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linuxdebug/drivers/block/xen-blkfront.c

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null pointer error
2024-07-16 15:50:57 +02:00
/*
* 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/blk-mq.h>
#include <linux/hdreg.h>
#include <linux/cdrom.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/scatterlist.h>
#include <linux/bitmap.h>
#include <linux/list.h>
#include <linux/workqueue.h>
#include <linux/sched/mm.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>
/*
* The minimal size of segment supported by the block framework is PAGE_SIZE.
* When Linux is using a different page size than Xen, it may not be possible
* to put all the data in a single segment.
* This can happen when the backend doesn't support indirect descriptor and
* therefore the maximum amount of data that a request can carry is
* BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
*
* Note that we only support one extra request. So the Linux page size
* should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
* 88KB.
*/
#define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
enum blkif_state {
BLKIF_STATE_DISCONNECTED,
BLKIF_STATE_CONNECTED,
BLKIF_STATE_SUSPENDED,
BLKIF_STATE_ERROR,
};
struct grant {
grant_ref_t gref;
struct page *page;
struct list_head node;
};
enum blk_req_status {
REQ_PROCESSING,
REQ_WAITING,
REQ_DONE,
REQ_ERROR,
REQ_EOPNOTSUPP,
};
struct blk_shadow {
struct blkif_request req;
struct request *request;
struct grant **grants_used;
struct grant **indirect_grants;
struct scatterlist *sg;
unsigned int num_sg;
enum blk_req_status status;
#define NO_ASSOCIATED_ID ~0UL
/*
* Id of the sibling if we ever need 2 requests when handling a
* block I/O request
*/
unsigned long associated_id;
};
struct blkif_req {
blk_status_t error;
};
static inline struct blkif_req *blkif_req(struct request *rq)
{
return blk_mq_rq_to_pdu(rq);
}
static DEFINE_MUTEX(blkfront_mutex);
static const struct block_device_operations xlvbd_block_fops;
static struct delayed_work blkfront_work;
static LIST_HEAD(info_list);
/*
* Maximum number of segments in indirect requests, the actual value used by
* the frontend driver is the minimum of this value and the value provided
* by the backend driver.
*/
static unsigned int xen_blkif_max_segments = 32;
module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
MODULE_PARM_DESC(max_indirect_segments,
"Maximum amount of segments in indirect requests (default is 32)");
static unsigned int xen_blkif_max_queues = 4;
module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
/*
* Maximum order of pages to be used for the shared ring between front and
* backend, 4KB page granularity is used.
*/
static unsigned int xen_blkif_max_ring_order;
module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
static bool __read_mostly xen_blkif_trusted = true;
module_param_named(trusted, xen_blkif_trusted, bool, 0644);
MODULE_PARM_DESC(trusted, "Is the backend trusted");
#define BLK_RING_SIZE(info) \
__CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
/*
* ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
* characters are enough. Define to 20 to keep consistent with backend.
*/
#define RINGREF_NAME_LEN (20)
/*
* queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
*/
#define QUEUE_NAME_LEN (17)
/*
* Per-ring info.
* Every blkfront device can associate with one or more blkfront_ring_info,
* depending on how many hardware queues/rings to be used.
*/
struct blkfront_ring_info {
/* Lock to protect data in every ring buffer. */
spinlock_t ring_lock;
struct blkif_front_ring ring;
unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
unsigned int evtchn, irq;
struct work_struct work;
struct gnttab_free_callback callback;
struct list_head indirect_pages;
struct list_head grants;
unsigned int persistent_gnts_c;
unsigned long shadow_free;
struct blkfront_info *dev_info;
struct blk_shadow shadow[];
};
/*
* We have one of these per vbd, whether ide, scsi or 'other'. They
* hang in private_data off the gendisk structure. We may end up
* putting all kinds of interesting stuff here :-)
*/
struct blkfront_info
{
struct mutex mutex;
struct xenbus_device *xbdev;
struct gendisk *gd;
u16 sector_size;
unsigned int physical_sector_size;
unsigned long vdisk_info;
int vdevice;
blkif_vdev_t handle;
enum blkif_state connected;
/* Number of pages per ring buffer. */
unsigned int nr_ring_pages;
struct request_queue *rq;
unsigned int feature_flush:1;
unsigned int feature_fua:1;
unsigned int feature_discard:1;
unsigned int feature_secdiscard:1;
/* Connect-time cached feature_persistent parameter */
unsigned int feature_persistent_parm:1;
/* Persistent grants feature negotiation result */
unsigned int feature_persistent:1;
unsigned int bounce:1;
unsigned int discard_granularity;
unsigned int discard_alignment;
/* Number of 4KB segments handled */
unsigned int max_indirect_segments;
int is_ready;
struct blk_mq_tag_set tag_set;
struct blkfront_ring_info *rinfo;
unsigned int nr_rings;
unsigned int rinfo_size;
/* Save uncomplete reqs and bios for migration. */
struct list_head requests;
struct bio_list bio_list;
struct list_head info_list;
};
static unsigned int nr_minors;
static unsigned long *minors;
static DEFINE_SPINLOCK(minor_lock);
#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 */
/*
* Grants are always the same size as a Xen page (i.e 4KB).
* A physical segment is always the same size as a Linux page.
* Number of grants per physical segment
*/
#define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
#define GRANTS_PER_INDIRECT_FRAME \
(XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
#define INDIRECT_GREFS(_grants) \
DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
static void blkfront_gather_backend_features(struct blkfront_info *info);
static int negotiate_mq(struct blkfront_info *info);
#define for_each_rinfo(info, ptr, idx) \
for ((ptr) = (info)->rinfo, (idx) = 0; \
(idx) < (info)->nr_rings; \
(idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
static inline struct blkfront_ring_info *
get_rinfo(const struct blkfront_info *info, unsigned int i)
{
BUG_ON(i >= info->nr_rings);
return (void *)info->rinfo + i * info->rinfo_size;
}
static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
{
unsigned long free = rinfo->shadow_free;
BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
return free;
}
static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
unsigned long id)
{
if (rinfo->shadow[id].req.u.rw.id != id)
return -EINVAL;
if (rinfo->shadow[id].request == NULL)
return -EINVAL;
rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free;
rinfo->shadow[id].request = NULL;
rinfo->shadow_free = id;
return 0;
}
static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
{
struct blkfront_info *info = rinfo->dev_info;
struct page *granted_page;
struct grant *gnt_list_entry, *n;
int i = 0;
while (i < num) {
gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
if (!gnt_list_entry)
goto out_of_memory;
if (info->bounce) {
granted_page = alloc_page(GFP_NOIO | __GFP_ZERO);
if (!granted_page) {
kfree(gnt_list_entry);
goto out_of_memory;
}
gnt_list_entry->page = granted_page;
}
gnt_list_entry->gref = INVALID_GRANT_REF;
list_add(&gnt_list_entry->node, &rinfo->grants);
i++;
}
return 0;
out_of_memory:
list_for_each_entry_safe(gnt_list_entry, n,
&rinfo->grants, node) {
list_del(&gnt_list_entry->node);
if (info->bounce)
__free_page(gnt_list_entry->page);
kfree(gnt_list_entry);
i--;
}
BUG_ON(i != 0);
return -ENOMEM;
}
static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry;
BUG_ON(list_empty(&rinfo->grants));
gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
node);
list_del(&gnt_list_entry->node);
if (gnt_list_entry->gref != INVALID_GRANT_REF)
rinfo->persistent_gnts_c--;
return gnt_list_entry;
}
static inline void grant_foreign_access(const struct grant *gnt_list_entry,
const struct blkfront_info *info)
{
gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
info->xbdev->otherend_id,
gnt_list_entry->page,
0);
}
static struct grant *get_grant(grant_ref_t *gref_head,
unsigned long gfn,
struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry = get_free_grant(rinfo);
struct blkfront_info *info = rinfo->dev_info;
if (gnt_list_entry->gref != INVALID_GRANT_REF)
return gnt_list_entry;
/* Assign a gref to this page */
gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
BUG_ON(gnt_list_entry->gref == -ENOSPC);
if (info->bounce)
grant_foreign_access(gnt_list_entry, info);
else {
/* Grant access to the GFN passed by the caller */
gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
info->xbdev->otherend_id,
gfn, 0);
}
return gnt_list_entry;
}
static struct grant *get_indirect_grant(grant_ref_t *gref_head,
struct blkfront_ring_info *rinfo)
{
struct grant *gnt_list_entry = get_free_grant(rinfo);
struct blkfront_info *info = rinfo->dev_info;
if (gnt_list_entry->gref != INVALID_GRANT_REF)
return gnt_list_entry;
/* Assign a gref to this page */
gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
BUG_ON(gnt_list_entry->gref == -ENOSPC);
if (!info->bounce) {
struct page *indirect_page;
/* Fetch a pre-allocated page to use for indirect grefs */
BUG_ON(list_empty(&rinfo->indirect_pages));
indirect_page = list_first_entry(&rinfo->indirect_pages,
struct page, lru);
list_del(&indirect_page->lru);
gnt_list_entry->page = indirect_page;
}
grant_foreign_access(gnt_list_entry, info);
return gnt_list_entry;
}
static const char *op_name(int op)
{
static const char *const names[] = {
[BLKIF_OP_READ] = "read",
[BLKIF_OP_WRITE] = "write",
[BLKIF_OP_WRITE_BARRIER] = "barrier",
[BLKIF_OP_FLUSH_DISKCACHE] = "flush",
[BLKIF_OP_DISCARD] = "discard" };
if (op < 0 || op >= ARRAY_SIZE(names))
return "unknown";
if (!names[op])
return "reserved";
return names[op];
}
static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
{
unsigned int end = minor + nr;
int rc;
if (end > nr_minors) {
unsigned long *bitmap, *old;
bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
GFP_KERNEL);
if (bitmap == NULL)
return -ENOMEM;
spin_lock(&minor_lock);
if (end > nr_minors) {
old = minors;
memcpy(bitmap, minors,
BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
minors = bitmap;
nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
} else
old = bitmap;
spin_unlock(&minor_lock);
kfree(old);
}
spin_lock(&minor_lock);
if (find_next_bit(minors, end, minor) >= end) {
bitmap_set(minors, minor, nr);
rc = 0;
} else
rc = -EBUSY;
spin_unlock(&minor_lock);
return rc;
}
static void xlbd_release_minors(unsigned int minor, unsigned int nr)
{
unsigned int end = minor + nr;
BUG_ON(end > nr_minors);
spin_lock(&minor_lock);
bitmap_clear(minors, minor, nr);
spin_unlock(&minor_lock);
}
static void blkif_restart_queue_callback(void *arg)
{
struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
schedule_work(&rinfo->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;
switch (command) {
case CDROMMULTISESSION:
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:
if (!(info->vdisk_info & VDISK_CDROM))
return -EINVAL;
return 0;
default:
return -EINVAL;
}
}
static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
struct request *req,
struct blkif_request **ring_req)
{
unsigned long id;
*ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
rinfo->ring.req_prod_pvt++;
id = get_id_from_freelist(rinfo);
rinfo->shadow[id].request = req;
rinfo->shadow[id].status = REQ_PROCESSING;
rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
rinfo->shadow[id].req.u.rw.id = id;
return id;
}
static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
{
struct blkfront_info *info = rinfo->dev_info;
struct blkif_request *ring_req, *final_ring_req;
unsigned long id;
/* Fill out a communications ring structure. */
id = blkif_ring_get_request(rinfo, req, &final_ring_req);
ring_req = &rinfo->shadow[id].req;
ring_req->operation = BLKIF_OP_DISCARD;
ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
ring_req->u.discard.id = id;
ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
else
ring_req->u.discard.flag = 0;
/* Copy the request to the ring page. */
*final_ring_req = *ring_req;
rinfo->shadow[id].status = REQ_WAITING;
return 0;
}
struct setup_rw_req {
unsigned int grant_idx;
struct blkif_request_segment *segments;
struct blkfront_ring_info *rinfo;
struct blkif_request *ring_req;
grant_ref_t gref_head;
unsigned int id;
/* Only used when persistent grant is used and it's a write request */
bool need_copy;
unsigned int bvec_off;
char *bvec_data;
bool require_extra_req;
struct blkif_request *extra_ring_req;
};
static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
unsigned int len, void *data)
{
struct setup_rw_req *setup = data;
int n, ref;
struct grant *gnt_list_entry;
unsigned int fsect, lsect;
/* Convenient aliases */
unsigned int grant_idx = setup->grant_idx;
struct blkif_request *ring_req = setup->ring_req;
struct blkfront_ring_info *rinfo = setup->rinfo;
/*
* We always use the shadow of the first request to store the list
* of grant associated to the block I/O request. This made the
* completion more easy to handle even if the block I/O request is
* split.
*/
struct blk_shadow *shadow = &rinfo->shadow[setup->id];
if (unlikely(setup->require_extra_req &&
grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
/*
* We are using the second request, setup grant_idx
* to be the index of the segment array.
*/
grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
ring_req = setup->extra_ring_req;
}
if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
(grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
if (setup->segments)
kunmap_atomic(setup->segments);
n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
shadow->indirect_grants[n] = gnt_list_entry;
setup->segments = kmap_atomic(gnt_list_entry->page);
ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
}
gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
ref = gnt_list_entry->gref;
/*
* All the grants are stored in the shadow of the first
* request. Therefore we have to use the global index.
*/
shadow->grants_used[setup->grant_idx] = gnt_list_entry;
if (setup->need_copy) {
void *shared_data;
shared_data = kmap_atomic(gnt_list_entry->page);
/*
* this does not wipe data stored outside the
* range sg->offset..sg->offset+sg->length.
* Therefore, blkback *could* see data from
* previous requests. This is OK as long as
* persistent grants are shared with just one
* domain. It may need refactoring if this
* changes
*/
memcpy(shared_data + offset,
setup->bvec_data + setup->bvec_off,
len);
kunmap_atomic(shared_data);
setup->bvec_off += len;
}
fsect = offset >> 9;
lsect = fsect + (len >> 9) - 1;
if (ring_req->operation != BLKIF_OP_INDIRECT) {
ring_req->u.rw.seg[grant_idx] =
(struct blkif_request_segment) {
.gref = ref,
.first_sect = fsect,
.last_sect = lsect };
} else {
setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
(struct blkif_request_segment) {
.gref = ref,
.first_sect = fsect,
.last_sect = lsect };
}
(setup->grant_idx)++;
}
static void blkif_setup_extra_req(struct blkif_request *first,
struct blkif_request *second)
{
uint16_t nr_segments = first->u.rw.nr_segments;
/*
* The second request is only present when the first request uses
* all its segments. It's always the continuity of the first one.
*/
first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
second->u.rw.sector_number = first->u.rw.sector_number +
(BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
second->u.rw.handle = first->u.rw.handle;
second->operation = first->operation;
}
static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
{
struct blkfront_info *info = rinfo->dev_info;
struct blkif_request *ring_req, *extra_ring_req = NULL;
struct blkif_request *final_ring_req, *final_extra_ring_req = NULL;
unsigned long id, extra_id = NO_ASSOCIATED_ID;
bool require_extra_req = false;
int i;
struct setup_rw_req setup = {
.grant_idx = 0,
.segments = NULL,
.rinfo = rinfo,
.need_copy = rq_data_dir(req) && info->bounce,
};
/*
* Used to store if we are able to queue the request by just using
* existing persistent grants, or if we have to get new grants,
* as there are not sufficiently many free.
*/
bool new_persistent_gnts = false;
struct scatterlist *sg;
int num_sg, max_grefs, num_grant;
max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
/*
* If we are using indirect segments we need to account
* for the indirect grefs used in the request.
*/
max_grefs += INDIRECT_GREFS(max_grefs);
/* Check if we have enough persistent grants to allocate a requests */
if (rinfo->persistent_gnts_c < max_grefs) {
new_persistent_gnts = true;
if (gnttab_alloc_grant_references(
max_grefs - rinfo->persistent_gnts_c,
&setup.gref_head) < 0) {
gnttab_request_free_callback(
&rinfo->callback,
blkif_restart_queue_callback,
rinfo,
max_grefs - rinfo->persistent_gnts_c);
return 1;
}
}
/* Fill out a communications ring structure. */
id = blkif_ring_get_request(rinfo, req, &final_ring_req);
ring_req = &rinfo->shadow[id].req;
num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
num_grant = 0;
/* Calculate the number of grant used */
for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
num_grant += gnttab_count_grant(sg->offset, sg->length);
require_extra_req = info->max_indirect_segments == 0 &&
num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
rinfo->shadow[id].num_sg = num_sg;
if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
likely(!require_extra_req)) {
/*
* The indirect operation can only be a BLKIF_OP_READ or
* BLKIF_OP_WRITE
*/
BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
ring_req->operation = BLKIF_OP_INDIRECT;
ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
BLKIF_OP_WRITE : BLKIF_OP_READ;
ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
ring_req->u.indirect.handle = info->handle;
ring_req->u.indirect.nr_segments = num_grant;
} else {
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_op(req) == REQ_OP_FLUSH ||
(req_op(req) == REQ_OP_WRITE && (req->cmd_flags & 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.)
*/
if (info->feature_flush && info->feature_fua)
ring_req->operation =
BLKIF_OP_WRITE_BARRIER;
else if (info->feature_flush)
ring_req->operation =
BLKIF_OP_FLUSH_DISKCACHE;
else
ring_req->operation = 0;
}
ring_req->u.rw.nr_segments = num_grant;
if (unlikely(require_extra_req)) {
extra_id = blkif_ring_get_request(rinfo, req,
&final_extra_ring_req);
extra_ring_req = &rinfo->shadow[extra_id].req;
/*
* Only the first request contains the scatter-gather
* list.
*/
rinfo->shadow[extra_id].num_sg = 0;
blkif_setup_extra_req(ring_req, extra_ring_req);
/* Link the 2 requests together */
rinfo->shadow[extra_id].associated_id = id;
rinfo->shadow[id].associated_id = extra_id;
}
}
setup.ring_req = ring_req;
setup.id = id;
setup.require_extra_req = require_extra_req;
if (unlikely(require_extra_req))
setup.extra_ring_req = extra_ring_req;
for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
BUG_ON(sg->offset + sg->length > PAGE_SIZE);
if (setup.need_copy) {
setup.bvec_off = sg->offset;
setup.bvec_data = kmap_atomic(sg_page(sg));
}
gnttab_foreach_grant_in_range(sg_page(sg),
sg->offset,
sg->length,
blkif_setup_rw_req_grant,
&setup);
if (setup.need_copy)
kunmap_atomic(setup.bvec_data);
}
if (setup.segments)
kunmap_atomic(setup.segments);
/* Copy request(s) to the ring page. */
*final_ring_req = *ring_req;
rinfo->shadow[id].status = REQ_WAITING;
if (unlikely(require_extra_req)) {
*final_extra_ring_req = *extra_ring_req;
rinfo->shadow[extra_id].status = REQ_WAITING;
}
if (new_persistent_gnts)
gnttab_free_grant_references(setup.gref_head);
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_ring_info *rinfo)
{
if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
return 1;
if (unlikely(req_op(req) == REQ_OP_DISCARD ||
req_op(req) == REQ_OP_SECURE_ERASE))
return blkif_queue_discard_req(req, rinfo);
else
return blkif_queue_rw_req(req, rinfo);
}
static inline void flush_requests(struct blkfront_ring_info *rinfo)
{
int notify;
RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
if (notify)
notify_remote_via_irq(rinfo->irq);
}
static inline bool blkif_request_flush_invalid(struct request *req,
struct blkfront_info *info)
{
return (blk_rq_is_passthrough(req) ||
((req_op(req) == REQ_OP_FLUSH) &&
!info->feature_flush) ||
((req->cmd_flags & REQ_FUA) &&
!info->feature_fua));
}
static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *qd)
{
unsigned long flags;
int qid = hctx->queue_num;
struct blkfront_info *info = hctx->queue->queuedata;
struct blkfront_ring_info *rinfo = NULL;
rinfo = get_rinfo(info, qid);
blk_mq_start_request(qd->rq);
spin_lock_irqsave(&rinfo->ring_lock, flags);
if (RING_FULL(&rinfo->ring))
goto out_busy;
if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
goto out_err;
if (blkif_queue_request(qd->rq, rinfo))
goto out_busy;
flush_requests(rinfo);
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
return BLK_STS_OK;
out_err:
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
return BLK_STS_IOERR;
out_busy:
blk_mq_stop_hw_queue(hctx);
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
return BLK_STS_DEV_RESOURCE;
}
static void blkif_complete_rq(struct request *rq)
{
blk_mq_end_request(rq, blkif_req(rq)->error);
}
static const struct blk_mq_ops blkfront_mq_ops = {
.queue_rq = blkif_queue_rq,
.complete = blkif_complete_rq,
};
static void blkif_set_queue_limits(struct blkfront_info *info)
{
struct request_queue *rq = info->rq;
struct gendisk *gd = info->gd;
unsigned int segments = info->max_indirect_segments ? :
BLKIF_MAX_SEGMENTS_PER_REQUEST;
blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
if (info->feature_discard) {
blk_queue_max_discard_sectors(rq, get_capacity(gd));
rq->limits.discard_granularity = info->discard_granularity ?:
info->physical_sector_size;
rq->limits.discard_alignment = info->discard_alignment;
if (info->feature_secdiscard)
blk_queue_max_secure_erase_sectors(rq,
get_capacity(gd));
}
/* Hard sector size and max sectors impersonate the equiv. hardware. */
blk_queue_logical_block_size(rq, info->sector_size);
blk_queue_physical_block_size(rq, info->physical_sector_size);
blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 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, segments / GRANTS_PER_PSEG);
/* Make sure buffer addresses are sector-aligned. */
blk_queue_dma_alignment(rq, 511);
}
static const char *flush_info(struct blkfront_info *info)
{
if (info->feature_flush && info->feature_fua)
return "barrier: enabled;";
else if (info->feature_flush)
return "flush diskcache: enabled;";
else
return "barrier or flush: disabled;";
}
static void xlvbd_flush(struct blkfront_info *info)
{
blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
info->feature_fua ? true : false);
pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
info->gd->disk_name, flush_info(info),
"persistent grants:", info->feature_persistent ?
"enabled;" : "disabled;", "indirect descriptors:",
info->max_indirect_segments ? "enabled;" : "disabled;",
"bounce buffer:", info->bounce ? "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 sector_size,
unsigned int physical_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)
return err;
memset(&info->tag_set, 0, sizeof(info->tag_set));
info->tag_set.ops = &blkfront_mq_ops;
info->tag_set.nr_hw_queues = info->nr_rings;
if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
/*
* When indirect descriptior is not supported, the I/O request
* will be split between multiple request in the ring.
* To avoid problems when sending the request, divide by
* 2 the depth of the queue.
*/
info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2;
} else
info->tag_set.queue_depth = BLK_RING_SIZE(info);
info->tag_set.numa_node = NUMA_NO_NODE;
info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
info->tag_set.cmd_size = sizeof(struct blkif_req);
info->tag_set.driver_data = info;
err = blk_mq_alloc_tag_set(&info->tag_set);
if (err)
goto out_release_minors;
gd = blk_mq_alloc_disk(&info->tag_set, info);
if (IS_ERR(gd)) {
err = PTR_ERR(gd);
goto out_free_tag_set;
}
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->minors = nr_minors;
gd->fops = &xlvbd_block_fops;
gd->private_data = info;
set_capacity(gd, capacity);
info->rq = gd->queue;
info->gd = gd;
info->sector_size = sector_size;
info->physical_sector_size = physical_sector_size;
blkif_set_queue_limits(info);
xlvbd_flush(info);
if (info->vdisk_info & VDISK_READONLY)
set_disk_ro(gd, 1);
if (info->vdisk_info & VDISK_REMOVABLE)
gd->flags |= GENHD_FL_REMOVABLE;
return 0;
out_free_tag_set:
blk_mq_free_tag_set(&info->tag_set);
out_release_minors:
xlbd_release_minors(minor, nr_minors);
return err;
}
/* Already hold rinfo->ring_lock. */
static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
{
if (!RING_FULL(&rinfo->ring))
blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
}
static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
{
unsigned long flags;
spin_lock_irqsave(&rinfo->ring_lock, flags);
kick_pending_request_queues_locked(rinfo);
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
}
static void blkif_restart_queue(struct work_struct *work)
{
struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
kick_pending_request_queues(rinfo);
}
static void blkif_free_ring(struct blkfront_ring_info *rinfo)
{
struct grant *persistent_gnt, *n;
struct blkfront_info *info = rinfo->dev_info;
int i, j, segs;
/*
* Remove indirect pages, this only happens when using indirect
* descriptors but not persistent grants
*/
if (!list_empty(&rinfo->indirect_pages)) {
struct page *indirect_page, *n;
BUG_ON(info->bounce);
list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
list_del(&indirect_page->lru);
__free_page(indirect_page);
}
}
/* Remove all persistent grants. */
if (!list_empty(&rinfo->grants)) {
list_for_each_entry_safe(persistent_gnt, n,
&rinfo->grants, node) {
list_del(&persistent_gnt->node);
if (persistent_gnt->gref != INVALID_GRANT_REF) {
gnttab_end_foreign_access(persistent_gnt->gref,
NULL);
rinfo->persistent_gnts_c--;
}
if (info->bounce)
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
}
BUG_ON(rinfo->persistent_gnts_c != 0);
for (i = 0; i < BLK_RING_SIZE(info); i++) {
/*
* Clear persistent grants present in requests already
* on the shared ring
*/
if (!rinfo->shadow[i].request)
goto free_shadow;
segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
rinfo->shadow[i].req.u.indirect.nr_segments :
rinfo->shadow[i].req.u.rw.nr_segments;
for (j = 0; j < segs; j++) {
persistent_gnt = rinfo->shadow[i].grants_used[j];
gnttab_end_foreign_access(persistent_gnt->gref, NULL);
if (info->bounce)
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
/*
* If this is not an indirect operation don't try to
* free indirect segments
*/
goto free_shadow;
for (j = 0; j < INDIRECT_GREFS(segs); j++) {
persistent_gnt = rinfo->shadow[i].indirect_grants[j];
gnttab_end_foreign_access(persistent_gnt->gref, NULL);
__free_page(persistent_gnt->page);
kfree(persistent_gnt);
}
free_shadow:
kvfree(rinfo->shadow[i].grants_used);
rinfo->shadow[i].grants_used = NULL;
kvfree(rinfo->shadow[i].indirect_grants);
rinfo->shadow[i].indirect_grants = NULL;
kvfree(rinfo->shadow[i].sg);
rinfo->shadow[i].sg = NULL;
}
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&rinfo->callback);
/* Flush gnttab callback work. Must be done with no locks held. */
flush_work(&rinfo->work);
/* Free resources associated with old device channel. */
xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages,
rinfo->ring_ref);
if (rinfo->irq)
unbind_from_irqhandler(rinfo->irq, rinfo);
rinfo->evtchn = rinfo->irq = 0;
}
static void blkif_free(struct blkfront_info *info, int suspend)
{
unsigned int i;
struct blkfront_ring_info *rinfo;
/* Prevent new requests being issued until we fix things up. */
info->connected = suspend ?
BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
/* No more blkif_request(). */
if (info->rq)
blk_mq_stop_hw_queues(info->rq);
for_each_rinfo(info, rinfo, i)
blkif_free_ring(rinfo);
kvfree(info->rinfo);
info->rinfo = NULL;
info->nr_rings = 0;
}
struct copy_from_grant {
const struct blk_shadow *s;
unsigned int grant_idx;
unsigned int bvec_offset;
char *bvec_data;
};
static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
unsigned int len, void *data)
{
struct copy_from_grant *info = data;
char *shared_data;
/* Convenient aliases */
const struct blk_shadow *s = info->s;
shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
memcpy(info->bvec_data + info->bvec_offset,
shared_data + offset, len);
info->bvec_offset += len;
info->grant_idx++;
kunmap_atomic(shared_data);
}
static enum blk_req_status blkif_rsp_to_req_status(int rsp)
{
switch (rsp)
{
case BLKIF_RSP_OKAY:
return REQ_DONE;
case BLKIF_RSP_EOPNOTSUPP:
return REQ_EOPNOTSUPP;
case BLKIF_RSP_ERROR:
default:
return REQ_ERROR;
}
}
/*
* Get the final status of the block request based on two ring response
*/
static int blkif_get_final_status(enum blk_req_status s1,
enum blk_req_status s2)
{
BUG_ON(s1 < REQ_DONE);
BUG_ON(s2 < REQ_DONE);
if (s1 == REQ_ERROR || s2 == REQ_ERROR)
return BLKIF_RSP_ERROR;
else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
return BLKIF_RSP_EOPNOTSUPP;
return BLKIF_RSP_OKAY;
}
/*
* Return values:
* 1 response processed.
* 0 missing further responses.
* -1 error while processing.
*/
static int blkif_completion(unsigned long *id,
struct blkfront_ring_info *rinfo,
struct blkif_response *bret)
{
int i = 0;
struct scatterlist *sg;
int num_sg, num_grant;
struct blkfront_info *info = rinfo->dev_info;
struct blk_shadow *s = &rinfo->shadow[*id];
struct copy_from_grant data = {
.grant_idx = 0,
};
num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
/* The I/O request may be split in two. */
if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
/* Keep the status of the current response in shadow. */
s->status = blkif_rsp_to_req_status(bret->status);
/* Wait the second response if not yet here. */
if (s2->status < REQ_DONE)
return 0;
bret->status = blkif_get_final_status(s->status,
s2->status);
/*
* All the grants is stored in the first shadow in order
* to make the completion code simpler.
*/
num_grant += s2->req.u.rw.nr_segments;
/*
* The two responses may not come in order. Only the
* first request will store the scatter-gather list.
*/
if (s2->num_sg != 0) {
/* Update "id" with the ID of the first response. */
*id = s->associated_id;
s = s2;
}
/*
* We don't need anymore the second request, so recycling
* it now.
*/
if (add_id_to_freelist(rinfo, s->associated_id))
WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
info->gd->disk_name, s->associated_id);
}
data.s = s;
num_sg = s->num_sg;
if (bret->operation == BLKIF_OP_READ && info->bounce) {
for_each_sg(s->sg, sg, num_sg, i) {
BUG_ON(sg->offset + sg->length > PAGE_SIZE);
data.bvec_offset = sg->offset;
data.bvec_data = kmap_atomic(sg_page(sg));
gnttab_foreach_grant_in_range(sg_page(sg),
sg->offset,
sg->length,
blkif_copy_from_grant,
&data);
kunmap_atomic(data.bvec_data);
}
}
/* Add the persistent grant into the list of free grants */
for (i = 0; i < num_grant; i++) {
if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) {
/*
* If the grant is still mapped by the backend (the
* backend has chosen to make this grant persistent)
* we add it at the head of the list, so it will be
* reused first.
*/
if (!info->feature_persistent) {
pr_alert("backed has not unmapped grant: %u\n",
s->grants_used[i]->gref);
return -1;
}
list_add(&s->grants_used[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
/*
* If the grant is not mapped by the backend we add it
* to the tail of the list, so it will not be picked
* again unless we run out of persistent grants.
*/
s->grants_used[i]->gref = INVALID_GRANT_REF;
list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
}
}
if (s->req.operation == BLKIF_OP_INDIRECT) {
for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) {
if (!info->feature_persistent) {
pr_alert("backed has not unmapped grant: %u\n",
s->indirect_grants[i]->gref);
return -1;
}
list_add(&s->indirect_grants[i]->node, &rinfo->grants);
rinfo->persistent_gnts_c++;
} else {
struct page *indirect_page;
/*
* Add the used indirect page back to the list of
* available pages for indirect grefs.
*/
if (!info->bounce) {
indirect_page = s->indirect_grants[i]->page;
list_add(&indirect_page->lru, &rinfo->indirect_pages);
}
s->indirect_grants[i]->gref = INVALID_GRANT_REF;
list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
}
}
}
return 1;
}
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_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
struct blkfront_info *info = rinfo->dev_info;
unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
return IRQ_HANDLED;
}
spin_lock_irqsave(&rinfo->ring_lock, flags);
again:
rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
pr_alert("%s: illegal number of responses %u\n",
info->gd->disk_name, rp - rinfo->ring.rsp_cons);
goto err;
}
for (i = rinfo->ring.rsp_cons; i != rp; i++) {
unsigned long id;
unsigned int op;
eoiflag = 0;
RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
id = bret.id;
/*
* The backend has messed up and given us an id that we would
* never have given to it (we stamp it up to BLK_RING_SIZE -
* look in get_id_from_freelist.
*/
if (id >= BLK_RING_SIZE(info)) {
pr_alert("%s: response has incorrect id (%ld)\n",
info->gd->disk_name, id);
goto err;
}
if (rinfo->shadow[id].status != REQ_WAITING) {
pr_alert("%s: response references no pending request\n",
info->gd->disk_name);
goto err;
}
rinfo->shadow[id].status = REQ_PROCESSING;
req = rinfo->shadow[id].request;
op = rinfo->shadow[id].req.operation;
if (op == BLKIF_OP_INDIRECT)
op = rinfo->shadow[id].req.u.indirect.indirect_op;
if (bret.operation != op) {
pr_alert("%s: response has wrong operation (%u instead of %u)\n",
info->gd->disk_name, bret.operation, op);
goto err;
}
if (bret.operation != BLKIF_OP_DISCARD) {
int ret;
/*
* We may need to wait for an extra response if the
* I/O request is split in 2
*/
ret = blkif_completion(&id, rinfo, &bret);
if (!ret)
continue;
if (unlikely(ret < 0))
goto err;
}
if (add_id_to_freelist(rinfo, id)) {
WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
info->gd->disk_name, op_name(bret.operation), id);
continue;
}
if (bret.status == BLKIF_RSP_OKAY)
blkif_req(req)->error = BLK_STS_OK;
else
blkif_req(req)->error = BLK_STS_IOERR;
switch (bret.operation) {
case BLKIF_OP_DISCARD:
if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
struct request_queue *rq = info->rq;
pr_warn_ratelimited("blkfront: %s: %s op failed\n",
info->gd->disk_name, op_name(bret.operation));
blkif_req(req)->error = BLK_STS_NOTSUPP;
info->feature_discard = 0;
info->feature_secdiscard = 0;
blk_queue_max_discard_sectors(rq, 0);
blk_queue_max_secure_erase_sectors(rq, 0);
}
break;
case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_WRITE_BARRIER:
if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
pr_warn_ratelimited("blkfront: %s: %s op failed\n",
info->gd->disk_name, op_name(bret.operation));
blkif_req(req)->error = BLK_STS_NOTSUPP;
}
if (unlikely(bret.status == BLKIF_RSP_ERROR &&
rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
info->gd->disk_name, op_name(bret.operation));
blkif_req(req)->error = BLK_STS_NOTSUPP;
}
if (unlikely(blkif_req(req)->error)) {
if (blkif_req(req)->error == BLK_STS_NOTSUPP)
blkif_req(req)->error = BLK_STS_OK;
info->feature_fua = 0;
info->feature_flush = 0;
xlvbd_flush(info);
}
fallthrough;
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
if (unlikely(bret.status != BLKIF_RSP_OKAY))
dev_dbg_ratelimited(&info->xbdev->dev,
"Bad return from blkdev data request: %#x\n",
bret.status);
break;
default:
BUG();
}
if (likely(!blk_should_fake_timeout(req->q)))
blk_mq_complete_request(req);
}
rinfo->ring.rsp_cons = i;
if (i != rinfo->ring.req_prod_pvt) {
int more_to_do;
RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
if (more_to_do)
goto again;
} else
rinfo->ring.sring->rsp_event = i + 1;
kick_pending_request_queues_locked(rinfo);
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
xen_irq_lateeoi(irq, eoiflag);
return IRQ_HANDLED;
err:
info->connected = BLKIF_STATE_ERROR;
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
/* No EOI in order to avoid further interrupts. */
pr_alert("%s disabled for further use\n", info->gd->disk_name);
return IRQ_HANDLED;
}
static int setup_blkring(struct xenbus_device *dev,
struct blkfront_ring_info *rinfo)
{
struct blkif_sring *sring;
int err;
struct blkfront_info *info = rinfo->dev_info;
unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring,
info->nr_ring_pages, rinfo->ring_ref);
if (err)
goto fail;
XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
if (err)
goto fail;
err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
0, "blkif", rinfo);
if (err <= 0) {
xenbus_dev_fatal(dev, err,
"bind_evtchn_to_irqhandler failed");
goto fail;
}
rinfo->irq = err;
return 0;
fail:
blkif_free(info, 0);
return err;
}
/*
* Write out per-ring/queue nodes including ring-ref and event-channel, and each
* ring buffer may have multi pages depending on ->nr_ring_pages.
*/
static int write_per_ring_nodes(struct xenbus_transaction xbt,
struct blkfront_ring_info *rinfo, const char *dir)
{
int err;
unsigned int i;
const char *message = NULL;
struct blkfront_info *info = rinfo->dev_info;
if (info->nr_ring_pages == 1) {
err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
if (err) {
message = "writing ring-ref";
goto abort_transaction;
}
} else {
for (i = 0; i < info->nr_ring_pages; i++) {
char ring_ref_name[RINGREF_NAME_LEN];
snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
err = xenbus_printf(xbt, dir, ring_ref_name,
"%u", rinfo->ring_ref[i]);
if (err) {
message = "writing ring-ref";
goto abort_transaction;
}
}
}
err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
if (err) {
message = "writing event-channel";
goto abort_transaction;
}
return 0;
abort_transaction:
xenbus_transaction_end(xbt, 1);
if (message)
xenbus_dev_fatal(info->xbdev, err, "%s", message);
return err;
}
/* Enable the persistent grants feature. */
static bool feature_persistent = true;
module_param(feature_persistent, bool, 0644);
MODULE_PARM_DESC(feature_persistent,
"Enables the persistent grants feature");
/* 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;
unsigned int i, max_page_order;
unsigned int ring_page_order;
struct blkfront_ring_info *rinfo;
if (!info)
return -ENODEV;
/* Check if backend is trusted. */
info->bounce = !xen_blkif_trusted ||
!xenbus_read_unsigned(dev->nodename, "trusted", 1);
max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
"max-ring-page-order", 0);
ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
info->nr_ring_pages = 1 << ring_page_order;
err = negotiate_mq(info);
if (err)
goto destroy_blkring;
for_each_rinfo(info, rinfo, i) {
/* Create shared ring, alloc event channel. */
err = setup_blkring(dev, rinfo);
if (err)
goto destroy_blkring;
}
again:
err = xenbus_transaction_start(&xbt);
if (err) {
xenbus_dev_fatal(dev, err, "starting transaction");
goto destroy_blkring;
}
if (info->nr_ring_pages > 1) {
err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
ring_page_order);
if (err) {
message = "writing ring-page-order";
goto abort_transaction;
}
}
/* We already got the number of queues/rings in _probe */
if (info->nr_rings == 1) {
err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
if (err)
goto destroy_blkring;
} else {
char *path;
size_t pathsize;
err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
info->nr_rings);
if (err) {
message = "writing multi-queue-num-queues";
goto abort_transaction;
}
pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
path = kmalloc(pathsize, GFP_KERNEL);
if (!path) {
err = -ENOMEM;
message = "ENOMEM while writing ring references";
goto abort_transaction;
}
for_each_rinfo(info, rinfo, i) {
memset(path, 0, pathsize);
snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
err = write_per_ring_nodes(xbt, rinfo, path);
if (err) {
kfree(path);
goto destroy_blkring;
}
}
kfree(path);
}
err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
XEN_IO_PROTO_ABI_NATIVE);
if (err) {
message = "writing protocol";
goto abort_transaction;
}
info->feature_persistent_parm = feature_persistent;
err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
info->feature_persistent_parm);
if (err)
dev_warn(&dev->dev,
"writing persistent grants feature to xenbus");
err = xenbus_transaction_end(xbt, 0);
if (err) {
if (err == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, err, "completing transaction");
goto destroy_blkring;
}
for_each_rinfo(info, rinfo, i) {
unsigned int j;
for (j = 0; j < BLK_RING_SIZE(info); j++)
rinfo->shadow[j].req.u.rw.id = j + 1;
rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
}
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);
return err;
}
static int negotiate_mq(struct blkfront_info *info)
{
unsigned int backend_max_queues;
unsigned int i;
struct blkfront_ring_info *rinfo;
BUG_ON(info->nr_rings);
/* Check if backend supports multiple queues. */
backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
"multi-queue-max-queues", 1);
info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
/* We need at least one ring. */
if (!info->nr_rings)
info->nr_rings = 1;
info->rinfo_size = struct_size(info->rinfo, shadow,
BLK_RING_SIZE(info));
info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
if (!info->rinfo) {
xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
info->nr_rings = 0;
return -ENOMEM;
}
for_each_rinfo(info, rinfo, i) {
INIT_LIST_HEAD(&rinfo->indirect_pages);
INIT_LIST_HEAD(&rinfo->grants);
rinfo->dev_info = info;
INIT_WORK(&rinfo->work, blkif_restart_queue);
spin_lock_init(&rinfo->ring_lock);
}
return 0;
}
/*
* 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;
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_has_pv_and_legacy_disk_devices()) {
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",
__func__, 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;
}
info->xbdev = dev;
mutex_init(&info->mutex);
info->vdevice = vdevice;
info->connected = BLKIF_STATE_DISCONNECTED;
/* 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);
mutex_lock(&blkfront_mutex);
list_add(&info->info_list, &info_list);
mutex_unlock(&blkfront_mutex);
return 0;
}
static int blkif_recover(struct blkfront_info *info)
{
unsigned int r_index;
struct request *req, *n;
int rc;
struct bio *bio;
unsigned int segs;
struct blkfront_ring_info *rinfo;
blkfront_gather_backend_features(info);
/* Reset limits changed by blk_mq_update_nr_hw_queues(). */
blkif_set_queue_limits(info);
segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
for_each_rinfo(info, rinfo, r_index) {
rc = blkfront_setup_indirect(rinfo);
if (rc)
return rc;
}
xenbus_switch_state(info->xbdev, XenbusStateConnected);
/* Now safe for us to use the shared ring */
info->connected = BLKIF_STATE_CONNECTED;
for_each_rinfo(info, rinfo, r_index) {
/* Kick any other new requests queued since we resumed */
kick_pending_request_queues(rinfo);
}
list_for_each_entry_safe(req, n, &info->requests, queuelist) {
/* Requeue pending requests (flush or discard) */
list_del_init(&req->queuelist);
BUG_ON(req->nr_phys_segments > segs);
blk_mq_requeue_request(req, false);
}
blk_mq_start_stopped_hw_queues(info->rq, true);
blk_mq_kick_requeue_list(info->rq);
while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
/* Traverse the list of pending bios and re-queue them */
submit_bio(bio);
}
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 = 0;
unsigned int i, j;
struct blkfront_ring_info *rinfo;
dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
bio_list_init(&info->bio_list);
INIT_LIST_HEAD(&info->requests);
for_each_rinfo(info, rinfo, i) {
struct bio_list merge_bio;
struct blk_shadow *shadow = rinfo->shadow;
for (j = 0; j < BLK_RING_SIZE(info); j++) {
/* Not in use? */
if (!shadow[j].request)
continue;
/*
* Get the bios in the request so we can re-queue them.
*/
if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
req_op(shadow[j].request) == REQ_OP_DISCARD ||
req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
shadow[j].request->cmd_flags & REQ_FUA) {
/*
* Flush operations don't contain bios, so
* we need to requeue the whole request
*
* XXX: but this doesn't make any sense for a
* write with the FUA flag set..
*/
list_add(&shadow[j].request->queuelist, &info->requests);
continue;
}
merge_bio.head = shadow[j].request->bio;
merge_bio.tail = shadow[j].request->biotail;
bio_list_merge(&info->bio_list, &merge_bio);
shadow[j].request->bio = NULL;
blk_mq_end_request(shadow[j].request, BLK_STS_OK);
}
}
blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
err = talk_to_blkback(dev, info);
if (!err)
blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
/*
* We have to wait for the backend to switch to
* connected state, since we want to read which
* features it supports.
*/
return err;
}
static void blkfront_closing(struct blkfront_info *info)
{
struct xenbus_device *xbdev = info->xbdev;
struct blkfront_ring_info *rinfo;
unsigned int i;
if (xbdev->state == XenbusStateClosing)
return;
/* No more blkif_request(). */
if (info->rq && info->gd) {
blk_mq_stop_hw_queues(info->rq);
blk_mark_disk_dead(info->gd);
set_capacity(info->gd, 0);
}
for_each_rinfo(info, rinfo, i) {
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&rinfo->callback);
/* Flush gnttab callback work. Must be done with no locks held. */
flush_work(&rinfo->work);
}
xenbus_frontend_closed(xbdev);
}
static void blkfront_setup_discard(struct blkfront_info *info)
{
info->feature_discard = 1;
info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
"discard-granularity",
0);
info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
"discard-alignment", 0);
info->feature_secdiscard =
!!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
0);
}
static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
{
unsigned int psegs, grants, memflags;
int err, i;
struct blkfront_info *info = rinfo->dev_info;
memflags = memalloc_noio_save();
if (info->max_indirect_segments == 0) {
if (!HAS_EXTRA_REQ)
grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
else {
/*
* When an extra req is required, the maximum
* grants supported is related to the size of the
* Linux block segment.
*/
grants = GRANTS_PER_PSEG;
}
}
else
grants = info->max_indirect_segments;
psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
err = fill_grant_buffer(rinfo,
(grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
if (err)
goto out_of_memory;
if (!info->bounce && info->max_indirect_segments) {
/*
* We are using indirect descriptors but don't have a bounce
* buffer, we need to allocate a set of pages that can be
* used for mapping indirect grefs
*/
int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
BUG_ON(!list_empty(&rinfo->indirect_pages));
for (i = 0; i < num; i++) {
struct page *indirect_page = alloc_page(GFP_KERNEL |
__GFP_ZERO);
if (!indirect_page)
goto out_of_memory;
list_add(&indirect_page->lru, &rinfo->indirect_pages);
}
}
for (i = 0; i < BLK_RING_SIZE(info); i++) {
rinfo->shadow[i].grants_used =
kvcalloc(grants,
sizeof(rinfo->shadow[i].grants_used[0]),
GFP_KERNEL);
rinfo->shadow[i].sg = kvcalloc(psegs,
sizeof(rinfo->shadow[i].sg[0]),
GFP_KERNEL);
if (info->max_indirect_segments)
rinfo->shadow[i].indirect_grants =
kvcalloc(INDIRECT_GREFS(grants),
sizeof(rinfo->shadow[i].indirect_grants[0]),
GFP_KERNEL);
if ((rinfo->shadow[i].grants_used == NULL) ||
(rinfo->shadow[i].sg == NULL) ||
(info->max_indirect_segments &&
(rinfo->shadow[i].indirect_grants == NULL)))
goto out_of_memory;
sg_init_table(rinfo->shadow[i].sg, psegs);
}
memalloc_noio_restore(memflags);
return 0;
out_of_memory:
for (i = 0; i < BLK_RING_SIZE(info); i++) {
kvfree(rinfo->shadow[i].grants_used);
rinfo->shadow[i].grants_used = NULL;
kvfree(rinfo->shadow[i].sg);
rinfo->shadow[i].sg = NULL;
kvfree(rinfo->shadow[i].indirect_grants);
rinfo->shadow[i].indirect_grants = NULL;
}
if (!list_empty(&rinfo->indirect_pages)) {
struct page *indirect_page, *n;
list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
list_del(&indirect_page->lru);
__free_page(indirect_page);
}
}
memalloc_noio_restore(memflags);
return -ENOMEM;
}
/*
* Gather all backend feature-*
*/
static void blkfront_gather_backend_features(struct blkfront_info *info)
{
unsigned int indirect_segments;
info->feature_flush = 0;
info->feature_fua = 0;
/*
* 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 (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
info->feature_flush = 1;
info->feature_fua = 1;
}
/*
* And if there is "feature-flush-cache" use that above
* barriers.
*/
if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
0)) {
info->feature_flush = 1;
info->feature_fua = 0;
}
if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
blkfront_setup_discard(info);
if (info->feature_persistent_parm)
info->feature_persistent =
!!xenbus_read_unsigned(info->xbdev->otherend,
"feature-persistent", 0);
if (info->feature_persistent)
info->bounce = true;
indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
"feature-max-indirect-segments", 0);
if (indirect_segments > xen_blkif_max_segments)
indirect_segments = xen_blkif_max_segments;
if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
indirect_segments = 0;
info->max_indirect_segments = indirect_segments;
if (info->feature_persistent) {
mutex_lock(&blkfront_mutex);
schedule_delayed_work(&blkfront_work, HZ * 10);
mutex_unlock(&blkfront_mutex);
}
}
/*
* 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 physical_sector_size;
int err, i;
struct blkfront_ring_info *rinfo;
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_and_notify(info->gd, sectors);
return;
case BLKIF_STATE_SUSPENDED:
/*
* If we are recovering from suspension, we need to wait
* for the backend to announce it's features before
* reconnecting, at least we need to know if the backend
* supports indirect descriptors, and how many.
*/
blkif_recover(info);
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", &info->vdisk_info,
"sector-size", "%lu", &sector_size,
NULL);
if (err) {
xenbus_dev_fatal(info->xbdev, err,
"reading backend fields at %s",
info->xbdev->otherend);
return;
}
/*
* physical-sector-size is a newer field, so old backends may not
* provide this. Assume physical sector size to be the same as
* sector_size in that case.
*/
physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
"physical-sector-size",
sector_size);
blkfront_gather_backend_features(info);
for_each_rinfo(info, rinfo, i) {
err = blkfront_setup_indirect(rinfo);
if (err) {
xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
info->xbdev->otherend);
blkif_free(info, 0);
break;
}
}
err = xlvbd_alloc_gendisk(sectors, info, sector_size,
physical_sector_size);
if (err) {
xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
info->xbdev->otherend);
goto fail;
}
xenbus_switch_state(info->xbdev, XenbusStateConnected);
/* Kick pending requests. */
info->connected = BLKIF_STATE_CONNECTED;
for_each_rinfo(info, rinfo, i)
kick_pending_request_queues(rinfo);
err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
if (err) {
put_disk(info->gd);
blk_mq_free_tag_set(&info->tag_set);
info->rq = NULL;
goto fail;
}
info->is_ready = 1;
return;
fail:
blkif_free(info, 0);
return;
}
/*
* 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 XenbusStateInitWait:
if (dev->state != XenbusStateInitialising)
break;
if (talk_to_blkback(dev, info))
break;
break;
case XenbusStateInitialising:
case XenbusStateInitialised:
case XenbusStateReconfiguring:
case XenbusStateReconfigured:
case XenbusStateUnknown:
break;
case XenbusStateConnected:
/*
* talk_to_blkback sets state to XenbusStateInitialised
* and blkfront_connect sets it to XenbusStateConnected
* (if connection went OK).
*
* If the backend (or toolstack) decides to poke at backend
* state (and re-trigger the watch by setting the state repeatedly
* to XenbusStateConnected (4)) we need to deal with this.
* This is allowed as this is used to communicate to the guest
* that the size of disk has changed!
*/
if ((dev->state != XenbusStateInitialised) &&
(dev->state != XenbusStateConnected)) {
if (talk_to_blkback(dev, info))
break;
}
blkfront_connect(info);
break;
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
fallthrough;
case XenbusStateClosing:
blkfront_closing(info);
break;
}
}
static int blkfront_remove(struct xenbus_device *xbdev)
{
struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
if (info->gd)
del_gendisk(info->gd);
mutex_lock(&blkfront_mutex);
list_del(&info->info_list);
mutex_unlock(&blkfront_mutex);
blkif_free(info, 0);
if (info->gd) {
xlbd_release_minors(info->gd->first_minor, info->gd->minors);
put_disk(info->gd);
blk_mq_free_tag_set(&info->tag_set);
}
kfree(info);
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 const struct block_device_operations xlvbd_block_fops =
{
.owner = THIS_MODULE,
.getgeo = blkif_getgeo,
.ioctl = blkif_ioctl,
.compat_ioctl = blkdev_compat_ptr_ioctl,
};
static const struct xenbus_device_id blkfront_ids[] = {
{ "vbd" },
{ "" }
};
static struct xenbus_driver blkfront_driver = {
.ids = blkfront_ids,
.probe = blkfront_probe,
.remove = blkfront_remove,
.resume = blkfront_resume,
.otherend_changed = blkback_changed,
.is_ready = blkfront_is_ready,
};
static void purge_persistent_grants(struct blkfront_info *info)
{
unsigned int i;
unsigned long flags;
struct blkfront_ring_info *rinfo;
for_each_rinfo(info, rinfo, i) {
struct grant *gnt_list_entry, *tmp;
LIST_HEAD(grants);
spin_lock_irqsave(&rinfo->ring_lock, flags);
if (rinfo->persistent_gnts_c == 0) {
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
continue;
}
list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
node) {
if (gnt_list_entry->gref == INVALID_GRANT_REF ||
!gnttab_try_end_foreign_access(gnt_list_entry->gref))
continue;
list_del(&gnt_list_entry->node);
rinfo->persistent_gnts_c--;
gnt_list_entry->gref = INVALID_GRANT_REF;
list_add_tail(&gnt_list_entry->node, &grants);
}
list_splice_tail(&grants, &rinfo->grants);
spin_unlock_irqrestore(&rinfo->ring_lock, flags);
}
}
static void blkfront_delay_work(struct work_struct *work)
{
struct blkfront_info *info;
bool need_schedule_work = false;
/*
* Note that when using bounce buffers but not persistent grants
* there's no need to run blkfront_delay_work because grants are
* revoked in blkif_completion or else an error is reported and the
* connection is closed.
*/
mutex_lock(&blkfront_mutex);
list_for_each_entry(info, &info_list, info_list) {
if (info->feature_persistent) {
need_schedule_work = true;
mutex_lock(&info->mutex);
purge_persistent_grants(info);
mutex_unlock(&info->mutex);
}
}
if (need_schedule_work)
schedule_delayed_work(&blkfront_work, HZ * 10);
mutex_unlock(&blkfront_mutex);
}
static int __init xlblk_init(void)
{
int ret;
int nr_cpus = num_online_cpus();
if (!xen_domain())
return -ENODEV;
if (!xen_has_pv_disk_devices())
return -ENODEV;
if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
pr_warn("xen_blk: can't get major %d with name %s\n",
XENVBD_MAJOR, DEV_NAME);
return -ENODEV;
}
if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
}
if (xen_blkif_max_queues > nr_cpus) {
pr_info("Invalid max_queues (%d), will use default max: %d.\n",
xen_blkif_max_queues, nr_cpus);
xen_blkif_max_queues = nr_cpus;
}
INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
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)
{
cancel_delayed_work_sync(&blkfront_work);
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");