On Fri, 20 Jan 2012 12:34:27 +0400
Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
> From: Steve French <sfrench@xxxxxxxxxx>
>
> Convert wait_for_free_request to wait on available credits
> for SMB2 servers and decrement a credit number for every call.
> Increment the credit number in smb2_sendrcv2 with every response
> got from the server.
>
> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
> ---
> fs/cifs/cifsglob.h | 1 +
> fs/cifs/cifsproto.h | 2 +-
> fs/cifs/smb2transport.c | 6 ++++++
> fs/cifs/transport.c | 20 ++++++++++++++++++--
> 4 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> index bb2af48..e5f0b86 100644
> --- a/fs/cifs/cifsglob.h
> +++ b/fs/cifs/cifsglob.h
> @@ -318,6 +318,7 @@ struct TCP_Server_Info {
> atomic_t num_waiters; /* blocked waiting to get in sendrecv */
> #endif
> #ifdef CONFIG_CIFS_SMB2
> + atomic_t credits; /* send no more simultaneous requests than this */
> __u64 current_smb2_mid; /* multiplex id - rotating counter */
> #endif
> };
> diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
> index d1e30d9..b6c784b 100644
> --- a/fs/cifs/cifsproto.h
> +++ b/fs/cifs/cifsproto.h
> @@ -1,7 +1,7 @@
> /*
> * fs/cifs/cifsproto.h
> *
> - * Copyright (c) International Business Machines Corp., 2002,2008
> + * Copyright (c) International Business Machines Corp., 2002,2011
> * Author(s): Steve French (sfrench@xxxxxxxxxx)
> *
> * This library is free software; you can redistribute it and/or modify
> diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
> index d7f1c05..b5702f3 100644
> --- a/fs/cifs/smb2transport.c
> +++ b/fs/cifs/smb2transport.c
> @@ -148,6 +148,7 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
> unsigned int receive_len;
> struct mid_q_entry *midQ;
> struct smb2_hdr *buf = iov[0].iov_base;
> + unsigned int credits = 1;
>
> if (status)
> *status = STATUS_SUCCESS;
> @@ -186,6 +187,7 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
> if (rc) {
> mutex_unlock(&ses->server->srv_mutex);
> cifs_small_buf_release(buf);
> + atomic_inc(&ses->server->credits);
> wake_up(&ses->server->request_q);
> return rc;
> }
> @@ -222,6 +224,7 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
> midQ->callback = cifs_delete_mid;
> spin_unlock(&GlobalMid_Lock);
> cifs_small_buf_release(buf);
> + atomic_inc(&ses->server->credits);
> wake_up(&ses->server->request_q);
> return rc;
> }
> @@ -232,6 +235,7 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
>
> rc = cifs_sync_mid_result(midQ, ses->server);
> if (rc) {
> + atomic_inc(&ses->server->credits);
> wake_up(&ses->server->request_q);
> return rc;
> }
> @@ -271,7 +275,9 @@ smb2_sendrcv2(const unsigned int xid, struct cifs_ses *ses,
> /* mark it so buf will not be freed by free_smb2mid */
> midQ->resp_buf = NULL;
>
> + credits = le16_to_cpu(buf->CreditRequest);
> out:
> + atomic_add(credits, &ses->server->credits);
> cifs_delete_mid(midQ);
> wake_up(&ses->server->request_q);
> return rc;
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index f7ac3f0..4414df8 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -287,7 +287,8 @@ cifs_wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
>
> spin_lock(&GlobalMid_Lock);
> while (1) {
> - if (atomic_read(&server->inFlight) >= cifs_max_pending) {
> + if ((server->is_smb2 == false) &&
> + atomic_read(&server->inFlight) >= cifs_max_pending) {
> spin_unlock(&GlobalMid_Lock);
> cifs_num_waiters_inc(server);
> wait_event(server->request_q,
> @@ -295,6 +296,16 @@ cifs_wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
> < cifs_max_pending);
> cifs_num_waiters_dec(server);
> spin_lock(&GlobalMid_Lock);
> +#ifdef CONFIG_CIFS_SMB2
> + } else if (server->is_smb2 &&
> + (atomic_read(&server->credits) < 1)) {
> + spin_unlock(&GlobalMid_Lock);
> + cifs_num_waiters_inc(server);
> + wait_event(server->request_q,
> + atomic_read(&server->credits) > 0);
> + cifs_num_waiters_dec(server);
> + spin_lock(&GlobalMid_Lock);
> +#endif /* CONFIG_CIFS_SMB2 */
> } else {
> if (server->tcpStatus == CifsExiting) {
> spin_unlock(&GlobalMid_Lock);
> @@ -305,8 +316,13 @@ cifs_wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
> as they are allowed to block on server */
>
> /* update # of requests on the wire to server */
> - if (long_op != CIFS_BLOCKING_OP)
> + if (server->is_smb2 == false &&
> + long_op != CIFS_BLOCKING_OP)
> atomic_inc(&server->inFlight);
> +#ifdef CONFIG_CIFS_SMB2
> + else if (server->is_smb2)
> + atomic_dec(&server->credits);
> +#endif
> spin_unlock(&GlobalMid_Lock);
> break;
> }
I'd like to suggest an alternate approach here...
Instead of considering this as a SMB1 vs. SMB2 either/or thing we
should consider the SMB1 case to be a special case of SMB2 credits. In
the SMB1 NEGOTIATE response, the server sends us a MaxMpx value. We
could consider that to be an initial set of credits. Every time we get
a SMB1 response from the server, we'll increment the credit value.
If we do that, then there's a lot less protocol dependent code that's
needed, and if done correctly should also fix the current bug in
the SMB1 code where it ignores the MaxMpx value.
Thoughts?
--
Jeff Layton <jlayton@xxxxxxxxxx>
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