xen: add virtual block device driver.
The block device frontend driver allows the kernel to access block devices exported exported by a virtual machine containing a physical block device driver. Signed-off-by: Ian Pratt <ian.pratt@xensource.com> Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Greg KH <greg@kroah.com> Cc: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jeremy Fitzhardinge
Jeremy Fitzhardinge
Родитель
4bac07c993
Коммит
9f27ee5950
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@ -427,4 +427,13 @@ config XILINX_SYSACE
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help
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Include support for the Xilinx SystemACE CompactFlash interface
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config XEN_BLKDEV_FRONTEND
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tristate "Xen virtual block device support"
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depends on XEN
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default y
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help
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This driver implements the front-end of the Xen virtual
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block device driver. It communicates with a back-end driver
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in another domain which drives the actual block device.
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endif # BLK_DEV
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@ -29,3 +29,4 @@ obj-$(CONFIG_VIODASD) += viodasd.o
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obj-$(CONFIG_BLK_DEV_SX8) += sx8.o
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obj-$(CONFIG_BLK_DEV_UB) += ub.o
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obj-$(CONFIG_XEN_BLKDEV_FRONTEND) += xen-blkfront.o
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@ -0,0 +1,988 @@
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/*
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* blkfront.c
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*
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* XenLinux virtual block device driver.
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*
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* Copyright (c) 2003-2004, Keir Fraser & Steve Hand
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* Modifications by Mark A. Williamson are (c) Intel Research Cambridge
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* Copyright (c) 2004, Christian Limpach
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* Copyright (c) 2004, Andrew Warfield
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* Copyright (c) 2005, Christopher Clark
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* Copyright (c) 2005, XenSource Ltd
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include <linux/interrupt.h>
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#include <linux/blkdev.h>
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#include <linux/module.h>
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#include <xen/xenbus.h>
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#include <xen/grant_table.h>
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#include <xen/events.h>
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#include <xen/page.h>
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#include <xen/interface/grant_table.h>
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#include <xen/interface/io/blkif.h>
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#include <asm/xen/hypervisor.h>
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enum blkif_state {
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BLKIF_STATE_DISCONNECTED,
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BLKIF_STATE_CONNECTED,
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BLKIF_STATE_SUSPENDED,
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};
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struct blk_shadow {
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struct blkif_request req;
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unsigned long request;
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unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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};
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static struct block_device_operations xlvbd_block_fops;
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#define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
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/*
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* We have one of these per vbd, whether ide, scsi or 'other'. They
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* hang in private_data off the gendisk structure. We may end up
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* putting all kinds of interesting stuff here :-)
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*/
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struct blkfront_info
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{
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struct xenbus_device *xbdev;
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dev_t dev;
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struct gendisk *gd;
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int vdevice;
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blkif_vdev_t handle;
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enum blkif_state connected;
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int ring_ref;
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struct blkif_front_ring ring;
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unsigned int evtchn, irq;
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struct request_queue *rq;
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struct work_struct work;
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struct gnttab_free_callback callback;
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struct blk_shadow shadow[BLK_RING_SIZE];
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unsigned long shadow_free;
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int feature_barrier;
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/**
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* The number of people holding this device open. We won't allow a
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* hot-unplug unless this is 0.
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*/
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int users;
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};
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static DEFINE_SPINLOCK(blkif_io_lock);
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#define MAXIMUM_OUTSTANDING_BLOCK_REQS \
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(BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
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#define GRANT_INVALID_REF 0
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#define PARTS_PER_DISK 16
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#define BLKIF_MAJOR(dev) ((dev)>>8)
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#define BLKIF_MINOR(dev) ((dev) & 0xff)
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#define DEV_NAME "xvd" /* name in /dev */
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/* Information about our VBDs. */
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#define MAX_VBDS 64
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static LIST_HEAD(vbds_list);
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static int get_id_from_freelist(struct blkfront_info *info)
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{
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unsigned long free = info->shadow_free;
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BUG_ON(free > BLK_RING_SIZE);
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info->shadow_free = info->shadow[free].req.id;
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info->shadow[free].req.id = 0x0fffffee; /* debug */
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return free;
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}
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static void add_id_to_freelist(struct blkfront_info *info,
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unsigned long id)
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{
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info->shadow[id].req.id = info->shadow_free;
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info->shadow[id].request = 0;
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info->shadow_free = id;
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}
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static void blkif_restart_queue_callback(void *arg)
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{
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struct blkfront_info *info = (struct blkfront_info *)arg;
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schedule_work(&info->work);
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}
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/*
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* blkif_queue_request
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*
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* request block io
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*
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* id: for guest use only.
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* operation: BLKIF_OP_{READ,WRITE,PROBE}
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* buffer: buffer to read/write into. this should be a
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* virtual address in the guest os.
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*/
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static int blkif_queue_request(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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unsigned long buffer_mfn;
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struct blkif_request *ring_req;
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struct bio *bio;
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struct bio_vec *bvec;
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int idx;
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unsigned long id;
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unsigned int fsect, lsect;
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int ref;
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grant_ref_t gref_head;
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if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
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return 1;
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if (gnttab_alloc_grant_references(
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BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
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gnttab_request_free_callback(
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&info->callback,
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blkif_restart_queue_callback,
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info,
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BLKIF_MAX_SEGMENTS_PER_REQUEST);
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return 1;
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}
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/* Fill out a communications ring structure. */
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ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
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id = get_id_from_freelist(info);
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info->shadow[id].request = (unsigned long)req;
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ring_req->id = id;
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ring_req->sector_number = (blkif_sector_t)req->sector;
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ring_req->handle = info->handle;
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ring_req->operation = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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if (blk_barrier_rq(req))
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ring_req->operation = BLKIF_OP_WRITE_BARRIER;
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ring_req->nr_segments = 0;
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rq_for_each_bio (bio, req) {
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bio_for_each_segment (bvec, bio, idx) {
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BUG_ON(ring_req->nr_segments
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== BLKIF_MAX_SEGMENTS_PER_REQUEST);
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buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
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fsect = bvec->bv_offset >> 9;
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lsect = fsect + (bvec->bv_len >> 9) - 1;
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/* install a grant reference. */
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ref = gnttab_claim_grant_reference(&gref_head);
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BUG_ON(ref == -ENOSPC);
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gnttab_grant_foreign_access_ref(
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ref,
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info->xbdev->otherend_id,
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buffer_mfn,
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rq_data_dir(req) );
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info->shadow[id].frame[ring_req->nr_segments] =
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mfn_to_pfn(buffer_mfn);
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ring_req->seg[ring_req->nr_segments] =
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(struct blkif_request_segment) {
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.gref = ref,
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.first_sect = fsect,
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.last_sect = lsect };
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ring_req->nr_segments++;
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}
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}
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info->ring.req_prod_pvt++;
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/* Keep a private copy so we can reissue requests when recovering. */
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info->shadow[id].req = *ring_req;
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gnttab_free_grant_references(gref_head);
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return 0;
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}
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static inline void flush_requests(struct blkfront_info *info)
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{
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int notify;
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RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
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if (notify)
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notify_remote_via_irq(info->irq);
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}
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/*
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* do_blkif_request
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* read a block; request is in a request queue
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*/
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static void do_blkif_request(request_queue_t *rq)
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{
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struct blkfront_info *info = NULL;
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struct request *req;
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int queued;
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pr_debug("Entered do_blkif_request\n");
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queued = 0;
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while ((req = elv_next_request(rq)) != NULL) {
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info = req->rq_disk->private_data;
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if (!blk_fs_request(req)) {
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end_request(req, 0);
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continue;
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}
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if (RING_FULL(&info->ring))
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goto wait;
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pr_debug("do_blk_req %p: cmd %p, sec %lx, "
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"(%u/%li) buffer:%p [%s]\n",
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req, req->cmd, (unsigned long)req->sector,
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req->current_nr_sectors,
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req->nr_sectors, req->buffer,
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rq_data_dir(req) ? "write" : "read");
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blkdev_dequeue_request(req);
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if (blkif_queue_request(req)) {
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blk_requeue_request(rq, req);
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wait:
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/* Avoid pointless unplugs. */
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blk_stop_queue(rq);
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break;
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}
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queued++;
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}
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if (queued != 0)
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flush_requests(info);
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}
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static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
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{
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request_queue_t *rq;
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rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
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if (rq == NULL)
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return -1;
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elevator_init(rq, "noop");
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/* Hard sector size and max sectors impersonate the equiv. hardware. */
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blk_queue_hardsect_size(rq, sector_size);
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blk_queue_max_sectors(rq, 512);
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/* Each segment in a request is up to an aligned page in size. */
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blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
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blk_queue_max_segment_size(rq, PAGE_SIZE);
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/* Ensure a merged request will fit in a single I/O ring slot. */
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blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
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blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
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/* Make sure buffer addresses are sector-aligned. */
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blk_queue_dma_alignment(rq, 511);
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gd->queue = rq;
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return 0;
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}
|
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|
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|
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static int xlvbd_barrier(struct blkfront_info *info)
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{
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int err;
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err = blk_queue_ordered(info->rq,
|
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info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE,
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NULL);
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|
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if (err)
|
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return err;
|
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|
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printk(KERN_INFO "blkfront: %s: barriers %s\n",
|
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info->gd->disk_name,
|
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info->feature_barrier ? "enabled" : "disabled");
|
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return 0;
|
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}
|
||||
|
||||
|
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static int xlvbd_alloc_gendisk(int minor, blkif_sector_t capacity,
|
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int vdevice, u16 vdisk_info, u16 sector_size,
|
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struct blkfront_info *info)
|
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{
|
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struct gendisk *gd;
|
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int nr_minors = 1;
|
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int err = -ENODEV;
|
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|
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BUG_ON(info->gd != NULL);
|
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BUG_ON(info->rq != NULL);
|
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|
||||
if ((minor % PARTS_PER_DISK) == 0)
|
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nr_minors = PARTS_PER_DISK;
|
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|
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gd = alloc_disk(nr_minors);
|
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if (gd == NULL)
|
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goto out;
|
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|
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if (nr_minors > 1)
|
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sprintf(gd->disk_name, "%s%c", DEV_NAME,
|
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'a' + minor / PARTS_PER_DISK);
|
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else
|
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sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
|
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'a' + minor / PARTS_PER_DISK,
|
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minor % PARTS_PER_DISK);
|
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|
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gd->major = XENVBD_MAJOR;
|
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gd->first_minor = minor;
|
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gd->fops = &xlvbd_block_fops;
|
||||
gd->private_data = info;
|
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gd->driverfs_dev = &(info->xbdev->dev);
|
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set_capacity(gd, capacity);
|
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|
||||
if (xlvbd_init_blk_queue(gd, sector_size)) {
|
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del_gendisk(gd);
|
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goto out;
|
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}
|
||||
|
||||
info->rq = gd->queue;
|
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info->gd = gd;
|
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|
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if (info->feature_barrier)
|
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xlvbd_barrier(info);
|
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|
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if (vdisk_info & VDISK_READONLY)
|
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set_disk_ro(gd, 1);
|
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|
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if (vdisk_info & VDISK_REMOVABLE)
|
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gd->flags |= GENHD_FL_REMOVABLE;
|
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|
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if (vdisk_info & VDISK_CDROM)
|
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gd->flags |= GENHD_FL_CD;
|
||||
|
||||
return 0;
|
||||
|
||||
out:
|
||||
return err;
|
||||
}
|
||||
|
||||
static void kick_pending_request_queues(struct blkfront_info *info)
|
||||
{
|
||||
if (!RING_FULL(&info->ring)) {
|
||||
/* Re-enable calldowns. */
|
||||
blk_start_queue(info->rq);
|
||||
/* Kick things off immediately. */
|
||||
do_blkif_request(info->rq);
|
||||
}
|
||||
}
|
||||
|
||||
static void blkif_restart_queue(struct work_struct *work)
|
||||
{
|
||||
struct blkfront_info *info = container_of(work, struct blkfront_info, work);
|
||||
|
||||
spin_lock_irq(&blkif_io_lock);
|
||||
if (info->connected == BLKIF_STATE_CONNECTED)
|
||||
kick_pending_request_queues(info);
|
||||
spin_unlock_irq(&blkif_io_lock);
|
||||
}
|
||||
|
||||
static void blkif_free(struct blkfront_info *info, int suspend)
|
||||
{
|
||||
/* Prevent new requests being issued until we fix things up. */
|
||||
spin_lock_irq(&blkif_io_lock);
|
||||
info->connected = suspend ?
|
||||
BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
|
||||
/* No more blkif_request(). */
|
||||
if (info->rq)
|
||||
blk_stop_queue(info->rq);
|
||||
/* No more gnttab callback work. */
|
||||
gnttab_cancel_free_callback(&info->callback);
|
||||
spin_unlock_irq(&blkif_io_lock);
|
||||
|
||||
/* Flush gnttab callback work. Must be done with no locks held. */
|
||||
flush_scheduled_work();
|
||||
|
||||
/* Free resources associated with old device channel. */
|
||||
if (info->ring_ref != GRANT_INVALID_REF) {
|
||||
gnttab_end_foreign_access(info->ring_ref, 0,
|
||||
(unsigned long)info->ring.sring);
|
||||
info->ring_ref = GRANT_INVALID_REF;
|
||||
info->ring.sring = NULL;
|
||||
}
|
||||
if (info->irq)
|
||||
unbind_from_irqhandler(info->irq, info);
|
||||
info->evtchn = info->irq = 0;
|
||||
|
||||
}
|
||||
|
||||
static void blkif_completion(struct blk_shadow *s)
|
||||
{
|
||||
int i;
|
||||
for (i = 0; i < s->req.nr_segments; i++)
|
||||
gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
|
||||
}
|
||||
|
||||
static irqreturn_t blkif_interrupt(int irq, void *dev_id)
|
||||
{
|
||||
struct request *req;
|
||||
struct blkif_response *bret;
|
||||
RING_IDX i, rp;
|
||||
unsigned long flags;
|
||||
struct blkfront_info *info = (struct blkfront_info *)dev_id;
|
||||
int uptodate;
|
||||
|
||||
spin_lock_irqsave(&blkif_io_lock, flags);
|
||||
|
||||
if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
|
||||
spin_unlock_irqrestore(&blkif_io_lock, flags);
|
||||
return IRQ_HANDLED;
|
||||
}
|
||||
|
||||
again:
|
||||
rp = info->ring.sring->rsp_prod;
|
||||
rmb(); /* Ensure we see queued responses up to 'rp'. */
|
||||
|
||||
for (i = info->ring.rsp_cons; i != rp; i++) {
|
||||
unsigned long id;
|
||||
int ret;
|
||||
|
||||
bret = RING_GET_RESPONSE(&info->ring, i);
|
||||
id = bret->id;
|
||||
req = (struct request *)info->shadow[id].request;
|
||||
|
||||
blkif_completion(&info->shadow[id]);
|
||||
|
||||
add_id_to_freelist(info, id);
|
||||
|
||||
uptodate = (bret->status == BLKIF_RSP_OKAY);
|
||||
switch (bret->operation) {
|
||||
case BLKIF_OP_WRITE_BARRIER:
|
||||
if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
|
||||
printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
|
||||
info->gd->disk_name);
|
||||
uptodate = -EOPNOTSUPP;
|
||||
info->feature_barrier = 0;
|
||||
xlvbd_barrier(info);
|
||||
}
|
||||
/* fall through */
|
||||
case BLKIF_OP_READ:
|
||||
case BLKIF_OP_WRITE:
|
||||
if (unlikely(bret->status != BLKIF_RSP_OKAY))
|
||||
dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
|
||||
"request: %x\n", bret->status);
|
||||
|
||||
ret = end_that_request_first(req, uptodate,
|
||||
req->hard_nr_sectors);
|
||||
BUG_ON(ret);
|
||||
end_that_request_last(req, uptodate);
|
||||
break;
|
||||
default:
|
||||
BUG();
|
||||
}
|
||||
}
|
||||
|
||||
info->ring.rsp_cons = i;
|
||||
|
||||
if (i != info->ring.req_prod_pvt) {
|
||||
int more_to_do;
|
||||
RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
|
||||
if (more_to_do)
|
||||
goto again;
|
||||
} else
|
||||
info->ring.sring->rsp_event = i + 1;
|
||||
|
||||
kick_pending_request_queues(info);
|
||||
|
||||
spin_unlock_irqrestore(&blkif_io_lock, flags);
|
||||
|
||||
return IRQ_HANDLED;
|
||||
}
|
||||
|
||||
|
||||
static int setup_blkring(struct xenbus_device *dev,
|
||||
struct blkfront_info *info)
|
||||
{
|
||||
struct blkif_sring *sring;
|
||||
int err;
|
||||
|
||||
info->ring_ref = GRANT_INVALID_REF;
|
||||
|
||||
sring = (struct blkif_sring *)__get_free_page(GFP_KERNEL);
|
||||
if (!sring) {
|
||||
xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
|
||||
return -ENOMEM;
|
||||
}
|
||||
SHARED_RING_INIT(sring);
|
||||
FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
|
||||
|
||||
err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
|
||||
if (err < 0) {
|
||||
free_page((unsigned long)sring);
|
||||
info->ring.sring = NULL;
|
||||
goto fail;
|
||||
}
|
||||
info->ring_ref = err;
|
||||
|
||||
err = xenbus_alloc_evtchn(dev, &info->evtchn);
|
||||
if (err)
|
||||
goto fail;
|
||||
|
||||
err = bind_evtchn_to_irqhandler(info->evtchn,
|
||||
blkif_interrupt,
|
||||
IRQF_SAMPLE_RANDOM, "blkif", info);
|
||||
if (err <= 0) {
|
||||
xenbus_dev_fatal(dev, err,
|
||||
"bind_evtchn_to_irqhandler failed");
|
||||
goto fail;
|
||||
}
|
||||
info->irq = err;
|
||||
|
||||
return 0;
|
||||
fail:
|
||||
blkif_free(info, 0);
|
||||
return err;
|
||||
}
|
||||
|
||||
|
||||
/* Common code used when first setting up, and when resuming. */
|
||||
static int talk_to_backend(struct xenbus_device *dev,
|
||||
struct blkfront_info *info)
|
||||
{
|
||||
const char *message = NULL;
|
||||
struct xenbus_transaction xbt;
|
||||
int err;
|
||||
|
||||
/* Create shared ring, alloc event channel. */
|
||||
err = setup_blkring(dev, info);
|
||||
if (err)
|
||||
goto out;
|
||||
|
||||
again:
|
||||
err = xenbus_transaction_start(&xbt);
|
||||
if (err) {
|
||||
xenbus_dev_fatal(dev, err, "starting transaction");
|
||||
goto destroy_blkring;
|
||||
}
|
||||
|
||||
err = xenbus_printf(xbt, dev->nodename,
|
||||
"ring-ref", "%u", info->ring_ref);
|
||||
if (err) {
|
||||
message = "writing ring-ref";
|
||||
goto abort_transaction;
|
||||
}
|
||||
err = xenbus_printf(xbt, dev->nodename,
|
||||
"event-channel", "%u", info->evtchn);
|
||||
if (err) {
|
||||
message = "writing event-channel";
|
||||
goto abort_transaction;
|
||||
}
|
||||
|
||||
err = xenbus_transaction_end(xbt, 0);
|
||||
if (err) {
|
||||
if (err == -EAGAIN)
|
||||
goto again;
|
||||
xenbus_dev_fatal(dev, err, "completing transaction");
|
||||
goto destroy_blkring;
|
||||
}
|
||||
|
||||
xenbus_switch_state(dev, XenbusStateInitialised);
|
||||
|
||||
return 0;
|
||||
|
||||
abort_transaction:
|
||||
xenbus_transaction_end(xbt, 1);
|
||||
if (message)
|
||||
xenbus_dev_fatal(dev, err, "%s", message);
|
||||
destroy_blkring:
|
||||
blkif_free(info, 0);
|
||||
out:
|
||||
return err;
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* Entry point to this code when a new device is created. Allocate the basic
|
||||
* structures and the ring buffer for communication with the backend, and
|
||||
* inform the backend of the appropriate details for those. Switch to
|
||||
* Initialised state.
|
||||
*/
|
||||
static int blkfront_probe(struct xenbus_device *dev,
|
||||
const struct xenbus_device_id *id)
|
||||
{
|
||||
int err, vdevice, i;
|
||||
struct blkfront_info *info;
|
||||
|
||||
/* FIXME: Use dynamic device id if this is not set. */
|
||||
err = xenbus_scanf(XBT_NIL, dev->nodename,
|
||||
"virtual-device", "%i", &vdevice);
|
||||
if (err != 1) {
|
||||
xenbus_dev_fatal(dev, err, "reading virtual-device");
|
||||
return err;
|
||||
}
|
||||
|
||||
info = kzalloc(sizeof(*info), GFP_KERNEL);
|
||||
if (!info) {
|
||||
xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
|
||||
return -ENOMEM;
|
||||
}
|
||||
|
||||
info->xbdev = dev;
|
||||
info->vdevice = vdevice;
|
||||
info->connected = BLKIF_STATE_DISCONNECTED;
|
||||
INIT_WORK(&info->work, blkif_restart_queue);
|
||||
|
||||
for (i = 0; i < BLK_RING_SIZE; i++)
|
||||
info->shadow[i].req.id = i+1;
|
||||
info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
|
||||
|
||||
/* Front end dir is a number, which is used as the id. */
|
||||
info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
|
||||
dev->dev.driver_data = info;
|
||||
|
||||
err = talk_to_backend(dev, info);
|
||||
if (err) {
|
||||
kfree(info);
|
||||
dev->dev.driver_data = NULL;
|
||||
return err;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
static int blkif_recover(struct blkfront_info *info)
|
||||
{
|
||||
int i;
|
||||
struct blkif_request *req;
|
||||
struct blk_shadow *copy;
|
||||
int j;
|
||||
|
||||
/* Stage 1: Make a safe copy of the shadow state. */
|
||||
copy = kmalloc(sizeof(info->shadow), GFP_KERNEL);
|
||||
if (!copy)
|
||||
return -ENOMEM;
|
||||
memcpy(copy, info->shadow, sizeof(info->shadow));
|
||||
|
||||
/* Stage 2: Set up free list. */
|
||||
memset(&info->shadow, 0, sizeof(info->shadow));
|
||||
for (i = 0; i < BLK_RING_SIZE; i++)
|
||||
info->shadow[i].req.id = i+1;
|
||||
info->shadow_free = info->ring.req_prod_pvt;
|
||||
info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
|
||||
|
||||
/* Stage 3: Find pending requests and requeue them. */
|
||||
for (i = 0; i < BLK_RING_SIZE; i++) {
|
||||
/* Not in use? */
|
||||
if (copy[i].request == 0)
|
||||
continue;
|
||||
|
||||
/* Grab a request slot and copy shadow state into it. */
|
||||
req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
|
||||
*req = copy[i].req;
|
||||
|
||||
/* We get a new request id, and must reset the shadow state. */
|
||||
req->id = get_id_from_freelist(info);
|
||||
memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i]));
|
||||
|
||||
/* Rewrite any grant references invalidated by susp/resume. */
|
||||
for (j = 0; j < req->nr_segments; j++)
|
||||
gnttab_grant_foreign_access_ref(
|
||||
req->seg[j].gref,
|
||||
info->xbdev->otherend_id,
|
||||
pfn_to_mfn(info->shadow[req->id].frame[j]),
|
||||
rq_data_dir(
|
||||
(struct request *)
|
||||
info->shadow[req->id].request));
|
||||
info->shadow[req->id].req = *req;
|
||||
|
||||
info->ring.req_prod_pvt++;
|
||||
}
|
||||
|
||||
kfree(copy);
|
||||
|
||||
xenbus_switch_state(info->xbdev, XenbusStateConnected);
|
||||
|
||||
spin_lock_irq(&blkif_io_lock);
|
||||
|
||||
/* Now safe for us to use the shared ring */
|
||||
info->connected = BLKIF_STATE_CONNECTED;
|
||||
|
||||
/* Send off requeued requests */
|
||||
flush_requests(info);
|
||||
|
||||
/* Kick any other new requests queued since we resumed */
|
||||
kick_pending_request_queues(info);
|
||||
|
||||
spin_unlock_irq(&blkif_io_lock);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* We are reconnecting to the backend, due to a suspend/resume, or a backend
|
||||
* driver restart. We tear down our blkif structure and recreate it, but
|
||||
* leave the device-layer structures intact so that this is transparent to the
|
||||
* rest of the kernel.
|
||||
*/
|
||||
static int blkfront_resume(struct xenbus_device *dev)
|
||||
{
|
||||
struct blkfront_info *info = dev->dev.driver_data;
|
||||
int err;
|
||||
|
||||
dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
|
||||
|
||||
blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
|
||||
|
||||
err = talk_to_backend(dev, info);
|
||||
if (info->connected == BLKIF_STATE_SUSPENDED && !err)
|
||||
err = blkif_recover(info);
|
||||
|
||||
return err;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Invoked when the backend is finally 'ready' (and has told produced
|
||||
* the details about the physical device - #sectors, size, etc).
|
||||
*/
|
||||
static void blkfront_connect(struct blkfront_info *info)
|
||||
{
|
||||
unsigned long long sectors;
|
||||
unsigned long sector_size;
|
||||
unsigned int binfo;
|
||||
int err;
|
||||
|
||||
if ((info->connected == BLKIF_STATE_CONNECTED) ||
|
||||
(info->connected == BLKIF_STATE_SUSPENDED) )
|
||||
return;
|
||||
|
||||
dev_dbg(&info->xbdev->dev, "%s:%s.\n",
|
||||
__func__, info->xbdev->otherend);
|
||||
|
||||
err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
|
||||
"sectors", "%llu", §ors,
|
||||
"info", "%u", &binfo,
|
||||
"sector-size", "%lu", §or_size,
|
||||
NULL);
|
||||
if (err) {
|
||||
xenbus_dev_fatal(info->xbdev, err,
|
||||
"reading backend fields at %s",
|
||||
info->xbdev->otherend);
|
||||
return;
|
||||
}
|
||||
|
||||
err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
|
||||
"feature-barrier", "%lu", &info->feature_barrier,
|
||||
NULL);
|
||||
if (err)
|
||||
info->feature_barrier = 0;
|
||||
|
||||
err = xlvbd_alloc_gendisk(BLKIF_MINOR(info->vdevice),
|
||||
sectors, info->vdevice,
|
||||
binfo, sector_size, info);
|
||||
if (err) {
|
||||
xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
|
||||
info->xbdev->otherend);
|
||||
return;
|
||||
}
|
||||
|
||||
xenbus_switch_state(info->xbdev, XenbusStateConnected);
|
||||
|
||||
/* Kick pending requests. */
|
||||
spin_lock_irq(&blkif_io_lock);
|
||||
info->connected = BLKIF_STATE_CONNECTED;
|
||||
kick_pending_request_queues(info);
|
||||
spin_unlock_irq(&blkif_io_lock);
|
||||
|
||||
add_disk(info->gd);
|
||||
}
|
||||
|
||||
/**
|
||||
* Handle the change of state of the backend to Closing. We must delete our
|
||||
* device-layer structures now, to ensure that writes are flushed through to
|
||||
* the backend. Once is this done, we can switch to Closed in
|
||||
* acknowledgement.
|
||||
*/
|
||||
static void blkfront_closing(struct xenbus_device *dev)
|
||||
{
|
||||
struct blkfront_info *info = dev->dev.driver_data;
|
||||
unsigned long flags;
|
||||
|
||||
dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
|
||||
|
||||
if (info->rq == NULL)
|
||||
goto out;
|
||||
|
||||
spin_lock_irqsave(&blkif_io_lock, flags);
|
||||
|
||||
del_gendisk(info->gd);
|
||||
|
||||
/* No more blkif_request(). */
|
||||
blk_stop_queue(info->rq);
|
||||
|
||||
/* No more gnttab callback work. */
|
||||
gnttab_cancel_free_callback(&info->callback);
|
||||
spin_unlock_irqrestore(&blkif_io_lock, flags);
|
||||
|
||||
/* Flush gnttab callback work. Must be done with no locks held. */
|
||||
flush_scheduled_work();
|
||||
|
||||
blk_cleanup_queue(info->rq);
|
||||
info->rq = NULL;
|
||||
|
||||
out:
|
||||
xenbus_frontend_closed(dev);
|
||||
}
|
||||
|
||||
/**
|
||||
* Callback received when the backend's state changes.
|
||||
*/
|
||||
static void backend_changed(struct xenbus_device *dev,
|
||||
enum xenbus_state backend_state)
|
||||
{
|
||||
struct blkfront_info *info = dev->dev.driver_data;
|
||||
struct block_device *bd;
|
||||
|
||||
dev_dbg(&dev->dev, "blkfront:backend_changed.\n");
|
||||
|
||||
switch (backend_state) {
|
||||
case XenbusStateInitialising:
|
||||
case XenbusStateInitWait:
|
||||
case XenbusStateInitialised:
|
||||
case XenbusStateUnknown:
|
||||
case XenbusStateClosed:
|
||||
break;
|
||||
|
||||
case XenbusStateConnected:
|
||||
blkfront_connect(info);
|
||||
break;
|
||||
|
||||
case XenbusStateClosing:
|
||||
bd = bdget(info->dev);
|
||||
if (bd == NULL)
|
||||
xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
|
||||
|
||||
mutex_lock(&bd->bd_mutex);
|
||||
if (info->users > 0)
|
||||
xenbus_dev_error(dev, -EBUSY,
|
||||
"Device in use; refusing to close");
|
||||
else
|
||||
blkfront_closing(dev);
|
||||
mutex_unlock(&bd->bd_mutex);
|
||||
bdput(bd);
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
static int blkfront_remove(struct xenbus_device *dev)
|
||||
{
|
||||
struct blkfront_info *info = dev->dev.driver_data;
|
||||
|
||||
dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
|
||||
|
||||
blkif_free(info, 0);
|
||||
|
||||
kfree(info);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int blkif_open(struct inode *inode, struct file *filep)
|
||||
{
|
||||
struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
|
||||
info->users++;
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int blkif_release(struct inode *inode, struct file *filep)
|
||||
{
|
||||
struct blkfront_info *info = inode->i_bdev->bd_disk->private_data;
|
||||
info->users--;
|
||||
if (info->users == 0) {
|
||||
/* Check whether we have been instructed to close. We will
|
||||
have ignored this request initially, as the device was
|
||||
still mounted. */
|
||||
struct xenbus_device *dev = info->xbdev;
|
||||
enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
|
||||
|
||||
if (state == XenbusStateClosing)
|
||||
blkfront_closing(dev);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
static struct block_device_operations xlvbd_block_fops =
|
||||
{
|
||||
.owner = THIS_MODULE,
|
||||
.open = blkif_open,
|
||||
.release = blkif_release,
|
||||
};
|
||||
|
||||
|
||||
static struct xenbus_device_id blkfront_ids[] = {
|
||||
{ "vbd" },
|
||||
{ "" }
|
||||
};
|
||||
|
||||
static struct xenbus_driver blkfront = {
|
||||
.name = "vbd",
|
||||
.owner = THIS_MODULE,
|
||||
.ids = blkfront_ids,
|
||||
.probe = blkfront_probe,
|
||||
.remove = blkfront_remove,
|
||||
.resume = blkfront_resume,
|
||||
.otherend_changed = backend_changed,
|
||||
};
|
||||
|
||||
static int __init xlblk_init(void)
|
||||
{
|
||||
if (!is_running_on_xen())
|
||||
return -ENODEV;
|
||||
|
||||
if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
|
||||
printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
|
||||
XENVBD_MAJOR, DEV_NAME);
|
||||
return -ENODEV;
|
||||
}
|
||||
|
||||
return xenbus_register_frontend(&blkfront);
|
||||
}
|
||||
module_init(xlblk_init);
|
||||
|
||||
|
||||
static void xlblk_exit(void)
|
||||
{
|
||||
return xenbus_unregister_driver(&blkfront);
|
||||
}
|
||||
module_exit(xlblk_exit);
|
||||
|
||||
MODULE_DESCRIPTION("Xen virtual block device frontend");
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
|
||||
|
|
@ -158,6 +158,8 @@
|
|||
#define VXSPEC_MAJOR 200 /* VERITAS volume config driver */
|
||||
#define VXDMP_MAJOR 201 /* VERITAS volume multipath driver */
|
||||
|
||||
#define XENVBD_MAJOR 202 /* Xen virtual block device */
|
||||
|
||||
#define MSR_MAJOR 202
|
||||
#define CPUID_MAJOR 203
|
||||
|
||||
|
|
|
|||
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