xen-blkfront.c 36.5 KB
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/*
 * 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>
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#include <linux/hdreg.h>
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#include <linux/cdrom.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/scatterlist.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
#include <xen/grant_table.h>
#include <xen/events.h>
#include <xen/page.h>
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#include <xen/platform_pci.h>
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#include <xen/interface/grant_table.h>
#include <xen/interface/io/blkif.h>
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#include <xen/interface/io/protocols.h>
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#include <asm/xen/hypervisor.h>

enum blkif_state {
	BLKIF_STATE_DISCONNECTED,
	BLKIF_STATE_CONNECTED,
	BLKIF_STATE_SUSPENDED,
};

struct blk_shadow {
	struct blkif_request req;
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	struct request *request;
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	unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
};

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static DEFINE_MUTEX(blkfront_mutex);
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static const struct block_device_operations xlvbd_block_fops;
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#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
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/*
 * 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
{
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	struct mutex mutex;
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	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;
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	struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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	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;
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	unsigned int feature_flush;
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	unsigned int flush_op;
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	unsigned int feature_discard;
	unsigned int discard_granularity;
	unsigned int discard_alignment;
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	int is_ready;
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};

static DEFINE_SPINLOCK(blkif_io_lock);

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static unsigned int nr_minors;
static unsigned long *minors;
static DEFINE_SPINLOCK(minor_lock);

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#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
	(BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
#define GRANT_INVALID_REF	0

#define PARTS_PER_DISK		16
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#define PARTS_PER_EXT_DISK      256
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#define BLKIF_MAJOR(dev) ((dev)>>8)
#define BLKIF_MINOR(dev) ((dev) & 0xff)

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#define EXT_SHIFT 28
#define EXTENDED (1<<EXT_SHIFT)
#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
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#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 (EMULATED_HD_DISK_MINOR_OFFSET + (4 * 16))
#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_HD_DISK_NAME_OFFSET + 4)
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#define DEV_NAME	"xvd"	/* name in /dev */
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static int get_id_from_freelist(struct blkfront_info *info)
{
	unsigned long free = info->shadow_free;
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	BUG_ON(free >= BLK_RING_SIZE);
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	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;
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	info->shadow[id].request = NULL;
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	info->shadow_free = id;
}

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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 = kzalloc(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) {
		for (; minor < end; ++minor)
			__set_bit(minor, minors);
		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);
	for (; minor < end; ++minor)
		__clear_bit(minor, minors);
	spin_unlock(&minor_lock);
}

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static void blkif_restart_queue_callback(void *arg)
{
	struct blkfront_info *info = (struct blkfront_info *)arg;
	schedule_work(&info->work);
}

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static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
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{
	/* 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;
}

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static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
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		       unsigned command, unsigned long argument)
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{
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	struct blkfront_info *info = bdev->bd_disk->private_data;
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	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;
}

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/*
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 * Generate a Xen blkfront IO request from a blk layer request.  Reads
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 * and writes are handled as expected.
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 *
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 * @req: a request struct
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 */
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;
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	int i, ref;
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	grant_ref_t gref_head;
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	struct scatterlist *sg;
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	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);
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	info->shadow[id].request = req;
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	ring_req->id = id;
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	ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
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	ring_req->handle = info->handle;

	ring_req->operation = rq_data_dir(req) ?
		BLKIF_OP_WRITE : BLKIF_OP_READ;
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	if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
		/*
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		 * Ideally we can do an unordered flush-to-disk. In case the
		 * backend onlysupports barriers, use that. A barrier request
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		 * 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.)
		 */
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		ring_req->operation = info->flush_op;
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	}
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	if (unlikely(req->cmd_flags & REQ_DISCARD)) {
		/* id, sector_number and handle are set above. */
		ring_req->operation = BLKIF_OP_DISCARD;
		ring_req->nr_segments = 0;
		ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
	} else {
		ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
		BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
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		for_each_sg(info->sg, sg, ring_req->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);
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			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 };
		}
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	}

	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
 */
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static void do_blkif_request(struct request_queue *rq)
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{
	struct blkfront_info *info = NULL;
	struct request *req;
	int queued;

	pr_debug("Entered do_blkif_request\n");

	queued = 0;

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	while ((req = blk_peek_request(rq)) != NULL) {
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		info = req->rq_disk->private_data;

		if (RING_FULL(&info->ring))
			goto wait;

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		blk_start_request(req);
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		if ((req->cmd_type != REQ_TYPE_FS) ||
		    ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
		    !info->flush_op)) {
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			__blk_end_request_all(req, -EIO);
			continue;
		}

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		pr_debug("do_blk_req %p: cmd %p, sec %lx, "
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			 "(%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");
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		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)
{
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	struct request_queue *rq;
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	struct blkfront_info *info = gd->private_data;
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	rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
	if (rq == NULL)
		return -1;

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	queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
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	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;
	}

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	/* Hard sector size and max sectors impersonate the equiv. hardware. */
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	blk_queue_logical_block_size(rq, sector_size);
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	blk_queue_max_hw_sectors(rq, 512);
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	/* 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. */
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	blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
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	/* Make sure buffer addresses are sector-aligned. */
	blk_queue_dma_alignment(rq, 511);

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	/* Make sure we don't use bounce buffers. */
	blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);

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	gd->queue = rq;

	return 0;
}


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static void xlvbd_flush(struct blkfront_info *info)
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{
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	blk_queue_flush(info->rq, info->feature_flush);
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	printk(KERN_INFO "blkfront: %s: %s: %s\n",
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	       info->gd->disk_name,
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	       info->flush_op == BLKIF_OP_WRITE_BARRIER ?
		"barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
		"flush diskcache" : "barrier or flush"),
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	       info->feature_flush ? "enabled" : "disabled");
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}

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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;
}
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static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
			       struct blkfront_info *info,
			       u16 vdisk_info, u16 sector_size)
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{
	struct gendisk *gd;
	int nr_minors = 1;
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	int err;
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	unsigned int offset;
	int minor;
	int nr_parts;
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	BUG_ON(info->gd != NULL);
	BUG_ON(info->rq != NULL);

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	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)) {
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		err = xen_translate_vdev(info->vdevice, &minor, &offset);
		if (err)
			return err;		
 		nr_parts = PARTS_PER_DISK;
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	} else {
		minor = BLKIF_MINOR_EXT(info->vdevice);
		nr_parts = PARTS_PER_EXT_DISK;
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		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);
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	}
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	err = -ENODEV;
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	if ((minor % nr_parts) == 0)
		nr_minors = nr_parts;
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	err = xlbd_reserve_minors(minor, nr_minors);
	if (err)
		goto out;
	err = -ENODEV;

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	gd = alloc_disk(nr_minors);
	if (gd == NULL)
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		goto release;
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	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));
	}
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	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);
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		goto release;
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	}

	info->rq = gd->queue;
	info->gd = gd;

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	xlvbd_flush(info);
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	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;

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 release:
	xlbd_release_minors(minor, nr_minors);
619 620 621 622
 out:
	return err;
}

D
Daniel Stodden 已提交
623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640
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(&blkif_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(&blkif_io_lock, flags);

	/* Flush gnttab callback work. Must be done with no locks held. */
T
Tejun Heo 已提交
641
	flush_work_sync(&info->work);
D
Daniel Stodden 已提交
642 643 644 645 646 647 648 649 650 651 652 653 654 655

	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;
}

656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689
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. */
T
Tejun Heo 已提交
690
	flush_work_sync(&info->work);
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708

	/* 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++)
709
		gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
710 711 712 713 714 715 716 717 718
}

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;
719
	int error;
720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736

	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;

		bret = RING_GET_RESPONSE(&info->ring, i);
		id   = bret->id;
737
		req  = info->shadow[id].request;
738 739 740 741 742

		blkif_completion(&info->shadow[id]);

		add_id_to_freelist(info, id);

743
		error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
744
		switch (bret->operation) {
745 746 747 748 749 750 751 752 753 754 755
		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;
				queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
			}
			__blk_end_request_all(req, error);
			break;
756
		case BLKIF_OP_FLUSH_DISKCACHE:
757 758
		case BLKIF_OP_WRITE_BARRIER:
			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
759 760 761
				printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
				       info->flush_op == BLKIF_OP_WRITE_BARRIER ?
				       "barrier" :  "flush disk cache",
762
				       info->gd->disk_name);
763
				error = -EOPNOTSUPP;
764 765 766
			}
			if (unlikely(bret->status == BLKIF_RSP_ERROR &&
				     info->shadow[id].req.nr_segments == 0)) {
767 768 769
				printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
				       info->flush_op == BLKIF_OP_WRITE_BARRIER ?
				       "barrier" :  "flush disk cache",
770 771 772 773 774 775
				       info->gd->disk_name);
				error = -EOPNOTSUPP;
			}
			if (unlikely(error)) {
				if (error == -EOPNOTSUPP)
					error = 0;
776
				info->feature_flush = 0;
777
				info->flush_op = 0;
778
				xlvbd_flush(info);
779 780 781 782 783 784 785 786
			}
			/* 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);

787
			__blk_end_request_all(req, error);
788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819
			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;

820
	sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
821 822 823 824 825 826
	if (!sring) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
		return -ENOMEM;
	}
	SHARED_RING_INIT(sring);
	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
827 828

	sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859

	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. */
860
static int talk_to_blkback(struct xenbus_device *dev,
861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890
			   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;
	}
891 892 893 894 895 896
	err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
			    XEN_IO_PROTO_ABI_NATIVE);
	if (err) {
		message = "writing protocol";
		goto abort_transaction;
	}
897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935

	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) {
936 937 938 939 940 941 942
		/* 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;
		}
943 944
	}

945 946 947 948
	if (xen_hvm_domain()) {
		char *type;
		int len;
		/* no unplug has been done: do not hook devices != xen vbds */
949
		if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969
			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);
970 971
			return -ENODEV;
		}
972
		kfree(type);
973
	}
974 975 976 977 978 979
	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
		return -ENOMEM;
	}

980
	mutex_init(&info->mutex);
981 982 983 984 985 986 987 988 989 990 991
	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);
992
	dev_set_drvdata(&dev->dev, info);
993

994
	err = talk_to_blkback(dev, info);
995 996
	if (err) {
		kfree(info);
997
		dev_set_drvdata(&dev->dev, NULL);
998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012
		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. */
1013 1014
	copy = kmalloc(sizeof(info->shadow),
		       GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
	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? */
1029
		if (!copy[i].request)
1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042
			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], &copy[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(
1043
				req->u.rw.seg[j].gref,
1044 1045
				info->xbdev->otherend_id,
				pfn_to_mfn(info->shadow[req->id].frame[j]),
1046
				rq_data_dir(info->shadow[req->id].request));
1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079
		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)
{
1080
	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1081 1082 1083 1084 1085 1086
	int err;

	dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);

	blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);

1087
	err = talk_to_blkback(dev, info);
1088 1089 1090 1091 1092 1093
	if (info->connected == BLKIF_STATE_SUSPENDED && !err)
		err = blkif_recover(info);

	return err;
}

1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118
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);

1119
	if (bdev->bd_openers) {
1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130
		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);
}
1131

1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
static void blkfront_setup_discard(struct blkfront_info *info)
{
	int err;
	char *type;
	unsigned int discard_granularity;
	unsigned int discard_alignment;

	type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
	if (IS_ERR(type))
		return;

	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;
		}
	} else if (strncmp(type, "file", 4) == 0)
		info->feature_discard = 1;

	kfree(type);
}

1159 1160 1161 1162 1163 1164 1165 1166 1167 1168
/*
 * 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;
1169
	int barrier, flush, discard;
1170

1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
	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", &sectors);
		if (XENBUS_EXIST_ERR(err))
			return;
		printk(KERN_INFO "Setting capacity to %Lu\n",
		       sectors);
		set_capacity(info->gd, sectors);
1184
		revalidate_disk(info->gd);
1185 1186 1187

		/* fall through */
	case BLKIF_STATE_SUSPENDED:
1188 1189
		return;

1190 1191
	default:
		break;
1192
	}
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208

	dev_dbg(&info->xbdev->dev, "%s:%s.\n",
		__func__, info->xbdev->otherend);

	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
			    "sectors", "%llu", &sectors,
			    "info", "%u", &binfo,
			    "sector-size", "%lu", &sector_size,
			    NULL);
	if (err) {
		xenbus_dev_fatal(info->xbdev, err,
				 "reading backend fields at %s",
				 info->xbdev->otherend);
		return;
	}

1209 1210 1211
	info->feature_flush = 0;
	info->flush_op = 0;

1212
	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1213
			    "feature-barrier", "%d", &barrier,
1214
			    NULL);
1215 1216 1217 1218

	/*
	 * If there's no "feature-barrier" defined, then it means
	 * we're dealing with a very old backend which writes
1219
	 * synchronously; nothing to do.
1220
	 *
T
Tejun Heo 已提交
1221
	 * If there are barriers, then we use flush.
1222
	 */
1223
	if (!err && barrier) {
1224
		info->feature_flush = REQ_FLUSH | REQ_FUA;
1225 1226 1227 1228 1229 1230 1231 1232 1233
		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);
1234

1235 1236 1237 1238
	if (!err && flush) {
		info->feature_flush = REQ_FLUSH;
		info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
	}
1239 1240 1241 1242 1243 1244 1245 1246

	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
			    "feature-discard", "%d", &discard,
			    NULL);

	if (!err && discard)
		blkfront_setup_discard(info);

1247
	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262
	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);
1263 1264

	info->is_ready = 1;
1265 1266 1267 1268 1269
}

/**
 * Callback received when the backend's state changes.
 */
1270
static void blkback_changed(struct xenbus_device *dev,
1271 1272
			    enum xenbus_state backend_state)
{
1273
	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1274

1275
	dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1276 1277 1278 1279 1280

	switch (backend_state) {
	case XenbusStateInitialising:
	case XenbusStateInitWait:
	case XenbusStateInitialised:
1281 1282
	case XenbusStateReconfiguring:
	case XenbusStateReconfigured:
1283 1284 1285 1286 1287 1288 1289 1290 1291
	case XenbusStateUnknown:
	case XenbusStateClosed:
		break;

	case XenbusStateConnected:
		blkfront_connect(info);
		break;

	case XenbusStateClosing:
1292
		blkfront_closing(info);
1293 1294 1295 1296
		break;
	}
}

1297
static int blkfront_remove(struct xenbus_device *xbdev)
1298
{
1299 1300 1301
	struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
	struct block_device *bdev = NULL;
	struct gendisk *disk;
1302

1303
	dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1304 1305 1306

	blkif_free(info, 0);

1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
	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;

1330 1331 1332 1333
	dev_warn(disk_to_dev(disk),
		 "%s was hot-unplugged, %d stale handles\n",
		 xbdev->nodename, bdev->bd_openers);

1334
	if (info && !bdev->bd_openers) {
1335 1336
		xlvbd_release_gendisk(info);
		disk->private_data = NULL;
1337
		kfree(info);
1338 1339 1340 1341
	}

	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1342 1343 1344 1345

	return 0;
}

1346 1347
static int blkfront_is_ready(struct xenbus_device *dev)
{
1348
	struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1349

1350
	return info->is_ready && info->xbdev;
1351 1352
}

A
Al Viro 已提交
1353
static int blkif_open(struct block_device *bdev, fmode_t mode)
1354
{
1355 1356 1357
	struct gendisk *disk = bdev->bd_disk;
	struct blkfront_info *info;
	int err = 0;
1358

1359
	mutex_lock(&blkfront_mutex);
1360

1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376
	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:
1377
	mutex_unlock(&blkfront_mutex);
1378
	return err;
1379 1380
}

A
Al Viro 已提交
1381
static int blkif_release(struct gendisk *disk, fmode_t mode)
1382
{
A
Al Viro 已提交
1383
	struct blkfront_info *info = disk->private_data;
1384 1385 1386
	struct block_device *bdev;
	struct xenbus_device *xbdev;

1387
	mutex_lock(&blkfront_mutex);
1388 1389 1390 1391

	bdev = bdget_disk(disk, 0);
	bdput(bdev);

1392 1393 1394
	if (bdev->bd_openers)
		goto out;

1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
	/*
	 * 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 */
1405
		dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1406 1407 1408 1409 1410 1411 1412 1413
		xlvbd_release_gendisk(info);
		xenbus_frontend_closed(info->xbdev);
 	}

	mutex_unlock(&info->mutex);

	if (!xbdev) {
		/* sudden device removal */
1414
		dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1415 1416 1417
		xlvbd_release_gendisk(info);
		disk->private_data = NULL;
		kfree(info);
1418
	}
1419

J
Jens Axboe 已提交
1420
out:
1421
	mutex_unlock(&blkfront_mutex);
1422 1423 1424
	return 0;
}

1425
static const struct block_device_operations xlvbd_block_fops =
1426 1427
{
	.owner = THIS_MODULE,
A
Al Viro 已提交
1428 1429
	.open = blkif_open,
	.release = blkif_release,
1430
	.getgeo = blkif_getgeo,
1431
	.ioctl = blkif_ioctl,
1432 1433 1434
};


1435
static const struct xenbus_device_id blkfront_ids[] = {
1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446
	{ "vbd" },
	{ "" }
};

static struct xenbus_driver blkfront = {
	.name = "vbd",
	.owner = THIS_MODULE,
	.ids = blkfront_ids,
	.probe = blkfront_probe,
	.remove = blkfront_remove,
	.resume = blkfront_resume,
1447
	.otherend_changed = blkback_changed,
1448
	.is_ready = blkfront_is_ready,
1449 1450 1451 1452
};

static int __init xlblk_init(void)
{
1453
	if (!xen_domain())
1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466
		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);


1467
static void __exit xlblk_exit(void)
1468 1469 1470 1471 1472 1473 1474 1475
{
	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);
1476
MODULE_ALIAS("xen:vbd");
1477
MODULE_ALIAS("xenblk");