ceph: add helper function that forcibly reconnects to ceph cluster.

It closes mds sessions, drop all caps and invalidates page caches,
then use new entity address to reconnect to the cluster.

After reconnect, all dirty data/metadata are dropped, file locks
get lost sliently. Open files continue to work because client will
try renewing caps on later read/write.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

3 files changed, 39 insertions, 5 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index df4bea231017..ed4d20a54af7 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1394,9 +1394,12 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
 		struct ceph_cap_flush *cf;
 		struct ceph_mds_client *mdsc = fsc->mdsc;
 
-		if (ci->i_wrbuffer_ref > 0 &&
-		    READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN)
-			invalidate = true;
+		if (READ_ONCE(fsc->mount_state) == CEPH_MOUNT_SHUTDOWN) {
+			if (inode->i_data.nrpages > 0)
+				invalidate = true;
+			if (ci->i_wrbuffer_ref > 0)
+				mapping_set_error(&inode->i_data, -EIO);
+		}
 
 		while (!list_empty(&ci->i_cap_flush_list)) {
 			cf = list_first_entry(&ci->i_cap_flush_list,
@@ -4369,7 +4372,12 @@ void ceph_mdsc_force_umount(struct ceph_mds_client *mdsc)
 		session = __ceph_lookup_mds_session(mdsc, mds);
 		if (!session)
 			continue;
+
+		if (session->s_state == CEPH_MDS_SESSION_REJECTED)
+			__unregister_session(mdsc, session);
+		__wake_requests(mdsc, &session->s_waiting);
 		mutex_unlock(&mdsc->mutex);
+
 		mutex_lock(&session->s_mutex);
 		__close_session(mdsc, session);
 		if (session->s_state == CEPH_MDS_SESSION_CLOSING) {
@@ -4378,6 +4386,7 @@ void ceph_mdsc_force_umount(struct ceph_mds_client *mdsc)
 		}
 		mutex_unlock(&session->s_mutex);
 		ceph_put_mds_session(session);
+
 		mutex_lock(&mdsc->mutex);
 		kick_requests(mdsc, mds);
 	}
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index ab4868c7308e..a95dd13bb628 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -829,7 +829,6 @@ static void ceph_umount_begin(struct super_block *sb)
 	fsc->mount_state = CEPH_MOUNT_SHUTDOWN;
 	ceph_osdc_abort_requests(&fsc->client->osdc, -EIO);
 	ceph_mdsc_force_umount(fsc->mdsc);
-	return;
 }
 
 static int ceph_remount(struct super_block *sb, int *flags, char *data)
@@ -1152,6 +1151,31 @@ static struct file_system_type ceph_fs_type = {
 };
 MODULE_ALIAS_FS("ceph");
 
+int ceph_force_reconnect(struct super_block *sb)
+{
+	struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
+	int err = 0;
+
+	ceph_umount_begin(sb);
+
+	/* Make sure all page caches get invalidated.
+	 * see remove_session_caps_cb() */
+	flush_workqueue(fsc->inode_wq);
+
+	/* In case that we were blacklisted. This also reset
+	 * all mon/osd connections */
+	ceph_reset_client_addr(fsc->client);
+
+	ceph_osdc_clear_abort_err(&fsc->client->osdc);
+	fsc->mount_state = CEPH_MOUNT_MOUNTED;
+
+	if (sb->s_root) {
+		err = __ceph_do_getattr(d_inode(sb->s_root), NULL,
+					CEPH_STAT_CAP_INODE, true);
+	}
+	return err;
+}
+
 static int __init init_ceph(void)
 {
 	int ret = init_caches();
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 1452f62445c3..7af7f2ba8da5 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -846,7 +846,8 @@ static inline int default_congestion_kb(void)
 }
 
 
-
+/* super.c */
+extern int ceph_force_reconnect(struct super_block *sb);
 /* snap.c */
 struct ceph_snap_realm *ceph_lookup_snap_realm(struct ceph_mds_client *mdsc,
 					       u64 ino);