| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Konrad Rzeszutek Wilk | 2507 | 39.59% | 40 | 34.78% |
| Roger Pau Monné | 2227 | 35.17% | 20 | 17.39% |
| Bob Liu | 348 | 5.50% | 7 | 6.09% |
| Jennifer Herbert | 313 | 4.94% | 1 | 0.87% |
| Juergen Gross | 215 | 3.39% | 4 | 3.48% |
| K. Y. Srinivasan | 125 | 1.97% | 2 | 1.74% |
| Li Dongyang | 113 | 1.78% | 1 | 0.87% |
| Jan Beulich | 99 | 1.56% | 7 | 6.09% |
| Christoph Hellwig | 59 | 0.93% | 5 | 4.35% |
| David Vrabel | 58 | 0.92% | 1 | 0.87% |
| SeongJae Park | 50 | 0.79% | 3 | 2.61% |
| Daniel Stodden | 37 | 0.58% | 1 | 0.87% |
| Jeremy Fitzhardinge | 35 | 0.55% | 2 | 1.74% |
| Daniel De Graaf | 29 | 0.46% | 2 | 1.74% |
| Michael Christie | 21 | 0.33% | 1 | 0.87% |
| Paul Durrant | 20 | 0.32% | 1 | 0.87% |
| Tao Chen | 18 | 0.28% | 1 | 0.87% |
| Chen Gang S | 12 | 0.19% | 1 | 0.87% |
| Julien Grall | 11 | 0.17% | 3 | 2.61% |
| Matthew Wilcox | 6 | 0.09% | 1 | 0.87% |
| Bastian Blank | 5 | 0.08% | 1 | 0.87% |
| Bart Van Assche | 5 | 0.08% | 1 | 0.87% |
| Stefano Stabellini | 5 | 0.08% | 2 | 1.74% |
| Akinobu Mita | 3 | 0.05% | 1 | 0.87% |
| Jiri Kosina | 3 | 0.05% | 1 | 0.87% |
| Matt Rushton | 3 | 0.05% | 1 | 0.87% |
| Gustavo A. R. Silva | 2 | 0.03% | 1 | 0.87% |
| Kent Overstreet | 2 | 0.03% | 1 | 0.87% |
| Laszlo Ersek | 1 | 0.02% | 1 | 0.87% |
| Joe Perches | 1 | 0.02% | 1 | 0.87% |
| Total | 6333 | 115 |
/****************************************************************************** * * 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 max_buffer_pages = 1024; module_param_named(max_buffer_pages, 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 max_pgrants = 1056; module_param_named(max_persistent_grants, max_pgrants, int, 0644); MODULE_PARM_DESC(max_persistent_grants, "Maximum number of grants to map persistently"); /* * How long a persistent grant is allowed to remain allocated without being in * use. The time is in seconds, 0 means indefinitely long. */ static unsigned int pgrant_timeout = 60; module_param_named(persistent_grant_unused_seconds, pgrant_timeout, uint, 0644); MODULE_PARM_DESC(persistent_grant_unused_seconds, "Time in seconds an unused persistent grant is allowed to " "remain allocated. Default is 60, 0 means unlimited."); /* * 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, 0444); 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) static inline bool persistent_gnt_timeout(struct persistent_gnt *persistent_gnt) { return pgrant_timeout && (jiffies - persistent_gnt->last_used >= HZ * pgrant_timeout); } #define vaddr(page) ((unsigned long)pfn_to_kaddr(page_to_pfn(page))) static int do_block_io_op(struct xen_blkif_ring *ring, unsigned int *eoi_flags); 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 >= 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; } } persistent_gnt->active = true; /* 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 (data->active) { pr_alert_ratelimited("requesting a grant already in use\n"); return NULL; } data->active = true; 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 (!persistent_gnt->active) pr_alert_ratelimited("freeing a grant already unused\n"); persistent_gnt->last_used = jiffies; persistent_gnt->active = false; 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)); gnttab_page_cache_put(&ring->free_pages, 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)); gnttab_page_cache_put(&ring->free_pages, 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)); gnttab_page_cache_put(&ring->free_pages, 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; struct rb_root *root; if (work_busy(&ring->persistent_purge_work)) { pr_alert_ratelimited("Scheduled work from previous purge is still busy, cannot purge list\n"); goto out; } if (ring->persistent_gnt_c < max_pgrants || (ring->persistent_gnt_c == max_pgrants && !ring->blkif->vbd.overflow_max_grants)) { num_clean = 0; } else { num_clean = (max_pgrants / 100) * LRU_PERCENT_CLEAN; num_clean = ring->persistent_gnt_c - max_pgrants + num_clean; num_clean = min(ring->persistent_gnt_c, num_clean); pr_debug("Going to purge at least %u persistent grants\n", num_clean); } /* * 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 = 0; 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 (persistent_gnt->active) continue; if (!scan_used && !persistent_gnt_timeout(persistent_gnt)) continue; if (scan_used && total >= num_clean) continue; rb_erase(&persistent_gnt->node, root); list_add(&persistent_gnt->remove_node, &ring->persistent_purge_list); total++; } /* * Check whether we also need to start cleaning * grants that were used since last purge in order to cope * with the requested num */ if (!scan_used && total < num_clean) { pr_debug("Still missing %u purged frames\n", num_clean - total); scan_used = true; goto purge_list; } if (total) { ring->persistent_gnt_c -= total; ring->blkif->vbd.overflow_max_grants = 0; /* We can defer this work */ schedule_work(&ring->persistent_purge_work); pr_debug("Purged %u/%u\n", 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, enum req_op 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, 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; bool do_eoi; unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS; 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; do_eoi = ring->waiting_reqs; ring->waiting_reqs = 0; smp_mb(); /* clear flag *before* checking for work */ ret = do_block_io_op(ring, &eoi_flags); if (ret > 0) ring->waiting_reqs = 1; if (ret == -EACCES) wait_event_interruptible(ring->shutdown_wq, kthread_should_stop()); if (do_eoi && !ring->waiting_reqs) { xen_irq_lateeoi(ring->irq, eoi_flags); eoi_flags |= XEN_EOI_FLAG_SPURIOUS; } 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 the free pages pool if it is too large. */ if (time_before(jiffies, blkif->buffer_squeeze_end)) gnttab_page_cache_shrink(&ring->free_pages, 0); else gnttab_page_cache_shrink(&ring->free_pages, 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 */ gnttab_page_cache_shrink(&ring->free_pages, 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); gnttab_page_cache_put(&ring->free_pages, 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); gnttab_page_cache_put(&ring->free_pages, 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 (gnttab_page_cache_get(&ring->free_pages, &pages[i]->page)) { gnttab_page_cache_put(&ring->free_pages, pages_to_gnt, segs_to_map); ret = -ENOMEM; goto out; } 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); /* * 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"); gnttab_page_cache_put(&ring->free_pages, &pages[seg_idx]->page, 1); pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; ret |= !ret; goto next; } pages[seg_idx]->handle = map[new_map_idx].handle; } else { continue; } if (use_persistent_gnts && ring->persistent_gnt_c < 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, 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 (!ret && map_until != num) goto again; out: for (i = last_map; i < num; i++) { /* Don't zap current batch's valid persistent grants. */ if(i >= map_until) pages[i]->persistent_gnt = NULL; pages[i]->handle = BLKBACK_INVALID_HANDLE; } return ret; } 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; 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; 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++; if (blkif->vbd.discard_secure && (req->u.discard.flag & BLKIF_DISCARD_SECURE)) err = blkdev_issue_secure_erase(bdev, req->u.discard.sector_number, req->u.discard.nr_sectors, GFP_KERNEL); else err = blkdev_issue_discard(bdev, req->u.discard.sector_number, req->u.discard.nr_sectors, GFP_KERNEL); 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, unsigned int *eoi_flags) { 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; /* We've seen a request, so clear spurious eoi flag. */ *eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS; 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, unsigned int *eoi_flags) { union blkif_back_rings *blk_rings = &ring->blk_rings; int more_to_do; do { more_to_do = __do_block_io_op(ring, eoi_flags); 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; enum req_op operation; blk_opf_t 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; fallthrough; 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)) { bio = bio_alloc(preq.bdev, bio_max_segs(nseg - i), operation | operation_flags, GFP_KERNEL); biolist[nbio++] = bio; 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_flags != REQ_PREFLUSH); bio = bio_alloc(preq.bdev, 0, operation | operation_flags, GFP_KERNEL); biolist[nbio++] = bio; 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(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; } /* * 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); static void __exit xen_blkif_fini(void) { xen_blkif_xenbus_fini(); xen_blkif_interface_fini(); } module_exit(xen_blkif_fini); MODULE_LICENSE("Dual BSD/GPL"); MODULE_ALIAS("xen-backend:vbd");
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