| /****************************************************************************** |
| * |
| * 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"); |
| |
| /* |
| * Maximum number of rings/queues blkback supports, allow as many queues as there |
| * are CPUs if user has not specified a value. |
| */ |
| unsigned int xenblk_max_queues; |
| module_param_named(max_queues, xenblk_max_queues, uint, 0644); |
| MODULE_PARM_DESC(max_queues, |
| "Maximum number of hardware queues per virtual disk." \ |
| "By default it is the number of online CPUs."); |
| |
| /* |
| * Maximum order of pages to be used for the shared ring between front and |
| * backend, 4KB page granularity is used. |
| */ |
| unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; |
| module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); |
| MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); |
| /* |
| * 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_ring *ring, struct page **page) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&ring->free_pages_lock, flags); |
| if (list_empty(&ring->free_pages)) { |
| BUG_ON(ring->free_pages_num != 0); |
| spin_unlock_irqrestore(&ring->free_pages_lock, flags); |
| return gnttab_alloc_pages(1, page); |
| } |
| BUG_ON(ring->free_pages_num == 0); |
| page[0] = list_first_entry(&ring->free_pages, struct page, lru); |
| list_del(&page[0]->lru); |
| ring->free_pages_num--; |
| spin_unlock_irqrestore(&ring->free_pages_lock, flags); |
| |
| return 0; |
| } |
| |
| static inline void put_free_pages(struct xen_blkif_ring *ring, struct page **page, |
| int num) |
| { |
| unsigned long flags; |
| int i; |
| |
| spin_lock_irqsave(&ring->free_pages_lock, flags); |
| for (i = 0; i < num; i++) |
| list_add(&page[i]->lru, &ring->free_pages); |
| ring->free_pages_num += num; |
| spin_unlock_irqrestore(&ring->free_pages_lock, flags); |
| } |
| |
| static inline void shrink_free_pagepool(struct xen_blkif_ring *ring, 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(&ring->free_pages_lock, flags); |
| while (ring->free_pages_num > num) { |
| BUG_ON(list_empty(&ring->free_pages)); |
| page[num_pages] = list_first_entry(&ring->free_pages, |
| struct page, lru); |
| list_del(&page[num_pages]->lru); |
| ring->free_pages_num--; |
| if (++num_pages == NUM_BATCH_FREE_PAGES) { |
| spin_unlock_irqrestore(&ring->free_pages_lock, flags); |
| gnttab_free_pages(num_pages, page); |
| spin_lock_irqsave(&ring->free_pages_lock, flags); |
| num_pages = 0; |
| } |
| } |
| spin_unlock_irqrestore(&ring->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_ring *ring); |
| static int dispatch_rw_block_io(struct xen_blkif_ring *ring, |
| struct blkif_request *req, |
| struct pending_req *pending_req); |
| static void make_response(struct xen_blkif_ring *ring, 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 backend, 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_ring *ring, |
| struct persistent_gnt *persistent_gnt) |
| { |
| struct rb_node **new = NULL, *parent = NULL; |
| struct persistent_gnt *this; |
| struct xen_blkif *blkif = ring->blkif; |
| |
| if (ring->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 = &ring->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), &ring->persistent_gnts); |
| ring->persistent_gnt_c++; |
| atomic_inc(&ring->persistent_gnt_in_use); |
| return 0; |
| } |
| |
| static struct persistent_gnt *get_persistent_gnt(struct xen_blkif_ring *ring, |
| grant_ref_t gref) |
| { |
| struct persistent_gnt *data; |
| struct rb_node *node = NULL; |
| |
| node = ring->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(&ring->persistent_gnt_in_use); |
| return data; |
| } |
| } |
| return NULL; |
| } |
| |
| static void put_persistent_gnt(struct xen_blkif_ring *ring, |
| 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(&ring->persistent_gnt_in_use); |
| } |
| |
| static void free_persistent_gnts(struct xen_blkif_ring *ring, 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(ring, 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_ring *ring = container_of(work, typeof(*ring), 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(&ring->persistent_purge_list)) { |
| persistent_gnt = list_first_entry(&ring->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(ring, 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(ring, pages, segs_to_unmap); |
| } |
| } |
| |
| static void purge_persistent_gnt(struct xen_blkif_ring *ring) |
| { |
| 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 (ring->persistent_gnt_c < xen_blkif_max_pgrants || |
| (ring->persistent_gnt_c == xen_blkif_max_pgrants && |
| !ring->blkif->vbd.overflow_max_grants)) { |
| goto out; |
| } |
| |
| if (work_busy(&ring->persistent_purge_work)) { |
| pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n"); |
| goto out; |
| } |
| |
| num_clean = (xen_blkif_max_pgrants / 100) * LRU_PERCENT_CLEAN; |
| num_clean = ring->persistent_gnt_c - xen_blkif_max_pgrants + num_clean; |
| num_clean = min(ring->persistent_gnt_c, num_clean); |
| if ((num_clean == 0) || |
| (num_clean > (ring->persistent_gnt_c - atomic_read(&ring->persistent_gnt_in_use)))) |
| goto out; |
| |
| /* |
| * 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(&ring->persistent_purge_list)); |
| root = &ring->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, |
| &ring->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; |
| } |
| |
| ring->persistent_gnt_c -= (total - num_clean); |
| ring->blkif->vbd.overflow_max_grants = 0; |
| |
| /* We can defer this work */ |
| schedule_work(&ring->persistent_purge_work); |
| pr_debug("Purged %u/%u\n", (total - num_clean), total); |
| |
| out: |
| return; |
| } |
| |
| /* |
| * Retrieve from the 'pending_reqs' a free pending_req structure to be used. |
| */ |
| static struct pending_req *alloc_req(struct xen_blkif_ring *ring) |
| { |
| struct pending_req *req = NULL; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&ring->pending_free_lock, flags); |
| if (!list_empty(&ring->pending_free)) { |
| req = list_entry(ring->pending_free.next, struct pending_req, |
| free_list); |
| list_del(&req->free_list); |
| } |
| spin_unlock_irqrestore(&ring->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_ring *ring, struct pending_req *req) |
| { |
| unsigned long flags; |
| int was_empty; |
| |
| spin_lock_irqsave(&ring->pending_free_lock, flags); |
| was_empty = list_empty(&ring->pending_free); |
| list_add(&req->free_list, &ring->pending_free); |
| spin_unlock_irqrestore(&ring->pending_free_lock, flags); |
| if (was_empty) |
| wake_up(&ring->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 != REQ_OP_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_ring *ring) |
| { |
| ring->waiting_reqs = 1; |
| wake_up(&ring->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_ring *ring) |
| { |
| pr_info("(%s): oo %3llu | rd %4llu | wr %4llu | f %4llu" |
| " | ds %4llu | pg: %4u/%4d\n", |
| current->comm, ring->st_oo_req, |
| ring->st_rd_req, ring->st_wr_req, |
| ring->st_f_req, ring->st_ds_req, |
| ring->persistent_gnt_c, |
| xen_blkif_max_pgrants); |
| ring->st_print = jiffies + msecs_to_jiffies(10 * 1000); |
| ring->st_rd_req = 0; |
| ring->st_wr_req = 0; |
| ring->st_oo_req = 0; |
| ring->st_ds_req = 0; |
| } |
| |
| int xen_blkif_schedule(void *arg) |
| { |
| struct xen_blkif_ring *ring = arg; |
| struct xen_blkif *blkif = ring->blkif; |
| struct xen_vbd *vbd = &blkif->vbd; |
| unsigned long timeout; |
| int ret; |
| |
| set_freezable(); |
| 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( |
| ring->wq, |
| ring->waiting_reqs || kthread_should_stop(), |
| timeout); |
| if (timeout == 0) |
| goto purge_gnt_list; |
| timeout = wait_event_interruptible_timeout( |
| ring->pending_free_wq, |
| !list_empty(&ring->pending_free) || |
| kthread_should_stop(), |
| timeout); |
| if (timeout == 0) |
| goto purge_gnt_list; |
| |
| ring->waiting_reqs = 0; |
| smp_mb(); /* clear flag *before* checking for work */ |
| |
| ret = do_block_io_op(ring); |
| if (ret > 0) |
| ring->waiting_reqs = 1; |
| if (ret == -EACCES) |
| wait_event_interruptible(ring->shutdown_wq, |
| kthread_should_stop()); |
| |
| purge_gnt_list: |
| if (blkif->vbd.feature_gnt_persistent && |
| time_after(jiffies, ring->next_lru)) { |
| purge_persistent_gnt(ring); |
| ring->next_lru = jiffies + msecs_to_jiffies(LRU_INTERVAL); |
| } |
| |
| /* Shrink if we have more than xen_blkif_max_buffer_pages */ |
| shrink_free_pagepool(ring, xen_blkif_max_buffer_pages); |
| |
| if (log_stats && time_after(jiffies, ring->st_print)) |
| print_stats(ring); |
| } |
| |
| /* Drain pending purge work */ |
| flush_work(&ring->persistent_purge_work); |
| |
| if (log_stats) |
| print_stats(ring); |
| |
| ring->xenblkd = NULL; |
| |
| return 0; |
| } |
| |
| /* |
| * Remove persistent grants and empty the pool of free pages |
| */ |
| void xen_blkbk_free_caches(struct xen_blkif_ring *ring) |
| { |
| /* Free all persistent grant pages */ |
| if (!RB_EMPTY_ROOT(&ring->persistent_gnts)) |
| free_persistent_gnts(ring, &ring->persistent_gnts, |
| ring->persistent_gnt_c); |
| |
| BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts)); |
| ring->persistent_gnt_c = 0; |
| |
| /* Since we are shutting down remove all pages from the buffer */ |
| shrink_free_pagepool(ring, 0 /* All */); |
| } |
| |
| static unsigned int xen_blkbk_unmap_prepare( |
| struct xen_blkif_ring *ring, |
| 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(ring, 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_ring *ring = pending_req->ring; |
| struct xen_blkif *blkif = ring->blkif; |
| |
| /* BUG_ON used to reproduce existing behaviour, |
| but is this the best way to deal with this? */ |
| BUG_ON(result); |
| |
| put_free_pages(ring, data->pages, data->count); |
| make_response(ring, pending_req->id, |
| pending_req->operation, pending_req->status); |
| free_req(ring, 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(&ring->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_ring *ring = req->ring; |
| struct grant_page **pages = req->segments; |
| unsigned int invcount; |
| |
| invcount = xen_blkbk_unmap_prepare(ring, pages, req->nr_segs, |
| 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_ring *ring, |
| 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(ring, pages, batch, |
| unmap, unmap_pages); |
| if (invcount) { |
| ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount); |
| BUG_ON(ret); |
| put_free_pages(ring, unmap_pages, invcount); |
| } |
| pages += batch; |
| num -= batch; |
| } |
| } |
| |
| static int xen_blkbk_map(struct xen_blkif_ring *ring, |
| 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; |
| struct xen_blkif *blkif = ring->blkif; |
| |
| 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( |
| ring, |
| 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(ring, &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(ring, &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 && |
| ring->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(ring, |
| 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, ring->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(ring, 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->ring, pending_req->segments, |
| pending_req->nr_segs, |
| (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_ring *ring = pending_req->ring; |
| int indirect_grefs, rc, n, nseg, i; |
| struct blkif_request_segment *segments = NULL; |
| |
| nseg = pending_req->nr_segs; |
| 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(ring, pages, indirect_grefs, true); |
| if (rc) |
| goto unmap; |
| |
| for (n = 0, i = 0; n < nseg; n++) { |
| uint8_t first_sect, last_sect; |
| |
| 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; |
| |
| first_sect = READ_ONCE(segments[i].first_sect); |
| last_sect = READ_ONCE(segments[i].last_sect); |
| if (last_sect >= (XEN_PAGE_SIZE >> 9) || last_sect < first_sect) { |
| rc = -EINVAL; |
| goto unmap; |
| } |
| |
| seg[n].nsec = last_sect - first_sect + 1; |
| seg[n].offset = first_sect << 9; |
| preq->nr_sects += seg[n].nsec; |
| } |
| |
| unmap: |
| if (segments) |
| kunmap_atomic(segments); |
| xen_blkbk_unmap(ring, pages, indirect_grefs); |
| return rc; |
| } |
| |
| static int dispatch_discard_io(struct xen_blkif_ring *ring, |
| struct blkif_request *req) |
| { |
| int err = 0; |
| int status = BLKIF_RSP_OKAY; |
| struct xen_blkif *blkif = ring->blkif; |
| 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, REQ_OP_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; |
| } |
| ring->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(ring, req->u.discard.id, req->operation, status); |
| xen_blkif_put(blkif); |
| return err; |
| } |
| |
| static int dispatch_other_io(struct xen_blkif_ring *ring, |
| struct blkif_request *req, |
| struct pending_req *pending_req) |
| { |
| free_req(ring, pending_req); |
| make_response(ring, req->u.other.id, req->operation, |
| BLKIF_RSP_EOPNOTSUPP); |
| return -EIO; |
| } |
| |
| static void xen_blk_drain_io(struct xen_blkif_ring *ring) |
| { |
| struct xen_blkif *blkif = ring->blkif; |
| |
| atomic_set(&blkif->drain, 1); |
| do { |
| if (atomic_read(&ring->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); |
| } |
| |
| static void __end_block_io_op(struct pending_req *pending_req, |
| blk_status_t error) |
| { |
| /* An error fails the entire request. */ |
| if (pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE && |
| error == BLK_STS_NOTSUPP) { |
| pr_debug("flush diskcache op failed, not supported\n"); |
| xen_blkbk_flush_diskcache(XBT_NIL, pending_req->ring->blkif->be, 0); |
| pending_req->status = BLKIF_RSP_EOPNOTSUPP; |
| } else if (pending_req->operation == BLKIF_OP_WRITE_BARRIER && |
| error == BLK_STS_NOTSUPP) { |
| pr_debug("write barrier op failed, not supported\n"); |
| xen_blkbk_barrier(XBT_NIL, pending_req->ring->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) |
| { |
| __end_block_io_op(bio->bi_private, bio->bi_status); |
| 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_ring *ring) |
| { |
| union blkif_back_rings *blk_rings = &ring->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, ring->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(ring); |
| if (NULL == pending_req) { |
| ring->st_oo_req++; |
| more_to_do = 1; |
| break; |
| } |
| |
| switch (ring->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(ring, &req, pending_req)) |
| goto done; |
| break; |
| case BLKIF_OP_DISCARD: |
| free_req(ring, pending_req); |
| if (dispatch_discard_io(ring, &req)) |
| goto done; |
| break; |
| default: |
| if (dispatch_other_io(ring, &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_ring *ring) |
| { |
| union blkif_back_rings *blk_rings = &ring->blk_rings; |
| int more_to_do; |
| |
| do { |
| more_to_do = __do_block_io_op(ring); |
| 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_ring *ring, |
| 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; |
| int operation_flags = 0; |
| 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: |
| ring->st_rd_req++; |
| operation = REQ_OP_READ; |
| break; |
| case BLKIF_OP_WRITE: |
| ring->st_wr_req++; |
| operation = REQ_OP_WRITE; |
| operation_flags = REQ_SYNC | REQ_IDLE; |
| break; |
| case BLKIF_OP_WRITE_BARRIER: |
| drain = true; |
| /* fall through */ |
| case BLKIF_OP_FLUSH_DISKCACHE: |
| ring->st_f_req++; |
| operation = REQ_OP_WRITE; |
| operation_flags = REQ_PREFLUSH; |
| 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_flags != REQ_PREFLUSH) || |
| 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->ring = ring; |
| pending_req->id = req->u.rw.id; |
| pending_req->operation = req_operation; |
| pending_req->status = BLKIF_RSP_OKAY; |
| pending_req->nr_segs = 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 >= (XEN_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, ring->blkif, operation) != 0) { |
| pr_debug("access denied: %s of [%llu,%llu] on dev=%04x\n", |
| operation == REQ_OP_READ ? "read" : "write", |
| preq.sector_number, |
| preq.sector_number + preq.nr_sects, |
| ring->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", |
| ring->blkif->domid); |
| goto fail_response; |
| } |
| } |
| |
| /* Wait on all outstanding I/O's and once that has been completed |
| * issue the flush. |
| */ |
| if (drain) |
| xen_blk_drain_io(pending_req->ring); |
| |
| /* |
| * 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(ring->blkif); |
| atomic_inc(&ring->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; |
| bio_set_op_attrs(bio, operation, operation_flags); |
| } |
| |
| preq.sector_number += seg[i].nsec; |
| } |
| |
| /* This will be hit if the operation was a flush or discard. */ |
| if (!bio) { |
| BUG_ON(operation_flags != REQ_PREFLUSH); |
| |
| 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; |
| bio_set_op_attrs(bio, operation, operation_flags); |
| } |
| |
| atomic_set(&pending_req->pendcnt, nbio); |
| blk_start_plug(&plug); |
| |
| for (i = 0; i < nbio; i++) |
| submit_bio(biolist[i]); |
| |
| /* Let the I/Os go.. */ |
| blk_finish_plug(&plug); |
| |
| if (operation == REQ_OP_READ) |
| ring->st_rd_sect += preq.nr_sects; |
| else if (operation == REQ_OP_WRITE) |
| ring->st_wr_sect += preq.nr_sects; |
| |
| return 0; |
| |
| fail_flush: |
| xen_blkbk_unmap(ring, pending_req->segments, |
| pending_req->nr_segs); |
| fail_response: |
| /* Haven't submitted any bio's yet. */ |
| make_response(ring, req->u.rw.id, req_operation, BLKIF_RSP_ERROR); |
| free_req(ring, 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, BLK_STS_RESOURCE); |
| 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_ring *ring, u64 id, |
| unsigned short op, int st) |
| { |
| struct blkif_response *resp; |
| unsigned long flags; |
| union blkif_back_rings *blk_rings; |
| int notify; |
| |
| spin_lock_irqsave(&ring->blk_ring_lock, flags); |
| blk_rings = &ring->blk_rings; |
| /* Place on the response ring for the relevant domain. */ |
| switch (ring->blkif->blk_protocol) { |
| case BLKIF_PROTOCOL_NATIVE: |
| resp = RING_GET_RESPONSE(&blk_rings->native, |
| blk_rings->native.rsp_prod_pvt); |
| break; |
| case BLKIF_PROTOCOL_X86_32: |
| resp = RING_GET_RESPONSE(&blk_rings->x86_32, |
| blk_rings->x86_32.rsp_prod_pvt); |
| break; |
| case BLKIF_PROTOCOL_X86_64: |
| resp = RING_GET_RESPONSE(&blk_rings->x86_64, |
| blk_rings->x86_64.rsp_prod_pvt); |
| break; |
| default: |
| BUG(); |
| } |
| |
| resp->id = id; |
| resp->operation = op; |
| resp->status = st; |
| |
| blk_rings->common.rsp_prod_pvt++; |
| RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify); |
| spin_unlock_irqrestore(&ring->blk_ring_lock, flags); |
| if (notify) |
| notify_remote_via_irq(ring->irq); |
| } |
| |
| static int __init xen_blkif_init(void) |
| { |
| int rc = 0; |
| |
| if (!xen_domain()) |
| return -ENODEV; |
| |
| if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { |
| pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", |
| xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); |
| xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; |
| } |
| |
| if (xenblk_max_queues == 0) |
| xenblk_max_queues = num_online_cpus(); |
| |
| 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"); |