev *ca2;
-	int i, nr_rw = 0, required;
+	int nr_rw = 0, required;
 
 	lockdep_assert_held(&c->state_lock);
 
@@ -1374,7 +1363,7 @@ bool bch2_dev_state_allowed(struct bch_fs *c, struct bch_dev *ca,
 			return true;
 
 		/* do we have enough devices to write to?  */
-		for_each_member_device(ca2, c, i)
+		for_each_member_device(c, ca2)
 			if (ca2 != ca)
 				nr_rw += ca2->mi.state == BCH_MEMBER_STATE_rw;