diff options
Diffstat (limited to 'drivers/block/xen-blkfront.c')
| -rw-r--r-- | drivers/block/xen-blkfront.c | 2649 |
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", §ors); + 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", §ors, + "info", "%u", &info->vdisk_info, + "sector-size", "%lu", §or_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"); |