A filesystem abnormal mount issue was found during current testing:
disk_container=$(...kata-runtime...io.kubernets.docker.type=container...)
docker_id=$(...kata-runtime...io.katacontainers.disk_share=
"{"src":"/dev/sdb","dest":"/dev/test"}"...)
${docker} stop "$disk_container"
${docker} exec "$docker_id" mount /dev/test /tmp -->success!!
When the "disk_container" is stopped, the created sda/sdb/sdc disks are
already deleted, but inside the "docker_id", /dev/test can still be mounted
successfully. The reason is that runc calls unshare, which triggers
clone_mnt(), increasing the "sb->s_active" reference count. As long as the
"docker_id" does not exit, the superblock still has a reference count.
So when mounting, the old superblock is reused in sget_fc(), and the mount
succeeds, even if the actual device no longer exists. The whole process can
be simplified as follows:
mkfs.ext4 -F /dev/sdb
mount /dev/sdb /mnt
mknod /dev/test b 8 16 # [sdb 8:16]
echo 1 > /sys/block/sdb/device/delete
mount /dev/test /mnt1 # -> mount success
Therefore, it is necessary to add an extra check. Solve this problem by
checking disk_live() in super_s_dev_test().
Fixes: aca740cecbe5 ("fs: open block device after superblock creation")
Link: https://lore.kernel.org/all/20250717091150.2156842-1-wozizhi@xxxxxxxxxx/
Signed-off-by: Zizhi Wo <wozizhi@xxxxxxxxxx>
---
fs/super.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 80418ca8e215..8030fb519eb5 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1376,8 +1376,16 @@ static int super_s_dev_set(struct super_block *s, struct fs_context *fc)
static int super_s_dev_test(struct super_block *s, struct fs_context *fc)
{
- return !(s->s_iflags & SB_I_RETIRED) &&
- s->s_dev == *(dev_t *)fc->sget_key;
+ if (s->s_iflags & SB_I_RETIRED)
+ return false;
+
+ if (s->s_dev != *(dev_t *)fc->sget_key)
+ return false;
+
+ if (s->s_bdev && !disk_live(s->s_bdev->bd_disk))
+ return false;
+
+ return true;
}
/**
--
2.39.2
