Merge branches 'for-jens/xen-backend-fixes' and 'for-jens/xen-blkback-v3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-2.6.40/drivers
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 83c32cb..717d6e4 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -470,6 +470,27 @@
block device driver. It communicates with a back-end driver
in another domain which drives the actual block device.
+config XEN_BLKDEV_BACKEND
+ tristate "Block-device backend driver"
+ depends on XEN_BACKEND
+ help
+ The block-device backend driver allows the kernel to export its
+ block devices to other guests via a high-performance shared-memory
+ interface.
+
+ The corresponding Linux frontend driver is enabled by the
+ CONFIG_XEN_BLKDEV_FRONTEND configuration option.
+
+ The backend driver attaches itself to a any block device specified
+ in the XenBus configuration. There are no limits to what the block
+ device as long as it has a major and minor.
+
+ If you are compiling a kernel to run in a Xen block backend driver
+ domain (often this is domain 0) you should say Y here. To
+ compile this driver as a module, chose M here: the module
+ will be called xen-blkback.
+
+
config VIRTIO_BLK
tristate "Virtio block driver (EXPERIMENTAL)"
depends on EXPERIMENTAL && VIRTIO
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 40528ba..76646e9 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -36,6 +36,7 @@
obj-$(CONFIG_BLK_DEV_HD) += hd.o
obj-$(CONFIG_XEN_BLKDEV_FRONTEND) += xen-blkfront.o
+obj-$(CONFIG_XEN_BLKDEV_BACKEND) += xen-blkback/
obj-$(CONFIG_BLK_DEV_DRBD) += drbd/
obj-$(CONFIG_BLK_DEV_RBD) += rbd.o
diff --git a/drivers/block/xen-blkback/Makefile b/drivers/block/xen-blkback/Makefile
new file mode 100644
index 0000000..e491c1b
--- /dev/null
+++ b/drivers/block/xen-blkback/Makefile
@@ -0,0 +1,3 @@
+obj-$(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 0000000..c73910c
--- /dev/null
+++ b/drivers/block/xen-blkback/blkback.c
@@ -0,0 +1,824 @@
+/******************************************************************************
+ *
+ * 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);
+ 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 0000000..9e40b28
--- /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 0000000..3457082
--- /dev/null
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -0,0 +1,768 @@
+/* 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;
+ vbd->size = vbd_sz(vbd);
+
+ if (vbd->bdev->bd_disk == NULL) {
+ DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
+ vbd->pdevice);
+ xen_vbd_free(vbd);
+ return -ENOENT;
+ }
+
+ 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);
+}