/* * blkfront.c * * XenLinux virtual block device driver. * * Copyright (c) 2003-2004, Keir Fraser & Steve Hand * Modifications by Mark A. Williamson are (c) Intel Research Cambridge * Copyright (c) 2004, Christian Limpach * Copyright (c) 2004, Andrew Warfield * Copyright (c) 2005, Christopher Clark * Copyright (c) 2005, XenSource Ltd * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include enum blkif_state { BLKIF_STATE_DISCONNECTED, BLKIF_STATE_CONNECTED, BLKIF_STATE_SUSPENDED, }; struct grant { grant_ref_t gref; unsigned long pfn; struct list_head node; }; struct blk_shadow { struct blkif_request req; struct request *request; struct grant *grants_used[BLKIF_MAX_SEGMENTS_PER_REQUEST]; }; static DEFINE_MUTEX(blkfront_mutex); static const struct block_device_operations xlvbd_block_fops; #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) /* * We have one of these per vbd, whether ide, scsi or 'other'. They * hang in private_data off the gendisk structure. We may end up * putting all kinds of interesting stuff here :-) */ struct blkfront_info { spinlock_t io_lock; struct mutex mutex; struct xenbus_device *xbdev; struct gendisk *gd; int vdevice; blkif_vdev_t handle; enum blkif_state connected; int ring_ref; struct blkif_front_ring ring; struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; unsigned int evtchn, irq; struct request_queue *rq; struct work_struct work; struct gnttab_free_callback callback; struct blk_shadow shadow[BLK_RING_SIZE]; struct list_head persistent_gnts; unsigned int persistent_gnts_c; unsigned long shadow_free; unsigned int feature_flush; unsigned int flush_op; unsigned int feature_discard:1; unsigned int feature_secdiscard:1; unsigned int discard_granularity; unsigned int discard_alignment; unsigned int feature_persistent:1; int is_ready; }; static unsigned int nr_minors; static unsigned long *minors; static DEFINE_SPINLOCK(minor_lock); #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) #define GRANT_INVALID_REF 0 #define PARTS_PER_DISK 16 #define PARTS_PER_EXT_DISK 256 #define BLKIF_MAJOR(dev) ((dev)>>8) #define BLKIF_MINOR(dev) ((dev) & 0xff) #define EXT_SHIFT 28 #define EXTENDED (1<shadow_free; BUG_ON(free >= BLK_RING_SIZE); info->shadow_free = info->shadow[free].req.u.rw.id; info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ return free; } static int add_id_to_freelist(struct blkfront_info *info, unsigned long id) { if (info->shadow[id].req.u.rw.id != id) return -EINVAL; if (info->shadow[id].request == NULL) return -EINVAL; info->shadow[id].req.u.rw.id = info->shadow_free; info->shadow[id].request = NULL; info->shadow_free = id; return 0; } static int fill_grant_buffer(struct blkfront_info *info, int num) { struct page *granted_page; struct grant *gnt_list_entry, *n; int i = 0; while(i < num) { gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); if (!gnt_list_entry) goto out_of_memory; granted_page = alloc_page(GFP_NOIO); if (!granted_page) { kfree(gnt_list_entry); goto out_of_memory; } gnt_list_entry->pfn = page_to_pfn(granted_page); gnt_list_entry->gref = GRANT_INVALID_REF; list_add(&gnt_list_entry->node, &info->persistent_gnts); i++; } return 0; out_of_memory: list_for_each_entry_safe(gnt_list_entry, n, &info->persistent_gnts, node) { list_del(&gnt_list_entry->node); __free_page(pfn_to_page(gnt_list_entry->pfn)); kfree(gnt_list_entry); i--; } BUG_ON(i != 0); return -ENOMEM; } static struct grant *get_grant(grant_ref_t *gref_head, struct blkfront_info *info) { struct grant *gnt_list_entry; unsigned long buffer_mfn; BUG_ON(list_empty(&info->persistent_gnts)); gnt_list_entry = list_first_entry(&info->persistent_gnts, struct grant, node); list_del(&gnt_list_entry->node); if (gnt_list_entry->gref != GRANT_INVALID_REF) { info->persistent_gnts_c--; return gnt_list_entry; } /* Assign a gref to this page */ gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); BUG_ON(gnt_list_entry->gref == -ENOSPC); buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); gnttab_grant_foreign_access_ref(gnt_list_entry->gref, info->xbdev->otherend_id, buffer_mfn, 0); return gnt_list_entry; } static const char *op_name(int op) { static const char *const names[] = { [BLKIF_OP_READ] = "read", [BLKIF_OP_WRITE] = "write", [BLKIF_OP_WRITE_BARRIER] = "barrier", [BLKIF_OP_FLUSH_DISKCACHE] = "flush", [BLKIF_OP_DISCARD] = "discard" }; if (op < 0 || op >= ARRAY_SIZE(names)) return "unknown"; if (!names[op]) return "reserved"; return names[op]; } static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) { unsigned int end = minor + nr; int rc; if (end > nr_minors) { unsigned long *bitmap, *old; bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), GFP_KERNEL); if (bitmap == NULL) return -ENOMEM; spin_lock(&minor_lock); if (end > nr_minors) { old = minors; memcpy(bitmap, minors, BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); minors = bitmap; nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; } else old = bitmap; spin_unlock(&minor_lock); kfree(old); } spin_lock(&minor_lock); if (find_next_bit(minors, end, minor) >= end) { bitmap_set(minors, minor, nr); rc = 0; } else rc = -EBUSY; spin_unlock(&minor_lock); return rc; } static void xlbd_release_minors(unsigned int minor, unsigned int nr) { unsigned int end = minor + nr; BUG_ON(end > nr_minors); spin_lock(&minor_lock); bitmap_clear(minors, minor, nr); spin_unlock(&minor_lock); } static void blkif_restart_queue_callback(void *arg) { struct blkfront_info *info = (struct blkfront_info *)arg; schedule_work(&info->work); } static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) { /* We don't have real geometry info, but let's at least return values consistent with the size of the device */ sector_t nsect = get_capacity(bd->bd_disk); sector_t cylinders = nsect; hg->heads = 0xff; hg->sectors = 0x3f; sector_div(cylinders, hg->heads * hg->sectors); hg->cylinders = cylinders; if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) hg->cylinders = 0xffff; return 0; } static int blkif_ioctl(struct block_device *bdev, fmode_t mode, unsigned command, unsigned long argument) { struct blkfront_info *info = bdev->bd_disk->private_data; int i; dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", command, (long)argument); switch (command) { case CDROMMULTISESSION: dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); for (i = 0; i < sizeof(struct cdrom_multisession); i++) if (put_user(0, (char __user *)(argument + i))) return -EFAULT; return 0; case CDROM_GET_CAPABILITY: { struct gendisk *gd = info->gd; if (gd->flags & GENHD_FL_CD) return 0; return -EINVAL; } default: /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", command);*/ return -EINVAL; /* same return as native Linux */ } return 0; } /* * Generate a Xen blkfront IO request from a blk layer request. Reads * and writes are handled as expected. * * @req: a request struct */ static int blkif_queue_request(struct request *req) { struct blkfront_info *info = req->rq_disk->private_data; struct blkif_request *ring_req; unsigned long id; unsigned int fsect, lsect; int i, ref; /* * Used to store if we are able to queue the request by just using * existing persistent grants, or if we have to get new grants, * as there are not sufficiently many free. */ bool new_persistent_gnts; grant_ref_t gref_head; struct grant *gnt_list_entry = NULL; struct scatterlist *sg; if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) return 1; /* Check if we have enought grants to allocate a requests */ if (info->persistent_gnts_c < BLKIF_MAX_SEGMENTS_PER_REQUEST) { new_persistent_gnts = 1; if (gnttab_alloc_grant_references( BLKIF_MAX_SEGMENTS_PER_REQUEST - info->persistent_gnts_c, &gref_head) < 0) { gnttab_request_free_callback( &info->callback, blkif_restart_queue_callback, info, BLKIF_MAX_SEGMENTS_PER_REQUEST); return 1; } } else new_persistent_gnts = 0; /* Fill out a communications ring structure. */ ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); id = get_id_from_freelist(info); info->shadow[id].request = req; ring_req->u.rw.id = id; ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); ring_req->u.rw.handle = info->handle; ring_req->operation = rq_data_dir(req) ? BLKIF_OP_WRITE : BLKIF_OP_READ; if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { /* * Ideally we can do an unordered flush-to-disk. In case the * backend onlysupports barriers, use that. A barrier request * a superset of FUA, so we can implement it the same * way. (It's also a FLUSH+FUA, since it is * guaranteed ordered WRT previous writes.) */ ring_req->operation = info->flush_op; } if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { /* id, sector_number and handle are set above. */ ring_req->operation = BLKIF_OP_DISCARD; ring_req->u.discard.nr_sectors = blk_rq_sectors(req); if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; else ring_req->u.discard.flag = 0; } else { ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req, info->sg); BUG_ON(ring_req->u.rw.nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) { fsect = sg->offset >> 9; lsect = fsect + (sg->length >> 9) - 1; gnt_list_entry = get_grant(&gref_head, info); ref = gnt_list_entry->gref; info->shadow[id].grants_used[i] = gnt_list_entry; if (rq_data_dir(req)) { char *bvec_data; void *shared_data; BUG_ON(sg->offset + sg->length > PAGE_SIZE); shared_data = kmap_atomic( pfn_to_page(gnt_list_entry->pfn)); bvec_data = kmap_atomic(sg_page(sg)); /* * this does not wipe data stored outside the * range sg->offset..sg->offset+sg->length. * Therefore, blkback *could* see data from * previous requests. This is OK as long as * persistent grants are shared with just one * domain. It may need refactoring if this * changes */ memcpy(shared_data + sg->offset, bvec_data + sg->offset, sg->length); kunmap_atomic(bvec_data); kunmap_atomic(shared_data); } ring_req->u.rw.seg[i] = (struct blkif_request_segment) { .gref = ref, .first_sect = fsect, .last_sect = lsect }; } } info->ring.req_prod_pvt++; /* Keep a private copy so we can reissue requests when recovering. */ info->shadow[id].req = *ring_req; if (new_persistent_gnts) gnttab_free_grant_references(gref_head); return 0; } static inline void flush_requests(struct blkfront_info *info) { int notify; RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); if (notify) notify_remote_via_irq(info->irq); } /* * do_blkif_request * read a block; request is in a request queue */ static void do_blkif_request(struct request_queue *rq) { struct blkfront_info *info = NULL; struct request *req; int queued; pr_debug("Entered do_blkif_request\n"); queued = 0; while ((req = blk_peek_request(rq)) != NULL) { info = req->rq_disk->private_data; if (RING_FULL(&info->ring)) goto wait; blk_start_request(req); if ((req->cmd_type != REQ_TYPE_FS) || ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) && !info->flush_op)) { __blk_end_request_all(req, -EIO); continue; } pr_debug("do_blk_req %p: cmd %p, sec %lx, " "(%u/%u) buffer:%p [%s]\n", req, req->cmd, (unsigned long)blk_rq_pos(req), blk_rq_cur_sectors(req), blk_rq_sectors(req), req->buffer, rq_data_dir(req) ? "write" : "read"); if (blkif_queue_request(req)) { blk_requeue_request(rq, req); wait: /* Avoid pointless unplugs. */ blk_stop_queue(rq); break; } queued++; } if (queued != 0) flush_requests(info); } static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) { struct request_queue *rq; struct blkfront_info *info = gd->private_data; rq = blk_init_queue(do_blkif_request, &info->io_lock); if (rq == NULL) return -1; queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); if (info->feature_discard) { queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); blk_queue_max_discard_sectors(rq, get_capacity(gd)); rq->limits.discard_granularity = info->discard_granularity; rq->limits.discard_alignment = info->discard_alignment; if (info->feature_secdiscard) queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); } /* Hard sector size and max sectors impersonate the equiv. hardware. */ blk_queue_logical_block_size(rq, sector_size); blk_queue_max_hw_sectors(rq, 512); /* Each segment in a request is up to an aligned page in size. */ blk_queue_segment_boundary(rq, PAGE_SIZE - 1); blk_queue_max_segment_size(rq, PAGE_SIZE); /* Ensure a merged request will fit in a single I/O ring slot. */ blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); /* Make sure buffer addresses are sector-aligned. */ blk_queue_dma_alignment(rq, 511); /* Make sure we don't use bounce buffers. */ blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); gd->queue = rq; return 0; } static void xlvbd_flush(struct blkfront_info *info) { blk_queue_flush(info->rq, info->feature_flush); printk(KERN_INFO "blkfront: %s: %s: %s %s\n", info->gd->disk_name, info->flush_op == BLKIF_OP_WRITE_BARRIER ? "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? "flush diskcache" : "barrier or flush"), info->feature_flush ? "enabled" : "disabled", info->feature_persistent ? "using persistent grants" : ""); } static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) { int major; major = BLKIF_MAJOR(vdevice); *minor = BLKIF_MINOR(vdevice); switch (major) { case XEN_IDE0_MAJOR: *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; *minor = ((*minor / 64) * PARTS_PER_DISK) + EMULATED_HD_DISK_MINOR_OFFSET; break; case XEN_IDE1_MAJOR: *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + EMULATED_HD_DISK_MINOR_OFFSET; break; case XEN_SCSI_DISK0_MAJOR: *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; break; case XEN_SCSI_DISK1_MAJOR: case XEN_SCSI_DISK2_MAJOR: case XEN_SCSI_DISK3_MAJOR: case XEN_SCSI_DISK4_MAJOR: case XEN_SCSI_DISK5_MAJOR: case XEN_SCSI_DISK6_MAJOR: case XEN_SCSI_DISK7_MAJOR: *offset = (*minor / PARTS_PER_DISK) + ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + EMULATED_SD_DISK_NAME_OFFSET; *minor = *minor + ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + EMULATED_SD_DISK_MINOR_OFFSET; break; case XEN_SCSI_DISK8_MAJOR: case XEN_SCSI_DISK9_MAJOR: case XEN_SCSI_DISK10_MAJOR: case XEN_SCSI_DISK11_MAJOR: case XEN_SCSI_DISK12_MAJOR: case XEN_SCSI_DISK13_MAJOR: case XEN_SCSI_DISK14_MAJOR: case XEN_SCSI_DISK15_MAJOR: *offset = (*minor / PARTS_PER_DISK) + ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + EMULATED_SD_DISK_NAME_OFFSET; *minor = *minor + ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + EMULATED_SD_DISK_MINOR_OFFSET; break; case XENVBD_MAJOR: *offset = *minor / PARTS_PER_DISK; break; default: printk(KERN_WARNING "blkfront: your disk configuration is " "incorrect, please use an xvd device instead\n"); return -ENODEV; } return 0; } static char *encode_disk_name(char *ptr, unsigned int n) { if (n >= 26) ptr = encode_disk_name(ptr, n / 26 - 1); *ptr = 'a' + n % 26; return ptr + 1; } static int xlvbd_alloc_gendisk(blkif_sector_t capacity, struct blkfront_info *info, u16 vdisk_info, u16 sector_size) { struct gendisk *gd; int nr_minors = 1; int err; unsigned int offset; int minor; int nr_parts; char *ptr; BUG_ON(info->gd != NULL); BUG_ON(info->rq != NULL); if ((info->vdevice>>EXT_SHIFT) > 1) { /* this is above the extended range; something is wrong */ printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); return -ENODEV; } if (!VDEV_IS_EXTENDED(info->vdevice)) { err = xen_translate_vdev(info->vdevice, &minor, &offset); if (err) return err; nr_parts = PARTS_PER_DISK; } else { minor = BLKIF_MINOR_EXT(info->vdevice); nr_parts = PARTS_PER_EXT_DISK; offset = minor / nr_parts; if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " "emulated IDE disks,\n\t choose an xvd device name" "from xvde on\n", info->vdevice); } if (minor >> MINORBITS) { pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", info->vdevice, minor); return -ENODEV; } if ((minor % nr_parts) == 0) nr_minors = nr_parts; err = xlbd_reserve_minors(minor, nr_minors); if (err) goto out; err = -ENODEV; gd = alloc_disk(nr_minors); if (gd == NULL) goto release; strcpy(gd->disk_name, DEV_NAME); ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); if (nr_minors > 1) *ptr = 0; else snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, "%d", minor & (nr_parts - 1)); gd->major = XENVBD_MAJOR; gd->first_minor = minor; gd->fops = &xlvbd_block_fops; gd->private_data = info; gd->driverfs_dev = &(info->xbdev->dev); set_capacity(gd, capacity); if (xlvbd_init_blk_queue(gd, sector_size)) { del_gendisk(gd); goto release; } info->rq = gd->queue; info->gd = gd; xlvbd_flush(info); if (vdisk_info & VDISK_READONLY) set_disk_ro(gd, 1); if (vdisk_info & VDISK_REMOVABLE) gd->flags |= GENHD_FL_REMOVABLE; if (vdisk_info & VDISK_CDROM) gd->flags |= GENHD_FL_CD; return 0; release: xlbd_release_minors(minor, nr_minors); out: return err; } static void xlvbd_release_gendisk(struct blkfront_info *info) { unsigned int minor, nr_minors; unsigned long flags; if (info->rq == NULL) return; spin_lock_irqsave(&info->io_lock, flags); /* No more blkif_request(). */ blk_stop_queue(info->rq); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); spin_unlock_irqrestore(&info->io_lock, flags); /* Flush gnttab callback work. Must be done with no locks held. */ flush_work(&info->work); del_gendisk(info->gd); minor = info->gd->first_minor; nr_minors = info->gd->minors; xlbd_release_minors(minor, nr_minors); blk_cleanup_queue(info->rq); info->rq = NULL; put_disk(info->gd); info->gd = NULL; } static void kick_pending_request_queues(struct blkfront_info *info) { if (!RING_FULL(&info->ring)) { /* Re-enable calldowns. */ blk_start_queue(info->rq); /* Kick things off immediately. */ do_blkif_request(info->rq); } } static void blkif_restart_queue(struct work_struct *work) { struct blkfront_info *info = container_of(work, struct blkfront_info, work); spin_lock_irq(&info->io_lock); if (info->connected == BLKIF_STATE_CONNECTED) kick_pending_request_queues(info); spin_unlock_irq(&info->io_lock); } static void blkif_free(struct blkfront_info *info, int suspend) { struct grant *persistent_gnt; struct grant *n; /* Prevent new requests being issued until we fix things up. */ spin_lock_irq(&info->io_lock); info->connected = suspend ? BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; /* No more blkif_request(). */ if (info->rq) blk_stop_queue(info->rq); /* Remove all persistent grants */ if (!list_empty(&info->persistent_gnts)) { list_for_each_entry_safe(persistent_gnt, n, &info->persistent_gnts, node) { list_del(&persistent_gnt->node); if (persistent_gnt->gref != GRANT_INVALID_REF) { gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); info->persistent_gnts_c--; } __free_page(pfn_to_page(persistent_gnt->pfn)); kfree(persistent_gnt); } } BUG_ON(info->persistent_gnts_c != 0); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); spin_unlock_irq(&info->io_lock); /* Flush gnttab callback work. Must be done with no locks held. */ flush_work(&info->work); /* Free resources associated with old device channel. */ if (info->ring_ref != GRANT_INVALID_REF) { gnttab_end_foreign_access(info->ring_ref, 0, (unsigned long)info->ring.sring); info->ring_ref = GRANT_INVALID_REF; info->ring.sring = NULL; } if (info->irq) unbind_from_irqhandler(info->irq, info); info->evtchn = info->irq = 0; } static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, struct blkif_response *bret) { int i = 0; struct bio_vec *bvec; struct req_iterator iter; unsigned long flags; char *bvec_data; void *shared_data; unsigned int offset = 0; if (bret->operation == BLKIF_OP_READ) { /* * Copy the data received from the backend into the bvec. * Since bv_offset can be different than 0, and bv_len different * than PAGE_SIZE, we have to keep track of the current offset, * to be sure we are copying the data from the right shared page. */ rq_for_each_segment(bvec, s->request, iter) { BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE); if (bvec->bv_offset < offset) i++; BUG_ON(i >= s->req.u.rw.nr_segments); shared_data = kmap_atomic( pfn_to_page(s->grants_used[i]->pfn)); bvec_data = bvec_kmap_irq(bvec, &flags); memcpy(bvec_data, shared_data + bvec->bv_offset, bvec->bv_len); bvec_kunmap_irq(bvec_data, &flags); kunmap_atomic(shared_data); offset = bvec->bv_offset + bvec->bv_len; } } /* Add the persistent grant into the list of free grants */ for (i = 0; i < s->req.u.rw.nr_segments; i++) { list_add(&s->grants_used[i]->node, &info->persistent_gnts); info->persistent_gnts_c++; } } static irqreturn_t blkif_interrupt(int irq, void *dev_id) { struct request *req; struct blkif_response *bret; RING_IDX i, rp; unsigned long flags; struct blkfront_info *info = (struct blkfront_info *)dev_id; int error; spin_lock_irqsave(&info->io_lock, flags); if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { spin_unlock_irqrestore(&info->io_lock, flags); return IRQ_HANDLED; } again: rp = info->ring.sring->rsp_prod; rmb(); /* Ensure we see queued responses up to 'rp'. */ for (i = info->ring.rsp_cons; i != rp; i++) { unsigned long id; bret = RING_GET_RESPONSE(&info->ring, i); id = bret->id; /* * The backend has messed up and given us an id that we would * never have given to it (we stamp it up to BLK_RING_SIZE - * look in get_id_from_freelist. */ if (id >= BLK_RING_SIZE) { WARN(1, "%s: response to %s has incorrect id (%ld)\n", info->gd->disk_name, op_name(bret->operation), id); /* We can't safely get the 'struct request' as * the id is busted. */ continue; } req = info->shadow[id].request; if (bret->operation != BLKIF_OP_DISCARD) blkif_completion(&info->shadow[id], info, bret); if (add_id_to_freelist(info, id)) { WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", info->gd->disk_name, op_name(bret->operation), id); continue; } error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; switch (bret->operation) { case BLKIF_OP_DISCARD: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { struct request_queue *rq = info->rq; printk(KERN_WARNING "blkfront: %s: %s op failed\n", info->gd->disk_name, op_name(bret->operation)); error = -EOPNOTSUPP; info->feature_discard = 0; info->feature_secdiscard = 0; queue_flag_clear(QUEUE_FLAG_DISCARD, rq); queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); } __blk_end_request_all(req, error); break; case BLKIF_OP_FLUSH_DISKCACHE: case BLKIF_OP_WRITE_BARRIER: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { printk(KERN_WARNING "blkfront: %s: %s op failed\n", info->gd->disk_name, op_name(bret->operation)); error = -EOPNOTSUPP; } if (unlikely(bret->status == BLKIF_RSP_ERROR && info->shadow[id].req.u.rw.nr_segments == 0)) { printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", info->gd->disk_name, op_name(bret->operation)); error = -EOPNOTSUPP; } if (unlikely(error)) { if (error == -EOPNOTSUPP) error = 0; info->feature_flush = 0; info->flush_op = 0; xlvbd_flush(info); } /* fall through */ case BLKIF_OP_READ: case BLKIF_OP_WRITE: if (unlikely(bret->status != BLKIF_RSP_OKAY)) dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " "request: %x\n", bret->status); __blk_end_request_all(req, error); break; default: BUG(); } } info->ring.rsp_cons = i; if (i != info->ring.req_prod_pvt) { int more_to_do; RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); if (more_to_do) goto again; } else info->ring.sring->rsp_event = i + 1; kick_pending_request_queues(info); spin_unlock_irqrestore(&info->io_lock, flags); return IRQ_HANDLED; } static int setup_blkring(struct xenbus_device *dev, struct blkfront_info *info) { struct blkif_sring *sring; int err; info->ring_ref = GRANT_INVALID_REF; sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); if (!sring) { xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); return -ENOMEM; } SHARED_RING_INIT(sring); FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST); /* Allocate memory for grants */ err = fill_grant_buffer(info, BLK_RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST); if (err) goto fail; err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); if (err < 0) { free_page((unsigned long)sring); info->ring.sring = NULL; goto fail; } info->ring_ref = err; err = xenbus_alloc_evtchn(dev, &info->evtchn); if (err) goto fail; err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, "blkif", info); if (err <= 0) { xenbus_dev_fatal(dev, err, "bind_evtchn_to_irqhandler failed"); goto fail; } info->irq = err; return 0; fail: blkif_free(info, 0); return err; } /* Common code used when first setting up, and when resuming. */ static int talk_to_blkback(struct xenbus_device *dev, struct blkfront_info *info) { const char *message = NULL; struct xenbus_transaction xbt; int err; /* Create shared ring, alloc event channel. */ err = setup_blkring(dev, info); if (err) goto out; again: err = xenbus_transaction_start(&xbt); if (err) { xenbus_dev_fatal(dev, err, "starting transaction"); goto destroy_blkring; } err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u", info->ring_ref); if (err) { message = "writing ring-ref"; goto abort_transaction; } err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", info->evtchn); if (err) { message = "writing event-channel"; goto abort_transaction; } err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", XEN_IO_PROTO_ABI_NATIVE); if (err) { message = "writing protocol"; goto abort_transaction; } err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); if (err) dev_warn(&dev->dev, "writing persistent grants feature to xenbus"); err = xenbus_transaction_end(xbt, 0); if (err) { if (err == -EAGAIN) goto again; xenbus_dev_fatal(dev, err, "completing transaction"); goto destroy_blkring; } xenbus_switch_state(dev, XenbusStateInitialised); return 0; abort_transaction: xenbus_transaction_end(xbt, 1); if (message) xenbus_dev_fatal(dev, err, "%s", message); destroy_blkring: blkif_free(info, 0); out: return err; } /** * Entry point to this code when a new device is created. Allocate the basic * structures and the ring buffer for communication with the backend, and * inform the backend of the appropriate details for those. Switch to * Initialised state. */ static int blkfront_probe(struct xenbus_device *dev, const struct xenbus_device_id *id) { int err, vdevice, i; struct blkfront_info *info; /* FIXME: Use dynamic device id if this is not set. */ err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device", "%i", &vdevice); if (err != 1) { /* go looking in the extended area instead */ err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", "%i", &vdevice); if (err != 1) { xenbus_dev_fatal(dev, err, "reading virtual-device"); return err; } } if (xen_hvm_domain()) { char *type; int len; /* no unplug has been done: do not hook devices != xen vbds */ if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) { int major; if (!VDEV_IS_EXTENDED(vdevice)) major = BLKIF_MAJOR(vdevice); else major = XENVBD_MAJOR; if (major != XENVBD_MAJOR) { printk(KERN_INFO "%s: HVM does not support vbd %d as xen block device\n", __FUNCTION__, vdevice); return -ENODEV; } } /* do not create a PV cdrom device if we are an HVM guest */ type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); if (IS_ERR(type)) return -ENODEV; if (strncmp(type, "cdrom", 5) == 0) { kfree(type); return -ENODEV; } kfree(type); } info = kzalloc(sizeof(*info), GFP_KERNEL); if (!info) { xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); return -ENOMEM; } mutex_init(&info->mutex); spin_lock_init(&info->io_lock); info->xbdev = dev; info->vdevice = vdevice; INIT_LIST_HEAD(&info->persistent_gnts); info->persistent_gnts_c = 0; info->connected = BLKIF_STATE_DISCONNECTED; INIT_WORK(&info->work, blkif_restart_queue); for (i = 0; i < BLK_RING_SIZE; i++) info->shadow[i].req.u.rw.id = i+1; info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; /* Front end dir is a number, which is used as the id. */ info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); dev_set_drvdata(&dev->dev, info); err = talk_to_blkback(dev, info); if (err) { kfree(info); dev_set_drvdata(&dev->dev, NULL); return err; } return 0; } static int blkif_recover(struct blkfront_info *info) { int i; struct blkif_request *req; struct blk_shadow *copy; int j; /* Stage 1: Make a safe copy of the shadow state. */ copy = kmemdup(info->shadow, sizeof(info->shadow), GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); if (!copy) return -ENOMEM; /* Stage 2: Set up free list. */ memset(&info->shadow, 0, sizeof(info->shadow)); for (i = 0; i < BLK_RING_SIZE; i++) info->shadow[i].req.u.rw.id = i+1; info->shadow_free = info->ring.req_prod_pvt; info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; /* Stage 3: Find pending requests and requeue them. */ for (i = 0; i < BLK_RING_SIZE; i++) { /* Not in use? */ if (!copy[i].request) continue; /* Grab a request slot and copy shadow state into it. */ req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); *req = copy[i].req; /* We get a new request id, and must reset the shadow state. */ req->u.rw.id = get_id_from_freelist(info); memcpy(&info->shadow[req->u.rw.id], ©[i], sizeof(copy[i])); if (req->operation != BLKIF_OP_DISCARD) { /* Rewrite any grant references invalidated by susp/resume. */ for (j = 0; j < req->u.rw.nr_segments; j++) gnttab_grant_foreign_access_ref( req->u.rw.seg[j].gref, info->xbdev->otherend_id, pfn_to_mfn(copy[i].grants_used[j]->pfn), 0); } info->shadow[req->u.rw.id].req = *req; info->ring.req_prod_pvt++; } kfree(copy); xenbus_switch_state(info->xbdev, XenbusStateConnected); spin_lock_irq(&info->io_lock); /* Now safe for us to use the shared ring */ info->connected = BLKIF_STATE_CONNECTED; /* Send off requeued requests */ flush_requests(info); /* Kick any other new requests queued since we resumed */ kick_pending_request_queues(info); spin_unlock_irq(&info->io_lock); return 0; } /** * We are reconnecting to the backend, due to a suspend/resume, or a backend * driver restart. We tear down our blkif structure and recreate it, but * leave the device-layer structures intact so that this is transparent to the * rest of the kernel. */ static int blkfront_resume(struct xenbus_device *dev) { struct blkfront_info *info = dev_get_drvdata(&dev->dev); int err; dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); err = talk_to_blkback(dev, info); if (info->connected == BLKIF_STATE_SUSPENDED && !err) err = blkif_recover(info); return err; } static void blkfront_closing(struct blkfront_info *info) { struct xenbus_device *xbdev = info->xbdev; struct block_device *bdev = NULL; mutex_lock(&info->mutex); if (xbdev->state == XenbusStateClosing) { mutex_unlock(&info->mutex); return; } if (info->gd) bdev = bdget_disk(info->gd, 0); mutex_unlock(&info->mutex); if (!bdev) { xenbus_frontend_closed(xbdev); return; } mutex_lock(&bdev->bd_mutex); if (bdev->bd_openers) { xenbus_dev_error(xbdev, -EBUSY, "Device in use; refusing to close"); xenbus_switch_state(xbdev, XenbusStateClosing); } else { xlvbd_release_gendisk(info); xenbus_frontend_closed(xbdev); } mutex_unlock(&bdev->bd_mutex); bdput(bdev); } static void blkfront_setup_discard(struct blkfront_info *info) { int err; char *type; unsigned int discard_granularity; unsigned int discard_alignment; unsigned int discard_secure; type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL); if (IS_ERR(type)) return; info->feature_secdiscard = 0; if (strncmp(type, "phy", 3) == 0) { err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "discard-granularity", "%u", &discard_granularity, "discard-alignment", "%u", &discard_alignment, NULL); if (!err) { info->feature_discard = 1; info->discard_granularity = discard_granularity; info->discard_alignment = discard_alignment; } err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "discard-secure", "%d", &discard_secure, NULL); if (!err) info->feature_secdiscard = discard_secure; } else if (strncmp(type, "file", 4) == 0) info->feature_discard = 1; kfree(type); } /* * Invoked when the backend is finally 'ready' (and has told produced * the details about the physical device - #sectors, size, etc). */ static void blkfront_connect(struct blkfront_info *info) { unsigned long long sectors; unsigned long sector_size; unsigned int binfo; int err; int barrier, flush, discard, persistent; switch (info->connected) { case BLKIF_STATE_CONNECTED: /* * Potentially, the back-end may be signalling * a capacity change; update the capacity. */ err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, "sectors", "%Lu", §ors); if (XENBUS_EXIST_ERR(err)) return; printk(KERN_INFO "Setting capacity to %Lu\n", sectors); set_capacity(info->gd, sectors); revalidate_disk(info->gd); /* fall through */ case BLKIF_STATE_SUSPENDED: return; default: break; } dev_dbg(&info->xbdev->dev, "%s:%s.\n", __func__, info->xbdev->otherend); err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "sectors", "%llu", §ors, "info", "%u", &binfo, "sector-size", "%lu", §or_size, NULL); if (err) { xenbus_dev_fatal(info->xbdev, err, "reading backend fields at %s", info->xbdev->otherend); return; } info->feature_flush = 0; info->flush_op = 0; err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-barrier", "%d", &barrier, NULL); /* * If there's no "feature-barrier" defined, then it means * we're dealing with a very old backend which writes * synchronously; nothing to do. * * If there are barriers, then we use flush. */ if (!err && barrier) { info->feature_flush = REQ_FLUSH | REQ_FUA; info->flush_op = BLKIF_OP_WRITE_BARRIER; } /* * And if there is "feature-flush-cache" use that above * barriers. */ err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-flush-cache", "%d", &flush, NULL); if (!err && flush) { info->feature_flush = REQ_FLUSH; info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; } err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-discard", "%d", &discard, NULL); if (!err && discard) blkfront_setup_discard(info); err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-persistent", "%u", &persistent, NULL); if (err) info->feature_persistent = 0; else info->feature_persistent = persistent; err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size); if (err) { xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", info->xbdev->otherend); return; } xenbus_switch_state(info->xbdev, XenbusStateConnected); /* Kick pending requests. */ spin_lock_irq(&info->io_lock); info->connected = BLKIF_STATE_CONNECTED; kick_pending_request_queues(info); spin_unlock_irq(&info->io_lock); add_disk(info->gd); info->is_ready = 1; } /** * Callback received when the backend's state changes. */ static void blkback_changed(struct xenbus_device *dev, enum xenbus_state backend_state) { struct blkfront_info *info = dev_get_drvdata(&dev->dev); dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); switch (backend_state) { case XenbusStateInitialising: case XenbusStateInitWait: case XenbusStateInitialised: case XenbusStateReconfiguring: case XenbusStateReconfigured: case XenbusStateUnknown: case XenbusStateClosed: break; case XenbusStateConnected: blkfront_connect(info); break; case XenbusStateClosing: blkfront_closing(info); break; } } static int blkfront_remove(struct xenbus_device *xbdev) { struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); struct block_device *bdev = NULL; struct gendisk *disk; dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); blkif_free(info, 0); mutex_lock(&info->mutex); disk = info->gd; if (disk) bdev = bdget_disk(disk, 0); info->xbdev = NULL; mutex_unlock(&info->mutex); if (!bdev) { kfree(info); return 0; } /* * The xbdev was removed before we reached the Closed * state. See if it's safe to remove the disk. If the bdev * isn't closed yet, we let release take care of it. */ mutex_lock(&bdev->bd_mutex); info = disk->private_data; dev_warn(disk_to_dev(disk), "%s was hot-unplugged, %d stale handles\n", xbdev->nodename, bdev->bd_openers); if (info && !bdev->bd_openers) { xlvbd_release_gendisk(info); disk->private_data = NULL; kfree(info); } mutex_unlock(&bdev->bd_mutex); bdput(bdev); return 0; } static int blkfront_is_ready(struct xenbus_device *dev) { struct blkfront_info *info = dev_get_drvdata(&dev->dev); return info->is_ready && info->xbdev; } static int blkif_open(struct block_device *bdev, fmode_t mode) { struct gendisk *disk = bdev->bd_disk; struct blkfront_info *info; int err = 0; mutex_lock(&blkfront_mutex); info = disk->private_data; if (!info) { /* xbdev gone */ err = -ERESTARTSYS; goto out; } mutex_lock(&info->mutex); if (!info->gd) /* xbdev is closed */ err = -ERESTARTSYS; mutex_unlock(&info->mutex); out: mutex_unlock(&blkfront_mutex); return err; } static void blkif_release(struct gendisk *disk, fmode_t mode) { struct blkfront_info *info = disk->private_data; struct block_device *bdev; struct xenbus_device *xbdev; mutex_lock(&blkfront_mutex); bdev = bdget_disk(disk, 0); if (bdev->bd_openers) goto out; /* * Check if we have been instructed to close. We will have * deferred this request, because the bdev was still open. */ mutex_lock(&info->mutex); xbdev = info->xbdev; if (xbdev && xbdev->state == XenbusStateClosing) { /* pending switch to state closed */ dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); xlvbd_release_gendisk(info); xenbus_frontend_closed(info->xbdev); } mutex_unlock(&info->mutex); if (!xbdev) { /* sudden device removal */ dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); xlvbd_release_gendisk(info); disk->private_data = NULL; kfree(info); } out: bdput(bdev); mutex_unlock(&blkfront_mutex); } static const struct block_device_operations xlvbd_block_fops = { .owner = THIS_MODULE, .open = blkif_open, .release = blkif_release, .getgeo = blkif_getgeo, .ioctl = blkif_ioctl, }; static const struct xenbus_device_id blkfront_ids[] = { { "vbd" }, { "" } }; static DEFINE_XENBUS_DRIVER(blkfront, , .probe = blkfront_probe, .remove = blkfront_remove, .resume = blkfront_resume, .otherend_changed = blkback_changed, .is_ready = blkfront_is_ready, ); static int __init xlblk_init(void) { int ret; if (!xen_domain()) return -ENODEV; if (xen_hvm_domain() && !xen_platform_pci_unplug) return -ENODEV; if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", XENVBD_MAJOR, DEV_NAME); return -ENODEV; } ret = xenbus_register_frontend(&blkfront_driver); if (ret) { unregister_blkdev(XENVBD_MAJOR, DEV_NAME); return ret; } return 0; } module_init(xlblk_init); static void __exit xlblk_exit(void) { xenbus_unregister_driver(&blkfront_driver); unregister_blkdev(XENVBD_MAJOR, DEV_NAME); kfree(minors); } module_exit(xlblk_exit); MODULE_DESCRIPTION("Xen virtual block device frontend"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); MODULE_ALIAS("xen:vbd"); MODULE_ALIAS("xenblk");