487 lines
16 KiB
C
487 lines
16 KiB
C
/*
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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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#ifndef __XEN_BLKIF__BACKEND__COMMON_H__
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#define __XEN_BLKIF__BACKEND__COMMON_H__
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/slab.h>
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#include <linux/blkdev.h>
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#include <linux/vmalloc.h>
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#include <linux/wait.h>
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#include <linux/io.h>
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#include <linux/rbtree.h>
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#include <asm/setup.h>
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#include <asm/pgalloc.h>
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#include <asm/hypervisor.h>
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#include <xen/grant_table.h>
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#include <xen/xenbus.h>
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#include <xen/interface/io/ring.h>
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#include <xen/interface/io/blkif.h>
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#include <xen/interface/io/protocols.h>
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#define DRV_PFX "xen-blkback:"
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#define DPRINTK(fmt, args...) \
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pr_debug(DRV_PFX "(%s:%d) " fmt ".\n", \
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__func__, __LINE__, ##args)
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/*
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* This is the maximum number of segments that would be allowed in indirect
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* requests. This value will also be passed to the frontend.
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*/
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#define MAX_INDIRECT_SEGMENTS 256
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#define SEGS_PER_INDIRECT_FRAME \
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(PAGE_SIZE/sizeof(struct blkif_request_segment))
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#define MAX_INDIRECT_PAGES \
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((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
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#define INDIRECT_PAGES(_segs) \
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((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
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/* Not a real protocol. Used to generate ring structs which contain
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* the elements common to all protocols only. This way we get a
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* compiler-checkable way to use common struct elements, so we can
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* avoid using switch(protocol) in a number of places. */
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struct blkif_common_request {
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char dummy;
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};
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struct blkif_common_response {
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char dummy;
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};
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struct blkif_x86_32_request_rw {
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uint8_t nr_segments; /* number of segments */
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blkif_vdev_t handle; /* only for read/write requests */
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uint64_t id; /* private guest value, echoed in resp */
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blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
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struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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} __attribute__((__packed__));
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struct blkif_x86_32_request_discard {
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uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
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blkif_vdev_t _pad1; /* was "handle" for read/write requests */
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uint64_t id; /* private guest value, echoed in resp */
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blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
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uint64_t nr_sectors;
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} __attribute__((__packed__));
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struct blkif_x86_32_request_other {
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uint8_t _pad1;
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blkif_vdev_t _pad2;
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uint64_t id; /* private guest value, echoed in resp */
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} __attribute__((__packed__));
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struct blkif_x86_32_request_indirect {
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uint8_t indirect_op;
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uint16_t nr_segments;
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uint64_t id;
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blkif_sector_t sector_number;
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blkif_vdev_t handle;
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uint16_t _pad1;
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grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
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/*
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* The maximum number of indirect segments (and pages) that will
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* be used is determined by MAX_INDIRECT_SEGMENTS, this value
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* is also exported to the guest (via xenstore
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* feature-max-indirect-segments entry), so the frontend knows how
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* many indirect segments the backend supports.
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*/
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uint64_t _pad2; /* make it 64 byte aligned */
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} __attribute__((__packed__));
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struct blkif_x86_32_request {
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uint8_t operation; /* BLKIF_OP_??? */
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union {
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struct blkif_x86_32_request_rw rw;
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struct blkif_x86_32_request_discard discard;
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struct blkif_x86_32_request_other other;
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struct blkif_x86_32_request_indirect indirect;
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} u;
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} __attribute__((__packed__));
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/* i386 protocol version */
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#pragma pack(push, 4)
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struct blkif_x86_32_response {
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uint64_t id; /* copied from request */
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uint8_t operation; /* copied from request */
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int16_t status; /* BLKIF_RSP_??? */
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};
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#pragma pack(pop)
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/* x86_64 protocol version */
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struct blkif_x86_64_request_rw {
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uint8_t nr_segments; /* number of segments */
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blkif_vdev_t handle; /* only for read/write requests */
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uint32_t _pad1; /* offsetof(blkif_reqest..,u.rw.id)==8 */
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uint64_t id;
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blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
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struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
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} __attribute__((__packed__));
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struct blkif_x86_64_request_discard {
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uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
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blkif_vdev_t _pad1; /* was "handle" for read/write requests */
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uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
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uint64_t id;
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blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
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uint64_t nr_sectors;
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} __attribute__((__packed__));
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struct blkif_x86_64_request_other {
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uint8_t _pad1;
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blkif_vdev_t _pad2;
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uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */
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uint64_t id; /* private guest value, echoed in resp */
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} __attribute__((__packed__));
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struct blkif_x86_64_request_indirect {
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uint8_t indirect_op;
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uint16_t nr_segments;
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uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */
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uint64_t id;
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blkif_sector_t sector_number;
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blkif_vdev_t handle;
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uint16_t _pad2;
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grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
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/*
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* The maximum number of indirect segments (and pages) that will
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* be used is determined by MAX_INDIRECT_SEGMENTS, this value
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* is also exported to the guest (via xenstore
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* feature-max-indirect-segments entry), so the frontend knows how
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* many indirect segments the backend supports.
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*/
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uint32_t _pad3; /* make it 64 byte aligned */
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} __attribute__((__packed__));
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struct blkif_x86_64_request {
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uint8_t operation; /* BLKIF_OP_??? */
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union {
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struct blkif_x86_64_request_rw rw;
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struct blkif_x86_64_request_discard discard;
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struct blkif_x86_64_request_other other;
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struct blkif_x86_64_request_indirect indirect;
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} u;
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} __attribute__((__packed__));
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struct blkif_x86_64_response {
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uint64_t __attribute__((__aligned__(8))) id;
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uint8_t operation; /* copied from request */
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int16_t status; /* BLKIF_RSP_??? */
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};
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DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
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struct blkif_common_response);
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DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
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struct blkif_x86_32_response);
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DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
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struct blkif_x86_64_response);
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union blkif_back_rings {
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struct blkif_back_ring native;
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struct blkif_common_back_ring common;
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struct blkif_x86_32_back_ring x86_32;
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struct blkif_x86_64_back_ring x86_64;
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};
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enum blkif_protocol {
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BLKIF_PROTOCOL_NATIVE = 1,
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BLKIF_PROTOCOL_X86_32 = 2,
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BLKIF_PROTOCOL_X86_64 = 3,
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};
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struct xen_vbd {
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/* What the domain refers to this vbd as. */
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blkif_vdev_t handle;
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/* Non-zero -> read-only */
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unsigned char readonly;
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/* VDISK_xxx */
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unsigned char type;
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/* phys device that this vbd maps to. */
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u32 pdevice;
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struct block_device *bdev;
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/* Cached size parameter. */
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sector_t size;
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unsigned int flush_support:1;
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unsigned int discard_secure:1;
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unsigned int feature_gnt_persistent:1;
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unsigned int overflow_max_grants:1;
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};
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struct backend_info;
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/* Number of available flags */
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#define PERSISTENT_GNT_FLAGS_SIZE 2
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/* This persistent grant is currently in use */
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#define PERSISTENT_GNT_ACTIVE 0
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/*
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* This persistent grant has been used, this flag is set when we remove the
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* PERSISTENT_GNT_ACTIVE, to know that this grant has been used recently.
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*/
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#define PERSISTENT_GNT_WAS_ACTIVE 1
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/* Number of requests that we can fit in a ring */
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#define XEN_BLKIF_REQS 32
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struct persistent_gnt {
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struct page *page;
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grant_ref_t gnt;
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grant_handle_t handle;
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DECLARE_BITMAP(flags, PERSISTENT_GNT_FLAGS_SIZE);
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struct rb_node node;
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struct list_head remove_node;
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};
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struct xen_blkif {
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/* Unique identifier for this interface. */
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domid_t domid;
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unsigned int handle;
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/* Physical parameters of the comms window. */
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unsigned int irq;
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/* Comms information. */
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enum blkif_protocol blk_protocol;
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union blkif_back_rings blk_rings;
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void *blk_ring;
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/* The VBD attached to this interface. */
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struct xen_vbd vbd;
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/* Back pointer to the backend_info. */
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struct backend_info *be;
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/* Private fields. */
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spinlock_t blk_ring_lock;
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atomic_t refcnt;
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wait_queue_head_t wq;
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/* for barrier (drain) requests */
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struct completion drain_complete;
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atomic_t drain;
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atomic_t inflight;
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/* One thread per one blkif. */
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struct task_struct *xenblkd;
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unsigned int waiting_reqs;
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/* tree to store persistent grants */
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struct rb_root persistent_gnts;
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unsigned int persistent_gnt_c;
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atomic_t persistent_gnt_in_use;
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unsigned long next_lru;
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/* used by the kworker that offload work from the persistent purge */
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struct list_head persistent_purge_list;
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struct work_struct persistent_purge_work;
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/* buffer of free pages to map grant refs */
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spinlock_t free_pages_lock;
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int free_pages_num;
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struct list_head free_pages;
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/* List of all 'pending_req' available */
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struct list_head pending_free;
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/* And its spinlock. */
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spinlock_t pending_free_lock;
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wait_queue_head_t pending_free_wq;
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/* statistics */
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unsigned long st_print;
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unsigned long long st_rd_req;
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unsigned long long st_wr_req;
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unsigned long long st_oo_req;
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unsigned long long st_f_req;
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unsigned long long st_ds_req;
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unsigned long long st_rd_sect;
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unsigned long long st_wr_sect;
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struct work_struct free_work;
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/* Thread shutdown wait queue. */
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wait_queue_head_t shutdown_wq;
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};
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struct seg_buf {
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unsigned long offset;
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unsigned int nsec;
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};
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struct grant_page {
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struct page *page;
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struct persistent_gnt *persistent_gnt;
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grant_handle_t handle;
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grant_ref_t gref;
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};
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/*
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* Each outstanding request that we've passed to the lower device layers has a
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* 'pending_req' allocated to it. Each buffer_head that completes decrements
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* the pendcnt towards zero. When it hits zero, the specified domain has a
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* response queued for it, with the saved 'id' passed back.
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*/
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struct pending_req {
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struct xen_blkif *blkif;
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u64 id;
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int nr_pages;
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atomic_t pendcnt;
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unsigned short operation;
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int status;
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struct list_head free_list;
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struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
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/* Indirect descriptors */
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struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
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struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
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struct bio *biolist[MAX_INDIRECT_SEGMENTS];
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};
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#define vbd_sz(_v) ((_v)->bdev->bd_part ? \
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(_v)->bdev->bd_part->nr_sects : \
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get_capacity((_v)->bdev->bd_disk))
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#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
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#define xen_blkif_put(_b) \
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do { \
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if (atomic_dec_and_test(&(_b)->refcnt)) \
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schedule_work(&(_b)->free_work);\
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} while (0)
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struct phys_req {
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unsigned short dev;
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blkif_sector_t nr_sects;
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struct block_device *bdev;
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blkif_sector_t sector_number;
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};
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int xen_blkif_interface_init(void);
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int xen_blkif_xenbus_init(void);
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irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
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int xen_blkif_schedule(void *arg);
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int xen_blkif_purge_persistent(void *arg);
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void xen_blkbk_free_caches(struct xen_blkif *blkif);
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int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
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struct backend_info *be, int state);
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int xen_blkbk_barrier(struct xenbus_transaction xbt,
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struct backend_info *be, int state);
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struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
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void xen_blkbk_unmap_purged_grants(struct work_struct *work);
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static inline void blkif_get_x86_32_req(struct blkif_request *dst,
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struct blkif_x86_32_request *src)
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{
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int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
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dst->operation = src->operation;
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switch (src->operation) {
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case BLKIF_OP_READ:
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case BLKIF_OP_WRITE:
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case BLKIF_OP_WRITE_BARRIER:
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case BLKIF_OP_FLUSH_DISKCACHE:
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dst->u.rw.nr_segments = src->u.rw.nr_segments;
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dst->u.rw.handle = src->u.rw.handle;
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dst->u.rw.id = src->u.rw.id;
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dst->u.rw.sector_number = src->u.rw.sector_number;
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barrier();
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if (n > dst->u.rw.nr_segments)
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n = dst->u.rw.nr_segments;
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for (i = 0; i < n; i++)
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dst->u.rw.seg[i] = src->u.rw.seg[i];
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break;
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case BLKIF_OP_DISCARD:
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dst->u.discard.flag = src->u.discard.flag;
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dst->u.discard.id = src->u.discard.id;
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dst->u.discard.sector_number = src->u.discard.sector_number;
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dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
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break;
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case BLKIF_OP_INDIRECT:
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dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
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dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
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dst->u.indirect.handle = src->u.indirect.handle;
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dst->u.indirect.id = src->u.indirect.id;
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dst->u.indirect.sector_number = src->u.indirect.sector_number;
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barrier();
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j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
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for (i = 0; i < j; i++)
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dst->u.indirect.indirect_grefs[i] =
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src->u.indirect.indirect_grefs[i];
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break;
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default:
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/*
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* Don't know how to translate this op. Only get the
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* ID so failure can be reported to the frontend.
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*/
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dst->u.other.id = src->u.other.id;
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break;
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}
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}
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static inline void blkif_get_x86_64_req(struct blkif_request *dst,
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struct blkif_x86_64_request *src)
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{
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int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
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dst->operation = src->operation;
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switch (src->operation) {
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case BLKIF_OP_READ:
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case BLKIF_OP_WRITE:
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case BLKIF_OP_WRITE_BARRIER:
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case BLKIF_OP_FLUSH_DISKCACHE:
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dst->u.rw.nr_segments = src->u.rw.nr_segments;
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dst->u.rw.handle = src->u.rw.handle;
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dst->u.rw.id = src->u.rw.id;
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dst->u.rw.sector_number = src->u.rw.sector_number;
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barrier();
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if (n > dst->u.rw.nr_segments)
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n = dst->u.rw.nr_segments;
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for (i = 0; i < n; i++)
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dst->u.rw.seg[i] = src->u.rw.seg[i];
|
|
break;
|
|
case BLKIF_OP_DISCARD:
|
|
dst->u.discard.flag = src->u.discard.flag;
|
|
dst->u.discard.id = src->u.discard.id;
|
|
dst->u.discard.sector_number = src->u.discard.sector_number;
|
|
dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
|
|
break;
|
|
case BLKIF_OP_INDIRECT:
|
|
dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
|
|
dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
|
|
dst->u.indirect.handle = src->u.indirect.handle;
|
|
dst->u.indirect.id = src->u.indirect.id;
|
|
dst->u.indirect.sector_number = src->u.indirect.sector_number;
|
|
barrier();
|
|
j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
|
|
for (i = 0; i < j; i++)
|
|
dst->u.indirect.indirect_grefs[i] =
|
|
src->u.indirect.indirect_grefs[i];
|
|
break;
|
|
default:
|
|
/*
|
|
* Don't know how to translate this op. Only get the
|
|
* ID so failure can be reported to the frontend.
|
|
*/
|
|
dst->u.other.id = src->u.other.id;
|
|
break;
|
|
}
|
|
}
|
|
|
|
#endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */
|