| /****************************************************************************** |
| * |
| * Back-end of the driver for virtual block devices. This portion of the |
| * driver exports a 'unified' block-device interface that can be accessed |
| * by any operating system that implements a compatible front end. A |
| * reference front-end implementation can be found in: |
| * drivers/block/xen-blkfront.c |
| * |
| * Copyright (c) 2003-2004, Keir Fraser & Steve Hand |
| * Copyright (c) 2005, Christopher Clark |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License version 2 |
| * as published by the Free Software Foundation; or, when distributed |
| * separately from the Linux kernel or incorporated into other |
| * software packages, subject to the following license: |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this source file (the "Software"), to deal in the Software without |
| * restriction, including without limitation the rights to use, copy, modify, |
| * merge, publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, subject to |
| * the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
| * IN THE SOFTWARE. |
| */ |
| |
| #include <linux/spinlock.h> |
| #include <linux/kthread.h> |
| #include <linux/list.h> |
| #include <linux/delay.h> |
| #include <linux/freezer.h> |
| #include <linux/loop.h> |
| #include <linux/falloc.h> |
| #include <linux/fs.h> |
| |
| #include <xen/events.h> |
| #include <xen/page.h> |
| #include <asm/xen/hypervisor.h> |
| #include <asm/xen/hypercall.h> |
| #include "common.h" |
| |
| /* |
| * These are rather arbitrary. They are fairly large because adjacent requests |
| * pulled from a communication ring are quite likely to end up being part of |
| * the same scatter/gather request at the disc. |
| * |
| * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW ** |
| * |
| * This will increase the chances of being able to write whole tracks. |
| * 64 should be enough to keep us competitive with Linux. |
| */ |
| static int xen_blkif_reqs = 64; |
| module_param_named(reqs, xen_blkif_reqs, int, 0); |
| MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); |
| |
| /* Run-time switchable: /sys/module/blkback/parameters/ */ |
| static unsigned int log_stats; |
| module_param(log_stats, int, 0644); |
| |
| /* |
| * Each outstanding request that we've passed to the lower device layers has a |
| * 'pending_req' allocated to it. Each buffer_head that completes decrements |
| * the pendcnt towards zero. When it hits zero, the specified domain has a |
| * response queued for it, with the saved 'id' passed back. |
| */ |
| struct pending_req { |
| struct xen_blkif *blkif; |
| u64 id; |
| int nr_pages; |
| atomic_t pendcnt; |
| unsigned short operation; |
| int status; |
| struct list_head free_list; |
| }; |
| |
| #define BLKBACK_INVALID_HANDLE (~0) |
| |
| struct xen_blkbk { |
| struct pending_req *pending_reqs; |
| /* List of all 'pending_req' available */ |
| struct list_head pending_free; |
| /* And its spinlock. */ |
| spinlock_t pending_free_lock; |
| wait_queue_head_t pending_free_wq; |
| /* The list of all pages that are available. */ |
| struct page **pending_pages; |
| /* And the grant handles that are available. */ |
| grant_handle_t *pending_grant_handles; |
| }; |
| |
| static struct xen_blkbk *blkbk; |
| |
| /* |
| * Little helpful macro to figure out the index and virtual address of the |
| * pending_pages[..]. For each 'pending_req' we have have up to |
| * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through |
| * 10 and would index in the pending_pages[..]. |
| */ |
| static inline int vaddr_pagenr(struct pending_req *req, int seg) |
| { |
| return (req - blkbk->pending_reqs) * |
| BLKIF_MAX_SEGMENTS_PER_REQUEST + seg; |
| } |
| |
| #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)] |
| |
| static inline unsigned long vaddr(struct pending_req *req, int seg) |
| { |
| unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg)); |
| return (unsigned long)pfn_to_kaddr(pfn); |
| } |
| |
| #define pending_handle(_req, _seg) \ |
| (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)]) |
| |
| |
| static int do_block_io_op(struct xen_blkif *blkif); |
| static int dispatch_rw_block_io(struct xen_blkif *blkif, |
| struct blkif_request *req, |
| struct pending_req *pending_req); |
| static void make_response(struct xen_blkif *blkif, u64 id, |
| unsigned short op, int st); |
| |
| /* |
| * Retrieve from the 'pending_reqs' a free pending_req structure to be used. |
| */ |
| static struct pending_req *alloc_req(void) |
| { |
| struct pending_req *req = NULL; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&blkbk->pending_free_lock, flags); |
| if (!list_empty(&blkbk->pending_free)) { |
| req = list_entry(blkbk->pending_free.next, struct pending_req, |
| free_list); |
| list_del(&req->free_list); |
| } |
| spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); |
| return req; |
| } |
| |
| /* |
| * Return the 'pending_req' structure back to the freepool. We also |
| * wake up the thread if it was waiting for a free page. |
| */ |
| static void free_req(struct pending_req *req) |
| { |
| unsigned long flags; |
| int was_empty; |
| |
| spin_lock_irqsave(&blkbk->pending_free_lock, flags); |
| was_empty = list_empty(&blkbk->pending_free); |
| list_add(&req->free_list, &blkbk->pending_free); |
| spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); |
| if (was_empty) |
| wake_up(&blkbk->pending_free_wq); |
| } |
| |
| /* |
| * Routines for managing virtual block devices (vbds). |
| */ |
| static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, |
| int operation) |
| { |
| struct xen_vbd *vbd = &blkif->vbd; |
| int rc = -EACCES; |
| |
| if ((operation != READ) && vbd->readonly) |
| goto out; |
| |
| if (likely(req->nr_sects)) { |
| blkif_sector_t end = req->sector_number + req->nr_sects; |
| |
| if (unlikely(end < req->sector_number)) |
| goto out; |
| if (unlikely(end > vbd_sz(vbd))) |
| goto out; |
| } |
| |
| req->dev = vbd->pdevice; |
| req->bdev = vbd->bdev; |
| rc = 0; |
| |
| out: |
| return rc; |
| } |
| |
| static void xen_vbd_resize(struct xen_blkif *blkif) |
| { |
| struct xen_vbd *vbd = &blkif->vbd; |
| struct xenbus_transaction xbt; |
| int err; |
| struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); |
| unsigned long long new_size = vbd_sz(vbd); |
| |
| pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", |
| blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); |
| pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); |
| vbd->size = new_size; |
| again: |
| err = xenbus_transaction_start(&xbt); |
| if (err) { |
| pr_warn(DRV_PFX "Error starting transaction"); |
| return; |
| } |
| err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", |
| (unsigned long long)vbd_sz(vbd)); |
| if (err) { |
| pr_warn(DRV_PFX "Error writing new size"); |
| goto abort; |
| } |
| /* |
| * Write the current state; we will use this to synchronize |
| * the front-end. If the current state is "connected" the |
| * front-end will get the new size information online. |
| */ |
| err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); |
| if (err) { |
| pr_warn(DRV_PFX "Error writing the state"); |
| goto abort; |
| } |
| |
| err = xenbus_transaction_end(xbt, 0); |
| if (err == -EAGAIN) |
| goto again; |
| if (err) |
| pr_warn(DRV_PFX "Error ending transaction"); |
| return; |
| abort: |
| xenbus_transaction_end(xbt, 1); |
| } |
| |
| /* |
| * Notification from the guest OS. |
| */ |
| static void blkif_notify_work(struct xen_blkif *blkif) |
| { |
| blkif->waiting_reqs = 1; |
| wake_up(&blkif->wq); |
| } |
| |
| irqreturn_t xen_blkif_be_int(int irq, void *dev_id) |
| { |
| blkif_notify_work(dev_id); |
| return IRQ_HANDLED; |
| } |
| |
| /* |
| * SCHEDULER FUNCTIONS |
| */ |
| |
| static void print_stats(struct xen_blkif *blkif) |
| { |
| pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d" |
| " | ds %4d\n", |
| current->comm, blkif->st_oo_req, |
| blkif->st_rd_req, blkif->st_wr_req, |
| blkif->st_f_req, blkif->st_ds_req); |
| blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); |
| blkif->st_rd_req = 0; |
| blkif->st_wr_req = 0; |
| blkif->st_oo_req = 0; |
| blkif->st_ds_req = 0; |
| } |
| |
| int xen_blkif_schedule(void *arg) |
| { |
| struct xen_blkif *blkif = arg; |
| struct xen_vbd *vbd = &blkif->vbd; |
| |
| xen_blkif_get(blkif); |
| |
| while (!kthread_should_stop()) { |
| if (try_to_freeze()) |
| continue; |
| if (unlikely(vbd->size != vbd_sz(vbd))) |
| xen_vbd_resize(blkif); |
| |
| wait_event_interruptible( |
| blkif->wq, |
| blkif->waiting_reqs || kthread_should_stop()); |
| wait_event_interruptible( |
| blkbk->pending_free_wq, |
| !list_empty(&blkbk->pending_free) || |
| kthread_should_stop()); |
| |
| blkif->waiting_reqs = 0; |
| smp_mb(); /* clear flag *before* checking for work */ |
| |
| if (do_block_io_op(blkif)) |
| blkif->waiting_reqs = 1; |
| |
| if (log_stats && time_after(jiffies, blkif->st_print)) |
| print_stats(blkif); |
| } |
| |
| if (log_stats) |
| print_stats(blkif); |
| |
| blkif->xenblkd = NULL; |
| xen_blkif_put(blkif); |
| |
| return 0; |
| } |
| |
| struct seg_buf { |
| unsigned long buf; |
| unsigned int nsec; |
| }; |
| /* |
| * Unmap the grant references, and also remove the M2P over-rides |
| * used in the 'pending_req'. |
| */ |
| static void xen_blkbk_unmap(struct pending_req *req) |
| { |
| struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; |
| unsigned int i, invcount = 0; |
| grant_handle_t handle; |
| int ret; |
| |
| for (i = 0; i < req->nr_pages; i++) { |
| handle = pending_handle(req, i); |
| if (handle == BLKBACK_INVALID_HANDLE) |
| continue; |
| gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), |
| GNTMAP_host_map, handle); |
| pending_handle(req, i) = BLKBACK_INVALID_HANDLE; |
| invcount++; |
| } |
| |
| ret = HYPERVISOR_grant_table_op( |
| GNTTABOP_unmap_grant_ref, unmap, invcount); |
| BUG_ON(ret); |
| /* |
| * Note, we use invcount, so nr->pages, so we can't index |
| * using vaddr(req, i). |
| */ |
| for (i = 0; i < invcount; i++) { |
| ret = m2p_remove_override( |
| virt_to_page(unmap[i].host_addr), false); |
| if (ret) { |
| pr_alert(DRV_PFX "Failed to remove M2P override for %lx\n", |
| (unsigned long)unmap[i].host_addr); |
| continue; |
| } |
| } |
| } |
| |
| static int xen_blkbk_map(struct blkif_request *req, |
| struct pending_req *pending_req, |
| struct seg_buf seg[]) |
| { |
| struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; |
| int i; |
| int nseg = req->u.rw.nr_segments; |
| int ret = 0; |
| |
| /* |
| * Fill out preq.nr_sects with proper amount of sectors, and setup |
| * assign map[..] with the PFN of the page in our domain with the |
| * corresponding grant reference for each page. |
| */ |
| for (i = 0; i < nseg; i++) { |
| uint32_t flags; |
| |
| flags = GNTMAP_host_map; |
| if (pending_req->operation != BLKIF_OP_READ) |
| flags |= GNTMAP_readonly; |
| gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags, |
| req->u.rw.seg[i].gref, |
| pending_req->blkif->domid); |
| } |
| |
| ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg); |
| BUG_ON(ret); |
| |
| /* |
| * Now swizzle the MFN in our domain with the MFN from the other domain |
| * so that when we access vaddr(pending_req,i) it has the contents of |
| * the page from the other domain. |
| */ |
| for (i = 0; i < nseg; i++) { |
| if (unlikely(map[i].status != 0)) { |
| pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); |
| map[i].handle = BLKBACK_INVALID_HANDLE; |
| ret |= 1; |
| } |
| |
| pending_handle(pending_req, i) = map[i].handle; |
| |
| if (ret) |
| continue; |
| |
| ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr), |
| blkbk->pending_page(pending_req, i), NULL); |
| if (ret) { |
| pr_alert(DRV_PFX "Failed to install M2P override for %lx (ret: %d)\n", |
| (unsigned long)map[i].dev_bus_addr, ret); |
| /* We could switch over to GNTTABOP_copy */ |
| continue; |
| } |
| |
| seg[i].buf = map[i].dev_bus_addr | |
| (req->u.rw.seg[i].first_sect << 9); |
| } |
| return ret; |
| } |
| |
| static void xen_blk_discard(struct xen_blkif *blkif, struct blkif_request *req) |
| { |
| int err = 0; |
| int status = BLKIF_RSP_OKAY; |
| struct block_device *bdev = blkif->vbd.bdev; |
| |
| if (blkif->blk_backend_type == BLKIF_BACKEND_PHY) |
| /* just forward the discard request */ |
| err = blkdev_issue_discard(bdev, |
| req->u.discard.sector_number, |
| req->u.discard.nr_sectors, |
| GFP_KERNEL, 0); |
| else if (blkif->blk_backend_type == BLKIF_BACKEND_FILE) { |
| /* punch a hole in the backing file */ |
| struct loop_device *lo = bdev->bd_disk->private_data; |
| struct file *file = lo->lo_backing_file; |
| |
| if (file->f_op->fallocate) |
| err = file->f_op->fallocate(file, |
| FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, |
| req->u.discard.sector_number << 9, |
| req->u.discard.nr_sectors << 9); |
| else |
| err = -EOPNOTSUPP; |
| } else |
| err = -EOPNOTSUPP; |
| |
| if (err == -EOPNOTSUPP) { |
| pr_debug(DRV_PFX "discard op failed, not supported\n"); |
| status = BLKIF_RSP_EOPNOTSUPP; |
| } else if (err) |
| status = BLKIF_RSP_ERROR; |
| |
| make_response(blkif, req->u.discard.id, req->operation, status); |
| } |
| |
| static void xen_blk_drain_io(struct xen_blkif *blkif) |
| { |
| atomic_set(&blkif->drain, 1); |
| do { |
| /* The initial value is one, and one refcnt taken at the |
| * start of the xen_blkif_schedule thread. */ |
| if (atomic_read(&blkif->refcnt) <= 2) |
| break; |
| wait_for_completion_interruptible_timeout( |
| &blkif->drain_complete, HZ); |
| |
| if (!atomic_read(&blkif->drain)) |
| break; |
| } while (!kthread_should_stop()); |
| atomic_set(&blkif->drain, 0); |
| } |
| |
| /* |
| * Completion callback on the bio's. Called as bh->b_end_io() |
| */ |
| |
| static void __end_block_io_op(struct pending_req *pending_req, int error) |
| { |
| /* An error fails the entire request. */ |
| if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && |
| (error == -EOPNOTSUPP)) { |
| pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); |
| xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); |
| pending_req->status = BLKIF_RSP_EOPNOTSUPP; |
| } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) && |
| (error == -EOPNOTSUPP)) { |
| pr_debug(DRV_PFX "write barrier op failed, not supported\n"); |
| xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0); |
| pending_req->status = BLKIF_RSP_EOPNOTSUPP; |
| } else if (error) { |
| pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," |
| " error=%d\n", error); |
| pending_req->status = BLKIF_RSP_ERROR; |
| } |
| |
| /* |
| * If all of the bio's have completed it is time to unmap |
| * the grant references associated with 'request' and provide |
| * the proper response on the ring. |
| */ |
| if (atomic_dec_and_test(&pending_req->pendcnt)) { |
| xen_blkbk_unmap(pending_req); |
| make_response(pending_req->blkif, pending_req->id, |
| pending_req->operation, pending_req->status); |
| xen_blkif_put(pending_req->blkif); |
| if (atomic_read(&pending_req->blkif->refcnt) <= 2) { |
| if (atomic_read(&pending_req->blkif->drain)) |
| complete(&pending_req->blkif->drain_complete); |
| } |
| free_req(pending_req); |
| } |
| } |
| |
| /* |
| * bio callback. |
| */ |
| static void end_block_io_op(struct bio *bio, int error) |
| { |
| __end_block_io_op(bio->bi_private, error); |
| bio_put(bio); |
| } |
| |
| |
| |
| /* |
| * Function to copy the from the ring buffer the 'struct blkif_request' |
| * (which has the sectors we want, number of them, grant references, etc), |
| * and transmute it to the block API to hand it over to the proper block disk. |
| */ |
| static int |
| __do_block_io_op(struct xen_blkif *blkif) |
| { |
| union blkif_back_rings *blk_rings = &blkif->blk_rings; |
| struct blkif_request req; |
| struct pending_req *pending_req; |
| RING_IDX rc, rp; |
| int more_to_do = 0; |
| |
| rc = blk_rings->common.req_cons; |
| rp = blk_rings->common.sring->req_prod; |
| rmb(); /* Ensure we see queued requests up to 'rp'. */ |
| |
| while (rc != rp) { |
| |
| if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) |
| break; |
| |
| if (kthread_should_stop()) { |
| more_to_do = 1; |
| break; |
| } |
| |
| pending_req = alloc_req(); |
| if (NULL == pending_req) { |
| blkif->st_oo_req++; |
| more_to_do = 1; |
| break; |
| } |
| |
| switch (blkif->blk_protocol) { |
| case BLKIF_PROTOCOL_NATIVE: |
| memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); |
| break; |
| case BLKIF_PROTOCOL_X86_32: |
| blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); |
| break; |
| case BLKIF_PROTOCOL_X86_64: |
| blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); |
| break; |
| default: |
| BUG(); |
| } |
| blk_rings->common.req_cons = ++rc; /* before make_response() */ |
| |
| /* Apply all sanity checks to /private copy/ of request. */ |
| barrier(); |
| |
| if (dispatch_rw_block_io(blkif, &req, pending_req)) |
| break; |
| |
| /* Yield point for this unbounded loop. */ |
| cond_resched(); |
| } |
| |
| return more_to_do; |
| } |
| |
| static int |
| do_block_io_op(struct xen_blkif *blkif) |
| { |
| union blkif_back_rings *blk_rings = &blkif->blk_rings; |
| int more_to_do; |
| |
| do { |
| more_to_do = __do_block_io_op(blkif); |
| if (more_to_do) |
| break; |
| |
| RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); |
| } while (more_to_do); |
| |
| return more_to_do; |
| } |
| /* |
| * Transmutation of the 'struct blkif_request' to a proper 'struct bio' |
| * and call the 'submit_bio' to pass it to the underlying storage. |
| */ |
| static int dispatch_rw_block_io(struct xen_blkif *blkif, |
| struct blkif_request *req, |
| struct pending_req *pending_req) |
| { |
| struct phys_req preq; |
| struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; |
| unsigned int nseg; |
| struct bio *bio = NULL; |
| struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; |
| int i, nbio = 0; |
| int operation; |
| struct blk_plug plug; |
| bool drain = false; |
| |
| switch (req->operation) { |
| case BLKIF_OP_READ: |
| blkif->st_rd_req++; |
| operation = READ; |
| break; |
| case BLKIF_OP_WRITE: |
| blkif->st_wr_req++; |
| operation = WRITE_ODIRECT; |
| break; |
| case BLKIF_OP_WRITE_BARRIER: |
| drain = true; |
| case BLKIF_OP_FLUSH_DISKCACHE: |
| blkif->st_f_req++; |
| operation = WRITE_FLUSH; |
| break; |
| case BLKIF_OP_DISCARD: |
| blkif->st_ds_req++; |
| operation = REQ_DISCARD; |
| break; |
| default: |
| operation = 0; /* make gcc happy */ |
| goto fail_response; |
| break; |
| } |
| |
| /* Check that the number of segments is sane. */ |
| nseg = req->u.rw.nr_segments; |
| |
| if (unlikely(nseg == 0 && operation != WRITE_FLUSH && |
| operation != REQ_DISCARD) || |
| unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { |
| pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", |
| nseg); |
| /* Haven't submitted any bio's yet. */ |
| goto fail_response; |
| } |
| |
| preq.dev = req->u.rw.handle; |
| preq.sector_number = req->u.rw.sector_number; |
| preq.nr_sects = 0; |
| |
| pending_req->blkif = blkif; |
| pending_req->id = req->u.rw.id; |
| pending_req->operation = req->operation; |
| pending_req->status = BLKIF_RSP_OKAY; |
| pending_req->nr_pages = nseg; |
| |
| for (i = 0; i < nseg; i++) { |
| seg[i].nsec = req->u.rw.seg[i].last_sect - |
| req->u.rw.seg[i].first_sect + 1; |
| if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || |
| (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) |
| goto fail_response; |
| preq.nr_sects += seg[i].nsec; |
| |
| } |
| |
| if (xen_vbd_translate(&preq, blkif, operation) != 0) { |
| pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", |
| operation == READ ? "read" : "write", |
| preq.sector_number, |
| preq.sector_number + preq.nr_sects, preq.dev); |
| goto fail_response; |
| } |
| |
| /* |
| * This check _MUST_ be done after xen_vbd_translate as the preq.bdev |
| * is set there. |
| */ |
| for (i = 0; i < nseg; i++) { |
| if (((int)preq.sector_number|(int)seg[i].nsec) & |
| ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { |
| pr_debug(DRV_PFX "Misaligned I/O request from domain %d", |
| blkif->domid); |
| goto fail_response; |
| } |
| } |
| |
| /* Wait on all outstanding I/O's and once that has been completed |
| * issue the WRITE_FLUSH. |
| */ |
| if (drain) |
| xen_blk_drain_io(pending_req->blkif); |
| |
| /* |
| * If we have failed at this point, we need to undo the M2P override, |
| * set gnttab_set_unmap_op on all of the grant references and perform |
| * the hypercall to unmap the grants - that is all done in |
| * xen_blkbk_unmap. |
| */ |
| if (operation != REQ_DISCARD && xen_blkbk_map(req, pending_req, seg)) |
| goto fail_flush; |
| |
| /* |
| * This corresponding xen_blkif_put is done in __end_block_io_op, or |
| * below (in "!bio") if we are handling a BLKIF_OP_DISCARD. |
| */ |
| xen_blkif_get(blkif); |
| |
| for (i = 0; i < nseg; i++) { |
| while ((bio == NULL) || |
| (bio_add_page(bio, |
| blkbk->pending_page(pending_req, i), |
| seg[i].nsec << 9, |
| seg[i].buf & ~PAGE_MASK) == 0)) { |
| |
| bio = bio_alloc(GFP_KERNEL, nseg-i); |
| if (unlikely(bio == NULL)) |
| goto fail_put_bio; |
| |
| biolist[nbio++] = bio; |
| bio->bi_bdev = preq.bdev; |
| bio->bi_private = pending_req; |
| bio->bi_end_io = end_block_io_op; |
| bio->bi_sector = preq.sector_number; |
| } |
| |
| preq.sector_number += seg[i].nsec; |
| } |
| |
| /* This will be hit if the operation was a flush or discard. */ |
| if (!bio) { |
| BUG_ON(operation != WRITE_FLUSH && operation != REQ_DISCARD); |
| |
| if (operation == WRITE_FLUSH) { |
| bio = bio_alloc(GFP_KERNEL, 0); |
| if (unlikely(bio == NULL)) |
| goto fail_put_bio; |
| |
| biolist[nbio++] = bio; |
| bio->bi_bdev = preq.bdev; |
| bio->bi_private = pending_req; |
| bio->bi_end_io = end_block_io_op; |
| } else if (operation == REQ_DISCARD) { |
| xen_blk_discard(blkif, req); |
| xen_blkif_put(blkif); |
| free_req(pending_req); |
| return 0; |
| } |
| } |
| |
| /* |
| * We set it one so that the last submit_bio does not have to call |
| * atomic_inc. |
| */ |
| atomic_set(&pending_req->pendcnt, nbio); |
| |
| /* Get a reference count for the disk queue and start sending I/O */ |
| blk_start_plug(&plug); |
| |
| for (i = 0; i < nbio; i++) |
| submit_bio(operation, biolist[i]); |
| |
| /* Let the I/Os go.. */ |
| blk_finish_plug(&plug); |
| |
| if (operation == READ) |
| blkif->st_rd_sect += preq.nr_sects; |
| else if (operation & WRITE) |
| blkif->st_wr_sect += preq.nr_sects; |
| |
| return 0; |
| |
| fail_flush: |
| xen_blkbk_unmap(pending_req); |
| fail_response: |
| /* Haven't submitted any bio's yet. */ |
| make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR); |
| free_req(pending_req); |
| msleep(1); /* back off a bit */ |
| return -EIO; |
| |
| fail_put_bio: |
| for (i = 0; i < nbio; i++) |
| bio_put(biolist[i]); |
| __end_block_io_op(pending_req, -EINVAL); |
| msleep(1); /* back off a bit */ |
| return -EIO; |
| } |
| |
| |
| |
| /* |
| * Put a response on the ring on how the operation fared. |
| */ |
| static void make_response(struct xen_blkif *blkif, u64 id, |
| unsigned short op, int st) |
| { |
| struct blkif_response resp; |
| unsigned long flags; |
| union blkif_back_rings *blk_rings = &blkif->blk_rings; |
| int notify; |
| |
| resp.id = id; |
| resp.operation = op; |
| resp.status = st; |
| |
| spin_lock_irqsave(&blkif->blk_ring_lock, flags); |
| /* Place on the response ring for the relevant domain. */ |
| switch (blkif->blk_protocol) { |
| case BLKIF_PROTOCOL_NATIVE: |
| memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), |
| &resp, sizeof(resp)); |
| break; |
| case BLKIF_PROTOCOL_X86_32: |
| memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), |
| &resp, sizeof(resp)); |
| break; |
| case BLKIF_PROTOCOL_X86_64: |
| memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), |
| &resp, sizeof(resp)); |
| break; |
| default: |
| BUG(); |
| } |
| blk_rings->common.rsp_prod_pvt++; |
| RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); |
| spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); |
| if (notify) |
| notify_remote_via_irq(blkif->irq); |
| } |
| |
| static int __init xen_blkif_init(void) |
| { |
| int i, mmap_pages; |
| int rc = 0; |
| |
| if (!xen_pv_domain()) |
| return -ENODEV; |
| |
| blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL); |
| if (!blkbk) { |
| pr_alert(DRV_PFX "%s: out of memory!\n", __func__); |
| return -ENOMEM; |
| } |
| |
| mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; |
| |
| blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) * |
| xen_blkif_reqs, GFP_KERNEL); |
| blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) * |
| mmap_pages, GFP_KERNEL); |
| blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) * |
| mmap_pages, GFP_KERNEL); |
| |
| if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || |
| !blkbk->pending_pages) { |
| rc = -ENOMEM; |
| goto out_of_memory; |
| } |
| |
| for (i = 0; i < mmap_pages; i++) { |
| blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; |
| blkbk->pending_pages[i] = alloc_page(GFP_KERNEL); |
| if (blkbk->pending_pages[i] == NULL) { |
| rc = -ENOMEM; |
| goto out_of_memory; |
| } |
| } |
| rc = xen_blkif_interface_init(); |
| if (rc) |
| goto failed_init; |
| |
| INIT_LIST_HEAD(&blkbk->pending_free); |
| spin_lock_init(&blkbk->pending_free_lock); |
| init_waitqueue_head(&blkbk->pending_free_wq); |
| |
| for (i = 0; i < xen_blkif_reqs; i++) |
| list_add_tail(&blkbk->pending_reqs[i].free_list, |
| &blkbk->pending_free); |
| |
| rc = xen_blkif_xenbus_init(); |
| if (rc) |
| goto failed_init; |
| |
| return 0; |
| |
| out_of_memory: |
| pr_alert(DRV_PFX "%s: out of memory\n", __func__); |
| failed_init: |
| kfree(blkbk->pending_reqs); |
| kfree(blkbk->pending_grant_handles); |
| if (blkbk->pending_pages) { |
| for (i = 0; i < mmap_pages; i++) { |
| if (blkbk->pending_pages[i]) |
| __free_page(blkbk->pending_pages[i]); |
| } |
| kfree(blkbk->pending_pages); |
| } |
| kfree(blkbk); |
| blkbk = NULL; |
| return rc; |
| } |
| |
| module_init(xen_blkif_init); |
| |
| MODULE_LICENSE("Dual BSD/GPL"); |
| MODULE_ALIAS("xen-backend:vbd"); |