--- /dev/null
+/******************************************************************************
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) "xen-blkback: " fmt
+
+#include <linux/spinlock.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <linux/bitmap.h>
+
+#include <xen/events.h>
+#include <xen/page.h>
+#include <xen/xen.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+#include <xen/balloon.h>
+#include <xen/grant_table.h>
+#include "common.h"
+
+/*
+ * Maximum number of unused free pages to keep in the internal buffer.
+ * Setting this to a value too low will reduce memory used in each backend,
+ * but can have a performance penalty.
+ *
+ * A sane value is xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST, but can
+ * be set to a lower value that might degrade performance on some intensive
+ * IO workloads.
+ */
+
+static int xen_blkif_max_buffer_pages = 1024;
+module_param_named(max_buffer_pages, xen_blkif_max_buffer_pages, int, 0644);
+MODULE_PARM_DESC(max_buffer_pages,
+"Maximum number of free pages to keep in each block backend buffer");
+
+/*
+ * Maximum number of grants to map persistently in blkback. For maximum
+ * performance this should be the total numbers of grants that can be used
+ * to fill the ring, but since this might become too high, specially with
+ * the use of indirect descriptors, we set it to a value that provides good
+ * performance without using too much memory.
+ *
+ * When the list of persistent grants is full we clean it up using a LRU
+ * algorithm.
+ */
+
+static int xen_blkif_max_pgrants = 1056;
+module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644);
+MODULE_PARM_DESC(max_persistent_grants,
+ "Maximum number of grants to map persistently");
+
+/*
+ * The LRU mechanism to clean the lists of persistent grants needs to
+ * be executed periodically. The time interval between consecutive executions
+ * of the purge mechanism is set in ms.
+ */
+#define LRU_INTERVAL 100
+
+/*
+ * When the persistent grants list is full we will remove unused grants
+ * from the list. The percent number of grants to be removed at each LRU
+ * execution.
+ */
+#define LRU_PERCENT_CLEAN 5
+
+/* Run-time switchable: /sys/module/blkback/parameters/ */
+static unsigned int log_stats;
+module_param(log_stats, int, 0644);
+
+#define BLKBACK_INVALID_HANDLE (~0)
+
+/* Number of free pages to remove on each call to gnttab_free_pages */
+#define NUM_BATCH_FREE_PAGES 10
+
+static inline int get_free_page(struct xen_blkif *blkif, struct page **page)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ if (list_empty(&blkif->free_pages)) {
+ BUG_ON(blkif->free_pages_num != 0);
+ spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ return gnttab_alloc_pages(1, page);
+ }
+ BUG_ON(blkif->free_pages_num == 0);
+ page[0] = list_first_entry(&blkif->free_pages, struct page, lru);
+ list_del(&page[0]->lru);
+ blkif->free_pages_num--;
+ spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+
+ return 0;
+}
+
+static inline void put_free_pages(struct xen_blkif *blkif, struct page **page,
+ int num)
+{
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ for (i = 0; i < num; i++)
+ list_add(&page[i]->lru, &blkif->free_pages);
+ blkif->free_pages_num += num;
+ spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+}
+
+static inline void shrink_free_pagepool(struct xen_blkif *blkif, int num)
+{
+ /* Remove requested pages in batches of NUM_BATCH_FREE_PAGES */
+ struct page *page[NUM_BATCH_FREE_PAGES];
+ unsigned int num_pages = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ while (blkif->free_pages_num > num) {
+ BUG_ON(list_empty(&blkif->free_pages));
+ page[num_pages] = list_first_entry(&blkif->free_pages,
+ struct page, lru);
+ list_del(&page[num_pages]->lru);
+ blkif->free_pages_num--;
+ if (++num_pages == NUM_BATCH_FREE_PAGES) {
+ spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ gnttab_free_pages(num_pages, page);
+ spin_lock_irqsave(&blkif->free_pages_lock, flags);
+ num_pages = 0;
+ }
+ }
+ spin_unlock_irqrestore(&blkif->free_pages_lock, flags);
+ if (num_pages != 0)
+ gnttab_free_pages(num_pages, page);
+}
+
+#define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page)))
+
+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);
+
+#define foreach_grant_safe(pos, n, rbtree, node) \
+ for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
+ (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL; \
+ &(pos)->node != NULL; \
+ (pos) = container_of(n, typeof(*(pos)), node), \
+ (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
+
+
+/*
+ * We don't need locking around the persistent grant helpers
+ * because blkback uses a single-thread for each backed, so we
+ * can be sure that this functions will never be called recursively.
+ *
+ * The only exception to that is put_persistent_grant, that can be called
+ * from interrupt context (by xen_blkbk_unmap), so we have to use atomic
+ * bit operations to modify the flags of a persistent grant and to count
+ * the number of used grants.
+ */
+static int add_persistent_gnt(struct xen_blkif *blkif,
+ struct persistent_gnt *persistent_gnt)
+{
+ struct rb_node **new = NULL, *parent = NULL;
+ struct persistent_gnt *this;
+
+ if (blkif->persistent_gnt_c >= xen_blkif_max_pgrants) {
+ if (!blkif->vbd.overflow_max_grants)
+ blkif->vbd.overflow_max_grants = 1;
+ return -EBUSY;
+ }
+ /* Figure out where to put new node */
+ new = &blkif->persistent_gnts.rb_node;
+ while (*new) {
+ this = container_of(*new, struct persistent_gnt, node);
+
+ parent = *new;
+ if (persistent_gnt->gnt < this->gnt)
+ new = &((*new)->rb_left);
+ else if (persistent_gnt->gnt > this->gnt)
+ new = &((*new)->rb_right);
+ else {
+ pr_alert_ratelimited("trying to add a gref that's already in the tree\n");
+ return -EINVAL;
+ }
+ }
+
+ bitmap_zero(persistent_gnt->flags, PERSISTENT_GNT_FLAGS_SIZE);
+ set_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
+ /* Add new node and rebalance tree. */
+ rb_link_node(&(persistent_gnt->node), parent, new);
+ rb_insert_color(&(persistent_gnt->node), &blkif->persistent_gnts);
+ blkif->persistent_gnt_c++;
+ atomic_inc(&blkif->persistent_gnt_in_use);
+ return 0;
+}
+
+static struct persistent_gnt *get_persistent_gnt(struct xen_blkif *blkif,
+ grant_ref_t gref)
+{
+ struct persistent_gnt *data;
+ struct rb_node *node = NULL;
+
+ node = blkif->persistent_gnts.rb_node;
+ while (node) {
+ data = container_of(node, struct persistent_gnt, node);
+
+ if (gref < data->gnt)
+ node = node->rb_left;
+ else if (gref > data->gnt)
+ node = node->rb_right;
+ else {
+ if(test_bit(PERSISTENT_GNT_ACTIVE, data->flags)) {
+ pr_alert_ratelimited("requesting a grant already in use\n");
+ return NULL;
+ }
+ set_bit(PERSISTENT_GNT_ACTIVE, data->flags);
+ atomic_inc(&blkif->persistent_gnt_in_use);
+ return data;
+ }
+ }
+ return NULL;
+}
+
+static void put_persistent_gnt(struct xen_blkif *blkif,
+ struct persistent_gnt *persistent_gnt)
+{
+ if(!test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
+ pr_alert_ratelimited("freeing a grant already unused\n");
+ set_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
+ clear_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags);
+ atomic_dec(&blkif->persistent_gnt_in_use);
+}
+
+static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
+ unsigned int num)
+{
+ struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct persistent_gnt *persistent_gnt;
+ struct rb_node *n;
+ int segs_to_unmap = 0;
+ struct gntab_unmap_queue_data unmap_data;
+
+ unmap_data.pages = pages;
+ unmap_data.unmap_ops = unmap;
+ unmap_data.kunmap_ops = NULL;
+
+ foreach_grant_safe(persistent_gnt, n, root, node) {
+ BUG_ON(persistent_gnt->handle ==
+ BLKBACK_INVALID_HANDLE);
+ gnttab_set_unmap_op(&unmap[segs_to_unmap],
+ (unsigned long) pfn_to_kaddr(page_to_pfn(
+ persistent_gnt->page)),
+ GNTMAP_host_map,
+ persistent_gnt->handle);
+
+ pages[segs_to_unmap] = persistent_gnt->page;
+
+ if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
+ !rb_next(&persistent_gnt->node)) {
+
+ unmap_data.count = segs_to_unmap;
+ BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
+
+ put_free_pages(blkif, pages, segs_to_unmap);
+ segs_to_unmap = 0;
+ }
+
+ rb_erase(&persistent_gnt->node, root);
+ kfree(persistent_gnt);
+ num--;
+ }
+ BUG_ON(num != 0);
+}
+
+void xen_blkbk_unmap_purged_grants(struct work_struct *work)
+{
+ struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct persistent_gnt *persistent_gnt;
+ int segs_to_unmap = 0;
+ struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
+ struct gntab_unmap_queue_data unmap_data;
+
+ unmap_data.pages = pages;
+ unmap_data.unmap_ops = unmap;
+ unmap_data.kunmap_ops = NULL;
+
+ while(!list_empty(&blkif->persistent_purge_list)) {
+ persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
+ struct persistent_gnt,
+ remove_node);
+ list_del(&persistent_gnt->remove_node);
+
+ gnttab_set_unmap_op(&unmap[segs_to_unmap],
+ vaddr(persistent_gnt->page),
+ GNTMAP_host_map,
+ persistent_gnt->handle);
+
+ pages[segs_to_unmap] = persistent_gnt->page;
+
+ if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
+ unmap_data.count = segs_to_unmap;
+ BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
+ put_free_pages(blkif, pages, segs_to_unmap);
+ segs_to_unmap = 0;
+ }
+ kfree(persistent_gnt);
+ }
+ if (segs_to_unmap > 0) {
+ unmap_data.count = segs_to_unmap;
+ BUG_ON(gnttab_unmap_refs_sync(&unmap_data));
+ put_free_pages(blkif, pages, segs_to_unmap);
+ }
+}
+
+static void purge_persistent_gnt(struct xen_blkif *blkif)
+{
+ struct persistent_gnt *persistent_gnt;
+ struct rb_node *n;
+ unsigned int num_clean, total;
+ bool scan_used = false, clean_used = false;
+ struct rb_root *root;
+
+ if (blkif->persistent_gnt_c < xen_blkif_max_pgrants ||
+ (blkif->persistent_gnt_c == xen_blkif_max_pgrants &&
+ !blkif->vbd.overflow_max_grants)) {
+ return;
+ }
+
+ if (work_pending(&blkif->persistent_purge_work)) {
+ pr_alert_ratelimited("Scheduled work from previous purge is still pending, cannot purge list\n");
+ return;
+ }
+
+ num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN;
+ num_clean = blkif->persistent_gnt_c - xen_blkif_max_pgrants + num_clean;
+ num_clean = min(blkif->persistent_gnt_c, num_clean);
+ if ((num_clean == 0) ||
+ (num_clean > (blkif->persistent_gnt_c - atomic_read(&blkif->persistent_gnt_in_use))))
+ return;
+
+ /*
+ * At this point, we can assure that there will be no calls
+ * to get_persistent_grant (because we are executing this code from
+ * xen_blkif_schedule), there can only be calls to put_persistent_gnt,
+ * which means that the number of currently used grants will go down,
+ * but never up, so we will always be able to remove the requested
+ * number of grants.
+ */
+
+ total = num_clean;
+
+ pr_debug("Going to purge %u persistent grants\n", num_clean);
+
+ BUG_ON(!list_empty(&blkif->persistent_purge_list));
+ root = &blkif->persistent_gnts;
+purge_list:
+ foreach_grant_safe(persistent_gnt, n, root, node) {
+ BUG_ON(persistent_gnt->handle ==
+ BLKBACK_INVALID_HANDLE);
+
+ if (clean_used) {
+ clear_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags);
+ continue;
+ }
+
+ if (test_bit(PERSISTENT_GNT_ACTIVE, persistent_gnt->flags))
+ continue;
+ if (!scan_used &&
+ (test_bit(PERSISTENT_GNT_WAS_ACTIVE, persistent_gnt->flags)))
+ continue;
+
+ rb_erase(&persistent_gnt->node, root);
+ list_add(&persistent_gnt->remove_node,
+ &blkif->persistent_purge_list);
+ if (--num_clean == 0)
+ goto finished;
+ }
+ /*
+ * If we get here it means we also need to start cleaning
+ * grants that were used since last purge in order to cope
+ * with the requested num
+ */
+ if (!scan_used && !clean_used) {
+ pr_debug("Still missing %u purged frames\n", num_clean);
+ scan_used = true;
+ goto purge_list;
+ }
+finished:
+ if (!clean_used) {
+ pr_debug("Finished scanning for grants to clean, removing used flag\n");
+ clean_used = true;
+ goto purge_list;
+ }
+
+ blkif->persistent_gnt_c -= (total - num_clean);
+ blkif->vbd.overflow_max_grants = 0;
+
+ /* We can defer this work */
+ schedule_work(&blkif->persistent_purge_work);
+ pr_debug("Purged %u/%u\n", (total - num_clean), total);
+ return;
+}
+
+/*
+ * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
+ */
+static struct pending_req *alloc_req(struct xen_blkif *blkif)
+{
+ struct pending_req *req = NULL;
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkif->pending_free_lock, flags);
+ if (!list_empty(&blkif->pending_free)) {
+ req = list_entry(blkif->pending_free.next, struct pending_req,
+ free_list);
+ list_del(&req->free_list);
+ }
+ spin_unlock_irqrestore(&blkif->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 xen_blkif *blkif, struct pending_req *req)
+{
+ unsigned long flags;
+ int was_empty;
+
+ spin_lock_irqsave(&blkif->pending_free_lock, flags);
+ was_empty = list_empty(&blkif->pending_free);
+ list_add(&req->free_list, &blkif->pending_free);
+ spin_unlock_irqrestore(&blkif->pending_free_lock, flags);
+ if (was_empty)
+ wake_up(&blkif->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("VBD Resize: Domid: %d, Device: (%d, %d)\n",
+ blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
+ pr_info("VBD Resize: new size %llu\n", new_size);
+ vbd->size = new_size;
+again:
+ err = xenbus_transaction_start(&xbt);
+ if (err) {
+ pr_warn("Error starting transaction\n");
+ return;
+ }
+ err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
+ (unsigned long long)vbd_sz(vbd));
+ if (err) {
+ pr_warn("Error writing new size\n");
+ 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("Error writing the state\n");
+ goto abort;
+ }
+
+ err = xenbus_transaction_end(xbt, 0);
+ if (err == -EAGAIN)
+ goto again;
+ if (err)
+ pr_warn("Error ending transaction\n");
+ 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("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu"
+ " | ds %4llu | pg: %4u/%4d\n",
+ current->comm, blkif->st_oo_req,
+ blkif->st_rd_req, blkif->st_wr_req,
+ blkif->st_f_req, blkif->st_ds_req,
+ blkif->persistent_gnt_c,
+ xen_blkif_max_pgrants);
+ blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
+ blkif->st_rd_req = 0;
+ blkif->st_wr_req = 0;
+ blkif->st_oo_req = 0;
+ blkif->st_ds_req = 0;
+}
+
+int xen_blkif_schedule(void *arg)
+{
+ struct xen_blkif *blkif = arg;
+ struct xen_vbd *vbd = &blkif->vbd;
+ unsigned long timeout;
+ int ret;
+
+ xen_blkif_get(blkif);
+
+ while (!kthread_should_stop()) {
+ if (try_to_freeze())
+ continue;
+ if (unlikely(vbd->size != vbd_sz(vbd)))
+ xen_vbd_resize(blkif);
+
+ timeout = msecs_to_jiffies(LRU_INTERVAL);
+
+ timeout = wait_event_interruptible_timeout(
+ blkif->wq,
+ blkif->waiting_reqs || kthread_should_stop(),
+ timeout);
+ if (timeout == 0)
+ goto purge_gnt_list;
+ timeout = wait_event_interruptible_timeout(
+ blkif->pending_free_wq,
+ !list_empty(&blkif->pending_free) ||
+ kthread_should_stop(),
+ timeout);
+ if (timeout == 0)
+ goto purge_gnt_list;
+
+ blkif->waiting_reqs = 0;
+ smp_mb(); /* clear flag *before* checking for work */
+
+ ret = do_block_io_op(blkif);
+ if (ret > 0)
+ blkif->waiting_reqs = 1;
+ if (ret == -EACCES)
+ wait_event_interruptible(blkif->shutdown_wq,
+ kthread_should_stop());
+
+purge_gnt_list:
+ if (blkif->vbd.feature_gnt_persistent &&
+ time_after(jiffies, blkif->next_lru)) {
+ purge_persistent_gnt(blkif);
+ blkif->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL);
+ }
+
+ /* Shrink if we have more than xen_blkif_max_buffer_pages */
+ shrink_free_pagepool(blkif, xen_blkif_max_buffer_pages);
+
+ if (log_stats && time_after(jiffies, blkif->st_print))
+ print_stats(blkif);
+ }
+
+ /* Drain pending purge work */
+ flush_work(&blkif->persistent_purge_work);
+
+ if (log_stats)
+ print_stats(blkif);
+
+ blkif->xenblkd = NULL;
+ xen_blkif_put(blkif);
+
+ return 0;
+}
+
+/*
+ * Remove persistent grants and empty the pool of free pages
+ */
+void xen_blkbk_free_caches(struct xen_blkif *blkif)
+{
+ /* Free all persistent grant pages */
+ if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
+ free_persistent_gnts(blkif, &blkif->persistent_gnts,
+ blkif->persistent_gnt_c);
+
+ BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
+ blkif->persistent_gnt_c = 0;
+
+ /* Since we are shutting down remove all pages from the buffer */
+ shrink_free_pagepool(blkif, 0 /* All */);
+}
+
+static unsigned int xen_blkbk_unmap_prepare(
+ struct xen_blkif *blkif,
+ struct grant_page **pages,
+ unsigned int num,
+ struct gnttab_unmap_grant_ref *unmap_ops,
+ struct page **unmap_pages)
+{
+ unsigned int i, invcount = 0;
+
+ for (i = 0; i < num; i++) {
+ if (pages[i]->persistent_gnt != NULL) {
+ put_persistent_gnt(blkif, pages[i]->persistent_gnt);
+ continue;
+ }
+ if (pages[i]->handle == BLKBACK_INVALID_HANDLE)
+ continue;
+ unmap_pages[invcount] = pages[i]->page;
+ gnttab_set_unmap_op(&unmap_ops[invcount], vaddr(pages[i]->page),
+ GNTMAP_host_map, pages[i]->handle);
+ pages[i]->handle = BLKBACK_INVALID_HANDLE;
+ invcount++;
+ }
+
+ return invcount;
+}
+
+static void xen_blkbk_unmap_and_respond_callback(int result, struct gntab_unmap_queue_data *data)
+{
+ struct pending_req* pending_req = (struct pending_req*) (data->data);
+ struct xen_blkif *blkif = pending_req->blkif;
+
+ /* BUG_ON used to reproduce existing behaviour,
+ but is this the best way to deal with this? */
+ BUG_ON(result);
+
+ put_free_pages(blkif, data->pages, data->count);
+ make_response(blkif, pending_req->id,
+ pending_req->operation, pending_req->status);
+ free_req(blkif, pending_req);
+ /*
+ * Make sure the request is freed before releasing blkif,
+ * or there could be a race between free_req and the
+ * cleanup done in xen_blkif_free during shutdown.
+ *
+ * NB: The fact that we might try to wake up pending_free_wq
+ * before drain_complete (in case there's a drain going on)
+ * it's not a problem with our current implementation
+ * because we can assure there's no thread waiting on
+ * pending_free_wq if there's a drain going on, but it has
+ * to be taken into account if the current model is changed.
+ */
+ if (atomic_dec_and_test(&blkif->inflight) && atomic_read(&blkif->drain)) {
+ complete(&blkif->drain_complete);
+ }
+ xen_blkif_put(blkif);
+}
+
+static void xen_blkbk_unmap_and_respond(struct pending_req *req)
+{
+ struct gntab_unmap_queue_data* work = &req->gnttab_unmap_data;
+ struct xen_blkif *blkif = req->blkif;
+ struct grant_page **pages = req->segments;
+ unsigned int invcount;
+
+ invcount = xen_blkbk_unmap_prepare(blkif, pages, req->nr_pages,
+ req->unmap, req->unmap_pages);
+
+ work->data = req;
+ work->done = xen_blkbk_unmap_and_respond_callback;
+ work->unmap_ops = req->unmap;
+ work->kunmap_ops = NULL;
+ work->pages = req->unmap_pages;
+ work->count = invcount;
+
+ gnttab_unmap_refs_async(&req->gnttab_unmap_data);
+}
+
+
+/*
+ * Unmap the grant references.
+ *
+ * This could accumulate ops up to the batch size to reduce the number
+ * of hypercalls, but since this is only used in error paths there's
+ * no real need.
+ */
+static void xen_blkbk_unmap(struct xen_blkif *blkif,
+ struct grant_page *pages[],
+ int num)
+{
+ struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct page *unmap_pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ unsigned int invcount = 0;
+ int ret;
+
+ while (num) {
+ unsigned int batch = min(num, BLKIF_MAX_SEGMENTS_PER_REQUEST);
+
+ invcount = xen_blkbk_unmap_prepare(blkif, pages, batch,
+ unmap, unmap_pages);
+ if (invcount) {
+ ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
+ BUG_ON(ret);
+ put_free_pages(blkif, unmap_pages, invcount);
+ }
+ pages += batch;
+ num -= batch;
+ }
+}
+
+static int xen_blkbk_map(struct xen_blkif *blkif,
+ struct grant_page *pages[],
+ int num, bool ro)
+{
+ struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+ struct persistent_gnt *persistent_gnt = NULL;
+ phys_addr_t addr = 0;
+ int i, seg_idx, new_map_idx;
+ int segs_to_map = 0;
+ int ret = 0;
+ int last_map = 0, map_until = 0;
+ int use_persistent_gnts;
+
+ use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
+
+ /*
+ * 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.
+ */
+again:
+ for (i = map_until; i < num; i++) {
+ uint32_t flags;
+
+ if (use_persistent_gnts)
+ persistent_gnt = get_persistent_gnt(
+ blkif,
+ pages[i]->gref);
+
+ if (persistent_gnt) {
+ /*
+ * We are using persistent grants and
+ * the grant is already mapped
+ */
+ pages[i]->page = persistent_gnt->page;
+ pages[i]->persistent_gnt = persistent_gnt;
+ } else {
+ if (get_free_page(blkif, &pages[i]->page))
+ goto out_of_memory;
+ addr = vaddr(pages[i]->page);
+ pages_to_gnt[segs_to_map] = pages[i]->page;
+ pages[i]->persistent_gnt = NULL;
+ flags = GNTMAP_host_map;
+ if (!use_persistent_gnts && ro)
+ flags |= GNTMAP_readonly;
+ gnttab_set_map_op(&map[segs_to_map++], addr,
+ flags, pages[i]->gref,
+ blkif->domid);
+ }
+ map_until = i + 1;
+ if (segs_to_map == BLKIF_MAX_SEGMENTS_PER_REQUEST)
+ break;
+ }
+
+ if (segs_to_map) {
+ ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
+ 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 (seg_idx = last_map, new_map_idx = 0; seg_idx < map_until; seg_idx++) {
+ if (!pages[seg_idx]->persistent_gnt) {
+ /* This is a newly mapped grant */
+ BUG_ON(new_map_idx >= segs_to_map);
+ if (unlikely(map[new_map_idx].status != 0)) {
+ pr_debug("invalid buffer -- could not remap it\n");
+ put_free_pages(blkif, &pages[seg_idx]->page, 1);
+ pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE;
+ ret |= 1;
+ goto next;
+ }
+ pages[seg_idx]->handle = map[new_map_idx].handle;
+ } else {
+ continue;
+ }
+ if (use_persistent_gnts &&
+ blkif->persistent_gnt_c < xen_blkif_max_pgrants) {
+ /*
+ * We are using persistent grants, the grant is
+ * not mapped but we might have room for it.
+ */
+ persistent_gnt = kmalloc(sizeof(struct persistent_gnt),
+ GFP_KERNEL);
+ if (!persistent_gnt) {
+ /*
+ * If we don't have enough memory to
+ * allocate the persistent_gnt struct
+ * map this grant non-persistenly
+ */
+ goto next;
+ }
+ persistent_gnt->gnt = map[new_map_idx].ref;
+ persistent_gnt->handle = map[new_map_idx].handle;
+ persistent_gnt->page = pages[seg_idx]->page;
+ if (add_persistent_gnt(blkif,
+ persistent_gnt)) {
+ kfree(persistent_gnt);
+ persistent_gnt = NULL;
+ goto next;
+ }
+ pages[seg_idx]->persistent_gnt = persistent_gnt;
+ pr_debug("grant %u added to the tree of persistent grants, using %u/%u\n",
+ persistent_gnt->gnt, blkif->persistent_gnt_c,
+ xen_blkif_max_pgrants);
+ goto next;
+ }
+ if (use_persistent_gnts && !blkif->vbd.overflow_max_grants) {
+ blkif->vbd.overflow_max_grants = 1;
+ pr_debug("domain %u, device %#x is using maximum number of persistent grants\n",
+ blkif->domid, blkif->vbd.handle);
+ }
+ /*
+ * We could not map this grant persistently, so use it as
+ * a non-persistent grant.
+ */
+next:
+ new_map_idx++;
+ }
+ segs_to_map = 0;
+ last_map = map_until;
+ if (map_until != num)
+ goto again;
+
+ return ret;
+
+out_of_memory:
+ pr_alert("%s: out of memory\n", __func__);
+ put_free_pages(blkif, pages_to_gnt, segs_to_map);
+ return -ENOMEM;
+}
+
+static int xen_blkbk_map_seg(struct pending_req *pending_req)
+{
+ int rc;
+
+ rc = xen_blkbk_map(pending_req->blkif, pending_req->segments,
+ pending_req->nr_pages,
+ (pending_req->operation != BLKIF_OP_READ));
+
+ return rc;
+}
+
+static int xen_blkbk_parse_indirect(struct blkif_request *req,
+ struct pending_req *pending_req,
+ struct seg_buf seg[],
+ struct phys_req *preq)
+{
+ struct grant_page **pages = pending_req->indirect_pages;
+ struct xen_blkif *blkif = pending_req->blkif;
+ int indirect_grefs, rc, n, nseg, i;
+ struct blkif_request_segment *segments = NULL;
+
+ nseg = pending_req->nr_pages;
+ indirect_grefs = INDIRECT_PAGES(nseg);
+ BUG_ON(indirect_grefs > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
+
+ for (i = 0; i < indirect_grefs; i++)
+ pages[i]->gref = req->u.indirect.indirect_grefs[i];
+
+ rc = xen_blkbk_map(blkif, pages, indirect_grefs, true);
+ if (rc)
+ goto unmap;
+
+ for (n = 0, i = 0; n < nseg; n++) {
+ if ((n % SEGS_PER_INDIRECT_FRAME) == 0) {
+ /* Map indirect segments */
+ if (segments)
+ kunmap_atomic(segments);
+ segments = kmap_atomic(pages[n/SEGS_PER_INDIRECT_FRAME]->page);
+ }
+ i = n % SEGS_PER_INDIRECT_FRAME;
+ pending_req->segments[n]->gref = segments[i].gref;
+ seg[n].nsec = segments[i].last_sect -
+ segments[i].first_sect + 1;
+ seg[n].offset = (segments[i].first_sect << 9);
+ if ((segments[i].last_sect >= (PAGE_SIZE >> 9)) ||
+ (segments[i].last_sect < segments[i].first_sect)) {
+ rc = -EINVAL;
+ goto unmap;
+ }
+ preq->nr_sects += seg[n].nsec;
+ }
+
+unmap:
+ if (segments)
+ kunmap_atomic(segments);
+ xen_blkbk_unmap(blkif, pages, indirect_grefs);
+ return rc;
+}
+
+static int dispatch_discard_io(struct xen_blkif *blkif,
+ struct blkif_request *req)
+{
+ int err = 0;
+ int status = BLKIF_RSP_OKAY;
+ struct block_device *bdev = blkif->vbd.bdev;
+ unsigned long secure;
+ struct phys_req preq;
+
+ xen_blkif_get(blkif);
+
+ preq.sector_number = req->u.discard.sector_number;
+ preq.nr_sects = req->u.discard.nr_sectors;
+
+ err = xen_vbd_translate(&preq, blkif, WRITE);
+ if (err) {
+ pr_warn("access denied: DISCARD [%llu->%llu] on dev=%04x\n",
+ preq.sector_number,
+ preq.sector_number + preq.nr_sects, blkif->vbd.pdevice);
+ goto fail_response;
+ }
+ blkif->st_ds_req++;
+
+ secure = (blkif->vbd.discard_secure &&
+ (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
+ BLKDEV_DISCARD_SECURE : 0;
+
+ err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
+ req->u.discard.nr_sectors,
+ GFP_KERNEL, secure);
+fail_response:
+ if (err == -EOPNOTSUPP) {
+ pr_debug("discard op failed, not supported\n");
+ status = BLKIF_RSP_EOPNOTSUPP;
+ } else if (err)
+ status = BLKIF_RSP_ERROR;
+
+ make_response(blkif, req->u.discard.id, req->operation, status);
+ xen_blkif_put(blkif);
+ return err;
+}
+
+static int dispatch_other_io(struct xen_blkif *blkif,
+ struct blkif_request *req,
+ struct pending_req *pending_req)
+{
+ free_req(blkif, pending_req);
+ make_response(blkif, req->u.other.id, req->operation,
+ BLKIF_RSP_EOPNOTSUPP);
+ return -EIO;
+}
+
+static void xen_blk_drain_io(struct xen_blkif *blkif)
+{
+ atomic_set(&blkif->drain, 1);
+ do {
+ if (atomic_read(&blkif->inflight) == 0)
+ break;
+ wait_for_completion_interruptible_timeout(
+ &blkif->drain_complete, HZ);
+
+ if (!atomic_read(&blkif->drain))
+ break;
+ } while (!kthread_should_stop());
+ atomic_set(&blkif->drain, 0);
+}
+
+/*
+ * 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("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 ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
+ (error == -EOPNOTSUPP)) {
+ pr_debug("write barrier op failed, not supported\n");
+ xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
+ pending_req->status = BLKIF_RSP_EOPNOTSUPP;
+ } else if (error) {
+ pr_debug("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_and_respond(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'. */
+
+ if (RING_REQUEST_PROD_OVERFLOW(&blk_rings->common, rp)) {
+ rc = blk_rings->common.rsp_prod_pvt;
+ pr_warn("Frontend provided bogus ring requests (%d - %d = %d). Halting ring processing on dev=%04x\n",
+ rp, rc, rp - rc, blkif->vbd.pdevice);
+ return -EACCES;
+ }
+ 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(blkif);
+ 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();
+
+ switch (req.operation) {
+ case BLKIF_OP_READ:
+ case BLKIF_OP_WRITE:
+ case BLKIF_OP_WRITE_BARRIER:
+ case BLKIF_OP_FLUSH_DISKCACHE:
+ case BLKIF_OP_INDIRECT:
+ if (dispatch_rw_block_io(blkif, &req, pending_req))
+ goto done;
+ break;
+ case BLKIF_OP_DISCARD:
+ free_req(blkif, pending_req);
+ if (dispatch_discard_io(blkif, &req))
+ goto done;
+ break;
+ default:
+ if (dispatch_other_io(blkif, &req, pending_req))
+ goto done;
+ break;
+ }
+
+ /* Yield point for this unbounded loop. */
+ cond_resched();
+ }
+done:
+ return more_to_do;
+}
+
+static int
+do_block_io_op(struct xen_blkif *blkif)
+{
+ union blkif_back_rings *blk_rings = &blkif->blk_rings;
+ int more_to_do;
+
+ do {
+ more_to_do = __do_block_io_op(blkif);
+ if (more_to_do)
+ break;
+
+ RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
+ } while (more_to_do);
+
+ 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 = pending_req->seg;
+ unsigned int nseg;
+ struct bio *bio = NULL;
+ struct bio **biolist = pending_req->biolist;
+ int i, nbio = 0;
+ int operation;
+ struct blk_plug plug;
+ bool drain = false;
+ struct grant_page **pages = pending_req->segments;
+ unsigned short req_operation;
+
+ req_operation = req->operation == BLKIF_OP_INDIRECT ?
+ req->u.indirect.indirect_op : req->operation;
+ if ((req->operation == BLKIF_OP_INDIRECT) &&
+ (req_operation != BLKIF_OP_READ) &&
+ (req_operation != BLKIF_OP_WRITE)) {
+ pr_debug("Invalid indirect operation (%u)\n", req_operation);
+ goto fail_response;
+ }
+
+ 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_WRITE_BARRIER:
+ drain = true;
+ case BLKIF_OP_FLUSH_DISKCACHE:
+ blkif->st_f_req++;
+ operation = WRITE_FLUSH;
+ break;
+ default:
+ operation = 0; /* make gcc happy */
+ goto fail_response;
+ break;
+ }
+
+ /* Check that the number of segments is sane. */
+ nseg = req->operation == BLKIF_OP_INDIRECT ?
+ req->u.indirect.nr_segments : req->u.rw.nr_segments;
+
+ if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
+ unlikely((req->operation != BLKIF_OP_INDIRECT) &&
+ (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) ||
+ unlikely((req->operation == BLKIF_OP_INDIRECT) &&
+ (nseg > MAX_INDIRECT_SEGMENTS))) {
+ pr_debug("Bad number of segments in request (%d)\n", nseg);
+ /* Haven't submitted any bio's yet. */
+ goto fail_response;
+ }
+
+ preq.nr_sects = 0;
+
+ pending_req->blkif = blkif;
+ pending_req->id = req->u.rw.id;
+ pending_req->operation = req_operation;
+ pending_req->status = BLKIF_RSP_OKAY;
+ pending_req->nr_pages = nseg;
+
+ if (req->operation != BLKIF_OP_INDIRECT) {
+ preq.dev = req->u.rw.handle;
+ preq.sector_number = req->u.rw.sector_number;
+ for (i = 0; i < nseg; i++) {
+ pages[i]->gref = req->u.rw.seg[i].gref;
+ seg[i].nsec = req->u.rw.seg[i].last_sect -
+ req->u.rw.seg[i].first_sect + 1;
+ seg[i].offset = (req->u.rw.seg[i].first_sect << 9);
+ 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;
+ }
+ } else {
+ preq.dev = req->u.indirect.handle;
+ preq.sector_number = req->u.indirect.sector_number;
+ if (xen_blkbk_parse_indirect(req, pending_req, seg, &preq))
+ goto fail_response;
+ }
+
+ if (xen_vbd_translate(&preq, blkif, operation) != 0) {
+ pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n",
+ operation == READ ? "read" : "write",
+ preq.sector_number,
+ preq.sector_number + preq.nr_sects,
+ blkif->vbd.pdevice);
+ 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("Misaligned I/O request from domain %d\n",
+ blkif->domid);
+ goto fail_response;
+ }
+ }
+
+ /* Wait on all outstanding I/O's and once that has been completed
+ * issue the WRITE_FLUSH.
+ */
+ if (drain)
+ xen_blk_drain_io(pending_req->blkif);
+
+ /*
+ * 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_seg(pending_req))
+ goto fail_flush;
+
+ /*
+ * This corresponding xen_blkif_put is done in __end_block_io_op, or
+ * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
+ */
+ xen_blkif_get(blkif);
+ atomic_inc(&blkif->inflight);
+
+ for (i = 0; i < nseg; i++) {
+ while ((bio == NULL) ||
+ (bio_add_page(bio,
+ pages[i]->page,
+ seg[i].nsec << 9,
+ seg[i].offset) == 0)) {
+
+ int nr_iovecs = min_t(int, (nseg-i), BIO_MAX_PAGES);
+ bio = bio_alloc(GFP_KERNEL, nr_iovecs);
+ 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_iter.bi_sector = preq.sector_number;
+ }
+
+ preq.sector_number += seg[i].nsec;
+ }
+
+ /* This will be hit if the operation was a flush or discard. */
+ 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;
+ }
+
+ atomic_set(&pending_req->pendcnt, nbio);
+ 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)
+ blkif->st_wr_sect += preq.nr_sects;
+
+ return 0;
+
+ fail_flush:
+ xen_blkbk_unmap(blkif, pending_req->segments,
+ pending_req->nr_pages);
+ fail_response:
+ /* Haven't submitted any bio's yet. */
+ make_response(blkif, req->u.rw.id, req_operation, BLKIF_RSP_ERROR);
+ free_req(blkif, pending_req);
+ msleep(1); /* back off a bit */
+ return -EIO;
+
+ fail_put_bio:
+ for (i = 0; i < nbio; i++)
+ bio_put(biolist[i]);
+ atomic_set(&pending_req->pendcnt, 1);
+ __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 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);
+ spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
+ if (notify)
+ notify_remote_via_irq(blkif->irq);
+}
+
+static int __init xen_blkif_init(void)
+{
+ int rc = 0;
+
+ if (!xen_domain())
+ return -ENODEV;
+
+ rc = xen_blkif_interface_init();
+ if (rc)
+ goto failed_init;
+
+ rc = xen_blkif_xenbus_init();
+ if (rc)
+ goto failed_init;
+
+ failed_init:
+ return rc;
+}
+
+module_init(xen_blkif_init);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("xen-backend:vbd");
Code Review / kvmfornfv.git / blobdiff