bcachefs: Clean up error reporting in the startup path

It used to be that error reporting in the startup path was done by
returning strings describing the error, but that turned out to be a
rather silly idea - if there's something we can describe about the
error, just print it right away.

This converts a good chunk of code to returning error codes, as is more
typical style.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/super.c

@@ -596,48 +596,53 @@ void bch2_fs_stop(struct bch_fs *c)
 	bch2_fs_free(c);
 }
 
-static const char *bch2_fs_online(struct bch_fs *c)
+static int bch2_fs_online(struct bch_fs *c)
 {
 	struct bch_dev *ca;
-	const char *err = NULL;
 	unsigned i;
-	int ret;
+	int ret = 0;
 
 	lockdep_assert_held(&bch_fs_list_lock);
 
-	if (!list_empty(&c->list))
-		return NULL;
-
-	if (__bch2_uuid_to_fs(c->sb.uuid))
-		return "filesystem UUID already open";
+	if (__bch2_uuid_to_fs(c->sb.uuid)) {
+		bch_err(c, "filesystem UUID already open");
+		return -EINVAL;
+	}
 
 	ret = bch2_fs_chardev_init(c);
-	if (ret)
-		return "error creating character device";
+	if (ret) {
+		bch_err(c, "error creating character device");
+		return ret;
+	}
 
 	bch2_fs_debug_init(c);
 
-	if (kobject_add(&c->kobj, NULL, "%pU", c->sb.user_uuid.b) ||
-	    kobject_add(&c->internal, &c->kobj, "internal") ||
-	    kobject_add(&c->opts_dir, &c->kobj, "options") ||
-	    kobject_add(&c->time_stats, &c->kobj, "time_stats") ||
-	    bch2_opts_create_sysfs_files(&c->opts_dir))
-		return "error creating sysfs objects";
+	ret = kobject_add(&c->kobj, NULL, "%pU", c->sb.user_uuid.b) ?:
+	    kobject_add(&c->internal, &c->kobj, "internal") ?:
+	    kobject_add(&c->opts_dir, &c->kobj, "options") ?:
+	    kobject_add(&c->time_stats, &c->kobj, "time_stats") ?:
+	    bch2_opts_create_sysfs_files(&c->opts_dir);
+	if (ret) {
+		bch_err(c, "error creating sysfs objects");
+		return ret;
+	}
 
 	down_write(&c->state_lock);
 
-	err = "error creating sysfs objects";
-	for_each_member_device(ca, c, i)
-		if (bch2_dev_sysfs_online(c, ca)) {
+	for_each_member_device(ca, c, i) {
+		ret = bch2_dev_sysfs_online(c, ca);
+		if (ret) {
+			bch_err(c, "error creating sysfs objects");
 			percpu_ref_put(&ca->ref);
 			goto err;
 		}
+	}
 
+	BUG_ON(!list_empty(&c->list));
 	list_add(&c->list, &bch_fs_list);
-	err = NULL;
 err:
 	up_write(&c->state_lock);
-	return err;
+	return ret;
 }
 
 static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
@@ -645,7 +650,6 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	struct bch_sb_field_members *mi;
 	struct bch_fs *c;
 	unsigned i, iter_size;
-	const char *err;
 	int ret = 0;
 
 	pr_verbose_init(opts, "");
@@ -735,20 +739,16 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 
 	mutex_init(&c->sectors_available_lock);
 
-	if (percpu_init_rwsem(&c->mark_lock)) {
-		ret = -ENOMEM;
+	ret = percpu_init_rwsem(&c->mark_lock);
+	if (ret)
 		goto err;
-	}
 
 	mutex_lock(&c->sb_lock);
+	ret = bch2_sb_to_fs(c, sb);
+	mutex_unlock(&c->sb_lock);
 
-	if (bch2_sb_to_fs(c, sb)) {
-		mutex_unlock(&c->sb_lock);
-		ret = -ENOMEM;
+	if (ret)
 		goto err;
-	}
-
-	mutex_unlock(&c->sb_lock);
 
 	scnprintf(c->name, sizeof(c->name), "%pU", &c->sb.user_uuid);
 
@@ -760,7 +760,8 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	c->btree_foreground_merge_threshold = BTREE_FOREGROUND_MERGE_THRESHOLD(c);
 
 	if (bch2_fs_init_fault("fs_alloc")) {
-		ret = -ENOMEM;
+		bch_err(c, "fs_alloc fault injected");
+		ret = -EFAULT;
 		goto err;
 	}
 
@@ -792,25 +793,25 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 					btree_bytes(c)) ||
 	    mempool_init_kmalloc_pool(&c->large_bkey_pool, 1, 2048) ||
 	    !(c->unused_inode_hints = kcalloc(1U << c->inode_shard_bits,
-					      sizeof(u64), GFP_KERNEL)) ||
-	    bch2_io_clock_init(&c->io_clock[READ]) ||
-	    bch2_io_clock_init(&c->io_clock[WRITE]) ||
-	    bch2_fs_journal_init(&c->journal) ||
-	    bch2_fs_replicas_init(c) ||
-	    bch2_fs_btree_cache_init(c) ||
-	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ||
-	    bch2_fs_btree_iter_init(c) ||
-	    bch2_fs_btree_interior_update_init(c) ||
-	    bch2_fs_subvolumes_init(c) ||
-	    bch2_fs_io_init(c) ||
-	    bch2_fs_compress_init(c) ||
-	    bch2_fs_ec_init(c) ||
-	    bch2_fs_fsio_init(c)) {
+					      sizeof(u64), GFP_KERNEL))) {
 		ret = -ENOMEM;
 		goto err;
 	}
 
-	ret = bch2_fs_encryption_init(c);
+	ret = bch2_io_clock_init(&c->io_clock[READ]) ?:
+	    bch2_io_clock_init(&c->io_clock[WRITE]) ?:
+	    bch2_fs_journal_init(&c->journal) ?:
+	    bch2_fs_replicas_init(c) ?:
+	    bch2_fs_btree_cache_init(c) ?:
+	    bch2_fs_btree_key_cache_init(&c->btree_key_cache) ?:
+	    bch2_fs_btree_iter_init(c) ?:
+	    bch2_fs_btree_interior_update_init(c) ?:
+	    bch2_fs_subvolumes_init(c) ?:
+	    bch2_fs_io_init(c) ?:
+	    bch2_fs_encryption_init(c) ?:
+	    bch2_fs_compress_init(c) ?:
+	    bch2_fs_ec_init(c) ?:
+	    bch2_fs_fsio_init(c);
 	if (ret)
 		goto err;
 
@@ -821,7 +822,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	for (i = 0; i < c->sb.nr_devices; i++)
 		if (bch2_dev_exists(c->disk_sb.sb, mi, i) &&
 		    bch2_dev_alloc(c, i)) {
-			ret = -ENOMEM;
+			ret = -EEXIST;
 			goto err;
 		}
 
@@ -834,13 +835,11 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 			(sizeof(struct jset_entry_clock) / sizeof(u64)) * 2);
 
 	mutex_lock(&bch_fs_list_lock);
-	err = bch2_fs_online(c);
+	ret = bch2_fs_online(c);
 	mutex_unlock(&bch_fs_list_lock);
-	if (err) {
-		bch_err(c, "bch2_fs_online() error: %s", err);
-		ret = -ENOMEM;
+
+	if (ret)
 		goto err;
-	}
 out:
 	pr_verbose_init(opts, "ret %i", PTR_ERR_OR_ZERO(c));
 	return c;
@@ -886,7 +885,6 @@ static void print_mount_opts(struct bch_fs *c)
 
 int bch2_fs_start(struct bch_fs *c)
 {
-	const char *err = "cannot allocate memory";
 	struct bch_sb_field_members *mi;
 	struct bch_dev *ca;
 	time64_t now = ktime_get_real_seconds();
@@ -922,10 +920,11 @@ int bch2_fs_start(struct bch_fs *c)
 	if (ret)
 		goto err;
 
-	err = "dynamic fault";
 	ret = -EINVAL;
-	if (bch2_fs_init_fault("fs_start"))
+	if (bch2_fs_init_fault("fs_start")) {
+		bch_err(c, "fs_start fault injected");
 		goto err;
+	}
 
 	set_bit(BCH_FS_STARTED, &c->flags);
 
@@ -946,7 +945,6 @@ int bch2_fs_start(struct bch_fs *c)
 	if (c->opts.read_only || c->opts.nochanges) {
 		bch2_fs_read_only(c);
 	} else {
-		err = "error going read write";
 		ret = !test_bit(BCH_FS_RW, &c->flags)
 			? bch2_fs_read_write(c)
 			: bch2_fs_read_write_late(c);
@@ -964,25 +962,22 @@ int bch2_fs_start(struct bch_fs *c)
 	case BCH_FSCK_ERRORS_NOT_FIXED:
 		bch_err(c, "filesystem contains errors: please report this to the developers");
 		pr_cont("mount with -o fix_errors to repair\n");
-		err = "fsck error";
 		break;
 	case BCH_FSCK_REPAIR_UNIMPLEMENTED:
 		bch_err(c, "filesystem contains errors: please report this to the developers");
 		pr_cont("repair unimplemented: inform the developers so that it can be added\n");
-		err = "fsck error";
 		break;
 	case BCH_FSCK_REPAIR_IMPOSSIBLE:
 		bch_err(c, "filesystem contains errors, but repair impossible");
-		err = "fsck error";
 		break;
 	case BCH_FSCK_UNKNOWN_VERSION:
-		err = "unknown metadata version";;
+		bch_err(c, "unknown metadata version");
 		break;
 	case -ENOMEM:
-		err = "cannot allocate memory";
+		bch_err(c, "cannot allocate memory");
 		break;
 	case -EIO:
-		err = "IO error";
+		bch_err(c, "IO error");
 		break;
 	}
 
@@ -1400,7 +1395,7 @@ static void __bch2_dev_read_only(struct bch_fs *c, struct bch_dev *ca)
 	bch2_copygc_start(c);
 }
 
-static const char *__bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
+static int __bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
 {
 	lockdep_assert_held(&c->state_lock);
 
@@ -1409,10 +1404,7 @@ static const char *__bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
 	bch2_dev_allocator_add(c, ca);
 	bch2_recalc_capacity(c);
 
-	if (bch2_dev_allocator_start(ca))
-		return "error starting allocator thread";
-
-	return NULL;
+	return bch2_dev_allocator_start(ca);
 }
 
 int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
@@ -1438,9 +1430,8 @@ int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
 	bch2_write_super(c);
 	mutex_unlock(&c->sb_lock);
 
-	if (new_state == BCH_MEMBER_STATE_rw &&
-	    __bch2_dev_read_write(c, ca))
-		ret = -ENOMEM;
+	if (new_state == BCH_MEMBER_STATE_rw)
+		ret = __bch2_dev_read_write(c, ca);
 
 	rebalance_wakeup(c);
 
@@ -1724,8 +1715,8 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 		goto err_late;
 
 	if (ca->mi.state == BCH_MEMBER_STATE_rw) {
-		err = __bch2_dev_read_write(c, ca);
-		if (err)
+		ret = __bch2_dev_read_write(c, ca);
+		if (ret)
 			goto err_late;
 	}
 
@@ -1769,24 +1760,27 @@ int bch2_dev_online(struct bch_fs *c, const char *path)
 	dev_idx = sb.sb->dev_idx;
 
 	err = bch2_dev_in_fs(c->disk_sb.sb, sb.sb);
-	if (err)
+	if (err) {
+		bch_err(c, "error bringing %s online: %s", path, err);
 		goto err;
+	}
 
-	if (bch2_dev_attach_bdev(c, &sb)) {
-		err = "bch2_dev_attach_bdev() error";
+	ret = bch2_dev_attach_bdev(c, &sb);
+	if (ret)
 		goto err;
-	}
 
 	ca = bch_dev_locked(c, dev_idx);
 
-	if (bch2_trans_mark_dev_sb(c, ca)) {
-		err = "bch2_trans_mark_dev_sb() error";
+	ret = bch2_trans_mark_dev_sb(c, ca);
+	if (ret) {
+		bch_err(c, "error bringing %s online: error %i from bch2_trans_mark_dev_sb",
+			path, ret);
 		goto err;
 	}
 
 	if (ca->mi.state == BCH_MEMBER_STATE_rw) {
-		err = __bch2_dev_read_write(c, ca);
-		if (err)
+		ret = __bch2_dev_read_write(c, ca);
+		if (ret)
 			goto err;
 	}
 
@@ -1804,7 +1798,6 @@ int bch2_dev_online(struct bch_fs *c, const char *path)
 err:
 	up_write(&c->state_lock);
 	bch2_free_super(&sb);
-	bch_err(c, "error bringing %s online: %s", path, err);
 	return -EINVAL;
 }
 
@@ -1908,7 +1901,7 @@ struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
 	struct bch_sb_field_members *mi;
 	unsigned i, best_sb = 0;
 	const char *err;
-	int ret = -ENOMEM;
+	int ret = 0;
 
 	pr_verbose_init(opts, "");
 
@@ -1923,8 +1916,10 @@ struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
 	}
 
 	sb = kcalloc(nr_devices, sizeof(*sb), GFP_KERNEL);
-	if (!sb)
+	if (!sb) {
+		ret = -ENOMEM;
 		goto err;
+	}
 
 	for (i = 0; i < nr_devices; i++) {
 		ret = bch2_read_super(devices[i], &opts, &sb[i]);
@@ -1965,13 +1960,14 @@ struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
 		goto err;
 	}
 
-	err = "bch2_dev_online() error";
 	down_write(&c->state_lock);
-	for (i = 0; i < nr_devices; i++)
-		if (bch2_dev_attach_bdev(c, &sb[i])) {
+	for (i = 0; i < nr_devices; i++) {
+		ret = bch2_dev_attach_bdev(c, &sb[i]);
+		if (ret) {
 			up_write(&c->state_lock);
-			goto err_print;
+			goto err;
 		}
+	}
 	up_write(&c->state_lock);
 
 	err = "insufficient devices";
@@ -1996,8 +1992,9 @@ struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
 err:
 	if (!IS_ERR_OR_NULL(c))
 		bch2_fs_stop(c);
-	for (i = 0; i < nr_devices; i++)
-		bch2_free_super(&sb[i]);
+	if (sb)
+		for (i = 0; i < nr_devices; i++)
+			bch2_free_super(&sb[i]);
 	c = ERR_PTR(ret);
 	goto out;
 }