Re: [PATCH 06/14] cifs: handle cases where a channel is closed

Steve French
2023-11-01T03:10:09Z

This patch wouldn't merge due to a merge conflict here. Am I missing
an earlier patch of yours before the series?

I have these in for-next:
d1ea8f36fa51 (HEAD -> for-next) cifs: force interface update before a
fresh session setup
1e27cedcaf4e (origin/for-next) cifs: do not reset chan_max if
multichannel is not supported at mount
e257df806ae0 cifs: display the endpoint IP details in DebugData
9d95130c9f78 cifs: reconnect helper should set reconnect for the right channel
7ac6866076bd smb: client: fix use-after-free in smb2_query_info_compound()
0779365fc10d smb: client: remove extra @chan_count check in __cifs_put_smb_ses()
4cf6e1101a25 cifs: add xid to query server interface call
52768695d36a cifs: print server capabilities in DebugData

--- fs/smb/client/connect.c
+++ fs/smb/client/connect.c
@@ -2037,7 +2041,9 @@ void __cifs_put_smb_ses(struct cifs_ses *ses)

kref_put(&ses->chans[i].iface->refcount, release_iface);
ses->chans[i].iface = NULL;
}
- cifs_put_tcp_session(ses->chans[i].server, 0);
+
+ if (ses->chans[i].server)
+ cifs_put_tcp_session(ses->chans[i].server, 0);
ses->chans[i].server = NULL;
}
}

On Mon, Oct 30, 2023 at 6:00 AM <nspmangalore@gmail.com> wrote:
>
> From: Shyam Prasad N <sprasad@microsoft.com>
>
> So far, SMB multichannel could only scale up, but not
> scale down the number of channels. In this series of
> patch, we now allow the client to deal with the case
> of multichannel disabled on the server when the share
> is mounted. With that change, we now need the ability
> to scale down the channels.
>
> This change allows the client to deal with cases of
> missing channels more gracefully.
>
> Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
> ---
> fs/smb/client/cifs_debug.c | 5 +++++
> fs/smb/client/cifsglob.h | 1 +
> fs/smb/client/cifsproto.h | 2 +-
> fs/smb/client/connect.c | 10 ++++++++--
> fs/smb/client/sess.c | 25 +++++++++++++++++++++----
> fs/smb/client/smb2transport.c | 8 +++++++-
> 6 files changed, 43 insertions(+), 8 deletions(-)
>
> diff --git a/fs/smb/client/cifs_debug.c b/fs/smb/client/cifs_debug.c
> index a9dfecc397a8..9fca09539728 100644
> --- a/fs/smb/client/cifs_debug.c
> +++ b/fs/smb/client/cifs_debug.c
> @@ -136,6 +136,11 @@ cifs_dump_channel(struct seq_file *m, int i, struct cifs_chan *chan)
> {
> struct TCP_Server_Info *server = chan->server;
>
> + if (!server) {
> + seq_printf(m, "\n\n\t\tChannel: %d DISABLED", i+1);
> + return;
> + }
> +
> seq_printf(m, "\n\n\t\tChannel: %d ConnectionId: 0x%llx"
> "\n\t\tNumber of credits: %d,%d,%d Dialect 0x%x"
> "\n\t\tTCP status: %d Instance: %d"
> diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
> index 02082621d8e0..552ed441281a 100644
> --- a/fs/smb/client/cifsglob.h
> +++ b/fs/smb/client/cifsglob.h
> @@ -1050,6 +1050,7 @@ struct cifs_ses {
> spinlock_t chan_lock;
> /* ========= begin: protected by chan_lock ======== */
> #define CIFS_MAX_CHANNELS 16
> +#define CIFS_INVAL_CHAN_INDEX (-1)
> #define CIFS_ALL_CHANNELS_SET(ses) \
> ((1UL << (ses)->chan_count) - 1)
> #define CIFS_ALL_CHANS_GOOD(ses) \
> diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
> index 0c37eefa18a5..65c84b3d1a65 100644
> --- a/fs/smb/client/cifsproto.h
> +++ b/fs/smb/client/cifsproto.h
> @@ -616,7 +616,7 @@ bool is_server_using_iface(struct TCP_Server_Info *server,
> bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
> void cifs_ses_mark_for_reconnect(struct cifs_ses *ses);
>
> -unsigned int
> +int
> cifs_ses_get_chan_index(struct cifs_ses *ses,
> struct TCP_Server_Info *server);
> void
> diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
> index 97c9a32cff36..8393977e21ee 100644
> --- a/fs/smb/client/connect.c
> +++ b/fs/smb/client/connect.c
> @@ -173,8 +173,12 @@ cifs_signal_cifsd_for_reconnect(struct TCP_Server_Info *server,
> list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
> spin_lock(&ses->chan_lock);
> for (i = 0; i < ses->chan_count; i++) {
> + if (!ses->chans[i].server)
> + continue;
> +
> spin_lock(&ses->chans[i].server->srv_lock);
> - ses->chans[i].server->tcpStatus = CifsNeedReconnect;
> + if (ses->chans[i].server->tcpStatus != CifsExiting)
> + ses->chans[i].server->tcpStatus = CifsNeedReconnect;
> spin_unlock(&ses->chans[i].server->srv_lock);
> }
> spin_unlock(&ses->chan_lock);
> @@ -2033,7 +2037,9 @@ void __cifs_put_smb_ses(struct cifs_ses *ses)
> kref_put(&ses->chans[i].iface->refcount, release_iface);
> ses->chans[i].iface = NULL;
> }
> - cifs_put_tcp_session(ses->chans[i].server, 0);
> +
> + if (ses->chans[i].server)
> + cifs_put_tcp_session(ses->chans[i].server, 0);
> ses->chans[i].server = NULL;
> }
> }
> diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
> index c899b05c92f7..9d2228c2d7e5 100644
> --- a/fs/smb/client/sess.c
> +++ b/fs/smb/client/sess.c
> @@ -69,7 +69,7 @@ bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
>
> /* channel helper functions. assumed that chan_lock is held by caller. */
>
> -unsigned int
> +int
> cifs_ses_get_chan_index(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> @@ -85,14 +85,16 @@ cifs_ses_get_chan_index(struct cifs_ses *ses,
> cifs_dbg(VFS, "unable to get chan index for server: 0x%llx",
> server->conn_id);
> WARN_ON(1);
> - return 0;
> + return CIFS_INVAL_CHAN_INDEX;
> }
>
> void
> cifs_chan_set_in_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> - unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return;
>
> ses->chans[chan_index].in_reconnect = true;
> }
> @@ -102,6 +104,8 @@ cifs_chan_clear_in_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return;
>
> ses->chans[chan_index].in_reconnect = false;
> }
> @@ -111,6 +115,8 @@ cifs_chan_in_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return true; /* err on the safer side */
>
> return CIFS_CHAN_IN_RECONNECT(ses, chan_index);
> }
> @@ -120,6 +126,8 @@ cifs_chan_set_need_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return;
>
> set_bit(chan_index, &ses->chans_need_reconnect);
> cifs_dbg(FYI, "Set reconnect bitmask for chan %u; now 0x%lx\n",
> @@ -131,6 +139,8 @@ cifs_chan_clear_need_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return;
>
> clear_bit(chan_index, &ses->chans_need_reconnect);
> cifs_dbg(FYI, "Cleared reconnect bitmask for chan %u; now 0x%lx\n",
> @@ -142,6 +152,8 @@ cifs_chan_needs_reconnect(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return true; /* err on the safer side */
>
> return CIFS_CHAN_NEEDS_RECONNECT(ses, chan_index);
> }
> @@ -151,6 +163,8 @@ cifs_chan_is_iface_active(struct cifs_ses *ses,
> struct TCP_Server_Info *server)
> {
> unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return true; /* err on the safer side */
>
> return ses->chans[chan_index].iface &&
> ses->chans[chan_index].iface->is_active;
> @@ -269,7 +283,7 @@ cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server)
>
> spin_lock(&ses->chan_lock);
> chan_index = cifs_ses_get_chan_index(ses, server);
> - if (!chan_index) {
> + if (chan_index == CIFS_INVAL_CHAN_INDEX) {
> spin_unlock(&ses->chan_lock);
> return 0;
> }
> @@ -319,6 +333,9 @@ cifs_chan_update_iface(struct cifs_ses *ses, struct TCP_Server_Info *server)
>
> spin_lock(&ses->chan_lock);
> chan_index = cifs_ses_get_chan_index(ses, server);
> + if (chan_index == CIFS_INVAL_CHAN_INDEX)
> + return 0;
> +
> ses->chans[chan_index].iface = iface;
>
> /* No iface is found. if secondary chan, drop connection */
> diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
> index 23c50ed7d4b5..84ea67301303 100644
> --- a/fs/smb/client/smb2transport.c
> +++ b/fs/smb/client/smb2transport.c
> @@ -413,7 +413,13 @@ generate_smb3signingkey(struct cifs_ses *ses,
> ses->ses_status == SES_GOOD);
>
> chan_index = cifs_ses_get_chan_index(ses, server);
> - /* TODO: introduce ref counting for channels when the can be freed */
> + if (chan_index == CIFS_INVAL_CHAN_INDEX) {
> + spin_unlock(&ses->chan_lock);
> + spin_unlock(&ses->ses_lock);
> +
> + return -EINVAL;
> + }
> +
> spin_unlock(&ses->chan_lock);
> spin_unlock(&ses->ses_lock);
>
> --
> 2.34.1
>

--
Thanks,

Steve