From patchwork Wed Mar 6 00:06:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10840251 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9B5C317E0 for ; Wed, 6 Mar 2019 00:06:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8AA0C2CF85 for ; Wed, 6 Mar 2019 00:06:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7E4B92D0B8; Wed, 6 Mar 2019 00:06:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0D3462CF85 for ; Wed, 6 Mar 2019 00:06:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728510AbfCFAGY (ORCPT ); Tue, 5 Mar 2019 19:06:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37786 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727591AbfCFAGY (ORCPT ); Tue, 5 Mar 2019 19:06:24 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1748459447; Wed, 6 Mar 2019 00:06:24 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-133.bne.redhat.com [10.64.54.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7820F17187; Wed, 6 Mar 2019 00:06:23 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French , Pavel Shilovsky , Ronnie Sahlberg Subject: [PATCH 1/5] cifs: change wait_for_free_request() to take flags as argument Date: Wed, 6 Mar 2019 10:06:03 +1000 Message-Id: <20190306000607.31787-2-lsahlber@redhat.com> In-Reply-To: <20190306000607.31787-1-lsahlber@redhat.com> References: <20190306000607.31787-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 06 Mar 2019 00:06:24 +0000 (UTC) Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP and compute timeout and optyp from it. Signed-off-by: Ronnie Sahlberg --- fs/cifs/transport.c | 33 +++++++++++++++++---------------- 1 file changed, 17 insertions(+), 16 deletions(-) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 849a45d7d732..5c4becefde4b 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -529,15 +529,20 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int timeout, } static int -wait_for_free_request(struct TCP_Server_Info *server, const int timeout, - const int optype, unsigned int *instance) +wait_for_free_request(struct TCP_Server_Info *server, const int flags, + unsigned int *instance) { int *val; + int timeout, optype; + + timeout = flags & CIFS_TIMEOUT_MASK; + optype = flags & CIFS_OP_MASK; val = server->ops->get_credits_field(server, optype); /* Since an echo is already inflight, no need to wait to send another */ if (*val <= 0 && optype == CIFS_ECHO_OP) return -EAGAIN; + return wait_for_free_credits(server, timeout, val, instance); } @@ -637,16 +642,16 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst, mid_handle_t *handle, void *cbdata, const int flags, const struct cifs_credits *exist_credits) { - int rc, timeout, optype; + int rc; struct mid_q_entry *mid; struct cifs_credits credits = { .value = 0, .instance = 0 }; unsigned int instance; + int optype; - timeout = flags & CIFS_TIMEOUT_MASK; optype = flags & CIFS_OP_MASK; if ((flags & CIFS_HAS_CREDITS) == 0) { - rc = wait_for_free_request(server, timeout, optype, &instance); + rc = wait_for_free_request(server, flags, &instance); if (rc) return rc; credits.value = 1; @@ -862,8 +867,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, const int flags, const int num_rqst, struct smb_rqst *rqst, int *resp_buf_type, struct kvec *resp_iov) { - int i, j, rc = 0; - int timeout, optype; + int i, j, optype, rc = 0; struct mid_q_entry *midQ[MAX_COMPOUND]; bool cancelled_mid[MAX_COMPOUND] = {false}; struct cifs_credits credits[MAX_COMPOUND] = { @@ -873,7 +877,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, unsigned int first_instance = 0; char *buf; - timeout = flags & CIFS_TIMEOUT_MASK; optype = flags & CIFS_OP_MASK; for (i = 0; i < num_rqst; i++) @@ -924,8 +927,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, * Ensure we obtain 1 credit per request in the compound chain. */ for (i = 0; i < num_rqst; i++) { - rc = wait_for_free_request(ses->server, timeout, optype, - &instance); + rc = wait_for_free_request(ses->server, flags, &instance); if (rc == 0) { credits[i].value = 1; @@ -1048,7 +1050,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, smb311_update_preauth_hash(ses, rqst[0].rq_iov, rqst[0].rq_nvec); - if (timeout == CIFS_ASYNC_OP) + if ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP) goto out; for (i = 0; i < num_rqst; i++) { @@ -1185,7 +1187,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, int SendReceive(const unsigned int xid, struct cifs_ses *ses, struct smb_hdr *in_buf, struct smb_hdr *out_buf, - int *pbytes_returned, const int timeout) + int *pbytes_returned, const int flags) { int rc = 0; struct mid_q_entry *midQ; @@ -1216,7 +1218,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses, return -EIO; } - rc = wait_for_free_request(ses->server, timeout, 0, &credits.instance); + rc = wait_for_free_request(ses->server, flags, &credits.instance); if (rc) return rc; @@ -1255,7 +1257,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses, if (rc < 0) goto out; - if (timeout == CIFS_ASYNC_OP) + if ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP) goto out; rc = wait_for_response(ses->server, midQ); @@ -1358,8 +1360,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon, return -EIO; } - rc = wait_for_free_request(ses->server, CIFS_BLOCKING_OP, 0, - &instance); + rc = wait_for_free_request(ses->server, CIFS_BLOCKING_OP, &instance); if (rc) return rc; From patchwork Wed Mar 6 00:06:04 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10840243 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id AE0C71669 for ; 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Tue, 5 Mar 2019 19:06:17 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4155B811A9; Wed, 6 Mar 2019 00:06:17 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-133.bne.redhat.com [10.64.54.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9F4705D782; Wed, 6 Mar 2019 00:06:16 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French , Pavel Shilovsky , Ronnie Sahlberg Subject: [PATCH 2/5] cifs: pass flags down into wait_for_free_credits() Date: Wed, 6 Mar 2019 10:06:04 +1000 Message-Id: <20190306000607.31787-3-lsahlber@redhat.com> In-Reply-To: <20190306000607.31787-1-lsahlber@redhat.com> References: <20190306000607.31787-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 06 Mar 2019 00:06:17 +0000 (UTC) Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Ronnie Sahlberg --- fs/cifs/transport.c | 30 ++++++++++++++---------------- 1 file changed, 14 insertions(+), 16 deletions(-) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 5c4becefde4b..8887db2cd582 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -477,15 +477,24 @@ smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer, } static int -wait_for_free_credits(struct TCP_Server_Info *server, const int timeout, - int *credits, unsigned int *instance) +wait_for_free_credits(struct TCP_Server_Info *server, const int flags, + unsigned int *instance) { int rc; + int *credits; + int optype; + + optype = flags & CIFS_OP_MASK; *instance = 0; + credits = server->ops->get_credits_field(server, optype); + /* Since an echo is already inflight, no need to wait to send another */ + if (*credits <= 0 && optype == CIFS_ECHO_OP) + return -EAGAIN; + spin_lock(&server->req_lock); - if (timeout == CIFS_ASYNC_OP) { + if ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP) { /* oplock breaks must not be held up */ server->in_flight++; *credits -= 1; @@ -516,7 +525,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int timeout, */ /* update # of requests on the wire to server */ - if (timeout != CIFS_BLOCKING_OP) { + if ((flags & CIFS_TIMEOUT_MASK) != CIFS_BLOCKING_OP) { *credits -= 1; server->in_flight++; *instance = server->reconnect_instance; @@ -532,18 +541,7 @@ static int wait_for_free_request(struct TCP_Server_Info *server, const int flags, unsigned int *instance) { - int *val; - int timeout, optype; - - timeout = flags & CIFS_TIMEOUT_MASK; - optype = flags & CIFS_OP_MASK; - - val = server->ops->get_credits_field(server, optype); - /* Since an echo is already inflight, no need to wait to send another */ - if (*val <= 0 && optype == CIFS_ECHO_OP) - return -EAGAIN; - - return wait_for_free_credits(server, timeout, val, instance); + return wait_for_free_credits(server, flags, instance); } int From patchwork Wed Mar 6 00:06:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10840245 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3BAB51803 for ; Wed, 6 Mar 2019 00:06:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 294852CF85 for ; Wed, 6 Mar 2019 00:06:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1DDAD2D0B2; Wed, 6 Mar 2019 00:06:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B5F4B2CF85 for ; Wed, 6 Mar 2019 00:06:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728433AbfCFAGT (ORCPT ); Tue, 5 Mar 2019 19:06:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37756 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727591AbfCFAGT (ORCPT ); Tue, 5 Mar 2019 19:06:19 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 03EC959457; Wed, 6 Mar 2019 00:06:19 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-133.bne.redhat.com [10.64.54.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id 630811001DD7; Wed, 6 Mar 2019 00:06:18 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French , Pavel Shilovsky , Ronnie Sahlberg Subject: [PATCH 3/5] cifs: wait_for_free_credits() make it possible to wait for >=1 credits Date: Wed, 6 Mar 2019 10:06:05 +1000 Message-Id: <20190306000607.31787-4-lsahlber@redhat.com> In-Reply-To: <20190306000607.31787-1-lsahlber@redhat.com> References: <20190306000607.31787-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 06 Mar 2019 00:06:19 +0000 (UTC) Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Change wait_for_free_credits() to allow waiting for >=1 credits instead of just a single credit. Signed-off-by: Ronnie Sahlberg --- fs/cifs/cifsglob.h | 4 ++-- fs/cifs/smb2ops.c | 2 +- fs/cifs/transport.c | 14 +++++++------- 3 files changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 31c63e7437fd..bc2bb14b2180 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -734,13 +734,13 @@ in_flight(struct TCP_Server_Info *server) } static inline bool -has_credits(struct TCP_Server_Info *server, int *credits) +has_credits(struct TCP_Server_Info *server, int *credits, int num_credits) { int num; spin_lock(&server->req_lock); num = *credits; spin_unlock(&server->req_lock); - return num > 0; + return num >= num_credits; } static inline void diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 1243407c9546..15bc7953b7a6 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -185,7 +185,7 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size, spin_unlock(&server->req_lock); cifs_num_waiters_inc(server); rc = wait_event_killable(server->request_q, - has_credits(server, &server->credits)); + has_credits(server, &server->credits, 1)); cifs_num_waiters_dec(server); if (rc) return rc; diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 8887db2cd582..baf15194aa3d 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -477,8 +477,8 @@ smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer, } static int -wait_for_free_credits(struct TCP_Server_Info *server, const int flags, - unsigned int *instance) +wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits, + const int flags, unsigned int *instance) { int rc; int *credits; @@ -504,11 +504,11 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int flags, } while (1) { - if (*credits <= 0) { + if (*credits < num_credits) { spin_unlock(&server->req_lock); cifs_num_waiters_inc(server); rc = wait_event_killable(server->request_q, - has_credits(server, credits)); + has_credits(server, credits, num_credits)); cifs_num_waiters_dec(server); if (rc) return rc; @@ -526,8 +526,8 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int flags, /* update # of requests on the wire to server */ if ((flags & CIFS_TIMEOUT_MASK) != CIFS_BLOCKING_OP) { - *credits -= 1; - server->in_flight++; + *credits -= num_credits; + server->in_flight += num_credits; *instance = server->reconnect_instance; } spin_unlock(&server->req_lock); @@ -541,7 +541,7 @@ static int wait_for_free_request(struct TCP_Server_Info *server, const int flags, unsigned int *instance) { - return wait_for_free_credits(server, flags, instance); + return wait_for_free_credits(server, 1, flags, instance); } int From patchwork Wed Mar 6 00:06:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10840249 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 858041669 for ; Wed, 6 Mar 2019 00:06:23 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 747842CF85 for ; Wed, 6 Mar 2019 00:06:23 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 689772D0B5; Wed, 6 Mar 2019 00:06:23 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 180DA2CF85 for ; Wed, 6 Mar 2019 00:06:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728471AbfCFAGW (ORCPT ); Tue, 5 Mar 2019 19:06:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57438 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727591AbfCFAGW (ORCPT ); Tue, 5 Mar 2019 19:06:22 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 59CB6356FF; Wed, 6 Mar 2019 00:06:22 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-133.bne.redhat.com [10.64.54.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id B7F2E5D783; Wed, 6 Mar 2019 00:06:21 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French , Pavel Shilovsky , Ronnie Sahlberg Subject: [PATCH 4/5] cifs: prevent starvation in wait_for_free_credits for multi-credit requests Date: Wed, 6 Mar 2019 10:06:06 +1000 Message-Id: <20190306000607.31787-5-lsahlber@redhat.com> In-Reply-To: <20190306000607.31787-1-lsahlber@redhat.com> References: <20190306000607.31787-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Wed, 06 Mar 2019 00:06:22 +0000 (UTC) Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Reserve the last MAX_COMPOUND credits for any request asking for >1 credit. This is to prevent future compound requests from becoming starved while waiting for potentially many requests is there is a large number of concurrent singe-credit requests. However, we need to protect from servers that are very slow to hand out new credits on new sessions so we only do this IFF there are 2*MAX_COMPOUND (arbitrary) credits already in flight. Signed-off-by: Ronnie Sahlberg --- fs/cifs/transport.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index baf15194aa3d..f4ec9635dab2 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -520,6 +520,34 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits, } /* + * For normal commands, reserve the last MAX_COMPOUND + * credits to compound requests. + * Otherwise these compounds could be permanently + * starved for credits by single-credit requests. + * + * To prevent spinning CPU, block this thread until + * there are >MAX_COMPOUND credits available. + * But only do this is we already have a lot of + * credits in flight to avoid triggering this check + * for servers that are slow to hand out credits on + * new sessions. + */ + if (!optype && num_credits == 1 && + server->in_flight > 2 * MAX_COMPOUND && + *credits <= MAX_COMPOUND) { + spin_unlock(&server->req_lock); + cifs_num_waiters_inc(server); + rc = wait_event_killable(server->request_q, + has_credits(server, credits, + MAX_COMPOUND + 1)); + cifs_num_waiters_dec(server); + if (rc) + return rc; + spin_lock(&server->req_lock); + continue; + } + + /* * Can not count locking commands against total * as they are allowed to block on server. */ From patchwork Wed Mar 6 00:06:07 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ronnie Sahlberg X-Patchwork-Id: 10840241 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 50CB617E0 for ; Wed, 6 Mar 2019 00:06:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 329862CF85 for ; Wed, 6 Mar 2019 00:06:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 225A02D0B5; Wed, 6 Mar 2019 00:06:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 04ABA2CF85 for ; Wed, 6 Mar 2019 00:06:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728410AbfCFAGQ (ORCPT ); Tue, 5 Mar 2019 19:06:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53910 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727591AbfCFAGQ (ORCPT ); Tue, 5 Mar 2019 19:06:16 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7DA30300C262; Wed, 6 Mar 2019 00:06:15 +0000 (UTC) Received: from test1135.test.redhat.com (vpn2-54-133.bne.redhat.com [10.64.54.133]) by smtp.corp.redhat.com (Postfix) with ESMTP id D8240600D7; Wed, 6 Mar 2019 00:06:14 +0000 (UTC) From: Ronnie Sahlberg To: linux-cifs Cc: Steve French , Pavel Shilovsky , Ronnie Sahlberg Subject: [PATCH 5/5] cifs: simplify how we handle credits in compond_send_recv() Date: Wed, 6 Mar 2019 10:06:07 +1000 Message-Id: <20190306000607.31787-6-lsahlber@redhat.com> In-Reply-To: <20190306000607.31787-1-lsahlber@redhat.com> References: <20190306000607.31787-1-lsahlber@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Wed, 06 Mar 2019 00:06:15 +0000 (UTC) Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Since we can now wait for multiple requests atomically in wait_for_free_request() we can now greatly simplify the handling of the credits in this function. This fixes a potential deadlock where many concurrent compound requests could each have reserved 1 or 2 credits each but are all blocked waiting for the final credits they need to be able to issue the requests to the server. Signed-off-by: Ronnie Sahlberg --- fs/cifs/transport.c | 81 +++++++++++++---------------------------------------- 1 file changed, 20 insertions(+), 61 deletions(-) diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index f4ec9635dab2..21801ebf63ad 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -572,6 +572,13 @@ wait_for_free_request(struct TCP_Server_Info *server, const int flags, return wait_for_free_credits(server, 1, flags, instance); } +static int +wait_for_compound_request(struct TCP_Server_Info *server, int num, + const int flags, unsigned int *instance) +{ + return wait_for_free_credits(server, num, flags, instance); +} + int cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size, unsigned int *num, struct cifs_credits *credits) @@ -900,7 +907,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, { .value = 0, .instance = 0 } }; unsigned int instance; - unsigned int first_instance = 0; char *buf; optype = flags & CIFS_OP_MASK; @@ -926,70 +932,27 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, spin_unlock(&ses->server->req_lock); return -ENOTSUPP; } - } else { - /* enough credits to send the whole compounded request */ - ses->server->credits -= num_rqst; - ses->server->in_flight += num_rqst; - first_instance = ses->server->reconnect_instance; } spin_unlock(&ses->server->req_lock); - if (first_instance) { - cifs_dbg(FYI, "Acquired %d credits at once\n", num_rqst); - for (i = 0; i < num_rqst; i++) { - credits[i].value = 1; - credits[i].instance = first_instance; - } - goto setup_rqsts; - } - /* - * There are not enough credits to send the whole compound request but - * there are requests in flight that may bring credits from the server. + * Wait for all the requests to become available. * This approach still leaves the possibility to be stuck waiting for * credits if the server doesn't grant credits to the outstanding - * requests. This should be fixed by returning immediately and letting - * a caller fallback to sequential commands instead of compounding. - * Ensure we obtain 1 credit per request in the compound chain. + * requests and if the client is completely idle, not generating any + * other requests. + * This can be handled by the eventual session reconnect. */ - for (i = 0; i < num_rqst; i++) { - rc = wait_for_free_request(ses->server, flags, &instance); - - if (rc == 0) { - credits[i].value = 1; - credits[i].instance = instance; - /* - * All parts of the compound chain must get credits from - * the same session, otherwise we may end up using more - * credits than the server granted. If there were - * reconnects in between, return -EAGAIN and let callers - * handle it. - */ - if (i == 0) - first_instance = instance; - else if (first_instance != instance) { - i++; - rc = -EAGAIN; - } - } + rc = wait_for_compound_request(ses->server, num_rqst, flags, + &instance); + if (rc) + return rc; - if (rc) { - /* - * We haven't sent an SMB packet to the server yet but - * we already obtained credits for i requests in the - * compound chain - need to return those credits back - * for future use. Note that we need to call add_credits - * multiple times to match the way we obtained credits - * in the first place and to account for in flight - * requests correctly. - */ - for (j = 0; j < i; j++) - add_credits(ses->server, &credits[j], optype); - return rc; - } + for (i = 0; i < num_rqst; i++) { + credits[i].value = 1; + credits[i].instance = instance; } -setup_rqsts: /* * Make sure that we sign in the same order that we send on this socket * and avoid races inside tcp sendmsg code that could cause corruption @@ -1000,17 +963,13 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, /* * All the parts of the compound chain belong obtained credits from the - * same session (see the appropriate checks above). In the same time - * there might be reconnects after those checks but before we acquired - * the srv_mutex. We can not use credits obtained from the previous + * same session. We can not use credits obtained from the previous * session to send this request. Check if there were reconnects after * we obtained credits and return -EAGAIN in such cases to let callers * handle it. */ - if (first_instance != ses->server->reconnect_instance) { + if (instance != ses->server->reconnect_instance) { mutex_unlock(&ses->server->srv_mutex); - for (j = 0; j < num_rqst; j++) - add_credits(ses->server, &credits[j], optype); return -EAGAIN; }