Re: [PATCH] cifs: Fix lookup of SMB connections on multichannel

[Steve French <smfrench@gmail.com>]

tentatively merged to cifs-2.6.git for-next and buildbot github tree
pending more testing

On Wed, Dec 4, 2019 at 8:25 AM Paulo Alcantara (SUSE) <pc@cjr.nz> wrote:
>
> With the addition of SMB session channels, we introduced new TCP
> server pointers that have no sessions or tcons associated with them.
>
> In this case, when we started looking for TCP connections, we might
> end up picking session channel rather than the master connection,
> hence failing to get either a session or a tcon.
>
> In order to fix that, this patch introduces a new "is_channel" field
> to TCP_Server_Info structure so we can skip session channels during
> lookup of connections.
>
> Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
> ---
>  fs/cifs/cifsglob.h | 1 +
>  fs/cifs/connect.c  | 6 +++++-
>  fs/cifs/sess.c     | 3 +++
>  3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index 5b976e01dd6b..fd0262ce5ad5 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -777,6 +777,7 @@ struct TCP_Server_Info {
>          */
>         int nr_targets;
>         bool noblockcnt; /* use non-blocking connect() */
> +       bool is_channel; /* if a session channel */
>  };
>
>  struct cifs_credits {
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 86d1baedf21c..05ea0e2b7e0e 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -2712,7 +2712,11 @@ cifs_find_tcp_session(struct smb_vol *vol)
>
>         spin_lock(&cifs_tcp_ses_lock);
>         list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
> -               if (!match_server(server, vol))
> +               /*
> +                * Skip ses channels since they're only handled in lower layers
> +                * (e.g. cifs_send_recv).
> +                */
> +               if (server->is_channel || !match_server(server, vol))
>                         continue;
>
>                 ++server->srv_count;
> diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
> index fb3bdc44775c..d95137304224 100644
> --- a/fs/cifs/sess.c
> +++ b/fs/cifs/sess.c
> @@ -213,6 +213,9 @@ cifs_ses_add_channel(struct cifs_ses *ses, struct cifs_server_iface *iface)
>                 chan->server = NULL;
>                 goto out;
>         }
> +       spin_lock(&cifs_tcp_ses_lock);
> +       chan->server->is_channel = true;
> +       spin_unlock(&cifs_tcp_ses_lock);
>
>         /*
>          * We need to allocate the server crypto now as we will need
> --
> 2.24.0
>


-- 
Thanks,

Steve