diff options
Diffstat (limited to 'drivers/block/xen-blkback/xenbus.c')
| -rw-r--r-- | drivers/block/xen-blkback/xenbus.c | 934 |
1 files changed, 934 insertions, 0 deletions
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c new file mode 100644 index 000000000..6ab69ad61 --- /dev/null +++ b/drivers/block/xen-blkback/xenbus.c @@ -0,0 +1,934 @@ +/* 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. + +*/ + +#define pr_fmt(fmt) "xen-blkback: " fmt + +#include <stdarg.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <xen/events.h> +#include <xen/grant_table.h> +#include "common.h" + +/* Enlarge the array size in order to fully show blkback name. */ +#define BLKBACK_NAME_LEN (20) + +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); +static void xen_blkif_free(struct xen_blkif *blkif); +static void xen_vbd_free(struct xen_vbd *vbd); + +struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be) +{ + return be->dev; +} + +/* + * The last request could free the device from softirq context and + * xen_blkif_free() can sleep. + */ +static void xen_blkif_deferred_free(struct work_struct *work) +{ + struct xen_blkif *blkif; + + blkif = container_of(work, struct xen_blkif, free_work); + xen_blkif_free(blkif); +} + +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, BLKBACK_NAME_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[BLKBACK_NAME_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, "%s", name); + if (IS_ERR(blkif->xenblkd)) { + err = PTR_ERR(blkif->xenblkd); + blkif->xenblkd = NULL; + xenbus_dev_error(blkif->be->dev, err, "start xenblkd"); + return; + } +} + +static struct xen_blkif *xen_blkif_alloc(domid_t domid) +{ + struct xen_blkif *blkif; + struct pending_req *req, *n; + int i, j; + + BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); + + blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL); + if (!blkif) + return ERR_PTR(-ENOMEM); + + blkif->domid = domid; + spin_lock_init(&blkif->blk_ring_lock); + atomic_set(&blkif->refcnt, 1); + init_waitqueue_head(&blkif->wq); + init_completion(&blkif->drain_complete); + atomic_set(&blkif->drain, 0); + blkif->st_print = jiffies; + blkif->persistent_gnts.rb_node = NULL; + spin_lock_init(&blkif->free_pages_lock); + INIT_LIST_HEAD(&blkif->free_pages); + INIT_LIST_HEAD(&blkif->persistent_purge_list); + blkif->free_pages_num = 0; + atomic_set(&blkif->persistent_gnt_in_use, 0); + atomic_set(&blkif->inflight, 0); + INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants); + + INIT_LIST_HEAD(&blkif->pending_free); + INIT_WORK(&blkif->free_work, xen_blkif_deferred_free); + + for (i = 0; i < XEN_BLKIF_REQS; i++) { + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + goto fail; + list_add_tail(&req->free_list, + &blkif->pending_free); + for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { + req->segments[j] = kzalloc(sizeof(*req->segments[0]), + GFP_KERNEL); + if (!req->segments[j]) + goto fail; + } + for (j = 0; j < MAX_INDIRECT_PAGES; j++) { + req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]), + GFP_KERNEL); + if (!req->indirect_pages[j]) + goto fail; + } + } + spin_lock_init(&blkif->pending_free_lock); + init_waitqueue_head(&blkif->pending_free_wq); + init_waitqueue_head(&blkif->shutdown_wq); + + return blkif; + +fail: + list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) { + list_del(&req->free_list); + for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { + if (!req->segments[j]) + break; + kfree(req->segments[j]); + } + for (j = 0; j < MAX_INDIRECT_PAGES; j++) { + if (!req->indirect_pages[j]) + break; + kfree(req->indirect_pages[j]); + } + kfree(req); + } + + kmem_cache_free(xen_blkif_cachep, blkif); + + return ERR_PTR(-ENOMEM); +} + +static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t gref, + unsigned int evtchn) +{ + int err; + + /* Already connected through? */ + if (blkif->irq) + return 0; + + err = xenbus_map_ring_valloc(blkif->be->dev, &gref, 1, + &blkif->blk_ring); + if (err < 0) + return err; + + switch (blkif->blk_protocol) { + case BLKIF_PROTOCOL_NATIVE: + { + struct blkif_sring *sring; + sring = (struct blkif_sring *)blkif->blk_ring; + 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; + 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; + 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) { + xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); + blkif->blk_rings.common.sring = NULL; + return err; + } + blkif->irq = err; + + return 0; +} + +static int xen_blkif_disconnect(struct xen_blkif *blkif) +{ + if (blkif->xenblkd) { + kthread_stop(blkif->xenblkd); + wake_up(&blkif->shutdown_wq); + blkif->xenblkd = NULL; + } + + /* The above kthread_stop() guarantees that at this point we + * don't have any discard_io or other_io requests. So, checking + * for inflight IO is enough. + */ + if (atomic_read(&blkif->inflight) > 0) + return -EBUSY; + + if (blkif->irq) { + unbind_from_irqhandler(blkif->irq, blkif); + blkif->irq = 0; + } + + if (blkif->blk_rings.common.sring) { + xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); + blkif->blk_rings.common.sring = NULL; + } + + /* Remove all persistent grants and the cache of ballooned pages. */ + xen_blkbk_free_caches(blkif); + + return 0; +} + +static void xen_blkif_free(struct xen_blkif *blkif) +{ + struct pending_req *req, *n; + int i = 0, j; + + xen_blkif_disconnect(blkif); + xen_vbd_free(&blkif->vbd); + + /* Make sure everything is drained before shutting down */ + BUG_ON(blkif->persistent_gnt_c != 0); + BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0); + BUG_ON(blkif->free_pages_num != 0); + BUG_ON(!list_empty(&blkif->persistent_purge_list)); + BUG_ON(!list_empty(&blkif->free_pages)); + BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); + + /* Check that there is no request in use */ + list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) { + list_del(&req->free_list); + + for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) + kfree(req->segments[j]); + + for (j = 0; j < MAX_INDIRECT_PAGES; j++) + kfree(req->indirect_pages[j]); + + kfree(req); + i++; + } + + WARN_ON(i != XEN_BLKIF_REQS); + + 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, "%llu\n", be->blkif->st_oo_req); +VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req); +VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req); +VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req); +VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req); +VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect); +VBD_SHOW(wr_sect, "%llu\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_ds_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); + +static 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; +} + +static 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)) { + pr_warn("xen_vbd_create: device %08x could not be opened\n", + vbd->pdevice); + return -ENOENT; + } + + vbd->bdev = bdev; + if (vbd->bdev->bd_disk == NULL) { + pr_warn("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; + + if (q && blk_queue_secdiscard(q)) + vbd->discard_secure = true; + + pr_debug("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); + + pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); + + 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; + } + + dev_set_drvdata(&dev->dev, NULL); + + if (be->blkif) { + xen_blkif_disconnect(be->blkif); + xen_blkif_put(be->blkif); + } + + kfree(be->mode); + kfree(be); + 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) + dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); + + return err; +} + +static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) +{ + struct xenbus_device *dev = be->dev; + struct xen_blkif *blkif = be->blkif; + int err; + int state = 0, discard_enable; + struct block_device *bdev = be->blkif->vbd.bdev; + struct request_queue *q = bdev_get_queue(bdev); + + err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d", + &discard_enable); + if (err == 1 && !discard_enable) + return; + + if (blk_queue_discard(q)) { + err = xenbus_printf(xbt, dev->nodename, + "discard-granularity", "%u", + q->limits.discard_granularity); + if (err) { + dev_warn(&dev->dev, "writing discard-granularity (%d)", err); + return; + } + err = xenbus_printf(xbt, dev->nodename, + "discard-alignment", "%u", + q->limits.discard_alignment); + if (err) { + dev_warn(&dev->dev, "writing discard-alignment (%d)", err); + return; + } + state = 1; + /* Optional. */ + err = xenbus_printf(xbt, dev->nodename, + "discard-secure", "%d", + blkif->vbd.discard_secure); + if (err) { + dev_warn(&dev->dev, "writing discard-secure (%d)", err); + return; + } + } + err = xenbus_printf(xbt, dev->nodename, "feature-discard", + "%d", state); + if (err) + dev_warn(&dev->dev, "writing feature-discard (%d)", err); +} +int xen_blkbk_barrier(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-barrier", + "%d", state); + if (err) + dev_warn(&dev->dev, "writing feature-barrier (%d)", err); + + 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); + + /* match the pr_debug in xen_blkbk_remove */ + pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); + + 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: + pr_warn("%s failed\n", __func__); + 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; + unsigned long handle; + char *device_type; + + pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); + + 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) { + if (be->major != major || be->minor != minor) + pr_warn("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); + } + + /* Front end dir is a number, which is used as the handle. */ + err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle); + if (err) + return; + + be->major = major; + be->minor = minor; + + err = xen_vbd_create(be->blkif, handle, major, minor, + !strchr(be->mode, 'w'), cdrom); + + if (err) + xenbus_dev_fatal(dev, err, "creating vbd structure"); + else { + err = xenvbd_sysfs_addif(dev); + if (err) { + xen_vbd_free(&be->blkif->vbd); + xenbus_dev_fatal(dev, err, "creating sysfs entries"); + } + } + + if (err) { + kfree(be->mode); + be->mode = NULL; + be->major = 0; + be->minor = 0; + } else { + /* 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; + + pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state)); + + switch (frontend_state) { + case XenbusStateInitialising: + if (dev->state == XenbusStateClosed) { + pr_info("%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 succession and we miss the intermediate value + * of frontend_state. + */ + if (dev->state == XenbusStateConnected) + break; + + /* + * Enforce precondition before potential leak point. + * xen_blkif_disconnect() is idempotent. + */ + err = xen_blkif_disconnect(be->blkif); + if (err) { + xenbus_dev_fatal(dev, err, "pending I/O"); + break; + } + + err = connect_ring(be); + if (err) + break; + xen_update_blkif_status(be->blkif); + break; + + case XenbusStateClosing: + xenbus_switch_state(dev, XenbusStateClosing); + break; + + case XenbusStateClosed: + xen_blkif_disconnect(be->blkif); + xenbus_switch_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + /* fall through if not online */ + case XenbusStateUnknown: + /* implies xen_blkif_disconnect() via xen_blkbk_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; + + pr_debug("%s %s\n", __func__, 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; + } + + /* If we can't advertise it is OK. */ + xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); + + xen_blkbk_discard(xbt, be); + + xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); + + err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); + if (err) { + xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", + dev->nodename); + goto abort; + } + err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u", + MAX_INDIRECT_SEGMENTS); + if (err) + dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)", + dev->nodename, err); + + 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_printf(xbt, dev->nodename, "physical-sector-size", "%u", + bdev_physical_block_size(be->blkif->vbd.bdev)); + if (err) + xenbus_dev_error(dev, err, "writing %s/physical-sector-size", + dev->nodename); + + 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, "%s: 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; + unsigned int pers_grants; + char protocol[64] = ""; + int err; + + pr_debug("%s %s\n", __func__, 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_DEFAULT; + err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", + "%63s", protocol, NULL); + if (err) + strcpy(protocol, "unspecified, assuming default"); + 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; + } + err = xenbus_gather(XBT_NIL, dev->otherend, + "feature-persistent", "%u", + &pers_grants, NULL); + if (err) + pers_grants = 0; + + be->blkif->vbd.feature_gnt_persistent = pers_grants; + be->blkif->vbd.overflow_max_grants = 0; + + pr_info("ring-ref %ld, event-channel %d, protocol %d (%s) %s\n", + ring_ref, evtchn, be->blkif->blk_protocol, protocol, + pers_grants ? "persistent grants" : ""); + + /* 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; +} + +static const struct xenbus_device_id xen_blkbk_ids[] = { + { "vbd" }, + { "" } +}; + +static struct xenbus_driver xen_blkbk_driver = { + .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_driver); +} |