diff options
Diffstat (limited to 'drivers/block/xen-blkback')
| -rw-r--r-- | drivers/block/xen-blkback/Makefile | 3 | ||||
| -rw-r--r-- | drivers/block/xen-blkback/blkback.c | 826 | ||||
| -rw-r--r-- | drivers/block/xen-blkback/common.h | 233 | ||||
| -rw-r--r-- | drivers/block/xen-blkback/xenbus.c | 767 |
4 files changed, 1829 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/Makefile b/drivers/block/xen-blkback/Makefile new file mode 100644 index 000000000000..e491c1b76878 --- /dev/null +++ b/drivers/block/xen-blkback/Makefile @@ -0,0 +1,3 @@ +obj-$(CONFIG_XEN_BLKDEV_BACKEND) := xen-blkback.o + +xen-blkback-y := blkback.o xenbus.o diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c new file mode 100644 index 000000000000..5cf2993a8338 --- /dev/null +++ b/drivers/block/xen-blkback/blkback.c @@ -0,0 +1,826 @@ +/****************************************************************************** + * + * Back-end of the driver for virtual block devices. This portion of the + * driver exports a 'unified' block-device interface that can be accessed + * by any operating system that implements a compatible front end. A + * reference front-end implementation can be found in: + * drivers/block/xen-blkfront.c + * + * Copyright (c) 2003-2004, Keir Fraser & Steve Hand + * Copyright (c) 2005, Christopher Clark + * + * 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/spinlock.h> +#include <linux/kthread.h> +#include <linux/list.h> +#include <linux/delay.h> +#include <linux/freezer.h> + +#include <xen/events.h> +#include <xen/page.h> +#include <asm/xen/hypervisor.h> +#include <asm/xen/hypercall.h> +#include "common.h" + +/* + * These are rather arbitrary. They are fairly large because adjacent requests + * pulled from a communication ring are quite likely to end up being part of + * the same scatter/gather request at the disc. + * + * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW ** + * + * This will increase the chances of being able to write whole tracks. + * 64 should be enough to keep us competitive with Linux. + */ +static int xen_blkif_reqs = 64; +module_param_named(reqs, xen_blkif_reqs, int, 0); +MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate"); + +/* Run-time switchable: /sys/module/blkback/parameters/ */ +static unsigned int log_stats; +module_param(log_stats, int, 0644); + +/* + * Each outstanding request that we've passed to the lower device layers has a + * 'pending_req' allocated to it. Each buffer_head that completes decrements + * the pendcnt towards zero. When it hits zero, the specified domain has a + * response queued for it, with the saved 'id' passed back. + */ +struct pending_req { + struct xen_blkif *blkif; + u64 id; + int nr_pages; + atomic_t pendcnt; + unsigned short operation; + int status; + struct list_head free_list; +}; + +#define BLKBACK_INVALID_HANDLE (~0) + +struct xen_blkbk { + struct pending_req *pending_reqs; + /* List of all 'pending_req' available */ + struct list_head pending_free; + /* And its spinlock. */ + spinlock_t pending_free_lock; + wait_queue_head_t pending_free_wq; + /* The list of all pages that are available. */ + struct page **pending_pages; + /* And the grant handles that are available. */ + grant_handle_t *pending_grant_handles; +}; + +static struct xen_blkbk *blkbk; + +/* + * Little helpful macro to figure out the index and virtual address of the + * pending_pages[..]. For each 'pending_req' we have have up to + * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through + * 10 and would index in the pending_pages[..]. + */ +static inline int vaddr_pagenr(struct pending_req *req, int seg) +{ + return (req - blkbk->pending_reqs) * + BLKIF_MAX_SEGMENTS_PER_REQUEST + seg; +} + +#define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)] + +static inline unsigned long vaddr(struct pending_req *req, int seg) +{ + unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg)); + return (unsigned long)pfn_to_kaddr(pfn); +} + +#define pending_handle(_req, _seg) \ + (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)]) + + +static int do_block_io_op(struct xen_blkif *blkif); +static int dispatch_rw_block_io(struct xen_blkif *blkif, + struct blkif_request *req, + struct pending_req *pending_req); +static void make_response(struct xen_blkif *blkif, u64 id, + unsigned short op, int st); + +/* + * Retrieve from the 'pending_reqs' a free pending_req structure to be used. + */ +static struct pending_req *alloc_req(void) +{ + struct pending_req *req = NULL; + unsigned long flags; + + spin_lock_irqsave(&blkbk->pending_free_lock, flags); + if (!list_empty(&blkbk->pending_free)) { + req = list_entry(blkbk->pending_free.next, struct pending_req, + free_list); + list_del(&req->free_list); + } + spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); + return req; +} + +/* + * Return the 'pending_req' structure back to the freepool. We also + * wake up the thread if it was waiting for a free page. + */ +static void free_req(struct pending_req *req) +{ + unsigned long flags; + int was_empty; + + spin_lock_irqsave(&blkbk->pending_free_lock, flags); + was_empty = list_empty(&blkbk->pending_free); + list_add(&req->free_list, &blkbk->pending_free); + spin_unlock_irqrestore(&blkbk->pending_free_lock, flags); + if (was_empty) + wake_up(&blkbk->pending_free_wq); +} + +/* + * Routines for managing virtual block devices (vbds). + */ +static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif, + int operation) +{ + struct xen_vbd *vbd = &blkif->vbd; + int rc = -EACCES; + + if ((operation != READ) && vbd->readonly) + goto out; + + if (likely(req->nr_sects)) { + blkif_sector_t end = req->sector_number + req->nr_sects; + + if (unlikely(end < req->sector_number)) + goto out; + if (unlikely(end > vbd_sz(vbd))) + goto out; + } + + req->dev = vbd->pdevice; + req->bdev = vbd->bdev; + rc = 0; + + out: + return rc; +} + +static void xen_vbd_resize(struct xen_blkif *blkif) +{ + struct xen_vbd *vbd = &blkif->vbd; + struct xenbus_transaction xbt; + int err; + struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be); + unsigned long long new_size = vbd_sz(vbd); + + pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n", + blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice)); + pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size); + vbd->size = new_size; +again: + err = xenbus_transaction_start(&xbt); + if (err) { + pr_warn(DRV_PFX "Error starting transaction"); + return; + } + err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", + (unsigned long long)vbd_sz(vbd)); + if (err) { + pr_warn(DRV_PFX "Error writing new size"); + goto abort; + } + /* + * Write the current state; we will use this to synchronize + * the front-end. If the current state is "connected" the + * front-end will get the new size information online. + */ + err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state); + if (err) { + pr_warn(DRV_PFX "Error writing the state"); + goto abort; + } + + err = xenbus_transaction_end(xbt, 0); + if (err == -EAGAIN) + goto again; + if (err) + pr_warn(DRV_PFX "Error ending transaction"); + return; +abort: + xenbus_transaction_end(xbt, 1); +} + +/* + * Notification from the guest OS. + */ +static void blkif_notify_work(struct xen_blkif *blkif) +{ + blkif->waiting_reqs = 1; + wake_up(&blkif->wq); +} + +irqreturn_t xen_blkif_be_int(int irq, void *dev_id) +{ + blkif_notify_work(dev_id); + return IRQ_HANDLED; +} + +/* + * SCHEDULER FUNCTIONS + */ + +static void print_stats(struct xen_blkif *blkif) +{ + pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d\n", + current->comm, blkif->st_oo_req, + blkif->st_rd_req, blkif->st_wr_req, blkif->st_f_req); + blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000); + blkif->st_rd_req = 0; + blkif->st_wr_req = 0; + blkif->st_oo_req = 0; +} + +int xen_blkif_schedule(void *arg) +{ + struct xen_blkif *blkif = arg; + struct xen_vbd *vbd = &blkif->vbd; + + xen_blkif_get(blkif); + + while (!kthread_should_stop()) { + if (try_to_freeze()) + continue; + if (unlikely(vbd->size != vbd_sz(vbd))) + xen_vbd_resize(blkif); + + wait_event_interruptible( + blkif->wq, + blkif->waiting_reqs || kthread_should_stop()); + wait_event_interruptible( + blkbk->pending_free_wq, + !list_empty(&blkbk->pending_free) || + kthread_should_stop()); + + blkif->waiting_reqs = 0; + smp_mb(); /* clear flag *before* checking for work */ + + if (do_block_io_op(blkif)) + blkif->waiting_reqs = 1; + + if (log_stats && time_after(jiffies, blkif->st_print)) + print_stats(blkif); + } + + if (log_stats) + print_stats(blkif); + + blkif->xenblkd = NULL; + xen_blkif_put(blkif); + + return 0; +} + +struct seg_buf { + unsigned long buf; + unsigned int nsec; +}; +/* + * Unmap the grant references, and also remove the M2P over-rides + * used in the 'pending_req'. + */ +static void xen_blkbk_unmap(struct pending_req *req) +{ + struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + unsigned int i, invcount = 0; + grant_handle_t handle; + int ret; + + for (i = 0; i < req->nr_pages; i++) { + handle = pending_handle(req, i); + if (handle == BLKBACK_INVALID_HANDLE) + continue; + gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i), + GNTMAP_host_map, handle); + pending_handle(req, i) = BLKBACK_INVALID_HANDLE; + invcount++; + } + + ret = HYPERVISOR_grant_table_op( + GNTTABOP_unmap_grant_ref, unmap, invcount); + BUG_ON(ret); + /* + * Note, we use invcount, so nr->pages, so we can't index + * using vaddr(req, i). + */ + for (i = 0; i < invcount; i++) { + ret = m2p_remove_override( + virt_to_page(unmap[i].host_addr), false); + if (ret) { + pr_alert(DRV_PFX "Failed to remove M2P override for %lx\n", + (unsigned long)unmap[i].host_addr); + continue; + } + } +} + +static int xen_blkbk_map(struct blkif_request *req, + struct pending_req *pending_req, + struct seg_buf seg[]) +{ + struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + int i; + int nseg = req->nr_segments; + int ret = 0; + + /* + * Fill out preq.nr_sects with proper amount of sectors, and setup + * assign map[..] with the PFN of the page in our domain with the + * corresponding grant reference for each page. + */ + for (i = 0; i < nseg; i++) { + uint32_t flags; + + flags = GNTMAP_host_map; + if (pending_req->operation != BLKIF_OP_READ) + flags |= GNTMAP_readonly; + gnttab_set_map_op(&map[i], vaddr(pending_req, i), flags, + req->u.rw.seg[i].gref, + pending_req->blkif->domid); + } + + ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map, nseg); + BUG_ON(ret); + + /* + * Now swizzle the MFN in our domain with the MFN from the other domain + * so that when we access vaddr(pending_req,i) it has the contents of + * the page from the other domain. + */ + for (i = 0; i < nseg; i++) { + if (unlikely(map[i].status != 0)) { + pr_debug(DRV_PFX "invalid buffer -- could not remap it\n"); + map[i].handle = BLKBACK_INVALID_HANDLE; + ret |= 1; + } + + pending_handle(pending_req, i) = map[i].handle; + + if (ret) + continue; + + ret = m2p_add_override(PFN_DOWN(map[i].dev_bus_addr), + blkbk->pending_page(pending_req, i), false); + if (ret) { + pr_alert(DRV_PFX "Failed to install M2P override for %lx (ret: %d)\n", + (unsigned long)map[i].dev_bus_addr, ret); + /* We could switch over to GNTTABOP_copy */ + continue; + } + + seg[i].buf = map[i].dev_bus_addr | + (req->u.rw.seg[i].first_sect << 9); + } + return ret; +} + +/* + * Completion callback on the bio's. Called as bh->b_end_io() + */ + +static void __end_block_io_op(struct pending_req *pending_req, int error) +{ + /* An error fails the entire request. */ + if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) && + (error == -EOPNOTSUPP)) { + pr_debug(DRV_PFX "flush diskcache op failed, not supported\n"); + xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0); + pending_req->status = BLKIF_RSP_EOPNOTSUPP; + } else if (error) { + pr_debug(DRV_PFX "Buffer not up-to-date at end of operation," + " error=%d\n", error); + pending_req->status = BLKIF_RSP_ERROR; + } + + /* + * If all of the bio's have completed it is time to unmap + * the grant references associated with 'request' and provide + * the proper response on the ring. + */ + if (atomic_dec_and_test(&pending_req->pendcnt)) { + xen_blkbk_unmap(pending_req); + make_response(pending_req->blkif, pending_req->id, + pending_req->operation, pending_req->status); + xen_blkif_put(pending_req->blkif); + free_req(pending_req); + } +} + +/* + * bio callback. + */ +static void end_block_io_op(struct bio *bio, int error) +{ + __end_block_io_op(bio->bi_private, error); + bio_put(bio); +} + + + +/* + * Function to copy the from the ring buffer the 'struct blkif_request' + * (which has the sectors we want, number of them, grant references, etc), + * and transmute it to the block API to hand it over to the proper block disk. + */ +static int do_block_io_op(struct xen_blkif *blkif) +{ + union blkif_back_rings *blk_rings = &blkif->blk_rings; + struct blkif_request req; + struct pending_req *pending_req; + RING_IDX rc, rp; + int more_to_do = 0; + + rc = blk_rings->common.req_cons; + rp = blk_rings->common.sring->req_prod; + rmb(); /* Ensure we see queued requests up to 'rp'. */ + + while (rc != rp) { + + if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc)) + break; + + if (kthread_should_stop()) { + more_to_do = 1; + break; + } + + pending_req = alloc_req(); + if (NULL == pending_req) { + blkif->st_oo_req++; + more_to_do = 1; + break; + } + + switch (blkif->blk_protocol) { + case BLKIF_PROTOCOL_NATIVE: + memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req)); + break; + case BLKIF_PROTOCOL_X86_32: + blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc)); + break; + case BLKIF_PROTOCOL_X86_64: + blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc)); + break; + default: + BUG(); + } + blk_rings->common.req_cons = ++rc; /* before make_response() */ + + /* Apply all sanity checks to /private copy/ of request. */ + barrier(); + + if (dispatch_rw_block_io(blkif, &req, pending_req)) + break; + + /* Yield point for this unbounded loop. */ + cond_resched(); + } + + return more_to_do; +} + +/* + * Transmutation of the 'struct blkif_request' to a proper 'struct bio' + * and call the 'submit_bio' to pass it to the underlying storage. + */ +static int dispatch_rw_block_io(struct xen_blkif *blkif, + struct blkif_request *req, + struct pending_req *pending_req) +{ + struct phys_req preq; + struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + unsigned int nseg; + struct bio *bio = NULL; + struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + int i, nbio = 0; + int operation; + struct blk_plug plug; + + switch (req->operation) { + case BLKIF_OP_READ: + blkif->st_rd_req++; + operation = READ; + break; + case BLKIF_OP_WRITE: + blkif->st_wr_req++; + operation = WRITE_ODIRECT; + break; + case BLKIF_OP_FLUSH_DISKCACHE: + blkif->st_f_req++; + operation = WRITE_FLUSH; + break; + case BLKIF_OP_WRITE_BARRIER: + default: + operation = 0; /* make gcc happy */ + goto fail_response; + break; + } + + /* Check that the number of segments is sane. */ + nseg = req->nr_segments; + if (unlikely(nseg == 0 && operation != WRITE_FLUSH) || + unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) { + pr_debug(DRV_PFX "Bad number of segments in request (%d)\n", + nseg); + /* Haven't submitted any bio's yet. */ + goto fail_response; + } + + preq.dev = req->handle; + preq.sector_number = req->u.rw.sector_number; + preq.nr_sects = 0; + + pending_req->blkif = blkif; + pending_req->id = req->id; + pending_req->operation = req->operation; + pending_req->status = BLKIF_RSP_OKAY; + pending_req->nr_pages = nseg; + + for (i = 0; i < nseg; i++) { + seg[i].nsec = req->u.rw.seg[i].last_sect - + req->u.rw.seg[i].first_sect + 1; + if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || + (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect)) + goto fail_response; + preq.nr_sects += seg[i].nsec; + + } + + if (xen_vbd_translate(&preq, blkif, operation) != 0) { + pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n", + operation == READ ? "read" : "write", + preq.sector_number, + preq.sector_number + preq.nr_sects, preq.dev); + goto fail_response; + } + + /* + * This check _MUST_ be done after xen_vbd_translate as the preq.bdev + * is set there. + */ + for (i = 0; i < nseg; i++) { + if (((int)preq.sector_number|(int)seg[i].nsec) & + ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) { + pr_debug(DRV_PFX "Misaligned I/O request from domain %d", + blkif->domid); + goto fail_response; + } + } + + /* + * If we have failed at this point, we need to undo the M2P override, + * set gnttab_set_unmap_op on all of the grant references and perform + * the hypercall to unmap the grants - that is all done in + * xen_blkbk_unmap. + */ + if (xen_blkbk_map(req, pending_req, seg)) + goto fail_flush; + + /* This corresponding xen_blkif_put is done in __end_block_io_op */ + xen_blkif_get(blkif); + + for (i = 0; i < nseg; i++) { + while ((bio == NULL) || + (bio_add_page(bio, + blkbk->pending_page(pending_req, i), + seg[i].nsec << 9, + seg[i].buf & ~PAGE_MASK) == 0)) { + + bio = bio_alloc(GFP_KERNEL, nseg-i); + if (unlikely(bio == NULL)) + goto fail_put_bio; + + biolist[nbio++] = bio; + bio->bi_bdev = preq.bdev; + bio->bi_private = pending_req; + bio->bi_end_io = end_block_io_op; + bio->bi_sector = preq.sector_number; + } + + preq.sector_number += seg[i].nsec; + } + + /* This will be hit if the operation was a flush. */ + if (!bio) { + BUG_ON(operation != WRITE_FLUSH); + + bio = bio_alloc(GFP_KERNEL, 0); + if (unlikely(bio == NULL)) + goto fail_put_bio; + + biolist[nbio++] = bio; + bio->bi_bdev = preq.bdev; + bio->bi_private = pending_req; + bio->bi_end_io = end_block_io_op; + } + + /* + * We set it one so that the last submit_bio does not have to call + * atomic_inc. + */ + atomic_set(&pending_req->pendcnt, nbio); + + /* Get a reference count for the disk queue and start sending I/O */ + blk_start_plug(&plug); + + for (i = 0; i < nbio; i++) + submit_bio(operation, biolist[i]); + + /* Let the I/Os go.. */ + blk_finish_plug(&plug); + + if (operation == READ) + blkif->st_rd_sect += preq.nr_sects; + else if (operation == WRITE || operation == WRITE_FLUSH) + blkif->st_wr_sect += preq.nr_sects; + + return 0; + + fail_flush: + xen_blkbk_unmap(pending_req); + fail_response: + /* Haven't submitted any bio's yet. */ + make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR); + free_req(pending_req); + msleep(1); /* back off a bit */ + return -EIO; + + fail_put_bio: + for (i = 0; i < nbio; i++) + bio_put(biolist[i]); + __end_block_io_op(pending_req, -EINVAL); + msleep(1); /* back off a bit */ + return -EIO; +} + + + +/* + * Put a response on the ring on how the operation fared. + */ +static void make_response(struct xen_blkif *blkif, u64 id, + unsigned short op, int st) +{ + struct blkif_response resp; + unsigned long flags; + union blkif_back_rings *blk_rings = &blkif->blk_rings; + int more_to_do = 0; + int notify; + + resp.id = id; + resp.operation = op; + resp.status = st; + + spin_lock_irqsave(&blkif->blk_ring_lock, flags); + /* Place on the response ring for the relevant domain. */ + switch (blkif->blk_protocol) { + case BLKIF_PROTOCOL_NATIVE: + memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt), + &resp, sizeof(resp)); + break; + case BLKIF_PROTOCOL_X86_32: + memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt), + &resp, sizeof(resp)); + break; + case BLKIF_PROTOCOL_X86_64: + memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt), + &resp, sizeof(resp)); + break; + default: + BUG(); + } + blk_rings->common.rsp_prod_pvt++; + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); + if (blk_rings->common.rsp_prod_pvt == blk_rings->common.req_cons) { + /* + * Tail check for pending requests. Allows frontend to avoid + * notifications if requests are already in flight (lower + * overheads and promotes batching). + */ + RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do); + + } else if (RING_HAS_UNCONSUMED_REQUESTS(&blk_rings->common)) { + more_to_do = 1; + } + + spin_unlock_irqrestore(&blkif->blk_ring_lock, flags); + + if (more_to_do) + blkif_notify_work(blkif); + if (notify) + notify_remote_via_irq(blkif->irq); +} + +static int __init xen_blkif_init(void) +{ + int i, mmap_pages; + int rc = 0; + + if (!xen_pv_domain()) + return -ENODEV; + + blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL); + if (!blkbk) { + pr_alert(DRV_PFX "%s: out of memory!\n", __func__); + return -ENOMEM; + } + + mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST; + + blkbk->pending_reqs = kmalloc(sizeof(blkbk->pending_reqs[0]) * + xen_blkif_reqs, GFP_KERNEL); + blkbk->pending_grant_handles = kzalloc(sizeof(blkbk->pending_grant_handles[0]) * + mmap_pages, GFP_KERNEL); + blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) * + mmap_pages, GFP_KERNEL); + + if (!blkbk->pending_reqs || !blkbk->pending_grant_handles || + !blkbk->pending_pages) { + rc = -ENOMEM; + goto out_of_memory; + } + + for (i = 0; i < mmap_pages; i++) { + blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE; + blkbk->pending_pages[i] = alloc_page(GFP_KERNEL); + if (blkbk->pending_pages[i] == NULL) { + rc = -ENOMEM; + goto out_of_memory; + } + } + rc = xen_blkif_interface_init(); + if (rc) + goto failed_init; + + memset(blkbk->pending_reqs, 0, sizeof(blkbk->pending_reqs)); + + INIT_LIST_HEAD(&blkbk->pending_free); + spin_lock_init(&blkbk->pending_free_lock); + init_waitqueue_head(&blkbk->pending_free_wq); + + for (i = 0; i < xen_blkif_reqs; i++) + list_add_tail(&blkbk->pending_reqs[i].free_list, + &blkbk->pending_free); + + rc = xen_blkif_xenbus_init(); + if (rc) + goto failed_init; + + return 0; + + out_of_memory: + pr_alert(DRV_PFX "%s: out of memory\n", __func__); + failed_init: + kfree(blkbk->pending_reqs); + kfree(blkbk->pending_grant_handles); + if (blkbk->pending_pages) { + for (i = 0; i < mmap_pages; i++) { + if (blkbk->pending_pages[i]) + __free_page(blkbk->pending_pages[i]); + } + kfree(blkbk->pending_pages); + } + kfree(blkbk); + blkbk = NULL; + return rc; +} + +module_init(xen_blkif_init); + +MODULE_LICENSE("Dual BSD/GPL"); diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h new file mode 100644 index 000000000000..9e40b283a468 --- /dev/null +++ b/drivers/block/xen-blkback/common.h @@ -0,0 +1,233 @@ +/* + * 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. + */ + +#ifndef __XEN_BLKIF__BACKEND__COMMON_H__ +#define __XEN_BLKIF__BACKEND__COMMON_H__ + +#include <linux/version.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/slab.h> +#include <linux/blkdev.h> +#include <linux/vmalloc.h> +#include <linux/wait.h> +#include <linux/io.h> +#include <asm/setup.h> +#include <asm/pgalloc.h> +#include <asm/hypervisor.h> +#include <xen/grant_table.h> +#include <xen/xenbus.h> +#include <xen/interface/io/ring.h> +#include <xen/interface/io/blkif.h> +#include <xen/interface/io/protocols.h> + +#define DRV_PFX "xen-blkback:" +#define DPRINTK(fmt, args...) \ + pr_debug(DRV_PFX "(%s:%d) " fmt ".\n", \ + __func__, __LINE__, ##args) + + +/* Not a real protocol. Used to generate ring structs which contain + * the elements common to all protocols only. This way we get a + * compiler-checkable way to use common struct elements, so we can + * avoid using switch(protocol) in a number of places. */ +struct blkif_common_request { + char dummy; +}; +struct blkif_common_response { + char dummy; +}; + +/* i386 protocol version */ +#pragma pack(push, 4) +struct blkif_x86_32_request { + uint8_t operation; /* BLKIF_OP_??? */ + uint8_t nr_segments; /* number of segments */ + blkif_vdev_t handle; /* only for read/write requests */ + uint64_t id; /* private guest value, echoed in resp */ + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; +}; +struct blkif_x86_32_response { + uint64_t id; /* copied from request */ + uint8_t operation; /* copied from request */ + int16_t status; /* BLKIF_RSP_??? */ +}; +#pragma pack(pop) + +/* x86_64 protocol version */ +struct blkif_x86_64_request { + uint8_t operation; /* BLKIF_OP_??? */ + uint8_t nr_segments; /* number of segments */ + blkif_vdev_t handle; /* only for read/write requests */ + uint64_t __attribute__((__aligned__(8))) id; + blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ + struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; +}; +struct blkif_x86_64_response { + uint64_t __attribute__((__aligned__(8))) id; + uint8_t operation; /* copied from request */ + int16_t status; /* BLKIF_RSP_??? */ +}; + +DEFINE_RING_TYPES(blkif_common, struct blkif_common_request, + struct blkif_common_response); +DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, + struct blkif_x86_32_response); +DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, + struct blkif_x86_64_response); + +union blkif_back_rings { + struct blkif_back_ring native; + struct blkif_common_back_ring common; + struct blkif_x86_32_back_ring x86_32; + struct blkif_x86_64_back_ring x86_64; +}; + +enum blkif_protocol { + BLKIF_PROTOCOL_NATIVE = 1, + BLKIF_PROTOCOL_X86_32 = 2, + BLKIF_PROTOCOL_X86_64 = 3, +}; + +struct xen_vbd { + /* What the domain refers to this vbd as. */ + blkif_vdev_t handle; + /* Non-zero -> read-only */ + unsigned char readonly; + /* VDISK_xxx */ + unsigned char type; + /* phys device that this vbd maps to. */ + u32 pdevice; + struct block_device *bdev; + /* Cached size parameter. */ + sector_t size; + bool flush_support; +}; + +struct backend_info; + +struct xen_blkif { + /* Unique identifier for this interface. */ + domid_t domid; + unsigned int handle; + /* Physical parameters of the comms window. */ + unsigned int irq; + /* Comms information. */ + enum blkif_protocol blk_protocol; + union blkif_back_rings blk_rings; + struct vm_struct *blk_ring_area; + /* The VBD attached to this interface. */ + struct xen_vbd vbd; + /* Back pointer to the backend_info. */ + struct backend_info *be; + /* Private fields. */ + spinlock_t blk_ring_lock; + atomic_t refcnt; + + wait_queue_head_t wq; + /* One thread per one blkif. */ + struct task_struct *xenblkd; + unsigned int waiting_reqs; + + /* statistics */ + unsigned long st_print; + int st_rd_req; + int st_wr_req; + int st_oo_req; + int st_f_req; + int st_rd_sect; + int st_wr_sect; + + wait_queue_head_t waiting_to_free; + + grant_handle_t shmem_handle; + grant_ref_t shmem_ref; +}; + + +#define vbd_sz(_v) ((_v)->bdev->bd_part ? \ + (_v)->bdev->bd_part->nr_sects : \ + get_capacity((_v)->bdev->bd_disk)) + +#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt)) +#define xen_blkif_put(_b) \ + do { \ + if (atomic_dec_and_test(&(_b)->refcnt)) \ + wake_up(&(_b)->waiting_to_free);\ + } while (0) + +struct phys_req { + unsigned short dev; + unsigned short nr_sects; + struct block_device *bdev; + blkif_sector_t sector_number; +}; +int xen_blkif_interface_init(void); + +int xen_blkif_xenbus_init(void); + +irqreturn_t xen_blkif_be_int(int irq, void *dev_id); +int xen_blkif_schedule(void *arg); + +int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, + struct backend_info *be, int state); + +struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be); + +static inline void blkif_get_x86_32_req(struct blkif_request *dst, + struct blkif_x86_32_request *src) +{ + int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; + dst->operation = src->operation; + dst->nr_segments = src->nr_segments; + dst->handle = src->handle; + dst->id = src->id; + dst->u.rw.sector_number = src->sector_number; + barrier(); + if (n > dst->nr_segments) + n = dst->nr_segments; + for (i = 0; i < n; i++) + dst->u.rw.seg[i] = src->seg[i]; +} + +static inline void blkif_get_x86_64_req(struct blkif_request *dst, + struct blkif_x86_64_request *src) +{ + int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; + dst->operation = src->operation; + dst->nr_segments = src->nr_segments; + dst->handle = src->handle; + dst->id = src->id; + dst->u.rw.sector_number = src->sector_number; + barrier(); + if (n > dst->nr_segments) + n = dst->nr_segments; + for (i = 0; i < n; i++) + dst->u.rw.seg[i] = src->seg[i]; +} + +#endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */ diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c new file mode 100644 index 000000000000..6cc0db1bf522 --- /dev/null +++ b/drivers/block/xen-blkback/xenbus.c @@ -0,0 +1,767 @@ +/* Xenbus code for blkif backend + Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au> + 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 as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + +*/ + +#include <stdarg.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <xen/events.h> +#include <xen/grant_table.h> +#include "common.h" + +struct backend_info { + struct xenbus_device *dev; + struct xen_blkif *blkif; + struct xenbus_watch backend_watch; + unsigned major; + unsigned minor; + char *mode; +}; + +static struct kmem_cache *xen_blkif_cachep; +static void connect(struct backend_info *); +static int connect_ring(struct backend_info *); +static void backend_changed(struct xenbus_watch *, const char **, + unsigned int); + +struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be) +{ + return be->dev; +} + +static int blkback_name(struct xen_blkif *blkif, char *buf) +{ + char *devpath, *devname; + struct xenbus_device *dev = blkif->be->dev; + + devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL); + if (IS_ERR(devpath)) + return PTR_ERR(devpath); + + devname = strstr(devpath, "/dev/"); + if (devname != NULL) + devname += strlen("/dev/"); + else + devname = devpath; + + snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname); + kfree(devpath); + + return 0; +} + +static void xen_update_blkif_status(struct xen_blkif *blkif) +{ + int err; + char name[TASK_COMM_LEN]; + + /* Not ready to connect? */ + if (!blkif->irq || !blkif->vbd.bdev) + return; + + /* Already connected? */ + if (blkif->be->dev->state == XenbusStateConnected) + return; + + /* Attempt to connect: exit if we fail to. */ + connect(blkif->be); + if (blkif->be->dev->state != XenbusStateConnected) + return; + + err = blkback_name(blkif, name); + if (err) { + xenbus_dev_error(blkif->be->dev, err, "get blkback dev name"); + return; + } + + err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping); + if (err) { + xenbus_dev_error(blkif->be->dev, err, "block flush"); + return; + } + invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping); + + blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, name); + if (IS_ERR(blkif->xenblkd)) { + err = PTR_ERR(blkif->xenblkd); + blkif->xenblkd = NULL; + xenbus_dev_error(blkif->be->dev, err, "start xenblkd"); + } +} + +static struct xen_blkif *xen_blkif_alloc(domid_t domid) +{ + struct xen_blkif *blkif; + + blkif = kmem_cache_alloc(xen_blkif_cachep, GFP_KERNEL); + if (!blkif) + return ERR_PTR(-ENOMEM); + + memset(blkif, 0, sizeof(*blkif)); + blkif->domid = domid; + spin_lock_init(&blkif->blk_ring_lock); + atomic_set(&blkif->refcnt, 1); + init_waitqueue_head(&blkif->wq); + blkif->st_print = jiffies; + init_waitqueue_head(&blkif->waiting_to_free); + + return blkif; +} + +static int map_frontend_page(struct xen_blkif *blkif, unsigned long shared_page) +{ + struct gnttab_map_grant_ref op; + + gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr, + GNTMAP_host_map, shared_page, blkif->domid); + + if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1)) + BUG(); + + if (op.status) { + DPRINTK("Grant table operation failure !\n"); + return op.status; + } + + blkif->shmem_ref = shared_page; + blkif->shmem_handle = op.handle; + + return 0; +} + +static void unmap_frontend_page(struct xen_blkif *blkif) +{ + struct gnttab_unmap_grant_ref op; + + gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr, + GNTMAP_host_map, blkif->shmem_handle); + + if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1)) + BUG(); +} + +static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page, + unsigned int evtchn) +{ + int err; + + /* Already connected through? */ + if (blkif->irq) + return 0; + + blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE); + if (!blkif->blk_ring_area) + return -ENOMEM; + + err = map_frontend_page(blkif, shared_page); + if (err) { + free_vm_area(blkif->blk_ring_area); + return err; + } + + switch (blkif->blk_protocol) { + case BLKIF_PROTOCOL_NATIVE: + { + struct blkif_sring *sring; + sring = (struct blkif_sring *)blkif->blk_ring_area->addr; + BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE); + break; + } + case BLKIF_PROTOCOL_X86_32: + { + struct blkif_x86_32_sring *sring_x86_32; + sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr; + BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE); + break; + } + case BLKIF_PROTOCOL_X86_64: + { + struct blkif_x86_64_sring *sring_x86_64; + sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr; + BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE); + break; + } + default: + BUG(); + } + + err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, + xen_blkif_be_int, 0, + "blkif-backend", blkif); + if (err < 0) { + unmap_frontend_page(blkif); + free_vm_area(blkif->blk_ring_area); + blkif->blk_rings.common.sring = NULL; + return err; + } + blkif->irq = err; + + return 0; +} + +static void xen_blkif_disconnect(struct xen_blkif *blkif) +{ + if (blkif->xenblkd) { + kthread_stop(blkif->xenblkd); + blkif->xenblkd = NULL; + } + + atomic_dec(&blkif->refcnt); + wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0); + atomic_inc(&blkif->refcnt); + + if (blkif->irq) { + unbind_from_irqhandler(blkif->irq, blkif); + blkif->irq = 0; + } + + if (blkif->blk_rings.common.sring) { + unmap_frontend_page(blkif); + free_vm_area(blkif->blk_ring_area); + blkif->blk_rings.common.sring = NULL; + } +} + +void xen_blkif_free(struct xen_blkif *blkif) +{ + if (!atomic_dec_and_test(&blkif->refcnt)) + BUG(); + kmem_cache_free(xen_blkif_cachep, blkif); +} + +int __init xen_blkif_interface_init(void) +{ + xen_blkif_cachep = kmem_cache_create("blkif_cache", + sizeof(struct xen_blkif), + 0, 0, NULL); + if (!xen_blkif_cachep) + return -ENOMEM; + + return 0; +} + +/* + * sysfs interface for VBD I/O requests + */ + +#define VBD_SHOW(name, format, args...) \ + static ssize_t show_##name(struct device *_dev, \ + struct device_attribute *attr, \ + char *buf) \ + { \ + struct xenbus_device *dev = to_xenbus_device(_dev); \ + struct backend_info *be = dev_get_drvdata(&dev->dev); \ + \ + return sprintf(buf, format, ##args); \ + } \ + static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) + +VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req); +VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req); +VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req); +VBD_SHOW(f_req, "%d\n", be->blkif->st_f_req); +VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect); +VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect); + +static struct attribute *xen_vbdstat_attrs[] = { + &dev_attr_oo_req.attr, + &dev_attr_rd_req.attr, + &dev_attr_wr_req.attr, + &dev_attr_f_req.attr, + &dev_attr_rd_sect.attr, + &dev_attr_wr_sect.attr, + NULL +}; + +static struct attribute_group xen_vbdstat_group = { + .name = "statistics", + .attrs = xen_vbdstat_attrs, +}; + +VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); +VBD_SHOW(mode, "%s\n", be->mode); + +int xenvbd_sysfs_addif(struct xenbus_device *dev) +{ + int error; + + error = device_create_file(&dev->dev, &dev_attr_physical_device); + if (error) + goto fail1; + + error = device_create_file(&dev->dev, &dev_attr_mode); + if (error) + goto fail2; + + error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); + if (error) + goto fail3; + + return 0; + +fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); +fail2: device_remove_file(&dev->dev, &dev_attr_mode); +fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); + return error; +} + +void xenvbd_sysfs_delif(struct xenbus_device *dev) +{ + sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); + device_remove_file(&dev->dev, &dev_attr_mode); + device_remove_file(&dev->dev, &dev_attr_physical_device); +} + + +static void xen_vbd_free(struct xen_vbd *vbd) +{ + if (vbd->bdev) + blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); + vbd->bdev = NULL; +} + +static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, + unsigned major, unsigned minor, int readonly, + int cdrom) +{ + struct xen_vbd *vbd; + struct block_device *bdev; + struct request_queue *q; + + vbd = &blkif->vbd; + vbd->handle = handle; + vbd->readonly = readonly; + vbd->type = 0; + + vbd->pdevice = MKDEV(major, minor); + + bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? + FMODE_READ : FMODE_WRITE, NULL); + + if (IS_ERR(bdev)) { + DPRINTK("xen_vbd_create: device %08x could not be opened.\n", + vbd->pdevice); + return -ENOENT; + } + + vbd->bdev = bdev; + if (vbd->bdev->bd_disk == NULL) { + DPRINTK("xen_vbd_create: device %08x doesn't exist.\n", + vbd->pdevice); + xen_vbd_free(vbd); + return -ENOENT; + } + vbd->size = vbd_sz(vbd); + + if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) + vbd->type |= VDISK_CDROM; + if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) + vbd->type |= VDISK_REMOVABLE; + + q = bdev_get_queue(bdev); + if (q && q->flush_flags) + vbd->flush_support = true; + + DPRINTK("Successful creation of handle=%04x (dom=%u)\n", + handle, blkif->domid); + return 0; +} +static int xen_blkbk_remove(struct xenbus_device *dev) +{ + struct backend_info *be = dev_get_drvdata(&dev->dev); + + DPRINTK(""); + + if (be->major || be->minor) + xenvbd_sysfs_delif(dev); + + if (be->backend_watch.node) { + unregister_xenbus_watch(&be->backend_watch); + kfree(be->backend_watch.node); + be->backend_watch.node = NULL; + } + + if (be->blkif) { + xen_blkif_disconnect(be->blkif); + xen_vbd_free(&be->blkif->vbd); + xen_blkif_free(be->blkif); + be->blkif = NULL; + } + + kfree(be); + dev_set_drvdata(&dev->dev, NULL); + return 0; +} + +int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, + struct backend_info *be, int state) +{ + struct xenbus_device *dev = be->dev; + int err; + + err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", + "%d", state); + if (err) + xenbus_dev_fatal(dev, err, "writing feature-flush-cache"); + + return err; +} + +/* + * Entry point to this code when a new device is created. Allocate the basic + * structures, and watch the store waiting for the hotplug scripts to tell us + * the device's physical major and minor numbers. Switch to InitWait. + */ +static int xen_blkbk_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + int err; + struct backend_info *be = kzalloc(sizeof(struct backend_info), + GFP_KERNEL); + if (!be) { + xenbus_dev_fatal(dev, -ENOMEM, + "allocating backend structure"); + return -ENOMEM; + } + be->dev = dev; + dev_set_drvdata(&dev->dev, be); + + be->blkif = xen_blkif_alloc(dev->otherend_id); + if (IS_ERR(be->blkif)) { + err = PTR_ERR(be->blkif); + be->blkif = NULL; + xenbus_dev_fatal(dev, err, "creating block interface"); + goto fail; + } + + /* setup back pointer */ + be->blkif->be = be; + + err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, + "%s/%s", dev->nodename, "physical-device"); + if (err) + goto fail; + + err = xenbus_switch_state(dev, XenbusStateInitWait); + if (err) + goto fail; + + return 0; + +fail: + DPRINTK("failed"); + xen_blkbk_remove(dev); + return err; +} + + +/* + * Callback received when the hotplug scripts have placed the physical-device + * node. Read it and the mode node, and create a vbd. If the frontend is + * ready, connect. + */ +static void backend_changed(struct xenbus_watch *watch, + const char **vec, unsigned int len) +{ + int err; + unsigned major; + unsigned minor; + struct backend_info *be + = container_of(watch, struct backend_info, backend_watch); + struct xenbus_device *dev = be->dev; + int cdrom = 0; + char *device_type; + + DPRINTK(""); + + err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", + &major, &minor); + if (XENBUS_EXIST_ERR(err)) { + /* + * Since this watch will fire once immediately after it is + * registered, we expect this. Ignore it, and wait for the + * hotplug scripts. + */ + return; + } + if (err != 2) { + xenbus_dev_fatal(dev, err, "reading physical-device"); + return; + } + + if ((be->major || be->minor) && + ((be->major != major) || (be->minor != minor))) { + pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n", + be->major, be->minor, major, minor); + return; + } + + be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); + if (IS_ERR(be->mode)) { + err = PTR_ERR(be->mode); + be->mode = NULL; + xenbus_dev_fatal(dev, err, "reading mode"); + return; + } + + device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); + if (!IS_ERR(device_type)) { + cdrom = strcmp(device_type, "cdrom") == 0; + kfree(device_type); + } + + if (be->major == 0 && be->minor == 0) { + /* Front end dir is a number, which is used as the handle. */ + + char *p = strrchr(dev->otherend, '/') + 1; + long handle; + err = strict_strtoul(p, 0, &handle); + if (err) + return; + + be->major = major; + be->minor = minor; + + err = xen_vbd_create(be->blkif, handle, major, minor, + (NULL == strchr(be->mode, 'w')), cdrom); + if (err) { + be->major = 0; + be->minor = 0; + xenbus_dev_fatal(dev, err, "creating vbd structure"); + return; + } + + err = xenvbd_sysfs_addif(dev); + if (err) { + xen_vbd_free(&be->blkif->vbd); + be->major = 0; + be->minor = 0; + xenbus_dev_fatal(dev, err, "creating sysfs entries"); + return; + } + + /* We're potentially connected now */ + xen_update_blkif_status(be->blkif); + } +} + + +/* + * Callback received when the frontend's state changes. + */ +static void frontend_changed(struct xenbus_device *dev, + enum xenbus_state frontend_state) +{ + struct backend_info *be = dev_get_drvdata(&dev->dev); + int err; + + DPRINTK("%s", xenbus_strstate(frontend_state)); + + switch (frontend_state) { + case XenbusStateInitialising: + if (dev->state == XenbusStateClosed) { + pr_info(DRV_PFX "%s: prepare for reconnect\n", + dev->nodename); + xenbus_switch_state(dev, XenbusStateInitWait); + } + break; + + case XenbusStateInitialised: + case XenbusStateConnected: + /* + * Ensure we connect even when two watches fire in + * close successsion and we miss the intermediate value + * of frontend_state. + */ + if (dev->state == XenbusStateConnected) + break; + + /* + * Enforce precondition before potential leak point. + * blkif_disconnect() is idempotent. + */ + xen_blkif_disconnect(be->blkif); + + err = connect_ring(be); + if (err) + break; + xen_update_blkif_status(be->blkif); + break; + + case XenbusStateClosing: + xen_blkif_disconnect(be->blkif); + xenbus_switch_state(dev, XenbusStateClosing); + break; + + case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + /* fall through if not online */ + case XenbusStateUnknown: + /* implies blkif_disconnect() via blkback_remove() */ + device_unregister(&dev->dev); + break; + + default: + xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", + frontend_state); + break; + } +} + + +/* ** Connection ** */ + + +/* + * Write the physical details regarding the block device to the store, and + * switch to Connected state. + */ +static void connect(struct backend_info *be) +{ + struct xenbus_transaction xbt; + int err; + struct xenbus_device *dev = be->dev; + + DPRINTK("%s", dev->otherend); + + /* Supply the information about the device the frontend needs */ +again: + err = xenbus_transaction_start(&xbt); + if (err) { + xenbus_dev_fatal(dev, err, "starting transaction"); + return; + } + + err = xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); + if (err) + goto abort; + + err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", + (unsigned long long)vbd_sz(&be->blkif->vbd)); + if (err) { + xenbus_dev_fatal(dev, err, "writing %s/sectors", + dev->nodename); + goto abort; + } + + /* FIXME: use a typename instead */ + err = xenbus_printf(xbt, dev->nodename, "info", "%u", + be->blkif->vbd.type | + (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); + if (err) { + xenbus_dev_fatal(dev, err, "writing %s/info", + dev->nodename); + goto abort; + } + err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", + (unsigned long) + bdev_logical_block_size(be->blkif->vbd.bdev)); + if (err) { + xenbus_dev_fatal(dev, err, "writing %s/sector-size", + dev->nodename); + goto abort; + } + + err = xenbus_transaction_end(xbt, 0); + if (err == -EAGAIN) + goto again; + if (err) + xenbus_dev_fatal(dev, err, "ending transaction"); + + err = xenbus_switch_state(dev, XenbusStateConnected); + if (err) + xenbus_dev_fatal(dev, err, "switching to Connected state", + dev->nodename); + + return; + abort: + xenbus_transaction_end(xbt, 1); +} + + +static int connect_ring(struct backend_info *be) +{ + struct xenbus_device *dev = be->dev; + unsigned long ring_ref; + unsigned int evtchn; + char protocol[64] = ""; + int err; + + DPRINTK("%s", dev->otherend); + + err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu", + &ring_ref, "event-channel", "%u", &evtchn, NULL); + if (err) { + xenbus_dev_fatal(dev, err, + "reading %s/ring-ref and event-channel", + dev->otherend); + return err; + } + + be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; + err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", + "%63s", protocol, NULL); + if (err) + strcpy(protocol, "unspecified, assuming native"); + else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) + be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; + else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) + be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; + else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) + be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; + else { + xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); + return -1; + } + pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n", + ring_ref, evtchn, be->blkif->blk_protocol, protocol); + + /* Map the shared frame, irq etc. */ + err = xen_blkif_map(be->blkif, ring_ref, evtchn); + if (err) { + xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u", + ring_ref, evtchn); + return err; + } + + return 0; +} + + +/* ** Driver Registration ** */ + + +static const struct xenbus_device_id xen_blkbk_ids[] = { + { "vbd" }, + { "" } +}; + + +static struct xenbus_driver xen_blkbk = { + .name = "vbd", + .owner = THIS_MODULE, + .ids = xen_blkbk_ids, + .probe = xen_blkbk_probe, + .remove = xen_blkbk_remove, + .otherend_changed = frontend_changed +}; + + +int xen_blkif_xenbus_init(void) +{ + return xenbus_register_backend(&xen_blkbk); +} |