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>
49 #include <xen/balloon.h>
53 * These are rather arbitrary. They are fairly large because adjacent requests
54 * pulled from a communication ring are quite likely to end up being part of
55 * the same scatter/gather request at the disc.
57 * ** TRY INCREASING 'xen_blkif_reqs' IF WRITE SPEEDS SEEM TOO LOW **
59 * This will increase the chances of being able to write whole tracks.
60 * 64 should be enough to keep us competitive with Linux.
62 static int xen_blkif_reqs = 64;
63 module_param_named(reqs, xen_blkif_reqs, int, 0);
64 MODULE_PARM_DESC(reqs, "Number of blkback requests to allocate");
66 /* Run-time switchable: /sys/module/blkback/parameters/ */
67 static unsigned int log_stats;
68 module_param(log_stats, int, 0644);
71 * Each outstanding request that we've passed to the lower device layers has a
72 * 'pending_req' allocated to it. Each buffer_head that completes decrements
73 * the pendcnt towards zero. When it hits zero, the specified domain has a
74 * response queued for it, with the saved 'id' passed back.
77 struct xen_blkif *blkif;
81 unsigned short operation;
83 struct list_head free_list;
84 DECLARE_BITMAP(unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
87 #define BLKBACK_INVALID_HANDLE (~0)
90 struct pending_req *pending_reqs;
91 /* List of all 'pending_req' available */
92 struct list_head pending_free;
93 /* And its spinlock. */
94 spinlock_t pending_free_lock;
95 wait_queue_head_t pending_free_wq;
96 /* The list of all pages that are available. */
97 struct page **pending_pages;
98 /* And the grant handles that are available. */
99 grant_handle_t *pending_grant_handles;
102 static struct xen_blkbk *blkbk;
105 * Maximum number of grant pages that can be mapped in blkback.
106 * BLKIF_MAX_SEGMENTS_PER_REQUEST * RING_SIZE is the maximum number of
107 * pages that blkback will persistently map.
108 * Currently, this is:
109 * RING_SIZE = 32 (for all known ring types)
110 * BLKIF_MAX_SEGMENTS_PER_REQUEST = 11
111 * sizeof(struct persistent_gnt) = 48
112 * So the maximum memory used to store the grants is:
113 * 32 * 11 * 48 = 16896 bytes
115 static inline unsigned int max_mapped_grant_pages(enum blkif_protocol protocol)
118 case BLKIF_PROTOCOL_NATIVE:
119 return __CONST_RING_SIZE(blkif, PAGE_SIZE) *
120 BLKIF_MAX_SEGMENTS_PER_REQUEST;
121 case BLKIF_PROTOCOL_X86_32:
122 return __CONST_RING_SIZE(blkif_x86_32, PAGE_SIZE) *
123 BLKIF_MAX_SEGMENTS_PER_REQUEST;
124 case BLKIF_PROTOCOL_X86_64:
125 return __CONST_RING_SIZE(blkif_x86_64, PAGE_SIZE) *
126 BLKIF_MAX_SEGMENTS_PER_REQUEST;
135 * Little helpful macro to figure out the index and virtual address of the
136 * pending_pages[..]. For each 'pending_req' we have have up to
137 * BLKIF_MAX_SEGMENTS_PER_REQUEST (11) pages. The seg would be from 0 through
138 * 10 and would index in the pending_pages[..].
140 static inline int vaddr_pagenr(struct pending_req *req, int seg)
142 return (req - blkbk->pending_reqs) *
143 BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
146 #define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)]
148 static inline unsigned long vaddr(struct pending_req *req, int seg)
150 unsigned long pfn = page_to_pfn(blkbk->pending_page(req, seg));
151 return (unsigned long)pfn_to_kaddr(pfn);
154 #define pending_handle(_req, _seg) \
155 (blkbk->pending_grant_handles[vaddr_pagenr(_req, _seg)])
158 static int do_block_io_op(struct xen_blkif *blkif);
159 static int dispatch_rw_block_io(struct xen_blkif *blkif,
160 struct blkif_request *req,
161 struct pending_req *pending_req);
162 static void make_response(struct xen_blkif *blkif, u64 id,
163 unsigned short op, int st);
165 #define foreach_grant_safe(pos, n, rbtree, node) \
166 for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
167 (n) = rb_next(&(pos)->node); \
168 &(pos)->node != NULL; \
169 (pos) = container_of(n, typeof(*(pos)), node), \
170 (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
173 static void add_persistent_gnt(struct rb_root *root,
174 struct persistent_gnt *persistent_gnt)
176 struct rb_node **new = &(root->rb_node), *parent = NULL;
177 struct persistent_gnt *this;
179 /* Figure out where to put new node */
181 this = container_of(*new, struct persistent_gnt, node);
184 if (persistent_gnt->gnt < this->gnt)
185 new = &((*new)->rb_left);
186 else if (persistent_gnt->gnt > this->gnt)
187 new = &((*new)->rb_right);
189 pr_alert(DRV_PFX " trying to add a gref that's already in the tree\n");
194 /* Add new node and rebalance tree. */
195 rb_link_node(&(persistent_gnt->node), parent, new);
196 rb_insert_color(&(persistent_gnt->node), root);
199 static struct persistent_gnt *get_persistent_gnt(struct rb_root *root,
202 struct persistent_gnt *data;
203 struct rb_node *node = root->rb_node;
206 data = container_of(node, struct persistent_gnt, node);
208 if (gref < data->gnt)
209 node = node->rb_left;
210 else if (gref > data->gnt)
211 node = node->rb_right;
218 static void free_persistent_gnts(struct rb_root *root, unsigned int num)
220 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
221 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
222 struct persistent_gnt *persistent_gnt;
225 int segs_to_unmap = 0;
227 foreach_grant_safe(persistent_gnt, n, root, node) {
228 BUG_ON(persistent_gnt->handle ==
229 BLKBACK_INVALID_HANDLE);
230 gnttab_set_unmap_op(&unmap[segs_to_unmap],
231 (unsigned long) pfn_to_kaddr(page_to_pfn(
232 persistent_gnt->page)),
234 persistent_gnt->handle);
236 pages[segs_to_unmap] = persistent_gnt->page;
238 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
239 !rb_next(&persistent_gnt->node)) {
240 ret = gnttab_unmap_refs(unmap, NULL, pages,
243 free_xenballooned_pages(segs_to_unmap, pages);
247 rb_erase(&persistent_gnt->node, root);
248 kfree(persistent_gnt);
255 * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
257 static struct pending_req *alloc_req(void)
259 struct pending_req *req = NULL;
262 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
263 if (!list_empty(&blkbk->pending_free)) {
264 req = list_entry(blkbk->pending_free.next, struct pending_req,
266 list_del(&req->free_list);
268 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
273 * Return the 'pending_req' structure back to the freepool. We also
274 * wake up the thread if it was waiting for a free page.
276 static void free_req(struct pending_req *req)
281 spin_lock_irqsave(&blkbk->pending_free_lock, flags);
282 was_empty = list_empty(&blkbk->pending_free);
283 list_add(&req->free_list, &blkbk->pending_free);
284 spin_unlock_irqrestore(&blkbk->pending_free_lock, flags);
286 wake_up(&blkbk->pending_free_wq);
290 * Routines for managing virtual block devices (vbds).
292 static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
295 struct xen_vbd *vbd = &blkif->vbd;
298 if ((operation != READ) && vbd->readonly)
301 if (likely(req->nr_sects)) {
302 blkif_sector_t end = req->sector_number + req->nr_sects;
304 if (unlikely(end < req->sector_number))
306 if (unlikely(end > vbd_sz(vbd)))
310 req->dev = vbd->pdevice;
311 req->bdev = vbd->bdev;
318 static void xen_vbd_resize(struct xen_blkif *blkif)
320 struct xen_vbd *vbd = &blkif->vbd;
321 struct xenbus_transaction xbt;
323 struct xenbus_device *dev = xen_blkbk_xenbus(blkif->be);
324 unsigned long long new_size = vbd_sz(vbd);
326 pr_info(DRV_PFX "VBD Resize: Domid: %d, Device: (%d, %d)\n",
327 blkif->domid, MAJOR(vbd->pdevice), MINOR(vbd->pdevice));
328 pr_info(DRV_PFX "VBD Resize: new size %llu\n", new_size);
329 vbd->size = new_size;
331 err = xenbus_transaction_start(&xbt);
333 pr_warn(DRV_PFX "Error starting transaction");
336 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
337 (unsigned long long)vbd_sz(vbd));
339 pr_warn(DRV_PFX "Error writing new size");
343 * Write the current state; we will use this to synchronize
344 * the front-end. If the current state is "connected" the
345 * front-end will get the new size information online.
347 err = xenbus_printf(xbt, dev->nodename, "state", "%d", dev->state);
349 pr_warn(DRV_PFX "Error writing the state");
353 err = xenbus_transaction_end(xbt, 0);
357 pr_warn(DRV_PFX "Error ending transaction");
360 xenbus_transaction_end(xbt, 1);
364 * Notification from the guest OS.
366 static void blkif_notify_work(struct xen_blkif *blkif)
368 blkif->waiting_reqs = 1;
372 irqreturn_t xen_blkif_be_int(int irq, void *dev_id)
374 blkif_notify_work(dev_id);
379 * SCHEDULER FUNCTIONS
382 static void print_stats(struct xen_blkif *blkif)
384 pr_info("xen-blkback (%s): oo %3d | rd %4d | wr %4d | f %4d"
386 current->comm, blkif->st_oo_req,
387 blkif->st_rd_req, blkif->st_wr_req,
388 blkif->st_f_req, blkif->st_ds_req);
389 blkif->st_print = jiffies + msecs_to_jiffies(10 * 1000);
390 blkif->st_rd_req = 0;
391 blkif->st_wr_req = 0;
392 blkif->st_oo_req = 0;
393 blkif->st_ds_req = 0;
396 int xen_blkif_schedule(void *arg)
398 struct xen_blkif *blkif = arg;
399 struct xen_vbd *vbd = &blkif->vbd;
401 xen_blkif_get(blkif);
403 while (!kthread_should_stop()) {
406 if (unlikely(vbd->size != vbd_sz(vbd)))
407 xen_vbd_resize(blkif);
409 wait_event_interruptible(
411 blkif->waiting_reqs || kthread_should_stop());
412 wait_event_interruptible(
413 blkbk->pending_free_wq,
414 !list_empty(&blkbk->pending_free) ||
415 kthread_should_stop());
417 blkif->waiting_reqs = 0;
418 smp_mb(); /* clear flag *before* checking for work */
420 if (do_block_io_op(blkif))
421 blkif->waiting_reqs = 1;
423 if (log_stats && time_after(jiffies, blkif->st_print))
427 /* Free all persistent grant pages */
428 if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
429 free_persistent_gnts(&blkif->persistent_gnts,
430 blkif->persistent_gnt_c);
432 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
433 blkif->persistent_gnt_c = 0;
438 blkif->xenblkd = NULL;
439 xen_blkif_put(blkif);
449 * Unmap the grant references, and also remove the M2P over-rides
450 * used in the 'pending_req'.
452 static void xen_blkbk_unmap(struct pending_req *req)
454 struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
455 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
456 unsigned int i, invcount = 0;
457 grant_handle_t handle;
460 for (i = 0; i < req->nr_pages; i++) {
461 if (!test_bit(i, req->unmap_seg))
463 handle = pending_handle(req, i);
464 if (handle == BLKBACK_INVALID_HANDLE)
466 gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
467 GNTMAP_host_map, handle);
468 pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
469 pages[invcount] = virt_to_page(vaddr(req, i));
473 ret = gnttab_unmap_refs(unmap, NULL, pages, invcount);
477 static int xen_blkbk_map(struct blkif_request *req,
478 struct pending_req *pending_req,
479 struct seg_buf seg[],
480 struct page *pages[])
482 struct gnttab_map_grant_ref map[BLKIF_MAX_SEGMENTS_PER_REQUEST];
483 struct persistent_gnt *persistent_gnts[BLKIF_MAX_SEGMENTS_PER_REQUEST];
484 struct page *pages_to_gnt[BLKIF_MAX_SEGMENTS_PER_REQUEST];
485 struct persistent_gnt *persistent_gnt = NULL;
486 struct xen_blkif *blkif = pending_req->blkif;
487 phys_addr_t addr = 0;
490 int nseg = req->u.rw.nr_segments;
493 int use_persistent_gnts;
495 use_persistent_gnts = (blkif->vbd.feature_gnt_persistent);
497 BUG_ON(blkif->persistent_gnt_c >
498 max_mapped_grant_pages(pending_req->blkif->blk_protocol));
501 * Fill out preq.nr_sects with proper amount of sectors, and setup
502 * assign map[..] with the PFN of the page in our domain with the
503 * corresponding grant reference for each page.
505 for (i = 0; i < nseg; i++) {
508 if (use_persistent_gnts)
509 persistent_gnt = get_persistent_gnt(
510 &blkif->persistent_gnts,
511 req->u.rw.seg[i].gref);
513 if (persistent_gnt) {
515 * We are using persistent grants and
516 * the grant is already mapped
519 } else if (use_persistent_gnts &&
520 blkif->persistent_gnt_c <
521 max_mapped_grant_pages(blkif->blk_protocol)) {
523 * We are using persistent grants, the grant is
524 * not mapped but we have room for it
527 persistent_gnt = kmalloc(
528 sizeof(struct persistent_gnt),
532 if (alloc_xenballooned_pages(1, &persistent_gnt->page,
534 kfree(persistent_gnt);
537 persistent_gnt->gnt = req->u.rw.seg[i].gref;
538 persistent_gnt->handle = BLKBACK_INVALID_HANDLE;
540 pages_to_gnt[segs_to_map] =
541 persistent_gnt->page;
542 addr = (unsigned long) pfn_to_kaddr(
543 page_to_pfn(persistent_gnt->page));
545 add_persistent_gnt(&blkif->persistent_gnts,
547 blkif->persistent_gnt_c++;
548 pr_debug(DRV_PFX " grant %u added to the tree of persistent grants, using %u/%u\n",
549 persistent_gnt->gnt, blkif->persistent_gnt_c,
550 max_mapped_grant_pages(blkif->blk_protocol));
553 * We are either using persistent grants and
554 * hit the maximum limit of grants mapped,
555 * or we are not using persistent grants.
557 if (use_persistent_gnts &&
558 !blkif->vbd.overflow_max_grants) {
559 blkif->vbd.overflow_max_grants = 1;
560 pr_alert(DRV_PFX " domain %u, device %#x is using maximum number of persistent grants\n",
561 blkif->domid, blkif->vbd.handle);
564 pages[i] = blkbk->pending_page(pending_req, i);
565 addr = vaddr(pending_req, i);
566 pages_to_gnt[segs_to_map] =
567 blkbk->pending_page(pending_req, i);
570 if (persistent_gnt) {
571 pages[i] = persistent_gnt->page;
572 persistent_gnts[i] = persistent_gnt;
574 persistent_gnts[i] = NULL;
578 flags = GNTMAP_host_map;
579 if (!persistent_gnt &&
580 (pending_req->operation != BLKIF_OP_READ))
581 flags |= GNTMAP_readonly;
582 gnttab_set_map_op(&map[segs_to_map++], addr,
583 flags, req->u.rw.seg[i].gref,
589 ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
594 * Now swizzle the MFN in our domain with the MFN from the other domain
595 * so that when we access vaddr(pending_req,i) it has the contents of
596 * the page from the other domain.
598 bitmap_zero(pending_req->unmap_seg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
599 for (i = 0, j = 0; i < nseg; i++) {
600 if (!persistent_gnts[i] ||
601 persistent_gnts[i]->handle == BLKBACK_INVALID_HANDLE) {
602 /* This is a newly mapped grant */
603 BUG_ON(j >= segs_to_map);
604 if (unlikely(map[j].status != 0)) {
605 pr_debug(DRV_PFX "invalid buffer -- could not remap it\n");
606 map[j].handle = BLKBACK_INVALID_HANDLE;
608 if (persistent_gnts[i]) {
609 rb_erase(&persistent_gnts[i]->node,
610 &blkif->persistent_gnts);
611 blkif->persistent_gnt_c--;
612 kfree(persistent_gnts[i]);
613 persistent_gnts[i] = NULL;
617 if (persistent_gnts[i]) {
618 if (persistent_gnts[i]->handle ==
619 BLKBACK_INVALID_HANDLE) {
621 * If this is a new persistent grant
624 persistent_gnts[i]->handle = map[j].handle;
625 persistent_gnts[i]->dev_bus_addr =
626 map[j++].dev_bus_addr;
628 pending_handle(pending_req, i) =
629 persistent_gnts[i]->handle;
634 seg[i].buf = persistent_gnts[i]->dev_bus_addr |
635 (req->u.rw.seg[i].first_sect << 9);
637 pending_handle(pending_req, i) = map[j].handle;
638 bitmap_set(pending_req->unmap_seg, i, 1);
645 seg[i].buf = map[j++].dev_bus_addr |
646 (req->u.rw.seg[i].first_sect << 9);
652 static int dispatch_discard_io(struct xen_blkif *blkif,
653 struct blkif_request *req)
656 int status = BLKIF_RSP_OKAY;
657 struct block_device *bdev = blkif->vbd.bdev;
658 unsigned long secure;
662 xen_blkif_get(blkif);
663 secure = (blkif->vbd.discard_secure &&
664 (req->u.discard.flag & BLKIF_DISCARD_SECURE)) ?
665 BLKDEV_DISCARD_SECURE : 0;
667 err = blkdev_issue_discard(bdev, req->u.discard.sector_number,
668 req->u.discard.nr_sectors,
671 if (err == -EOPNOTSUPP) {
672 pr_debug(DRV_PFX "discard op failed, not supported\n");
673 status = BLKIF_RSP_EOPNOTSUPP;
675 status = BLKIF_RSP_ERROR;
677 make_response(blkif, req->u.discard.id, req->operation, status);
678 xen_blkif_put(blkif);
682 static void xen_blk_drain_io(struct xen_blkif *blkif)
684 atomic_set(&blkif->drain, 1);
686 /* The initial value is one, and one refcnt taken at the
687 * start of the xen_blkif_schedule thread. */
688 if (atomic_read(&blkif->refcnt) <= 2)
690 wait_for_completion_interruptible_timeout(
691 &blkif->drain_complete, HZ);
693 if (!atomic_read(&blkif->drain))
695 } while (!kthread_should_stop());
696 atomic_set(&blkif->drain, 0);
700 * Completion callback on the bio's. Called as bh->b_end_io()
703 static void __end_block_io_op(struct pending_req *pending_req, int error)
705 /* An error fails the entire request. */
706 if ((pending_req->operation == BLKIF_OP_FLUSH_DISKCACHE) &&
707 (error == -EOPNOTSUPP)) {
708 pr_debug(DRV_PFX "flush diskcache op failed, not supported\n");
709 xen_blkbk_flush_diskcache(XBT_NIL, pending_req->blkif->be, 0);
710 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
711 } else if ((pending_req->operation == BLKIF_OP_WRITE_BARRIER) &&
712 (error == -EOPNOTSUPP)) {
713 pr_debug(DRV_PFX "write barrier op failed, not supported\n");
714 xen_blkbk_barrier(XBT_NIL, pending_req->blkif->be, 0);
715 pending_req->status = BLKIF_RSP_EOPNOTSUPP;
717 pr_debug(DRV_PFX "Buffer not up-to-date at end of operation,"
718 " error=%d\n", error);
719 pending_req->status = BLKIF_RSP_ERROR;
723 * If all of the bio's have completed it is time to unmap
724 * the grant references associated with 'request' and provide
725 * the proper response on the ring.
727 if (atomic_dec_and_test(&pending_req->pendcnt)) {
728 xen_blkbk_unmap(pending_req);
729 make_response(pending_req->blkif, pending_req->id,
730 pending_req->operation, pending_req->status);
731 xen_blkif_put(pending_req->blkif);
732 if (atomic_read(&pending_req->blkif->refcnt) <= 2) {
733 if (atomic_read(&pending_req->blkif->drain))
734 complete(&pending_req->blkif->drain_complete);
736 free_req(pending_req);
743 static void end_block_io_op(struct bio *bio, int error)
745 __end_block_io_op(bio->bi_private, error);
752 * Function to copy the from the ring buffer the 'struct blkif_request'
753 * (which has the sectors we want, number of them, grant references, etc),
754 * and transmute it to the block API to hand it over to the proper block disk.
757 __do_block_io_op(struct xen_blkif *blkif)
759 union blkif_back_rings *blk_rings = &blkif->blk_rings;
760 struct blkif_request req;
761 struct pending_req *pending_req;
765 rc = blk_rings->common.req_cons;
766 rp = blk_rings->common.sring->req_prod;
767 rmb(); /* Ensure we see queued requests up to 'rp'. */
771 if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
774 if (kthread_should_stop()) {
779 pending_req = alloc_req();
780 if (NULL == pending_req) {
786 switch (blkif->blk_protocol) {
787 case BLKIF_PROTOCOL_NATIVE:
788 memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc), sizeof(req));
790 case BLKIF_PROTOCOL_X86_32:
791 blkif_get_x86_32_req(&req, RING_GET_REQUEST(&blk_rings->x86_32, rc));
793 case BLKIF_PROTOCOL_X86_64:
794 blkif_get_x86_64_req(&req, RING_GET_REQUEST(&blk_rings->x86_64, rc));
799 blk_rings->common.req_cons = ++rc; /* before make_response() */
801 /* Apply all sanity checks to /private copy/ of request. */
803 if (unlikely(req.operation == BLKIF_OP_DISCARD)) {
804 free_req(pending_req);
805 if (dispatch_discard_io(blkif, &req))
807 } else if (dispatch_rw_block_io(blkif, &req, pending_req))
810 /* Yield point for this unbounded loop. */
818 do_block_io_op(struct xen_blkif *blkif)
820 union blkif_back_rings *blk_rings = &blkif->blk_rings;
824 more_to_do = __do_block_io_op(blkif);
828 RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
829 } while (more_to_do);
834 * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
835 * and call the 'submit_bio' to pass it to the underlying storage.
837 static int dispatch_rw_block_io(struct xen_blkif *blkif,
838 struct blkif_request *req,
839 struct pending_req *pending_req)
841 struct phys_req preq;
842 struct seg_buf seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
844 struct bio *bio = NULL;
845 struct bio *biolist[BLKIF_MAX_SEGMENTS_PER_REQUEST];
848 struct blk_plug plug;
850 struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
852 switch (req->operation) {
859 operation = WRITE_ODIRECT;
861 case BLKIF_OP_WRITE_BARRIER:
863 case BLKIF_OP_FLUSH_DISKCACHE:
865 operation = WRITE_FLUSH;
868 operation = 0; /* make gcc happy */
873 /* Check that the number of segments is sane. */
874 nseg = req->u.rw.nr_segments;
876 if (unlikely(nseg == 0 && operation != WRITE_FLUSH) ||
877 unlikely(nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
878 pr_debug(DRV_PFX "Bad number of segments in request (%d)\n",
880 /* Haven't submitted any bio's yet. */
884 preq.sector_number = req->u.rw.sector_number;
887 pending_req->blkif = blkif;
888 pending_req->id = req->u.rw.id;
889 pending_req->operation = req->operation;
890 pending_req->status = BLKIF_RSP_OKAY;
891 pending_req->nr_pages = nseg;
893 for (i = 0; i < nseg; i++) {
894 seg[i].nsec = req->u.rw.seg[i].last_sect -
895 req->u.rw.seg[i].first_sect + 1;
896 if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) ||
897 (req->u.rw.seg[i].last_sect < req->u.rw.seg[i].first_sect))
899 preq.nr_sects += seg[i].nsec;
903 if (xen_vbd_translate(&preq, blkif, operation) != 0) {
904 pr_debug(DRV_PFX "access denied: %s of [%llu,%llu] on dev=%04x\n",
905 operation == READ ? "read" : "write",
907 preq.sector_number + preq.nr_sects, preq.dev);
912 * This check _MUST_ be done after xen_vbd_translate as the preq.bdev
915 for (i = 0; i < nseg; i++) {
916 if (((int)preq.sector_number|(int)seg[i].nsec) &
917 ((bdev_logical_block_size(preq.bdev) >> 9) - 1)) {
918 pr_debug(DRV_PFX "Misaligned I/O request from domain %d",
924 /* Wait on all outstanding I/O's and once that has been completed
925 * issue the WRITE_FLUSH.
928 xen_blk_drain_io(pending_req->blkif);
931 * If we have failed at this point, we need to undo the M2P override,
932 * set gnttab_set_unmap_op on all of the grant references and perform
933 * the hypercall to unmap the grants - that is all done in
936 if (xen_blkbk_map(req, pending_req, seg, pages))
940 * This corresponding xen_blkif_put is done in __end_block_io_op, or
941 * below (in "!bio") if we are handling a BLKIF_OP_DISCARD.
943 xen_blkif_get(blkif);
945 for (i = 0; i < nseg; i++) {
946 while ((bio == NULL) ||
950 seg[i].buf & ~PAGE_MASK) == 0)) {
952 bio = bio_alloc(GFP_KERNEL, nseg-i);
953 if (unlikely(bio == NULL))
956 biolist[nbio++] = bio;
957 bio->bi_bdev = preq.bdev;
958 bio->bi_private = pending_req;
959 bio->bi_end_io = end_block_io_op;
960 bio->bi_sector = preq.sector_number;
963 preq.sector_number += seg[i].nsec;
966 /* This will be hit if the operation was a flush or discard. */
968 BUG_ON(operation != WRITE_FLUSH);
970 bio = bio_alloc(GFP_KERNEL, 0);
971 if (unlikely(bio == NULL))
974 biolist[nbio++] = bio;
975 bio->bi_bdev = preq.bdev;
976 bio->bi_private = pending_req;
977 bio->bi_end_io = end_block_io_op;
981 * We set it one so that the last submit_bio does not have to call
984 atomic_set(&pending_req->pendcnt, nbio);
986 /* Get a reference count for the disk queue and start sending I/O */
987 blk_start_plug(&plug);
989 for (i = 0; i < nbio; i++)
990 submit_bio(operation, biolist[i]);
992 /* Let the I/Os go.. */
993 blk_finish_plug(&plug);
995 if (operation == READ)
996 blkif->st_rd_sect += preq.nr_sects;
997 else if (operation & WRITE)
998 blkif->st_wr_sect += preq.nr_sects;
1003 xen_blkbk_unmap(pending_req);
1005 /* Haven't submitted any bio's yet. */
1006 make_response(blkif, req->u.rw.id, req->operation, BLKIF_RSP_ERROR);
1007 free_req(pending_req);
1008 msleep(1); /* back off a bit */
1012 for (i = 0; i < nbio; i++)
1013 bio_put(biolist[i]);
1014 __end_block_io_op(pending_req, -EINVAL);
1015 msleep(1); /* back off a bit */
1022 * Put a response on the ring on how the operation fared.
1024 static void make_response(struct xen_blkif *blkif, u64 id,
1025 unsigned short op, int st)
1027 struct blkif_response resp;
1028 unsigned long flags;
1029 union blkif_back_rings *blk_rings = &blkif->blk_rings;
1033 resp.operation = op;
1036 spin_lock_irqsave(&blkif->blk_ring_lock, flags);
1037 /* Place on the response ring for the relevant domain. */
1038 switch (blkif->blk_protocol) {
1039 case BLKIF_PROTOCOL_NATIVE:
1040 memcpy(RING_GET_RESPONSE(&blk_rings->native, blk_rings->native.rsp_prod_pvt),
1041 &resp, sizeof(resp));
1043 case BLKIF_PROTOCOL_X86_32:
1044 memcpy(RING_GET_RESPONSE(&blk_rings->x86_32, blk_rings->x86_32.rsp_prod_pvt),
1045 &resp, sizeof(resp));
1047 case BLKIF_PROTOCOL_X86_64:
1048 memcpy(RING_GET_RESPONSE(&blk_rings->x86_64, blk_rings->x86_64.rsp_prod_pvt),
1049 &resp, sizeof(resp));
1054 blk_rings->common.rsp_prod_pvt++;
1055 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
1056 spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
1058 notify_remote_via_irq(blkif->irq);
1061 static int __init xen_blkif_init(void)
1069 blkbk = kzalloc(sizeof(struct xen_blkbk), GFP_KERNEL);
1071 pr_alert(DRV_PFX "%s: out of memory!\n", __func__);
1075 mmap_pages = xen_blkif_reqs * BLKIF_MAX_SEGMENTS_PER_REQUEST;
1077 blkbk->pending_reqs = kzalloc(sizeof(blkbk->pending_reqs[0]) *
1078 xen_blkif_reqs, GFP_KERNEL);
1079 blkbk->pending_grant_handles = kmalloc(sizeof(blkbk->pending_grant_handles[0]) *
1080 mmap_pages, GFP_KERNEL);
1081 blkbk->pending_pages = kzalloc(sizeof(blkbk->pending_pages[0]) *
1082 mmap_pages, GFP_KERNEL);
1084 if (!blkbk->pending_reqs || !blkbk->pending_grant_handles ||
1085 !blkbk->pending_pages) {
1090 for (i = 0; i < mmap_pages; i++) {
1091 blkbk->pending_grant_handles[i] = BLKBACK_INVALID_HANDLE;
1092 blkbk->pending_pages[i] = alloc_page(GFP_KERNEL);
1093 if (blkbk->pending_pages[i] == NULL) {
1098 rc = xen_blkif_interface_init();
1102 INIT_LIST_HEAD(&blkbk->pending_free);
1103 spin_lock_init(&blkbk->pending_free_lock);
1104 init_waitqueue_head(&blkbk->pending_free_wq);
1106 for (i = 0; i < xen_blkif_reqs; i++)
1107 list_add_tail(&blkbk->pending_reqs[i].free_list,
1108 &blkbk->pending_free);
1110 rc = xen_blkif_xenbus_init();
1117 pr_alert(DRV_PFX "%s: out of memory\n", __func__);
1119 kfree(blkbk->pending_reqs);
1120 kfree(blkbk->pending_grant_handles);
1121 if (blkbk->pending_pages) {
1122 for (i = 0; i < mmap_pages; i++) {
1123 if (blkbk->pending_pages[i])
1124 __free_page(blkbk->pending_pages[i]);
1126 kfree(blkbk->pending_pages);
1133 module_init(xen_blkif_init);
1135 MODULE_LICENSE("Dual BSD/GPL");
1136 MODULE_ALIAS("xen-backend:vbd");