bcachefs: Journal resize fixes

 - Fix a sleeping-in-atomic bug due to calling
   bch2_journal_buckets_to_sb() under the journal lock.
 - Additionally, now we mark buckets as journal buckets before adding
   them to the journal in memory and the superblock. This ensures that
   if we crash part way through we'll never be writing to journal
   buckets that aren't marked correctly.

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

1 files changed, 74 insertions, 80 deletions

diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index 00e806a64247..3cc93caf563a 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -757,19 +757,10 @@ static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
 	u64 *new_bucket_seq = NULL, *new_buckets = NULL;
 	struct open_bucket **ob = NULL;
 	long *bu = NULL;
-	unsigned i, nr_got = 0, nr_want = nr - ja->nr;
-	unsigned old_nr			= ja->nr;
-	unsigned old_discard_idx	= ja->discard_idx;
-	unsigned old_dirty_idx_ondisk	= ja->dirty_idx_ondisk;
-	unsigned old_dirty_idx		= ja->dirty_idx;
-	unsigned old_cur_idx		= ja->cur_idx;
+	unsigned i, pos, nr_got = 0, nr_want = nr - ja->nr;
 	int ret = 0;
 
-	if (c) {
-		bch2_journal_flush_all_pins(&c->journal);
-		bch2_journal_block(&c->journal);
-		mutex_lock(&c->sb_lock);
-	}
+	BUG_ON(nr <= ja->nr);
 
 	bu		= kcalloc(nr_want, sizeof(*bu), GFP_KERNEL);
 	ob		= kcalloc(nr_want, sizeof(*ob), GFP_KERNEL);
@@ -777,7 +768,7 @@ static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
 	new_bucket_seq	= kcalloc(nr, sizeof(u64), GFP_KERNEL);
 	if (!bu || !ob || !new_buckets || !new_bucket_seq) {
 		ret = -ENOMEM;
-		goto err_unblock;
+		goto err_free;
 	}
 
 	for (nr_got = 0; nr_got < nr_want; nr_got++) {
@@ -794,87 +785,92 @@ static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
 			if (ret)
 				break;
 
+			ret = bch2_trans_run(c,
+				bch2_trans_mark_metadata_bucket(&trans, ca,
+						ob[nr_got]->bucket, BCH_DATA_journal,
+						ca->mi.bucket_size));
+			if (ret) {
+				bch2_open_bucket_put(c, ob[nr_got]);
+				bch_err(c, "error marking new journal buckets: %s", bch2_err_str(ret));
+				break;
+			}
+
 			bu[nr_got] = ob[nr_got]->bucket;
 		}
 	}
 
 	if (!nr_got)
-		goto err_unblock;
+		goto err_free;
 
-	/*
-	 * We may be called from the device add path, before the new device has
-	 * actually been added to the running filesystem:
-	 */
-	if (!new_fs)
-		spin_lock(&c->journal.lock);
+	/* Don't return an error if we successfully allocated some buckets: */
+	ret = 0;
+
+	if (c) {
+		bch2_journal_flush_all_pins(&c->journal);
+		bch2_journal_block(&c->journal);
+		mutex_lock(&c->sb_lock);
+	}
 
 	memcpy(new_buckets,	ja->buckets,	ja->nr * sizeof(u64));
 	memcpy(new_bucket_seq,	ja->bucket_seq,	ja->nr * sizeof(u64));
-	swap(new_buckets,	ja->buckets);
-	swap(new_bucket_seq,	ja->bucket_seq);
+
+	BUG_ON(ja->discard_idx > ja->nr);
+
+	pos = ja->discard_idx ?: ja->nr;
+
+	memmove(new_buckets + pos + nr_got,
+		new_buckets + pos,
+		sizeof(new_buckets[0]) * (ja->nr - pos));
+	memmove(new_bucket_seq + pos + nr_got,
+		new_bucket_seq + pos,
+		sizeof(new_bucket_seq[0]) * (ja->nr - pos));
 
 	for (i = 0; i < nr_got; i++) {
-		unsigned pos = ja->discard_idx ?: ja->nr;
-		long b = bu[i];
-
-		__array_insert_item(ja->buckets,		ja->nr, pos);
-		__array_insert_item(ja->bucket_seq,		ja->nr, pos);
-		ja->nr++;
-
-		ja->buckets[pos] = b;
-		ja->bucket_seq[pos] = 0;
-
-		if (pos <= ja->discard_idx)
-			ja->discard_idx = (ja->discard_idx + 1) % ja->nr;
-		if (pos <= ja->dirty_idx_ondisk)
-			ja->dirty_idx_ondisk = (ja->dirty_idx_ondisk + 1) % ja->nr;
-		if (pos <= ja->dirty_idx)
-			ja->dirty_idx = (ja->dirty_idx + 1) % ja->nr;
-		if (pos <= ja->cur_idx)
-			ja->cur_idx = (ja->cur_idx + 1) % ja->nr;
+		new_buckets[pos + i] = bu[i];
+		new_bucket_seq[pos + i] = 0;
 	}
 
-	ret = bch2_journal_buckets_to_sb(c, ca);
-	if (ret) {
-		/* Revert: */
-		swap(new_buckets,	ja->buckets);
-		swap(new_bucket_seq,	ja->bucket_seq);
-		ja->nr			= old_nr;
-		ja->discard_idx		= old_discard_idx;
-		ja->dirty_idx_ondisk	= old_dirty_idx_ondisk;
-		ja->dirty_idx		= old_dirty_idx;
-		ja->cur_idx		= old_cur_idx;
-	}
+	nr = ja->nr + nr_got;
 
-	if (!new_fs)
-		spin_unlock(&c->journal.lock);
+	ret = bch2_journal_buckets_to_sb(c, ca, new_buckets, nr);
+	if (ret)
+		goto err_unblock;
 
-	if (ja->nr != old_nr && !new_fs)
+	if (!new_fs)
 		bch2_write_super(c);
 
+	/* Commit: */
 	if (c)
-		bch2_journal_unblock(&c->journal);
+		spin_lock(&c->journal.lock);
 
-	if (ret)
-		goto err;
+	swap(new_buckets,	ja->buckets);
+	swap(new_bucket_seq,	ja->bucket_seq);
+	ja->nr = nr;
+
+	if (pos <= ja->discard_idx)
+		ja->discard_idx = (ja->discard_idx + nr_got) % ja->nr;
+	if (pos <= ja->dirty_idx_ondisk)
+		ja->dirty_idx_ondisk = (ja->dirty_idx_ondisk + nr_got) % ja->nr;
+	if (pos <= ja->dirty_idx)
+		ja->dirty_idx = (ja->dirty_idx + nr_got) % ja->nr;
+	if (pos <= ja->cur_idx)
+		ja->cur_idx = (ja->cur_idx + nr_got) % ja->nr;
 
-	if (!new_fs) {
-		for (i = 0; i < nr_got; i++) {
-			ret = bch2_trans_run(c,
-				bch2_trans_mark_metadata_bucket(&trans, ca,
-						bu[i], BCH_DATA_journal,
-						ca->mi.bucket_size));
-			if (ret) {
-				bch2_fs_inconsistent(c, "error marking new journal buckets: %i", ret);
-				goto err;
-			}
-		}
-	}
-err:
 	if (c)
+		spin_unlock(&c->journal.lock);
+err_unblock:
+	if (c) {
+		bch2_journal_unblock(&c->journal);
 		mutex_unlock(&c->sb_lock);
+	}
 
-	if (ob && !new_fs)
+	if (ret && !new_fs)
+		for (i = 0; i < nr_got; i++)
+			bch2_trans_run(c,
+				bch2_trans_mark_metadata_bucket(&trans, ca,
+						bu[i], BCH_DATA_free, 0));
+err_free:
+	if (!new_fs)
 		for (i = 0; i < nr_got; i++)
 			bch2_open_bucket_put(c, ob[i]);
 
@@ -882,12 +878,7 @@ err:
 	kfree(new_buckets);
 	kfree(ob);
 	kfree(bu);
-
 	return ret;
-err_unblock:
-	if (c)
-		bch2_journal_unblock(&c->journal);
-	goto err;
 }
 
 /*
@@ -901,13 +892,15 @@ int bch2_set_nr_journal_buckets(struct bch_fs *c, struct bch_dev *ca,
 	struct closure cl;
 	int ret = 0;
 
+	closure_init_stack(&cl);
+
+	down_write(&c->state_lock);
+
 	/* don't handle reducing nr of buckets yet: */
 	if (nr < ja->nr)
-		return 0;
-
-	closure_init_stack(&cl);
+		goto unlock;
 
-	while (ja->nr != nr) {
+	while (ja->nr < nr) {
 		struct disk_reservation disk_res = { 0, 0 };
 
 		/*
@@ -938,7 +931,8 @@ int bch2_set_nr_journal_buckets(struct bch_fs *c, struct bch_dev *ca,
 
 	if (ret)
 		bch_err(c, "%s: err %s", __func__, bch2_err_str(ret));
-
+unlock:
+	up_write(&c->state_lock);
 	return ret;
 }