From 86755b7a96faed57f910f9e6b8061e019ac1ec08 Mon Sep 17 00:00:00 2001
From: Michael Lyle <mlyle@lyle.org>
Date: Mon, 5 Mar 2018 13:41:55 -0800
Subject: [PATCH] bcache: don't attach backing with duplicate UUID
Git-commit: 86755b7a96faed57f910f9e6b8061e019ac1ec08
Patch-mainline: v4.16-rc5
References: bsc#1076110
This can happen e.g. during disk cloning.
This is an incomplete fix: it does not catch duplicate UUIDs earlier
when things are still unattached. It does not unregister the device.
Further changes to cope better with this are planned but conflict with
Coly's ongoing improvements to handling device errors. In the meantime,
one can manually stop the device after this has happened.
Attempts to attach a duplicate device result in:
[ 136.372404] loop: module loaded
[ 136.424461] bcache: register_bdev() registered backing device loop0
[ 136.424464] bcache: bch_cached_dev_attach() Tried to attach loop0 but duplicate UUID already attached
My test procedure is:
dd if=/dev/sdb1 of=imgfile bs=1024 count=262144
losetup -f imgfile
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Tang Junhui <tang.junhui@zte.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/bcache/super.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 58d8998529de..f2273143b3cb 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -963,6 +963,7 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
uint32_t rtime = cpu_to_le32(get_seconds());
struct uuid_entry *u;
char buf[BDEVNAME_SIZE];
+ struct cached_dev *exist_dc, *t;
bdevname(dc->bdev, buf);
@@ -987,6 +988,16 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
return -EINVAL;
}
+ /* Check whether already attached */
+ list_for_each_entry_safe(exist_dc, t, &c->cached_devs, list) {
+ if (!memcmp(dc->sb.uuid, exist_dc->sb.uuid, 16)) {
+ pr_err("Tried to attach %s but duplicate UUID already attached",
+ buf);
+
+ return -EINVAL;
+ }
+ }
+
u = uuid_find(c, dc->sb.uuid);
if (u &&
--
2.16.2