From patchwork Tue Apr 27 21:56:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 12227537 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6101C433ED for ; Tue, 27 Apr 2021 21:58:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B80DD613B0 for ; Tue, 27 Apr 2021 21:58:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239479AbhD0V7e (ORCPT ); Tue, 27 Apr 2021 17:59:34 -0400 Received: from smtp.infotech.no ([82.134.31.41]:38851 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239418AbhD0V7Q (ORCPT ); Tue, 27 Apr 2021 17:59:16 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id 7346F20424C; Tue, 27 Apr 2021 23:58:31 +0200 (CEST) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xjlkenUjfPnS; Tue, 27 Apr 2021 23:58:29 +0200 (CEST) Received: from xtwo70.bingwo.ca (host-45-58-219-4.dyn.295.ca [45.58.219.4]) by smtp.infotech.no (Postfix) with ESMTPA id 9D172204196; Tue, 27 Apr 2021 23:58:28 +0200 (CEST) From: Douglas Gilbert To: linux-scsi@vger.kernel.org Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, hare@suse.de Subject: [PATCH v18 37/83] sg: defang allow_dio Date: Tue, 27 Apr 2021 17:56:47 -0400 Message-Id: <20210427215733.417746-39-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210427215733.417746-1-dgilbert@interlog.com> References: <20210427215733.417746-1-dgilbert@interlog.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Before direct IO was permitted by this driver, the user either had to give 'allow_dio=1' as a module parameter or write to procfs with 'echo 1 > /proc/scsi/sg/allow_dio'. The user also needs to set the SG_FLAG_DIRECT_IO flag in the flags field of either the sg v3 or v3 interface. The reason this "belts and braces" approach was taken is lost in the mists of time (done over 20 years ago). So this patch keeps the allow_dio attribute for backward compatibility but ignores it, relying on the SG_FLAG_DIRECT_IO flag alone. This brings the use of the SG_FLAG_DIRECT_IO flag into line with the SG_FLAG_MMAP_IO flag; the two mechanisms are no more, or less, safe than one another in recent Linux kernels. Reviewed-by: Hannes Reinecke Signed-off-by: Douglas Gilbert --- drivers/scsi/sg.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 4d0a5a50a00b..e4d4afe7be34 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -141,7 +141,7 @@ int sg_big_buff = SG_DEF_RESERVED_SIZE; * not enough memory) will be reserved for use by this file descriptor. */ static int def_reserved_size = -1; /* picks up init parameter */ -static int sg_allow_dio = SG_ALLOW_DIO_DEF; +static int sg_allow_dio = SG_ALLOW_DIO_DEF; /* ignored by code */ static int scatter_elem_sz = SG_SCATTER_SZ; @@ -2845,19 +2845,6 @@ exit_sg(void) idr_destroy(&sg_index_idr); } -static inline bool -sg_chk_dio_allowed(struct sg_device *sdp, struct sg_request *srp, - int iov_count, int dir) -{ - if (sg_allow_dio && (srp->rq_flags & SG_FLAG_DIRECT_IO)) { - if (dir != SG_DXFER_UNKNOWN && !iov_count) { - if (!sdp->device->host->unchecked_isa_dma) - return true; - } - } - return false; -} - static inline void sg_set_map_data(const struct sg_scatter_hold *schp, bool up_valid, struct rq_map_data *mdp) @@ -2876,6 +2863,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir) int res = 0; int dxfer_len = 0; int r0w = READ; + u32 rq_flags = srp->rq_flags; unsigned int iov_count = 0; void __user *up; struct request *rq; @@ -2954,7 +2942,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir) goto fini; scsi_rp->cmd_len = cwrp->cmd_len; srp->cmd_opcode = scsi_rp->cmd[0]; - us_xfer = !(srp->rq_flags & (SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO)); + us_xfer = !(rq_flags & (SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO)); assign_bit(SG_FRQ_NO_US_XFER, srp->frq_bm, !us_xfer); reserved = (sfp->rsv_srp == srp); rq->end_io_data = srp; @@ -2965,7 +2953,8 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir) SG_LOG(4, sfp, "%s: no data xfer [0x%pK]\n", __func__, srp); set_bit(SG_FRQ_NO_US_XFER, srp->frq_bm); goto fini; /* path of reqs with no din nor dout */ - } else if (sg_chk_dio_allowed(sdp, srp, iov_count, dxfer_dir) && + } else if ((rq_flags & SG_FLAG_DIRECT_IO) && iov_count == 0 && + !sdp->device->host->unchecked_isa_dma && blk_rq_aligned(q, (unsigned long)up, dxfer_len)) { srp->rq_info |= SG_INFO_DIRECT_IO; md = NULL; @@ -2976,7 +2965,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir) } if (likely(md)) { /* normal, "indirect" IO */ - if (unlikely(srp->rq_flags & SG_FLAG_MMAP_IO)) { + if (unlikely(rq_flags & SG_FLAG_MMAP_IO)) { /* mmap IO must use and fit in reserve request */ if (!reserved || dxfer_len > req_schp->buflen) res = reserved ? -ENOMEM : -EBUSY; @@ -3861,6 +3850,7 @@ sg_proc_single_open_adio(struct inode *inode, struct file *filp) return single_open(filp, sg_proc_seq_show_int, &sg_allow_dio); } +/* Kept for backward compatibility. sg_allow_dio is now ignored. */ static ssize_t sg_proc_write_adio(struct file *filp, const char __user *buffer, size_t count, loff_t *off) @@ -4481,6 +4471,6 @@ MODULE_ALIAS_CHARDEV_MAJOR(SCSI_GENERIC_MAJOR); MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element size (default: max(SG_SCATTER_SZ, PAGE_SIZE))"); MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd"); -MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))"); +MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow)); now ignored"); module_init(init_sg); module_exit(exit_sg);