diff options
Diffstat (limited to 'drivers/block/xen-blkfront.c')
| -rw-r--r-- | drivers/block/xen-blkfront.c | 1507 |
1 files changed, 1507 insertions, 0 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c new file mode 100644 index 00000000..4e86393a --- /dev/null +++ b/drivers/block/xen-blkfront.c @@ -0,0 +1,1507 @@ +/* + * 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/hdreg.h> +#include <linux/cdrom.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/mutex.h> +#include <linux/scatterlist.h> +#include <linux/bitmap.h> + +#include <xen/xen.h> +#include <xen/xenbus.h> +#include <xen/grant_table.h> +#include <xen/events.h> +#include <xen/page.h> +#include <xen/platform_pci.h> + +#include <xen/interface/grant_table.h> +#include <xen/interface/io/blkif.h> +#include <xen/interface/io/protocols.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; + struct request *request; + unsigned long frame[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]; + 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; + 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<<EXT_SHIFT) +#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) +#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) +#define EMULATED_HD_DISK_MINOR_OFFSET (0) +#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) +#define EMULATED_SD_DISK_MINOR_OFFSET (0) +#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) + +#define DEV_NAME "xvd" /* name in /dev */ + +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.u.rw.id; + info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ + return free; +} + +static void add_id_to_freelist(struct blkfront_info *info, + unsigned long id) +{ + info->shadow[id].req.u.rw.id = info->shadow_free; + info->shadow[id].request = NULL; + info->shadow_free = id; +} + +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; + unsigned long buffer_mfn; + struct blkif_request *ring_req; + unsigned long id; + unsigned int fsect, lsect; + int i, ref; + grant_ref_t gref_head; + struct scatterlist *sg; + + 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 = 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) { + buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg))); + fsect = sg->offset >> 9; + lsect = fsect + (sg->length >> 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[i] = mfn_to_pfn(buffer_mfn); + 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; + + 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\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"); +} + +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 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; + + 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); + } + err = -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; + + if (nr_minors > 1) { + if (offset < 26) + sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset); + else + sprintf(gd->disk_name, "%s%c%c", DEV_NAME, + 'a' + ((offset / 26)-1), 'a' + (offset % 26)); + } else { + if (offset < 26) + sprintf(gd->disk_name, "%s%c%d", DEV_NAME, + 'a' + offset, + minor & (nr_parts - 1)); + else + sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME, + 'a' + ((offset / 26) - 1), + 'a' + (offset % 26), + 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_sync(&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) +{ + /* 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); + /* 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_sync(&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) +{ + int i; + /* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place + * flag. */ + for (i = 0; i < s->req.u.rw.nr_segments; i++) + gnttab_end_foreign_access(s->req.u.rw.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(&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; + req = info->shadow[id].request; + + if (bret->operation != BLKIF_OP_DISCARD) + 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_DISCARD: + if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { + struct request_queue *rq = info->rq; + printk(KERN_WARNING "blkfront: %s: discard op failed\n", + info->gd->disk_name); + 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: write %s op failed\n", + info->flush_op == BLKIF_OP_WRITE_BARRIER ? + "barrier" : "flush disk cache", + info->gd->disk_name); + error = -EOPNOTSUPP; + } + if (unlikely(bret->status == BLKIF_RSP_ERROR && + info->shadow[id].req.u.rw.nr_segments == 0)) { + printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n", + info->flush_op == BLKIF_OP_WRITE_BARRIER ? + "barrier" : "flush disk cache", + info->gd->disk_name); + 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); + + 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_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_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; + 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 = kmalloc(sizeof(info->shadow), + GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); + 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.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(info->shadow[req->u.rw.id].frame[j]), + rq_data_dir(info->shadow[req->u.rw.id].request)); + } + 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; + + 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 = 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 int 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); + return 0; +} + +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) +{ + return xenbus_unregister_driver(&blkfront_driver); +} +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"); |