From patchwork Tue Apr 27 21:56:46 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 428277 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 DD32BC433B4 for ; Tue, 27 Apr 2021 21:58:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD99A613FE for ; Tue, 27 Apr 2021 21:58:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239450AbhD0V7Z (ORCPT ); Tue, 27 Apr 2021 17:59:25 -0400 Received: from smtp.infotech.no ([82.134.31.41]:38909 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239382AbhD0V7O (ORCPT ); Tue, 27 Apr 2021 17:59:14 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id CB50920419E; Tue, 27 Apr 2021 23:58:29 +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 Oywaj-4FPF5P; Tue, 27 Apr 2021 23:58:28 +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 0140720424C; Tue, 27 Apr 2021 23:58:26 +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 36/83] sg: rework mmap support Date: Tue, 27 Apr 2021 17:56:46 -0400 Message-Id: <20210427215733.417746-38-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 Linux has an issue with mmap-ed multiple pages issued by alloc_pages() [with order > 0]. So when mmap(2) is called if the reserve request's scatter gather (sgat) list is either: - not big enough, or - made up of elements of order > 0 (i.e. size > PAGE_SIZE) then throw away reserve requests sgat list and rebuild it meeting those requirements. Clean up related code and stop doing mmap+indirect_io. This new mmap implementation is marginally more flexible (but still compatible with) the production driver. Previously if the user wanted a larger mmap(2) 'length' than the reserve request's size, then they needed to use ioctl(SG_SET_RESERVED_SIZE) to set the new size first. Now mmap(2) called on a sg device node will adjust to the size given by 'length' [mmap's second parameter]. Tweak some SG_LOG() levels to control the amount of debug output. Add some WRITE_ONCE() macros when bitop integers are being initialised. Reviewed-by: Hannes Reinecke Signed-off-by: Douglas Gilbert --- drivers/scsi/sg.c | 177 +++++++++++++++++++++++++++------------------- 1 file changed, 106 insertions(+), 71 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index fdbff29669d3..4d0a5a50a00b 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -115,6 +115,7 @@ enum sg_rq_state { /* N.B. sg_rq_state_arr assumes SG_RS_AWAIT_RCV==2 */ #define SG_FRQ_NO_US_XFER 3 /* no user space transfer of data */ #define SG_FRQ_DEACT_ORPHAN 6 /* not keeping orphan so de-activate */ #define SG_FRQ_RECEIVING 7 /* guard against multiple receivers */ +#define SG_FRQ_FOR_MMAP 8 /* request needs PAGE_SIZE elements */ /* Bit positions (flags) for sg_fd::ffd_bm bitmask follow */ #define SG_FFD_FORCE_PACKID 0 /* receive only given pack_id/tag */ @@ -707,7 +708,7 @@ sg_write(struct file *filp, const char __user *p, size_t count, loff_t *ppos) input_size, (unsigned int)opcode, current->comm); } cwr.h3p = h3p; - cwr.frq_bm[0] = 0; + WRITE_ONCE(cwr.frq_bm[0], 0); cwr.timeout = sfp->timeout; cwr.cmd_len = cmd_size; cwr.filp = filp; @@ -768,7 +769,7 @@ sg_v3_submit(struct file *filp, struct sg_fd *sfp, struct sg_io_hdr *hp, /* when v3 seen, allow cmd_q on this fd (def: no cmd_q) */ set_bit(SG_FFD_CMD_Q, sfp->ffd_bm); ul_timeout = msecs_to_jiffies(hp->timeout); - cwr.frq_bm[0] = 0; + WRITE_ONCE(cwr.frq_bm[0], 0); __assign_bit(SG_FRQ_SYNC_INVOC, cwr.frq_bm, (int)sync); cwr.h3p = hp; cwr.timeout = min_t(unsigned long, ul_timeout, INT_MAX); @@ -809,7 +810,7 @@ sg_submit_v4(struct file *filp, struct sg_fd *sfp, void __user *p, ul_timeout = msecs_to_jiffies(h4p->timeout); cwr.filp = filp; cwr.sfp = sfp; - cwr.frq_bm[0] = 0; + WRITE_ONCE(cwr.frq_bm[0], 0); __assign_bit(SG_FRQ_SYNC_INVOC, cwr.frq_bm, (int)sync); __set_bit(SG_FRQ_IS_V4I, cwr.frq_bm); cwr.h4p = h4p; @@ -2225,13 +2226,39 @@ sg_fasync(int fd, struct file *filp, int mode) return fasync_helper(fd, filp, mode, &sfp->async_qp); } +static void +sg_vma_open(struct vm_area_struct *vma) +{ + struct sg_fd *sfp = vma->vm_private_data; + + if (unlikely(!sfp)) { + pr_warn("%s: sfp null\n", __func__); + return; + } + kref_get(&sfp->f_ref); +} + +static void +sg_vma_close(struct vm_area_struct *vma) +{ + struct sg_fd *sfp = vma->vm_private_data; + + if (unlikely(!sfp)) { + pr_warn("%s: sfp null\n", __func__); + return; + } + kref_put(&sfp->f_ref, sg_remove_sfp); /* get in: sg_vma_open() */ +} + /* Note: the error return: VM_FAULT_SIGBUS causes a "bus error" */ static vm_fault_t sg_vma_fault(struct vm_fault *vmf) { - int k, length; - unsigned long offset, len, sa, iflags; + int k, n, length; + int res = VM_FAULT_SIGBUS; + unsigned long offset; struct vm_area_struct *vma = vmf->vma; + struct page *page; struct sg_scatter_hold *rsv_schp; struct sg_request *srp; struct sg_device *sdp; @@ -2257,7 +2284,7 @@ sg_vma_fault(struct vm_fault *vmf) SG_LOG(1, sfp, "%s: srp%s\n", __func__, nbp); goto out_err; } - xa_lock_irqsave(&sfp->srp_arr, iflags); + mutex_lock(&sfp->f_mutex); rsv_schp = &srp->sgat_h; offset = vmf->pgoff << PAGE_SHIFT; if (offset >= (unsigned int)rsv_schp->buflen) { @@ -2265,44 +2292,37 @@ sg_vma_fault(struct vm_fault *vmf) offset); goto out_err_unlock; } - sa = vma->vm_start; - SG_LOG(3, sfp, "%s: vm_start=0x%lx, off=%lu\n", __func__, sa, offset); + SG_LOG(5, sfp, "%s: vm_start=0x%lx, off=%lu\n", __func__, + vma->vm_start, offset); length = 1 << (PAGE_SHIFT + rsv_schp->page_order); - for (k = 0; k < rsv_schp->num_sgat && sa < vma->vm_end; ++k) { - len = vma->vm_end - sa; - len = min_t(int, len, (int)length); - if (offset < len) { - struct page *page; - struct page *pp; - - pp = rsv_schp->pages[k]; - xa_unlock_irqrestore(&sfp->srp_arr, iflags); - page = nth_page(pp, offset >> PAGE_SHIFT); - get_page(page); /* increment page count */ - vmf->page = page; - return 0; /* success */ - } - sa += len; - offset -= len; - } + k = (int)offset / length; + n = ((int)offset % length) >> PAGE_SHIFT; + page = nth_page(rsv_schp->pages[k], n); + get_page(page); + vmf->page = page; + res = 0; out_err_unlock: - xa_unlock_irqrestore(&sfp->srp_arr, iflags); + mutex_unlock(&sfp->f_mutex); out_err: - return VM_FAULT_SIGBUS; + return res; } static const struct vm_operations_struct sg_mmap_vm_ops = { .fault = sg_vma_fault, + .open = sg_vma_open, + .close = sg_vma_close, }; -/* Entry point for mmap(2) system call */ +/* + * Entry point for mmap(2) system call. For mmap(2) to work, request's + * scatter gather list needs to be order 0 which it is unlikely to be + * by default. mmap(2) cannot be called more than once per fd. + */ static int sg_mmap(struct file *filp, struct vm_area_struct *vma) { - int k, length; - int ret = 0; - unsigned long req_sz, len, sa, iflags; - struct sg_scatter_hold *rsv_schp; + int res = 0; + unsigned long req_sz; struct sg_fd *sfp; struct sg_request *srp; @@ -2313,40 +2333,48 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma) pr_warn("sg: %s: sfp is NULL\n", __func__); return -ENXIO; } + mutex_lock(&sfp->f_mutex); req_sz = vma->vm_end - vma->vm_start; SG_LOG(3, sfp, "%s: vm_start=%pK, len=%d\n", __func__, (void *)vma->vm_start, (int)req_sz); - if (vma->vm_pgoff) - return -EINVAL; /* only an offset of 0 accepted */ + if (vma->vm_pgoff) { + res = -EINVAL; /* only an offset of 0 accepted */ + goto fini; + } /* Check reserve request is inactive and has large enough buffer */ - mutex_lock(&sfp->f_mutex); srp = sfp->rsv_srp; - xa_lock_irqsave(&sfp->srp_arr, iflags); if (SG_RS_ACTIVE(srp)) { - ret = -EBUSY; - goto out; + res = -EBUSY; + goto fini; } - rsv_schp = &srp->sgat_h; - if (req_sz > (unsigned long)rsv_schp->buflen) { - ret = -ENOMEM; - goto out; + if (req_sz > SG_WRITE_COUNT_LIMIT) { /* sanity check */ + res = -ENOMEM; + goto fini; } - sa = vma->vm_start; - length = 1 << (PAGE_SHIFT + rsv_schp->page_order); - for (k = 0; k < rsv_schp->num_sgat && sa < vma->vm_end; ++k) { - len = vma->vm_end - sa; - len = min_t(unsigned long, len, (unsigned long)length); - sa += len; + if (test_and_set_bit(SG_FFD_MMAP_CALLED, sfp->ffd_bm)) { + SG_LOG(1, sfp, "%s: multiple invocations on this fd\n", + __func__); + res = -EADDRINUSE; + goto fini; + } + if (srp->sgat_h.page_order > 0 || + req_sz > (unsigned long)srp->sgat_h.buflen) { + sg_remove_sgat(srp); + set_bit(SG_FRQ_FOR_MMAP, srp->frq_bm); + res = sg_mk_sgat(srp, sfp, req_sz); + if (res) { + SG_LOG(1, sfp, "%s: sg_mk_sgat failed, wanted=%lu\n", + __func__, req_sz); + goto fini; + } } - - set_bit(SG_FFD_MMAP_CALLED, sfp->ffd_bm); vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_private_data = sfp; vma->vm_ops = &sg_mmap_vm_ops; -out: - xa_unlock_irqrestore(&sfp->srp_arr, iflags); + sg_vma_open(vma); +fini: mutex_unlock(&sfp->f_mutex); - return ret; + return res; } static void @@ -2926,7 +2954,7 @@ 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); + us_xfer = !(srp->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; @@ -3061,6 +3089,7 @@ sg_mk_sgat(struct sg_request *srp, struct sg_fd *sfp, int minlen) gfp_t mask_kz = GFP_ATOMIC | __GFP_NOWARN; struct sg_device *sdp = sfp->parentdp; struct sg_scatter_hold *schp = &srp->sgat_h; + struct page **pgp; if (unlikely(minlen <= 0)) { if (minlen < 0) @@ -3076,32 +3105,37 @@ sg_mk_sgat(struct sg_request *srp, struct sg_fd *sfp, int minlen) if (unlikely(!schp->pages)) return -ENOMEM; - elem_sz = sfp->sgat_elem_sz; /* power of 2 and >= PAGE_SIZE */ + /* elem_sz must be power of 2 and >= PAGE_SIZE */ + elem_sz = test_bit(SG_FRQ_FOR_MMAP, srp->frq_bm) ? (int)PAGE_SIZE : sfp->sgat_elem_sz; if (sdp && unlikely(sdp->device->host->unchecked_isa_dma)) mask_ap |= GFP_DMA; o_order = get_order(elem_sz); order = o_order; again: - for (k = 0, rem_sz = align_sz; rem_sz > 0 && k < mx_sgat_elems; - ++k, rem_sz -= elem_sz) { - schp->pages[k] = alloc_pages(mask_ap, order); - if (!schp->pages[k]) + if (elem_sz * mx_sgat_elems < align_sz) { /* misfit ? */ + SG_LOG(1, sfp, "%s: align_sz=%d too big\n", __func__, + align_sz); + goto b4_alloc_pages; + } + rem_sz = align_sz; + for (pgp = schp->pages; rem_sz > 0; ++pgp, rem_sz -= elem_sz) { + *pgp = alloc_pages(mask_ap, order); + if (unlikely(!*pgp)) goto err_out; - SG_LOG(5, sfp, "%s: k=%d, order=%d [0x%pK ++]\n", __func__, k, - order, schp->pages[k]); + SG_LOG(6, sfp, "%s: elem_sz=%d [0x%pK ++]\n", __func__, + elem_sz, *pgp); } + k = pgp - schp->pages; + SG_LOG(((order != o_order || rem_sz > 0) ? 2 : 5), sfp, + "%s: num_sgat=%d, order=%d,%d rem_sz=%d\n", __func__, k, + o_order, order, rem_sz); schp->page_order = order; schp->num_sgat = k; - SG_LOG(((order != o_order || rem_sz > 0) ? 2 : 5), sfp, - "%s: num_sgat=%d, order=%d,%d\n", __func__, k, o_order, order); - if (unlikely(rem_sz > 0)) { /* hit mx_sgat_elems */ - order = 0; /* force exit */ - goto err_out; - } schp->buflen = align_sz; return 0; err_out: + k = pgp - schp->pages; for (j = 0; j < k; ++j) __free_pages(schp->pages[j], order); @@ -3109,6 +3143,7 @@ sg_mk_sgat(struct sg_request *srp, struct sg_fd *sfp, int minlen) elem_sz >>= 1; goto again; } +b4_alloc_pages: kfree(schp->pages); schp->pages = NULL; return -ENOMEM; @@ -3124,7 +3159,7 @@ sg_remove_sgat_helper(struct sg_fd *sfp, struct sg_scatter_hold *schp) return; for (k = 0; k < schp->num_sgat; ++k) { p = schp->pages[k]; - SG_LOG(5, sfp, "%s: pg[%d]=0x%pK --\n", __func__, k, p); + SG_LOG(6, sfp, "%s: pg[%d]=0x%pK --\n", __func__, k, p); if (unlikely(!p)) continue; __free_pages(p, schp->page_order); @@ -3254,7 +3289,7 @@ sg_find_srp_by_id(struct sg_fd *sfp, int pack_id) } return NULL; good: - SG_LOG(6, sfp, "%s: %s%d found [srp=0x%pK]\n", __func__, "pack_id=", + SG_LOG(5, sfp, "%s: %s%d found [srp=0x%pK]\n", __func__, "pack_id=", pack_id, srp); return srp; } @@ -3450,7 +3485,7 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, int dxfr_len) r_srp->parentfp = fp; SG_LOG(4, fp, "%s: mk_new_srp=0x%pK ++\n", __func__, r_srp); } - r_srp->frq_bm[0] = cwrp->frq_bm[0]; /* assumes <= 32 req flags */ + WRITE_ONCE(r_srp->frq_bm[0], cwrp->frq_bm[0]); /* assumes <= 32 req flags */ r_srp->sgat_h.dlen = dxfr_len;/* must be <= r_srp->sgat_h.buflen */ r_srp->cmd_opcode = 0xff; /* set invalid opcode (VS), 0x0 is TUR */ fini: @@ -3477,7 +3512,7 @@ sg_deact_request(struct sg_fd *sfp, struct sg_request *srp) return; sbp = srp->sense_bp; srp->sense_bp = NULL; - srp->frq_bm[0] = 0; + WRITE_ONCE(srp->frq_bm[0], 0); sg_rq_state_chg(srp, 0, SG_RS_INACTIVE, true /* force */, __func__); /* maybe orphaned req, thus never read */ if (sbp)