Re: [PATCH] ceph: break up send_cap_msg

[Ilya Dryomov <idryomov@gmail.com>]

On Wed, Oct 7, 2020 at 2:25 PM Jeff Layton <jlayton@kernel.org> wrote:
>
> Push the allocation of the msg and the send into the caller. Rename
> the function to marshal_cap_msg and make it void return.
>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/ceph/caps.c | 61 +++++++++++++++++++++++++-------------------------
>  1 file changed, 30 insertions(+), 31 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 4e84b39a6ebd..6f4adfaf761f 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -1222,36 +1222,29 @@ struct cap_msg_args {
>  };
>
>  /*
> - * Build and send a cap message to the given MDS.
> - *
> - * Caller should be holding s_mutex.
> + * cap struct size + flock buffer size + inline version + inline data size +
> + * osd_epoch_barrier + oldest_flush_tid
>   */
> -static int send_cap_msg(struct cap_msg_args *arg)
> +#define CAP_MSG_SIZE (sizeof(struct ceph_mds_caps) + \
> +                     4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4)
> +
> +/* Marshal up the cap msg to the MDS */
> +static void marshal_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)

Nit: functions like this usually have "encode" or "build" in their
names across the codebase, so I'd go with "encode_cap_msg".


>  {
>         struct ceph_mds_caps *fc;
> -       struct ceph_msg *msg;
>         void *p;
> -       size_t extra_len;
>         struct ceph_osd_client *osdc = &arg->session->s_mdsc->fsc->client->osdc;
>
> -       dout("send_cap_msg %s %llx %llx caps %s wanted %s dirty %s"
> +       dout("%s %s %llx %llx caps %s wanted %s dirty %s"
>              " seq %u/%u tid %llu/%llu mseq %u follows %lld size %llu/%llu"
> -            " xattr_ver %llu xattr_len %d\n", ceph_cap_op_name(arg->op),
> -            arg->cid, arg->ino, ceph_cap_string(arg->caps),
> -            ceph_cap_string(arg->wanted), ceph_cap_string(arg->dirty),
> -            arg->seq, arg->issue_seq, arg->flush_tid, arg->oldest_flush_tid,
> -            arg->mseq, arg->follows, arg->size, arg->max_size,
> -            arg->xattr_version,
> +            " xattr_ver %llu xattr_len %d\n", __func__,
> +            ceph_cap_op_name(arg->op), arg->cid, arg->ino,
> +            ceph_cap_string(arg->caps), ceph_cap_string(arg->wanted),
> +            ceph_cap_string(arg->dirty), arg->seq, arg->issue_seq,
> +            arg->flush_tid, arg->oldest_flush_tid, arg->mseq, arg->follows,
> +            arg->size, arg->max_size, arg->xattr_version,
>              arg->xattr_buf ? (int)arg->xattr_buf->vec.iov_len : 0);
>
> -       /* flock buffer size + inline version + inline data size +
> -        * osd_epoch_barrier + oldest_flush_tid */
> -       extra_len = 4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4;
> -       msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, sizeof(*fc) + extra_len,
> -                          GFP_NOFS, false);
> -       if (!msg)
> -               return -ENOMEM;
> -
>         msg->hdr.version = cpu_to_le16(10);
>         msg->hdr.tid = cpu_to_le64(arg->flush_tid);
>
> @@ -1323,9 +1316,6 @@ static int send_cap_msg(struct cap_msg_args *arg)
>
>         /* Advisory flags (version 10) */
>         ceph_encode_32(&p, arg->flags);
> -
> -       ceph_con_send(&arg->session->s_con, msg);
> -       return 0;
>  }
>
>  /*
> @@ -1456,22 +1446,24 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
>   */
>  static void __send_cap(struct cap_msg_args *arg, struct ceph_inode_info *ci)
>  {
> +       struct ceph_msg *msg;
>         struct inode *inode = &ci->vfs_inode;
> -       int ret;
>
> -       ret = send_cap_msg(arg);
> -       if (ret < 0) {
> -               pr_err("error sending cap msg, ino (%llx.%llx) "
> -                      "flushing %s tid %llu, requeue\n",
> +       msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, CAP_MSG_SIZE, GFP_NOFS, false);
> +       if (!msg) {
> +               pr_err("error allocating cap msg: ino (%llx.%llx) "
> +                      "flushing %s tid %llu, requeuing cap.\n",

Don't break new user-visible strings.  This makes grepping harder than
it should be.

Thanks,

                Ilya