From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 0D19EC5518E for ; Tue, 21 Apr 2020 21:53:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6BBC20735 for ; Tue, 21 Apr 2020 21:53:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726507AbgDUVx4 (ORCPT ); Tue, 21 Apr 2020 17:53:56 -0400 Received: from smtp.infotech.no ([82.134.31.41]:43202 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726499AbgDUVxw (ORCPT ); Tue, 21 Apr 2020 17:53:52 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id C2B272041CF; Tue, 21 Apr 2020 23:53:50 +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 Ge-xPDxaf5XH; Tue, 21 Apr 2020 23:53:49 +0200 (CEST) Received: from xtwo70.bingwo.ca (host-23-251-188-50.dyn.295.ca [23.251.188.50]) by smtp.infotech.no (Postfix) with ESMTPA id B978F204247; Tue, 21 Apr 2020 23:53:44 +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 v9 37/40] sg: defang allow_dio Date: Tue, 21 Apr 2020 17:52:55 -0400 Message-Id: <20200421215258.14348-38-dgilbert@interlog.com> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200421215258.14348-1-dgilbert@interlog.com> References: <20200421215258.14348-1-dgilbert@interlog.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-scsi-owner@vger.kernel.org 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. 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 e355d472aa72..05d1908ff031 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; @@ -2866,19 +2866,6 @@ 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) @@ -2897,6 +2884,7 @@ 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; @@ -2977,7 +2965,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir) } 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; @@ -2988,7 +2976,8 @@ 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; @@ -2999,7 +2988,7 @@ 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; @@ -3898,6 +3887,7 @@ 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) @@ -4518,6 +4508,6 @@ 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); -- 2.26.1