bcachefs: Redo data_update interface

This patch significantly cleans up and simplifies the data_update
interface. Instead of only being able to specify a single pointer by
device to rewrite, we're now able to specify any or all of the pointers
in the original extent to be rewrited, as a bitmask.

data_cmd is no more: the various pred functions now just return true if
the extent should be moved/updated. All the data_update path does is
rewrite existing replicas, or add new ones.

This fixes a bug where with background compression on replicated
filesystems, where rebalance -> data_update would incorrectly drop the
wrong old replica, and keep trying to recompress an extent pointer and
each time failing to drop the right replica. Oops.

Now, the data update path doesn't look at the io options to decide which
pointers to keep and which to drop - it only goes off of the
data_update_options passed to it.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 54 insertions, 86 deletions

diff --git a/fs/bcachefs/move.c b/fs/bcachefs/move.c
index a3a486cff28e..4060678cf716 100644
--- a/fs/bcachefs/move.c
+++ b/fs/bcachefs/move.c
@@ -38,17 +38,9 @@ struct moving_io {
 static void move_free(struct moving_io *io)
 {
 	struct moving_context *ctxt = io->write.ctxt;
-	struct bvec_iter_all iter;
-	struct bio_vec *bv;
-
-	bch2_disk_reservation_put(io->write.op.c, &io->write.op.res);
-
-	bio_for_each_segment_all(bv, &io->write.op.wbio.bio, iter)
-		if (bv->bv_page)
-			__free_page(bv->bv_page);
 
+	bch2_data_update_exit(&io->write);
 	wake_up(&ctxt->wait);
-
 	kfree(io);
 }
 
@@ -72,8 +64,7 @@ static void move_write(struct moving_io *io)
 	closure_get(&io->write.ctxt->cl);
 	atomic_add(io->write_sectors, &io->write.ctxt->write_sectors);
 
-	bch2_data_update_read_done(&io->write, &io->rbio);
-	closure_call(&io->write.op.cl, bch2_write, NULL, NULL);
+	bch2_data_update_read_done(&io->write, io->rbio.pick.crc);
 }
 
 static inline struct moving_io *next_pending_write(struct moving_context *ctxt)
@@ -135,8 +126,7 @@ static int bch2_move_extent(struct btree_trans *trans,
 			    struct bch_io_opts io_opts,
 			    enum btree_id btree_id,
 			    struct bkey_s_c k,
-			    enum data_cmd data_cmd,
-			    struct data_opts data_opts)
+			    struct data_update_opts data_opts)
 {
 	struct bch_fs *c = trans->c;
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
@@ -180,10 +170,11 @@ static int bch2_move_extent(struct btree_trans *trans,
 	io->rbio.bio.bi_end_io		= move_read_endio;
 
 	ret = bch2_data_update_init(c, &io->write, wp, io_opts,
-				    data_cmd, data_opts, btree_id, k);
+				    data_opts, btree_id, k);
 	if (ret)
 		goto err_free_pages;
 
+	io->write.ctxt = ctxt;
 	io->write.op.end_io = move_write_done;
 
 	atomic64_inc(&ctxt->stats->keys_moved);
@@ -262,8 +253,7 @@ static int __bch2_move_data(struct bch_fs *c,
 	struct btree_trans trans;
 	struct btree_iter iter;
 	struct bkey_s_c k;
-	struct data_opts data_opts;
-	enum data_cmd data_cmd;
+	struct data_update_opts data_opts;
 	u64 delay, cur_inum = U64_MAX;
 	int ret = 0, ret2;
 
@@ -350,18 +340,9 @@ static int __bch2_move_data(struct bch_fs *c,
 			cur_inum = k.k->p.inode;
 		}
 
-		switch ((data_cmd = pred(c, arg, k, &io_opts, &data_opts))) {
-		case DATA_SKIP:
+		memset(&data_opts, 0, sizeof(data_opts));
+		if (!pred(c, arg, k, &io_opts, &data_opts))
 			goto next;
-		case DATA_SCRUB:
-			BUG();
-		case DATA_ADD_REPLICAS:
-		case DATA_REWRITE:
-		case DATA_PROMOTE:
-			break;
-		default:
-			BUG();
-		}
 
 		/*
 		 * The iterator gets unlocked by __bch2_read_extent - need to
@@ -370,8 +351,8 @@ static int __bch2_move_data(struct bch_fs *c,
 		bch2_bkey_buf_reassemble(&sk, c, k);
 		k = bkey_i_to_s_c(sk.k);
 
-		ret2 = bch2_move_extent(&trans, ctxt, wp, io_opts, btree_id, k,
-					data_cmd, data_opts);
+		ret2 = bch2_move_extent(&trans, ctxt, wp, io_opts,
+					btree_id, k, data_opts);
 		if (ret2) {
 			if (ret2 == -EINTR)
 				continue;
@@ -476,9 +457,9 @@ int bch2_move_data(struct bch_fs *c,
 	return ret;
 }
 
-typedef enum data_cmd (*move_btree_pred)(struct bch_fs *, void *,
-					 struct btree *, struct bch_io_opts *,
-					 struct data_opts *);
+typedef bool (*move_btree_pred)(struct bch_fs *, void *,
+				struct btree *, struct bch_io_opts *,
+				struct data_update_opts *);
 
 static int bch2_move_btree(struct bch_fs *c,
 			   enum btree_id start_btree_id, struct bpos start_pos,
@@ -492,8 +473,7 @@ static int bch2_move_btree(struct bch_fs *c,
 	struct btree_iter iter;
 	struct btree *b;
 	enum btree_id id;
-	struct data_opts data_opts;
-	enum data_cmd cmd;
+	struct data_update_opts data_opts;
 	int ret = 0;
 
 	bch2_trans_init(&trans, c, 0, 0);
@@ -522,17 +502,8 @@ retry:
 
 			stats->pos = iter.pos;
 
-			switch ((cmd = pred(c, arg, b, &io_opts, &data_opts))) {
-			case DATA_SKIP:
+			if (!pred(c, arg, b, &io_opts, &data_opts))
 				goto next;
-			case DATA_SCRUB:
-				BUG();
-			case DATA_ADD_REPLICAS:
-			case DATA_REWRITE:
-				break;
-			default:
-				BUG();
-			}
 
 			ret = bch2_btree_node_rewrite(&trans, &iter, b, 0) ?: ret;
 			if (ret == -EINTR)
@@ -562,20 +533,10 @@ next:
 	return ret;
 }
 
-#if 0
-static enum data_cmd scrub_pred(struct bch_fs *c, void *arg,
-				struct bkey_s_c k,
-				struct bch_io_opts *io_opts,
-				struct data_opts *data_opts)
-{
-	return DATA_SCRUB;
-}
-#endif
-
-static enum data_cmd rereplicate_pred(struct bch_fs *c, void *arg,
-				      struct bkey_s_c k,
-				      struct bch_io_opts *io_opts,
-				      struct data_opts *data_opts)
+static bool rereplicate_pred(struct bch_fs *c, void *arg,
+			     struct bkey_s_c k,
+			     struct bch_io_opts *io_opts,
+			     struct data_update_opts *data_opts)
 {
 	unsigned nr_good = bch2_bkey_durability(c, k);
 	unsigned replicas = bkey_is_btree_ptr(k.k)
@@ -583,43 +544,50 @@ static enum data_cmd rereplicate_pred(struct bch_fs *c, void *arg,
 		: io_opts->data_replicas;
 
 	if (!nr_good || nr_good >= replicas)
-		return DATA_SKIP;
+		return false;
 
 	data_opts->target		= 0;
-	data_opts->nr_replicas		= 1;
+	data_opts->extra_replicas	= replicas - nr_good;
 	data_opts->btree_insert_flags	= 0;
-	return DATA_ADD_REPLICAS;
+	return true;
 }
 
-static enum data_cmd migrate_pred(struct bch_fs *c, void *arg,
-				  struct bkey_s_c k,
-				  struct bch_io_opts *io_opts,
-				  struct data_opts *data_opts)
+static bool migrate_pred(struct bch_fs *c, void *arg,
+			 struct bkey_s_c k,
+			 struct bch_io_opts *io_opts,
+			 struct data_update_opts *data_opts)
 {
+	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+	const struct bch_extent_ptr *ptr;
 	struct bch_ioctl_data *op = arg;
+	unsigned i = 0;
 
-	if (!bch2_bkey_has_device(k, op->migrate.dev))
-		return DATA_SKIP;
-
+	data_opts->rewrite_ptrs		= 0;
 	data_opts->target		= 0;
-	data_opts->nr_replicas		= 1;
+	data_opts->extra_replicas	= 0;
 	data_opts->btree_insert_flags	= 0;
-	data_opts->rewrite_dev		= op->migrate.dev;
-	return DATA_REWRITE;
+
+	bkey_for_each_ptr(ptrs, ptr) {
+		if (ptr->dev == op->migrate.dev)
+			data_opts->rewrite_ptrs |= 1U << i;
+		i++;
+	}
+
+	return data_opts->rewrite_ptrs != 0;;
 }
 
-static enum data_cmd rereplicate_btree_pred(struct bch_fs *c, void *arg,
-					    struct btree *b,
-					    struct bch_io_opts *io_opts,
-					    struct data_opts *data_opts)
+static bool rereplicate_btree_pred(struct bch_fs *c, void *arg,
+				   struct btree *b,
+				   struct bch_io_opts *io_opts,
+				   struct data_update_opts *data_opts)
 {
 	return rereplicate_pred(c, arg, bkey_i_to_s_c(&b->key), io_opts, data_opts);
 }
 
-static enum data_cmd migrate_btree_pred(struct bch_fs *c, void *arg,
-					struct btree *b,
-					struct bch_io_opts *io_opts,
-					struct data_opts *data_opts)
+static bool migrate_btree_pred(struct bch_fs *c, void *arg,
+			       struct btree *b,
+			       struct bch_io_opts *io_opts,
+			       struct data_update_opts *data_opts)
 {
 	return migrate_pred(c, arg, bkey_i_to_s_c(&b->key), io_opts, data_opts);
 }
@@ -648,21 +616,21 @@ static bool bformat_needs_redo(struct bkey_format *f)
 	return false;
 }
 
-static enum data_cmd rewrite_old_nodes_pred(struct bch_fs *c, void *arg,
-					    struct btree *b,
-					    struct bch_io_opts *io_opts,
-					    struct data_opts *data_opts)
+static bool rewrite_old_nodes_pred(struct bch_fs *c, void *arg,
+				   struct btree *b,
+				   struct bch_io_opts *io_opts,
+				   struct data_update_opts *data_opts)
 {
 	if (b->version_ondisk != c->sb.version ||
 	    btree_node_need_rewrite(b) ||
 	    bformat_needs_redo(&b->format)) {
 		data_opts->target		= 0;
-		data_opts->nr_replicas		= 1;
+		data_opts->extra_replicas	= 0;
 		data_opts->btree_insert_flags	= 0;
-		return DATA_REWRITE;
+		return true;
 	}
 
-	return DATA_SKIP;
+	return false;
 }
 
 int bch2_scan_old_btree_nodes(struct bch_fs *c, struct bch_move_stats *stats)