From 4d6128dca6d940015fe2aa383ec1a0eeb9632f08 Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Mon, 6 Nov 2023 11:59:05 -0500
Subject: [PATCH] bcachefs: Guard against insufficient devices to create
stripes
We can't create stripes if we don't have enough devices - this
manifested as an integer underflow bug later.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/ec.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/bcachefs/ec.c b/fs/bcachefs/ec.c
index 875f7c5a6fca6..2a77de18c004e 100644
--- a/fs/bcachefs/ec.c
+++ b/fs/bcachefs/ec.c
@@ -1373,6 +1373,15 @@ ec_new_stripe_head_alloc(struct bch_fs *c, unsigned target,
h->nr_active_devs++;
rcu_read_unlock();
+
+ /*
+ * If we only have redundancy + 1 devices, we're better off with just
+ * replication:
+ */
+ if (h->nr_active_devs < h->redundancy + 2)
+ bch_err(c, "insufficient devices available to create stripe (have %u, need %u) - mismatched bucket sizes?",
+ h->nr_active_devs, h->redundancy + 2);
+
list_add(&h->list, &c->ec_stripe_head_list);
return h;
}
@@ -1424,6 +1433,11 @@ __bch2_ec_stripe_head_get(struct btree_trans *trans,
h = ec_new_stripe_head_alloc(c, target, algo, redundancy, watermark);
found:
+ if (!IS_ERR_OR_NULL(h) &&
+ h->nr_active_devs < h->redundancy + 2) {
+ mutex_unlock(&h->lock);
+ h = NULL;
+ }
mutex_unlock(&c->ec_stripe_head_lock);
return h;
}
@@ -1681,8 +1695,6 @@ struct ec_stripe_head *bch2_ec_stripe_head_get(struct btree_trans *trans,
int ret;
h = __bch2_ec_stripe_head_get(trans, target, algo, redundancy, watermark);
- if (!h)
- bch_err(c, "no stripe head");
if (IS_ERR_OR_NULL(h))
return h;
--
2.30.2