On 10/27/21 8:31 PM, Jeff Layton wrote:
Writing a non-zero value to this file will trigger spurious shutdown of
the client, simulating the effect of receiving a bad mdsmap or fsmap.
Note that this effect cannot be reversed. The only remedy is to unmount.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/ceph/debugfs.c | 28 ++++++++++++++++++++++++++++
fs/ceph/super.h | 1 +
2 files changed, 29 insertions(+)
I used this patch to do some fault injection testing before I proposed
the patch recently to shut down the mount on receipt of a bad fsmap or
mdsmap.
Is this something we should consider for mainline kernels?
We could put it behind a new Kconfig option if we're worried about
footguns in production kernels. Maybe we could call the new file
"fault_inject", and allow writing a mask value to it? We could roll
tests for teuthology that use this too.
How about adding one mount option to enable this ? And disable it as
default.
There are a lot of possibilities.
diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
index 55426514491b..57a72f267f6e 100644
--- a/fs/ceph/debugfs.c
+++ b/fs/ceph/debugfs.c
@@ -401,11 +401,32 @@ DEFINE_SIMPLE_ATTRIBUTE(congestion_kb_fops, congestion_kb_get,
congestion_kb_set, "%llu\n");
+static int client_shutdown_set(void *data, u64 val)
+{
+ struct ceph_fs_client *fsc = (struct ceph_fs_client *)data;
+
+ if (val)
+ ceph_umount_begin(fsc->sb);
+ return 0;
+}
+
+static int client_shutdown_get(void *data, u64 *val)
+{
+ struct ceph_fs_client *fsc = (struct ceph_fs_client *)data;
+
+ *val = (u64)(fsc->mount_state == CEPH_MOUNT_SHUTDOWN);
+ return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(client_shutdown_fops, client_shutdown_get,
+ client_shutdown_set, "%llu\n");
+
void ceph_fs_debugfs_cleanup(struct ceph_fs_client *fsc)
{
dout("ceph_fs_debugfs_cleanup\n");
debugfs_remove(fsc->debugfs_bdi);
debugfs_remove(fsc->debugfs_congestion_kb);
+ debugfs_remove(fsc->debugfs_client_shutdown);
debugfs_remove(fsc->debugfs_mdsmap);
debugfs_remove(fsc->debugfs_mds_sessions);
debugfs_remove(fsc->debugfs_caps);
@@ -426,6 +447,13 @@ void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
fsc,
&congestion_kb_fops);
+ fsc->debugfs_client_shutdown =
+ debugfs_create_file("client_shutdown",
+ 0600,
+ fsc->client->debugfs_dir,
+ fsc,
+ &client_shutdown_fops);
+
snprintf(name, sizeof(name), "../../bdi/%s",
bdi_dev_name(fsc->sb->s_bdi));
fsc->debugfs_bdi =
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index ed51e04739c4..e5d0ad5c6135 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -135,6 +135,7 @@ struct ceph_fs_client {
struct dentry *debugfs_status;
struct dentry *debugfs_mds_sessions;
struct dentry *debugfs_metrics_dir;
+ struct dentry *debugfs_client_shutdown;
#endif
#ifdef CONFIG_CEPH_FSCACHE
