ceph: reencode gid_list when reconnecting

On reconnect, cap and dentry releases are dropped and the fields
that follow must be reencoded into the freed space.  Currently these
are timestamp and gid_list, but gid_list isn't reencoded.  This
results in

  failed to decode message of type 24 v4: End of buffer

errors on the MDS.

While at it, make a change to encode gid_list unconditionally,
without regard to what head/which version was used as a result
of checking whether CEPH_FEATURE_FS_BTIME is supported or not.

URL: https://tracker.ceph.com/issues/48618
Fixes: 4f1ddb1ea874 ("ceph: implement updated ceph_mds_request_head structure")
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 98c15ff..8405870 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2475,6 +2475,22 @@ static int set_request_path_attr(struct inode *rinode, struct dentry *rdentry,
        return r;
 }
 
+static void encode_timestamp_and_gids(void **p,
+                                     const struct ceph_mds_request *req)
+{
+       struct ceph_timespec ts;
+       int i;
+
+       ceph_encode_timespec64(&ts, &req->r_stamp);
+       ceph_encode_copy(p, &ts, sizeof(ts));
+
+       /* gid_list */
+       ceph_encode_32(p, req->r_cred->group_info->ngroups);
+       for (i = 0; i < req->r_cred->group_info->ngroups; i++)
+               ceph_encode_64(p, from_kgid(&init_user_ns,
+                                           req->r_cred->group_info->gid[i]));
+}
+
 /*
  * called under mdsc->mutex
  */
@@ -2491,7 +2507,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
        u64 ino1 = 0, ino2 = 0;
        int pathlen1 = 0, pathlen2 = 0;
        bool freepath1 = false, freepath2 = false;
-       int len, i;
+       int len;
        u16 releases;
        void *p, *end;
        int ret;
@@ -2517,17 +2533,10 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
                goto out_free1;
        }
 
-       if (legacy) {
-               /* Old style */
-               len = sizeof(*head);
-       } else {
-               /* New style: add gid_list and any later fields */
-               len = sizeof(struct ceph_mds_request_head) + sizeof(u32) +
-                     (sizeof(u64) * req->r_cred->group_info->ngroups);
-       }
-
+       len = legacy ? sizeof(*head) : sizeof(struct ceph_mds_request_head);
        len += pathlen1 + pathlen2 + 2*(1 + sizeof(u32) + sizeof(u64)) +
                sizeof(struct ceph_timespec);
+       len += sizeof(u32) + (sizeof(u64) * req->r_cred->group_info->ngroups);
 
        /* calculate (max) length for cap releases */
        len += sizeof(struct ceph_mds_request_release) *
@@ -2548,7 +2557,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
        msg->hdr.tid = cpu_to_le64(req->r_tid);
 
        /*
-        * The old ceph_mds_request_header didn't contain a version field, and
+        * The old ceph_mds_request_head didn't contain a version field, and
         * one was added when we moved the message version from 3->4.
         */
        if (legacy) {
@@ -2609,20 +2618,7 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
 
        head->num_releases = cpu_to_le16(releases);
 
-       /* time stamp */
-       {
-               struct ceph_timespec ts;
-               ceph_encode_timespec64(&ts, &req->r_stamp);
-               ceph_encode_copy(&p, &ts, sizeof(ts));
-       }
-
-       /* gid list */
-       if (!legacy) {
-               ceph_encode_32(&p, req->r_cred->group_info->ngroups);
-               for (i = 0; i < req->r_cred->group_info->ngroups; i++)
-                       ceph_encode_64(&p, from_kgid(&init_user_ns,
-                                      req->r_cred->group_info->gid[i]));
-       }
+       encode_timestamp_and_gids(&p, req);
 
        if (WARN_ON_ONCE(p > end)) {
                ceph_msg_put(msg);
@@ -2730,13 +2726,8 @@ static int __prepare_send_request(struct ceph_mds_session *session,
                /* remove cap/dentry releases from message */
                rhead->num_releases = 0;
 
-               /* time stamp */
                p = msg->front.iov_base + req->r_request_release_offset;
-               {
-                       struct ceph_timespec ts;
-                       ceph_encode_timespec64(&ts, &req->r_stamp);
-                       ceph_encode_copy(&p, &ts, sizeof(ts));
-               }
+               encode_timestamp_and_gids(&p, req);
 
                msg->front.iov_len = p - msg->front.iov_base;
                msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);