1 /******************************************************************************
3 * Back-end of the driver for virtual block devices. This portion of the
4 * driver exports a 'unified' block-device interface that can be accessed
5 * by any operating system that implements a compatible front end. A
6 * reference front-end implementation can be found in:
7 * drivers/block/xen-blkfront.c
9 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
10 * Copyright (c) 2005, Christopher Clark
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License version 2
14 * as published by the Free Software Foundation; or, when distributed
15 * separately from the Linux kernel or incorporated into other
16 * software packages, subject to the following license:
18 * Permission is hereby granted, free of charge, to any person obtaining a copy
19 * of this source file (the "Software"), to deal in the Software without
20 * restriction, including without limitation the rights to use, copy, modify,
21 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
22 * and to permit persons to whom the Software is furnished to do so, subject to
23 * the following conditions:
25 * The above copyright notice and this permission notice shall be included in
26 * all copies or substantial portions of the Software.
28 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
29 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
30 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
31 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
32 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
33 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
37 #include <linux/spinlock.h>
38 #include <linux/kthread.h>
39 #include <linux/list.h>
40 #include <linux/delay.h>
41 #include <linux/freezer.h>
42 #include <linux/bitmap.h>
44 #include <xen/events.h>
47 #include <asm/xen/hypervisor.h>
48 #include <asm/xen/hypercall.h>
52 * These are rather arbitrary. They are fairly large because adjacent requests
53 * pulled from a communication ring are quite likely to end up being part of
54 * the same scatter/gather request at the disc.
56 * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW **
58 * This will increase the chances of being able to write whole tracks.
59 * 64 should be enough to keep us competitive with Linux.
61 static int xen_blkif_reqs = 64;
62 module_param_named(reqs, xen_blkif_reqs, int, 0);
63 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate");
65 /* Run-time switchable: /sys/module/blkback/parameters/ */
66 static unsigned int log_stats;
67 module_param(log_stats, int, 0644);
70 * Each outstanding request that we've passed to the lower device layers has a
71 * 'pending_req' allocated to it. Each buffer_head that completes decrements
72 * the pendcnt towards zero. When it hits zero, the specified domain has a
73 * response queued for it, with the saved 'id' passed back.
76 struct xen_blkif *blkif;
80 unsigned short operation;
82 struct list_head free_list;
83 DECLARE_BITMAP(unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
86 #define BLKBACK_INVALID_HANDLE (~0)
89 struct pending_req *pending_reqs;
90 /* List of all 'pending_req' available */
91 struct list_head pending_free;
92 /* And its spinlock. */
93 spinlock_t pending_free_lock;
94 wait_queue_head_t pending_free_wq;
95 /* The list of all pages that are available. */
96 struct page **pending_pages;
97 /* And the grant handles that are available. */
98 grant_handle_t *pending_grant_handles;
101 static struct xen_blkbk *blkbk;
104 * Maximum number of grant pages that can be mapped in blkback.
105 * BLKIF_MAX_SEGMENTS_PER_REQUEST * RING_SIZE is the maximum number of
106 * pages that blkback will persistently map.
107 * Currently, this is:
108 * RING_SIZE = 32 (for all known ring types)
109 * BLKIF_MAX_SEGMENTS_PER_REQUEST = 11
110 * sizeof(struct persistent_gnt) = 48
111 * So the maximum memory used to store the grants is:
112 * 32 * 11 * 48 = 16896 bytes
114 static inline unsigned int max_mapped_grant_pages(enum blkif_protocol protocol)
117 case BLKIF_PROTOCOL_NATIVE:
118 return __CONST_RING_SIZE(blkif, PAGE_SIZE) *
119 BLKIF_MAX_SEGMENTS_PER_REQUEST;
120 case BLKIF_PROTOCOL_X86_32:
121 return __CONST_RING_SIZE(blkif_x86_32, PAGE_SIZE) *
122 BLKIF_MAX_SEGMENTS_PER_REQUEST;
123 case BLKIF_PROTOCOL_X86_64:
124 return __CONST_RING_SIZE(blkif_x86_64, PAGE_SIZE) *
125 BLKIF_MAX_SEGMENTS_PER_REQUEST;
134 * Little helpful macro to figure out the index and virtual address of the
135 * pending_pages[..]. For each 'pending_req' we have have up to
136 * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through
137 * 10 and would index in the pending_pages[..].
139 static inline int vaddr_pagenr(struct pending_req *req, int seg)
141 return (req - blkbk->pending_reqs) *
142 BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
145 #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)]
147 static inline unsigned long vaddr(struct pending_req *req, int seg)
149 unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg));
150 return (unsigned long)pfn_to_kaddr(pfn);
153 #define pending_handle(_req, _seg) \
154 (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)])
157 static int do_block_io_op(struct xen_blkif *blkif);
158 static int dispatch_rw_block_io(struct xen_blkif *blkif,
159 struct blkif_request *req,
160 struct pending_req *pending_req);
161 static void make_response(struct xen_blkif *blkif, u64 id,
162 unsigned short op, int st);
164 #define foreach_grant(pos, rbtree, node) \
165 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node); \
166 &(pos)->node != NULL; \
167 (pos) = container_of(rb_next(&(pos)->node), typeof(*(pos)), node))
170 static void add_persistent_gnt(struct rb_root *root,
171 struct persistent_gnt *persistent_gnt)
173 struct rb_node **new = &(root->rb_node), *parent = NULL;
174 struct persistent_gnt *this;
176 /* Figure out where to put new node */
178 this = container_of(*new, struct persistent_gnt, node);
181 if (persistent_gnt->gnt < this->gnt)
182 new = &((*new)->rb_left);
183 else if (persistent_gnt->gnt > this->gnt)
184 new = &((*new)->rb_right);
186 pr_alert(DRV_PFX " trying to add a gref that's already in the tree\n");
191 /* Add new node and rebalance tree. */
192 rb_link_node(&(persistent_gnt->node), parent, new);
193 rb_insert_color(&(persistent_gnt->node), root);
196 static struct persistent_gnt *get_persistent_gnt(struct rb_root *root,
199 struct persistent_gnt *data;
200 struct rb_node *node = root->rb_node;
203 data = container_of(node, struct persistent_gnt, node);
205 if (gref < data->gnt)
206 node = node->rb_left;
207 else if (gref > data->gnt)
208 node = node->rb_right;
215 static void free_persistent_gnts(struct rb_root *root, unsigned int num)
217 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
218 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
219 struct persistent_gnt *persistent_gnt;
221 int segs_to_unmap = 0;
223 foreach_grant(persistent_gnt, root, node) {
224 BUG_ON(persistent_gnt->handle ==
225 BLKBACK_INVALID_HANDLE);
226 gnttab_set_unmap_op(&unmap[segs_to_unmap],
227 (unsigned long) pfn_to_kaddr(page_to_pfn(
228 persistent_gnt->page)),
230 persistent_gnt->handle);
232 pages[segs_to_unmap] = persistent_gnt->page;
233 rb_erase(&persistent_gnt->node, root);
234 kfree(persistent_gnt);
237 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
238 !rb_next(&persistent_gnt->node)) {
239 ret = gnttab_unmap_refs(unmap, NULL, pages,
249 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
251 static struct pending_req *alloc_req(void)
253 struct pending_req *req = NULL;
256 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
257 if (!list_empty(&blkbk->pending_free)) {
258 req = list_entry(blkbk->pending_free.next, struct pending_req,
260 list_del(&req->free_list);
262 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
267 * Return the 'pending_req' structure back to the freepool. We also
268 * wake up the thread if it was waiting for a free page.
270 static void free_req(struct pending_req *req)
275 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
276 was_empty = list_empty(&blkbk->pending_free);
277 list_add(&req->free_list, &blkbk->pending_free);
278 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
280 wake_up(&blkbk->pending_free_wq);
284 * Routines for managing virtual block devices (vbds).
286 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
289 struct xen_vbd *vbd = &blkif->vbd;
292 if ((operation != READ) && vbd->readonly)
295 if (likely(req->nr_sects)) {
296 blkif_sector_t end = req->sector_number + req->nr_sects;
298 if (unlikely(end < req->sector_number))
300 if (unlikely(end > vbd_sz(vbd)))
304 req->dev = vbd->pdevice;
305 req->bdev = vbd->bdev;
312 static void xen_vbd_resize(struct xen_blkif *blkif)
314 struct xen_vbd *vbd = &blkif->vbd;
315 struct xenbus_transaction xbt;
317 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
318 unsigned long long new_size = vbd_sz(vbd);
320 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
321 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
322 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
323 vbd->size = new_size;
325 err = xenbus_transaction_start(&xbt);
327 pr_warn(DRV_PFX "Error starting transaction");
330 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
331 (unsigned long long)vbd_sz(vbd));
333 pr_warn(DRV_PFX "Error writing new size");
337 * Write the current state; we will use this to synchronize
338 * the front-end. If the current state is "connected" the
339 * front-end will get the new size information online.
341 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
343 pr_warn(DRV_PFX "Error writing the state");
347 err = xenbus_transaction_end(xbt, 0);
351 pr_warn(DRV_PFX "Error ending transaction");
354 xenbus_transaction_end(xbt, 1);
358 * Notification from the guest OS.
360 static void blkif_notify_work(struct xen_blkif *blkif)
362 blkif->waiting_reqs = 1;
366 irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
368 blkif_notify_work(dev_id);
373 * SCHEDULER FUNCTIONS
376 static void print_stats(struct xen_blkif *blkif)
378 pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d"
380 current->comm, blkif->st_oo_req,
381 blkif->st_rd_req, blkif->st_wr_req,
382 blkif->st_f_req, blkif->st_ds_req);
383 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
384 blkif->st_rd_req = 0;
385 blkif->st_wr_req = 0;
386 blkif->st_oo_req = 0;
387 blkif->st_ds_req = 0;
390 int xen_blkif_schedule(void *arg)
392 struct xen_blkif *blkif = arg;
393 struct xen_vbd *vbd = &blkif->vbd;
395 xen_blkif_get(blkif);
397 while (!kthread_should_stop()) {
400 if (unlikely(vbd->size != vbd_sz(vbd)))
401 xen_vbd_resize(blkif);
403 wait_event_interruptible(
405 blkif->waiting_reqs || kthread_should_stop());
406 wait_event_interruptible(
407 blkbk->pending_free_wq,
408 !list_empty(&blkbk->pending_free) ||
409 kthread_should_stop());
411 blkif->waiting_reqs = 0;
412 smp_mb(); /* clear flag *before* checking for work */
414 if (do_block_io_op(blkif))
415 blkif->waiting_reqs = 1;
417 if (log_stats && time_after(jiffies, blkif->st_print))
421 /* Free all persistent grant pages */
422 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
423 free_persistent_gnts(&blkif->persistent_gnts,
424 blkif->persistent_gnt_c);
426 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
427 blkif->persistent_gnt_c = 0;
432 blkif->xenblkd = NULL;
433 xen_blkif_put(blkif);
443 * Unmap the grant references, and also remove the M2P over-rides
444 * used in the 'pending_req'.
446 static void xen_blkbk_unmap(struct pending_req *req)
448 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
449 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
450 unsigned int i, invcount = 0;
451 grant_handle_t handle;
454 for (i = 0; i < req->nr_pages; i++) {
455 if (!test_bit(i, req->unmap_seg))
457 handle = pending_handle(req, i);
458 if (handle == BLKBACK_INVALID_HANDLE)
460 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
461 GNTMAP_host_map, handle);
462 pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
463 pages[invcount] = virt_to_page(vaddr(req, i));
467 ret = gnttab_unmap_refs(unmap, NULL, pages, invcount);
471 static int xen_blkbk_map(struct blkif_request *req,
472 struct pending_req *pending_req,
473 struct seg_buf seg[],
474 struct page *pages[])
476 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
477 struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST];
478 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
479 struct persistent_gnt *persistent_gnt = NULL;
480 struct xen_blkif *blkif = pending_req->blkif;
481 phys_addr_t addr = 0;
484 int nseg = req->u.rw.nr_segments;
487 int use_persistent_gnts;
489 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
491 BUG_ON(blkif->persistent_gnt_c >
492 max_mapped_grant_pages(pending_req->blkif->blk_protocol));
495 * Fill out preq.nr_sects with proper amount of sectors, and setup
496 * assign map[..] with the PFN of the page in our domain with the
497 * corresponding grant reference for each page.
499 for (i = 0; i < nseg; i++) {
502 if (use_persistent_gnts)
503 persistent_gnt = get_persistent_gnt(
504 &blkif->persistent_gnts,
505 req->u.rw.seg[i].gref);
507 if (persistent_gnt) {
509 * We are using persistent grants and
510 * the grant is already mapped
513 } else if (use_persistent_gnts &&
514 blkif->persistent_gnt_c <
515 max_mapped_grant_pages(blkif->blk_protocol)) {
517 * We are using persistent grants, the grant is
518 * not mapped but we have room for it
521 persistent_gnt = kmalloc(
522 sizeof(struct persistent_gnt),
526 persistent_gnt->page = alloc_page(GFP_KERNEL);
527 if (!persistent_gnt->page) {
528 kfree(persistent_gnt);
531 persistent_gnt->gnt = req->u.rw.seg[i].gref;
532 persistent_gnt->handle = BLKBACK_INVALID_HANDLE;
534 pages_to_gnt[segs_to_map] =
535 persistent_gnt->page;
536 addr = (unsigned long) pfn_to_kaddr(
537 page_to_pfn(persistent_gnt->page));
539 add_persistent_gnt(&blkif->persistent_gnts,
541 blkif->persistent_gnt_c++;
542 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
543 persistent_gnt->gnt, blkif->persistent_gnt_c,
544 max_mapped_grant_pages(blkif->blk_protocol));
547 * We are either using persistent grants and
548 * hit the maximum limit of grants mapped,
549 * or we are not using persistent grants.
551 if (use_persistent_gnts &&
552 !blkif->vbd.overflow_max_grants) {
553 blkif->vbd.overflow_max_grants = 1;
554 pr_alert(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
555 blkif->domid, blkif->vbd.handle);
558 pages[i] = blkbk->pending_page(pending_req, i);
559 addr = vaddr(pending_req, i);
560 pages_to_gnt[segs_to_map] =
561 blkbk->pending_page(pending_req, i);
564 if (persistent_gnt) {
565 pages[i] = persistent_gnt->page;
566 persistent_gnts[i] = persistent_gnt;
568 persistent_gnts[i] = NULL;
572 flags = GNTMAP_host_map;
573 if (!persistent_gnt &&
574 (pending_req->operation != BLKIF_OP_READ))
575 flags |= GNTMAP_readonly;
576 gnttab_set_map_op(&map[segs_to_map++], addr,
577 flags, req->u.rw.seg[i].gref,
583 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
588 * Now swizzle the MFN in our domain with the MFN from the other domain
589 * so that when we access vaddr(pending_req,i) it has the contents of
590 * the page from the other domain.
592 bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
593 for (i = 0, j = 0; i < nseg; i++) {
594 if (!persistent_gnts[i] ||
595 persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) {
596 /* This is a newly mapped grant */
597 BUG_ON(j >= segs_to_map);
598 if (unlikely(map[j].status != 0)) {
599 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
600 map[j].handle = BLKBACK_INVALID_HANDLE;
602 if (persistent_gnts[i]) {
603 rb_erase(&persistent_gnts[i]->node,
604 &blkif->persistent_gnts);
605 blkif->persistent_gnt_c--;
606 kfree(persistent_gnts[i]);
607 persistent_gnts[i] = NULL;
611 if (persistent_gnts[i]) {
612 if (persistent_gnts[i]->handle ==
613 BLKBACK_INVALID_HANDLE) {
615 * If this is a new persistent grant
618 persistent_gnts[i]->handle = map[j].handle;
619 persistent_gnts[i]->dev_bus_addr =
620 map[j++].dev_bus_addr;
622 pending_handle(pending_req, i) =
623 persistent_gnts[i]->handle;
628 seg[i].buf = persistent_gnts[i]->dev_bus_addr |
629 (req->u.rw.seg[i].first_sect << 9);
631 pending_handle(pending_req, i) = map[j].handle;
632 bitmap_set(pending_req->unmap_seg, i, 1);
639 seg[i].buf = map[j++].dev_bus_addr |
640 (req->u.rw.seg[i].first_sect << 9);
646 static int dispatch_discard_io(struct xen_blkif *blkif,
647 struct blkif_request *req)
650 int status = BLKIF_RSP_OKAY;
651 struct block_device *bdev = blkif->vbd.bdev;
652 unsigned long secure;
656 xen_blkif_get(blkif);
657 secure = (blkif->vbd.discard_secure &&
658 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
659 BLKDEV_DISCARD_SECURE : 0;
661 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
662 req->u.discard.nr_sectors,
665 if (err == -EOPNOTSUPP) {
666 pr_debug(DRV_PFX "discard op failed, not supported\n");
667 status = BLKIF_RSP_EOPNOTSUPP;
669 status = BLKIF_RSP_ERROR;
671 make_response(blkif, req->u.discard.id, req->operation, status);
672 xen_blkif_put(blkif);
676 static void xen_blk_drain_io(struct xen_blkif *blkif)
678 atomic_set(&blkif->drain, 1);
680 /* The initial value is one, and one refcnt taken at the
681 * start of the xen_blkif_schedule thread. */
682 if (atomic_read(&blkif->refcnt) <= 2)
684 wait_for_completion_interruptible_timeout(
685 &blkif->drain_complete, HZ);
687 if (!atomic_read(&blkif->drain))
689 } while (!kthread_should_stop());
690 atomic_set(&blkif->drain, 0);
694 * Completion callback on the bio's. Called as bh->b_end_io()
697 static void __end_block_io_op(struct pending_req *pending_req, int error)
699 /* An error fails the entire request. */
700 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
701 (error == -EOPNOTSUPP)) {
702 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
703 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
704 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
705 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
706 (error == -EOPNOTSUPP)) {
707 pr_debug(DRV_PFX "write barrier op failed, not supported\n");
708 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
709 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
711 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
712 " error=%d\n", error);
713 pending_req->status = BLKIF_RSP_ERROR;
717 * If all of the bio's have completed it is time to unmap
718 * the grant references associated with 'request' and provide
719 * the proper response on the ring.
721 if (atomic_dec_and_test(&pending_req->pendcnt)) {
722 xen_blkbk_unmap(pending_req);
723 make_response(pending_req->blkif, pending_req->id,
724 pending_req->operation, pending_req->status);
725 xen_blkif_put(pending_req->blkif);
726 if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
727 if (atomic_read(&pending_req->blkif->drain))
728 complete(&pending_req->blkif->drain_complete);
730 free_req(pending_req);
737 static void end_block_io_op(struct bio *bio, int error)
739 __end_block_io_op(bio->bi_private, error);
746 * Function to copy the from the ring buffer the 'struct blkif_request'
747 * (which has the sectors we want, number of them, grant references, etc),
748 * and transmute it to the block API to hand it over to the proper block disk.
751 __do_block_io_op(struct xen_blkif *blkif)
753 union blkif_back_rings *blk_rings = &blkif->blk_rings;
754 struct blkif_request req;
755 struct pending_req *pending_req;
759 rc = blk_rings->common.req_cons;
760 rp = blk_rings->common.sring->req_prod;
761 rmb(); /* Ensure we see queued requests up to 'rp'. */
765 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
768 if (kthread_should_stop()) {
773 pending_req = alloc_req();
774 if (NULL == pending_req) {
780 switch (blkif->blk_protocol) {
781 case BLKIF_PROTOCOL_NATIVE:
782 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
784 case BLKIF_PROTOCOL_X86_32:
785 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
787 case BLKIF_PROTOCOL_X86_64:
788 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
793 blk_rings->common.req_cons = ++rc; /* before make_response() */
795 /* Apply all sanity checks to /private copy/ of request. */
797 if (unlikely(req.operation == BLKIF_OP_DISCARD)) {
798 free_req(pending_req);
799 if (dispatch_discard_io(blkif, &req))
801 } else if (dispatch_rw_block_io(blkif, &req, pending_req))
804 /* Yield point for this unbounded loop. */
812 do_block_io_op(struct xen_blkif *blkif)
814 union blkif_back_rings *blk_rings = &blkif->blk_rings;
818 more_to_do = __do_block_io_op(blkif);
822 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
823 } while (more_to_do);
828 * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
829 * and call the 'submit_bio' to pass it to the underlying storage.
831 static int dispatch_rw_block_io(struct xen_blkif *blkif,
832 struct blkif_request *req,
833 struct pending_req *pending_req)
835 struct phys_req preq;
836 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
838 struct bio *bio = NULL;
839 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
842 struct blk_plug plug;
844 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
846 switch (req->operation) {
853 operation = WRITE_ODIRECT;
855 case BLKIF_OP_WRITE_BARRIER:
857 case BLKIF_OP_FLUSH_DISKCACHE:
859 operation = WRITE_FLUSH;
862 operation = 0; /* make gcc happy */
867 /* Check that the number of segments is sane. */
868 nseg = req->u.rw.nr_segments;
870 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
871 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
872 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
874 /* Haven't submitted any bio's yet. */
878 preq.dev = req->u.rw.handle;
879 preq.sector_number = req->u.rw.sector_number;
882 pending_req->blkif = blkif;
883 pending_req->id = req->u.rw.id;
884 pending_req->operation = req->operation;
885 pending_req->status = BLKIF_RSP_OKAY;
886 pending_req->nr_pages = nseg;
888 for (i = 0; i < nseg; i++) {
889 seg[i].nsec = req->u.rw.seg[i].last_sect -
890 req->u.rw.seg[i].first_sect + 1;
891 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
892 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
894 preq.nr_sects += seg[i].nsec;
898 if (xen_vbd_translate(&preq, blkif, operation) != 0) {
899 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
900 operation == READ ? "read" : "write",
902 preq.sector_number + preq.nr_sects, preq.dev);
907 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev
910 for (i = 0; i < nseg; i++) {
911 if (((int)preq.sector_number|(int)seg[i].nsec) &
912 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
913 pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
919 /* Wait on all outstanding I/O's and once that has been completed
920 * issue the WRITE_FLUSH.
923 xen_blk_drain_io(pending_req->blkif);
926 * If we have failed at this point, we need to undo the M2P override,
927 * set gnttab_set_unmap_op on all of the grant references and perform
928 * the hypercall to unmap the grants - that is all done in
931 if (xen_blkbk_map(req, pending_req, seg, pages))
935 * This corresponding xen_blkif_put is done in __end_block_io_op, or
936 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
938 xen_blkif_get(blkif);
940 for (i = 0; i < nseg; i++) {
941 while ((bio == NULL) ||
945 seg[i].buf & ~PAGE_MASK) == 0)) {
947 bio = bio_alloc(GFP_KERNEL, nseg-i);
948 if (unlikely(bio == NULL))
951 biolist[nbio++] = bio;
952 bio->bi_bdev = preq.bdev;
953 bio->bi_private = pending_req;
954 bio->bi_end_io = end_block_io_op;
955 bio->bi_sector = preq.sector_number;
958 preq.sector_number += seg[i].nsec;
961 /* This will be hit if the operation was a flush or discard. */
963 BUG_ON(operation != WRITE_FLUSH);
965 bio = bio_alloc(GFP_KERNEL, 0);
966 if (unlikely(bio == NULL))
969 biolist[nbio++] = bio;
970 bio->bi_bdev = preq.bdev;
971 bio->bi_private = pending_req;
972 bio->bi_end_io = end_block_io_op;
976 * We set it one so that the last submit_bio does not have to call
979 atomic_set(&pending_req->pendcnt, nbio);
981 /* Get a reference count for the disk queue and start sending I/O */
982 blk_start_plug(&plug);
984 for (i = 0; i < nbio; i++)
985 submit_bio(operation, biolist[i]);
987 /* Let the I/Os go.. */
988 blk_finish_plug(&plug);
990 if (operation == READ)
991 blkif->st_rd_sect += preq.nr_sects;
992 else if (operation & WRITE)
993 blkif->st_wr_sect += preq.nr_sects;
998 xen_blkbk_unmap(pending_req);
1000 /* Haven't submitted any bio's yet. */
1001 make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR);
1002 free_req(pending_req);
1003 msleep(1); /* back off a bit */
1007 for (i = 0; i < nbio; i++)
1008 bio_put(biolist[i]);
1009 __end_block_io_op(pending_req, -EINVAL);
1010 msleep(1); /* back off a bit */
1017 * Put a response on the ring on how the operation fared.
1019 static void make_response(struct xen_blkif *blkif, u64 id,
1020 unsigned short op, int st)
1022 struct blkif_response resp;
1023 unsigned long flags;
1024 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1028 resp.operation = op;
1031 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
1032 /* Place on the response ring for the relevant domain. */
1033 switch (blkif->blk_protocol) {
1034 case BLKIF_PROTOCOL_NATIVE:
1035 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
1036 &resp, sizeof(resp));
1038 case BLKIF_PROTOCOL_X86_32:
1039 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
1040 &resp, sizeof(resp));
1042 case BLKIF_PROTOCOL_X86_64:
1043 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
1044 &resp, sizeof(resp));
1049 blk_rings->common.rsp_prod_pvt++;
1050 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1051 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
1053 notify_remote_via_irq(blkif->irq);
1056 static int __init xen_blkif_init(void)
1064 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL);
1066 pr_alert(DRV_PFX "%s: out of memory!\n", __func__);
1070 mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
1072 blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) *
1073 xen_blkif_reqs, GFP_KERNEL);
1074 blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) *
1075 mmap_pages, GFP_KERNEL);
1076 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) *
1077 mmap_pages, GFP_KERNEL);
1079 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles ||
1080 !blkbk->pending_pages) {
1085 for (i = 0; i < mmap_pages; i++) {
1086 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
1087 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL);
1088 if (blkbk->pending_pages[i] == NULL) {
1093 rc = xen_blkif_interface_init();
1097 INIT_LIST_HEAD(&blkbk->pending_free);
1098 spin_lock_init(&blkbk->pending_free_lock);
1099 init_waitqueue_head(&blkbk->pending_free_wq);
1101 for (i = 0; i < xen_blkif_reqs; i++)
1102 list_add_tail(&blkbk->pending_reqs[i].free_list,
1103 &blkbk->pending_free);
1105 rc = xen_blkif_xenbus_init();
1112 pr_alert(DRV_PFX "%s: out of memory\n", __func__);
1114 kfree(blkbk->pending_reqs);
1115 kfree(blkbk->pending_grant_handles);
1116 if (blkbk->pending_pages) {
1117 for (i = 0; i < mmap_pages; i++) {
1118 if (blkbk->pending_pages[i])
1119 __free_page(blkbk->pending_pages[i]);
1121 kfree(blkbk->pending_pages);
1128 module_init(xen_blkif_init);
1130 MODULE_LICENSE("Dual BSD/GPL");
1131 MODULE_ALIAS("xen-backend:vbd");