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-rw-r--r--drivers/block/xen-blkfront.c2649
1 files changed, 2649 insertions, 0 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
new file mode 100644
index 000000000..5ddf393aa
--- /dev/null
+++ b/drivers/block/xen-blkfront.c
@@ -0,0 +1,2649 @@
+/*
+ * 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");