/* * 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 <linux/interrupt.h> #include <linux/blkdev.h> #include <linux/module.h> #include <xen/xenbus.h> #include <xen/grant_table.h> #include <xen/events.h> #include <xen/page.h> #include <xen/interface/grant_table.h> #include <xen/interface/io/blkif.h> #include <asm/xen/hypervisor.h> enum blkif_state { BLKIF_STATE_DISCONNECTED, BLKIF_STATE_CONNECTED, BLKIF_STATE_SUSPENDED, }; struct blk_shadow { struct blkif_request req; unsigned long request; unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST]; }; static struct block_device_operations xlvbd_block_fops; #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, 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 { struct xenbus_device *xbdev; dev_t dev; struct gendisk *gd; int vdevice; blkif_vdev_t handle; enum blkif_state connected; int ring_ref; struct blkif_front_ring ring; unsigned int evtchn, irq; struct request_queue *rq; struct work_struct work; struct gnttab_free_callback callback; struct blk_shadow shadow[BLK_RING_SIZE]; unsigned long shadow_free; int feature_barrier; /** * The number of people holding this device open. We won't allow a * hot-unplug unless this is 0. */ int users; }; static DEFINE_SPINLOCK(blkif_io_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 BLKIF_MAJOR(dev) ((dev)>>8) #define BLKIF_MINOR(dev) ((dev) & 0xff) #define DEV_NAME "xvd" /* name in /dev */ /* Information about our VBDs. */ #define MAX_VBDS 64 static LIST_HEAD(vbds_list); static int get_id_from_freelist(struct blkfront_info *info) { unsigned long free = info->shadow_free; BUG_ON(free > BLK_RING_SIZE); info->shadow_free = info->shadow[free].req.id; info->shadow[free].req.id = 0x0fffffee; /* debug */ return free; } static void add_id_to_freelist(struct blkfront_info *info, unsigned long id) { info->shadow[id].req.id = info->shadow_free; info->shadow[id].request = 0; info->shadow_free = id; } static void blkif_restart_queue_callback(void *arg) { struct blkfront_info *info = (struct blkfront_info *)arg; schedule_work(&info->work); } /* * blkif_queue_request * * request block io * * id: for guest use only. * operation: BLKIF_OP_{READ,WRITE,PROBE} * buffer: buffer to read/write into. this should be a * virtual address in the guest os. */ static int blkif_queue_request(struct request *req) { struct blkfront_info *info = req->rq_disk->private_data; unsigned long buffer_mfn; struct blkif_request *ring_req; struct req_iterator iter; struct bio_vec *bvec; unsigned long id; unsigned int fsect, lsect; int ref; grant_ref_t gref_head; if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) return 1; if (gnttab_alloc_grant_references( BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) { gnttab_request_free_callback( &info->callback, blkif_restart_queue_callback, info, BLKIF_MAX_SEGMENTS_PER_REQUEST); return 1; } /* 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 = (unsigned long)req; ring_req->id = id; ring_req->sector_number = (blkif_sector_t)req->sector; ring_req->handle = info->handle; ring_req->operation = rq_data_dir(req) ? BLKIF_OP_WRITE : BLKIF_OP_READ; if (blk_barrier_rq(req)) ring_req->operation = BLKIF_OP_WRITE_BARRIER; ring_req->nr_segments = 0; rq_for_each_segment(bvec, req, iter) { BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST); buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page)); fsect = bvec->bv_offset >> 9; lsect = fsect + (bvec->bv_len >> 9) - 1; /* install a grant reference. */ ref = gnttab_claim_grant_reference(&gref_head); BUG_ON(ref == -ENOSPC); gnttab_grant_foreign_access_ref( ref, info->xbdev->otherend_id, buffer_mfn, rq_data_dir(req) ); info->shadow[id].frame[ring_req->nr_segments] = mfn_to_pfn(buffer_mfn); ring_req->seg[ring_req->nr_segments] = (struct blkif_request_segment) { .gref = ref, .first_sect = fsect, .last_sect = lsect }; ring_req->nr_segments++; } info->ring.req_prod_pvt++; /* Keep a private copy so we can reissue requests when recovering. */ info->shadow[id].req = *ring_req; 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 = elv_next_request(rq)) != NULL) { info = req->rq_disk->private_data; if (!blk_fs_request(req)) { end_request(req, 0); continue; } if (RING_FULL(&info->ring)) goto wait; pr_debug("do_blk_req %p: cmd %p, sec %lx, " "(%u/%li) buffer:%p [%s]\n", req, req->cmd, (unsigned long)req->sector, req->current_nr_sectors, req->nr_sectors, req->buffer, rq_data_dir(req) ? "write" : "read"); blkdev_dequeue_request(req); 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; rq = blk_init_queue(do_blkif_request, &blkif_io_lock); if (rq == NULL) return -1; elevator_init(rq, "noop"); /* Hard sector size and max sectors impersonate the equiv. hardware. */ blk_queue_hardsect_size(rq, sector_size); blk_queue_max_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_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); /* Make sure buffer addresses are sector-aligned. */ blk_queue_dma_alignment(rq, 511); gd->queue = rq; return 0; } static int xlvbd_barrier(struct blkfront_info *info) { int err; err = blk_queue_ordered(info->rq, info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE, NULL); if (err) return err; printk(KERN_INFO "blkfront: %s: barriers %s\n", info->gd->disk_name, info->feature_barrier ? "enabled" : "disabled"); return 0; } static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity, int vdevice, u16 vdisk_info, u16 sector_size, struct blkfront_info *info) { struct gendisk *gd; int nr_minors = 1; int err = -ENODEV; BUG_ON(info->gd != NULL); BUG_ON(info->rq != NULL); if ((minor % PARTS_PER_DISK) == 0) nr_minors = PARTS_PER_DISK; gd = alloc_disk(nr_minors); if (gd == NULL) goto out; if (nr_minors > 1) sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + minor / PARTS_PER_DISK); else sprintf(gd->disk_name, "%s%c%d", DEV_NAME, 'a' + minor / PARTS_PER_DISK, minor % PARTS_PER_DISK); 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 out; } info->rq = gd->queue; info->gd = gd; if (info->feature_barrier) xlvbd_barrier(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; out: return err; } 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(&blkif_io_lock); if (info->connected == BLKIF_STATE_CONNECTED) kick_pending_request_queues(info); spin_unlock_irq(&blkif_io_lock); } static void blkif_free(struct blkfront_info *info, int suspend) { /* Prevent new requests being issued until we fix things up. */ spin_lock_irq(&blkif_io_lock); info->connected = suspend ? BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; /* No more blkif_request(). */ if (info->rq) blk_stop_queue(info->rq); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); spin_unlock_irq(&blkif_io_lock); /* Flush gnttab callback work. Must be done with no locks held. */ flush_scheduled_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) { int i; for (i = 0; i < s->req.nr_segments; i++) gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL); } 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(&blkif_io_lock, flags); if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { spin_unlock_irqrestore(&blkif_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; int ret; bret = RING_GET_RESPONSE(&info->ring, i); id = bret->id; req = (struct request *)info->shadow[id].request; blkif_completion(&info->shadow[id]); add_id_to_freelist(info, id); error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; switch (bret->operation) { case BLKIF_OP_WRITE_BARRIER: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { printk(KERN_WARNING "blkfront: %s: write barrier op failed\n", info->gd->disk_name); error = -EOPNOTSUPP; info->feature_barrier = 0; xlvbd_barrier(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); ret = __blk_end_request(req, error, blk_rq_bytes(req)); BUG_ON(ret); 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(&blkif_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_KERNEL); if (!sring) { xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); return -ENOMEM; } SHARED_RING_INIT(sring); FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 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, IRQF_SAMPLE_RANDOM, "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_backend(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_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) { xenbus_dev_fatal(dev, err, "reading virtual-device"); return err; } info = kzalloc(sizeof(*info), GFP_KERNEL); if (!info) { xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); return -ENOMEM; } info->xbdev = dev; info->vdevice = vdevice; info->connected = BLKIF_STATE_DISCONNECTED; INIT_WORK(&info->work, blkif_restart_queue); for (i = 0; i < BLK_RING_SIZE; i++) info->shadow[i].req.id = i+1; info->shadow[BLK_RING_SIZE-1].req.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->dev.driver_data = info; err = talk_to_backend(dev, info); if (err) { kfree(info); dev->dev.driver_data = 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 = kmalloc(sizeof(info->shadow), GFP_KERNEL); if (!copy) return -ENOMEM; memcpy(copy, info->shadow, sizeof(info->shadow)); /* 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.id = i+1; info->shadow_free = info->ring.req_prod_pvt; info->shadow[BLK_RING_SIZE-1].req.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 == 0) 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->id = get_id_from_freelist(info); memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i])); /* Rewrite any grant references invalidated by susp/resume. */ for (j = 0; j < req->nr_segments; j++) gnttab_grant_foreign_access_ref( req->seg[j].gref, info->xbdev->otherend_id, pfn_to_mfn(info->shadow[req->id].frame[j]), rq_data_dir( (struct request *) info->shadow[req->id].request)); info->shadow[req->id].req = *req; info->ring.req_prod_pvt++; } kfree(copy); xenbus_switch_state(info->xbdev, XenbusStateConnected); spin_lock_irq(&blkif_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(&blkif_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->dev.driver_data; int err; dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); err = talk_to_backend(dev, info); if (info->connected == BLKIF_STATE_SUSPENDED && !err) err = blkif_recover(info); return err; } /* * 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; if ((info->connected == BLKIF_STATE_CONNECTED) || (info->connected == BLKIF_STATE_SUSPENDED) ) return; 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; } err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "feature-barrier", "%lu", &info->feature_barrier, NULL); if (err) info->feature_barrier = 0; err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice), sectors, info->vdevice, binfo, sector_size, info); 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(&blkif_io_lock); info->connected = BLKIF_STATE_CONNECTED; kick_pending_request_queues(info); spin_unlock_irq(&blkif_io_lock); add_disk(info->gd); } /** * Handle the change of state of the backend to Closing. We must delete our * device-layer structures now, to ensure that writes are flushed through to * the backend. Once is this done, we can switch to Closed in * acknowledgement. */ static void blkfront_closing(struct xenbus_device *dev) { struct blkfront_info *info = dev->dev.driver_data; unsigned long flags; dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename); if (info->rq == NULL) goto out; spin_lock_irqsave(&blkif_io_lock, flags); del_gendisk(info->gd); /* No more blkif_request(). */ blk_stop_queue(info->rq); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); spin_unlock_irqrestore(&blkif_io_lock, flags); /* Flush gnttab callback work. Must be done with no locks held. */ flush_scheduled_work(); blk_cleanup_queue(info->rq); info->rq = NULL; out: xenbus_frontend_closed(dev); } /** * Callback received when the backend's state changes. */ static void backend_changed(struct xenbus_device *dev, enum xenbus_state backend_state) { struct blkfront_info *info = dev->dev.driver_data; struct block_device *bd; dev_dbg(&dev->dev, "blkfront:backend_changed.\n"); switch (backend_state) { case XenbusStateInitialising: case XenbusStateInitWait: case XenbusStateInitialised: case XenbusStateUnknown: case XenbusStateClosed: break; case XenbusStateConnected: blkfront_connect(info); break; case XenbusStateClosing: bd = bdget(info->dev); if (bd == NULL) xenbus_dev_fatal(dev, -ENODEV, "bdget failed"); mutex_lock(&bd->bd_mutex); if (info->users > 0) xenbus_dev_error(dev, -EBUSY, "Device in use; refusing to close"); else blkfront_closing(dev); mutex_unlock(&bd->bd_mutex); bdput(bd); break; } } static int blkfront_remove(struct xenbus_device *dev) { struct blkfront_info *info = dev->dev.driver_data; dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename); blkif_free(info, 0); kfree(info); return 0; } static int blkif_open(struct inode *inode, struct file *filep) { struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; info->users++; return 0; } static int blkif_release(struct inode *inode, struct file *filep) { struct blkfront_info *info = inode->i_bdev->bd_disk->private_data; info->users--; if (info->users == 0) { /* Check whether we have been instructed to close. We will have ignored this request initially, as the device was still mounted. */ struct xenbus_device *dev = info->xbdev; enum xenbus_state state = xenbus_read_driver_state(dev->otherend); if (state == XenbusStateClosing) blkfront_closing(dev); } return 0; } static struct block_device_operations xlvbd_block_fops = { .owner = THIS_MODULE, .open = blkif_open, .release = blkif_release, }; static struct xenbus_device_id blkfront_ids[] = { { "vbd" }, { "" } }; static struct xenbus_driver blkfront = { .name = "vbd", .owner = THIS_MODULE, .ids = blkfront_ids, .probe = blkfront_probe, .remove = blkfront_remove, .resume = blkfront_resume, .otherend_changed = backend_changed, }; static int __init xlblk_init(void) { if (!is_running_on_xen()) 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; } return xenbus_register_frontend(&blkfront); } module_init(xlblk_init); static void xlblk_exit(void) { return xenbus_unregister_driver(&blkfront); } module_exit(xlblk_exit); MODULE_DESCRIPTION("Xen virtual block device frontend"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);