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WSL2-Linux-Kernel/drivers/block/xen-blkfront.c

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38 KiB
C
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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>
#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 char *encode_disk_name(char *ptr, unsigned int n)
{
if (n >= 26)
ptr = encode_disk_name(ptr, n / 26 - 1);
*ptr = 'a' + n % 26;
return ptr + 1;
}
static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
struct blkfront_info *info,
u16 vdisk_info, u16 sector_size)
{
struct gendisk *gd;
int nr_minors = 1;
int err;
unsigned int offset;
int minor;
int nr_parts;
char *ptr;
BUG_ON(info->gd != NULL);
BUG_ON(info->rq != NULL);
if ((info->vdevice>>EXT_SHIFT) > 1) {
/* this is above the extended range; something is wrong */
printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
return -ENODEV;
}
if (!VDEV_IS_EXTENDED(info->vdevice)) {
err = xen_translate_vdev(info->vdevice, &minor, &offset);
if (err)
return err;
nr_parts = PARTS_PER_DISK;
} else {
minor = BLKIF_MINOR_EXT(info->vdevice);
nr_parts = PARTS_PER_EXT_DISK;
offset = minor / nr_parts;
if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
"emulated IDE disks,\n\t choose an xvd device name"
"from xvde on\n", info->vdevice);
}
if (minor >> MINORBITS) {
pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
info->vdevice, minor);
return -ENODEV;
}
if ((minor % nr_parts) == 0)
nr_minors = nr_parts;
err = xlbd_reserve_minors(minor, nr_minors);
if (err)
goto out;
err = -ENODEV;
gd = alloc_disk(nr_minors);
if (gd == NULL)
goto release;
strcpy(gd->disk_name, DEV_NAME);
ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
if (nr_minors > 1)
*ptr = 0;
else
snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
"%d", minor & (nr_parts - 1));
gd->major = XENVBD_MAJOR;
gd->first_minor = minor;
gd->fops = &xlvbd_block_fops;
gd->private_data = info;
gd->driverfs_dev = &(info->xbdev->dev);
set_capacity(gd, capacity);
if (xlvbd_init_blk_queue(gd, sector_size)) {
del_gendisk(gd);
goto release;
}
info->rq = gd->queue;
info->gd = gd;
xlvbd_flush(info);
if (vdisk_info & VDISK_READONLY)
set_disk_ro(gd, 1);
if (vdisk_info & VDISK_REMOVABLE)
gd->flags |= GENHD_FL_REMOVABLE;
if (vdisk_info & VDISK_CDROM)
gd->flags |= GENHD_FL_CD;
return 0;
release:
xlbd_release_minors(minor, nr_minors);
out:
return err;
}
static void xlvbd_release_gendisk(struct blkfront_info *info)
{
unsigned int minor, nr_minors;
unsigned long flags;
if (info->rq == NULL)
return;
spin_lock_irqsave(&info->io_lock, flags);
/* No more blkif_request(). */
blk_stop_queue(info->rq);
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&info->callback);
spin_unlock_irqrestore(&info->io_lock, flags);
/* Flush gnttab callback work. Must be done with no locks held. */
flush_work_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], &copy[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", &sectors);
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", &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;
}
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)
{
xenbus_unregister_driver(&blkfront_driver);
unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
kfree(minors);
}
module_exit(xlblk_exit);
MODULE_DESCRIPTION("Xen virtual block device frontend");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
MODULE_ALIAS("xen:vbd");
MODULE_ALIAS("xenblk");
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