From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Wed, 14 May 2025 14:44:21 +0000 (-0400)
Subject: bcachefs: fix can_write_extent()
X-Git-Tag: v6.16-rc1~211^2~61
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=648c1142c9f1ad914c9fd79cedbd6b92ac788cd6;p=thirdparty%2Flinux.git

bcachefs: fix can_write_extent()

Failing to check the return value of bch2_dev_rcu(): we could
(technically) race with device removal.

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

diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index c39ea51e9e484..de096ca65b4ba 100644
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -744,7 +744,9 @@ static int can_write_extent(struct bch_fs *c, struct data_update *m)
 	rcu_read_lock();
 	unsigned nr_replicas = 0, i;
 	for_each_set_bit(i, devs.d, BCH_SB_MEMBERS_MAX) {
-		struct bch_dev *ca = bch2_dev_rcu(c, i);
+		struct bch_dev *ca = bch2_dev_rcu_noerror(c, i);
+		if (!ca)
+			continue;
 
 		struct bch_dev_usage usage;
 		bch2_dev_usage_read_fast(ca, &usage);