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https://github.com/xen-project/xen.git
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Keir Fraser
bd5573a630
Benefits to blktap2 over the old version of blktap: * Isolation from xenstore - Blktap devices are now created directly on the linux dom0 command line, rather than being spawned in response to XenStore events. This is handy for debugging, makes blktap generally easier to work with, and is a step toward a generic user-level block device implementation that is not Xen-specific. * Improved tapdisk infrastructure: simpler request forwarding, new request scheduler, request merging, more efficient use of AIO. * Improved tapdisk error handling and memory management. No allocations on the block data path, IO retry logic to protect guests transient block device failures. This has been tested and is known to work on weird environments such as NFS soft mounts. * Pause and snapshot of live virtual disks (see xmsnap script). * VHD support. The VHD code in this release has been rigorously tested, and represents a very mature implementation of the VHD image format. * No more duplication of mechanism with blkback. The blktap kernel module has changed dramatically from the original blktap. Blkback is now always used to talk to Xen guests, blktap just presents a Linux gendisk that blkback can export. This is done while preserving the zero-copy data path from domU to physical device. These patches deprecate the old blktap code, which can hopefully be removed from the tree completely at some point in the future. Signed-off-by: Jake Wires <jake.wires@citrix.com> Signed-off-by: Dutch Meyer <dmeyer@cs.ubc.ca>
142 lines
4.3 KiB
C
142 lines
4.3 KiB
C
/* Copyright (c) 2008, XenSource Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of XenSource Inc. nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _TAPDISK_MESSAGE_H_
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#define _TAPDISK_MESSAGE_H_
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#include <inttypes.h>
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#define TAPDISK_MESSAGE_MAX_PATH_LENGTH 256
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#define TAPDISK_MESSAGE_STRING_LENGTH 256
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#define TAPDISK_MESSAGE_FLAG_SHARED 0x01
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#define TAPDISK_MESSAGE_FLAG_RDONLY 0x02
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#define TAPDISK_MESSAGE_FLAG_ADD_CACHE 0x04
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#define TAPDISK_MESSAGE_FLAG_VHD_INDEX 0x08
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#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY 0x10
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typedef struct tapdisk_message tapdisk_message_t;
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typedef uint8_t tapdisk_message_flag_t;
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typedef struct tapdisk_message_image tapdisk_message_image_t;
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typedef struct tapdisk_message_params tapdisk_message_params_t;
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typedef struct tapdisk_message_string tapdisk_message_string_t;
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struct tapdisk_message_params {
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tapdisk_message_flag_t flags;
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uint8_t storage;
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uint32_t devnum;
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uint32_t domid;
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uint16_t path_len;
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char path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
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};
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struct tapdisk_message_image {
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uint64_t sectors;
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uint32_t sector_size;
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uint32_t info;
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};
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struct tapdisk_message_string {
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char text[TAPDISK_MESSAGE_STRING_LENGTH];
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};
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struct tapdisk_message {
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uint16_t type;
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uint16_t cookie;
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uint16_t drivertype;
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union {
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pid_t tapdisk_pid;
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tapdisk_message_image_t image;
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tapdisk_message_params_t params;
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tapdisk_message_string_t string;
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} u;
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};
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enum tapdisk_message_id {
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TAPDISK_MESSAGE_ERROR = 1,
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TAPDISK_MESSAGE_RUNTIME_ERROR,
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TAPDISK_MESSAGE_PID,
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TAPDISK_MESSAGE_PID_RSP,
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TAPDISK_MESSAGE_OPEN,
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TAPDISK_MESSAGE_OPEN_RSP,
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TAPDISK_MESSAGE_PAUSE,
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TAPDISK_MESSAGE_PAUSE_RSP,
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TAPDISK_MESSAGE_RESUME,
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TAPDISK_MESSAGE_RESUME_RSP,
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TAPDISK_MESSAGE_CLOSE,
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TAPDISK_MESSAGE_CLOSE_RSP,
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TAPDISK_MESSAGE_EXIT,
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};
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static inline char *
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tapdisk_message_name(enum tapdisk_message_id id)
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{
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switch (id) {
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case TAPDISK_MESSAGE_ERROR:
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return "error";
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case TAPDISK_MESSAGE_PID:
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return "pid";
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case TAPDISK_MESSAGE_PID_RSP:
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return "pid response";
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case TAPDISK_MESSAGE_OPEN:
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return "open";
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case TAPDISK_MESSAGE_OPEN_RSP:
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return "open response";
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case TAPDISK_MESSAGE_PAUSE:
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return "pause";
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case TAPDISK_MESSAGE_PAUSE_RSP:
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return "pause response";
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case TAPDISK_MESSAGE_RESUME:
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return "resume";
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case TAPDISK_MESSAGE_RESUME_RSP:
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return "resume response";
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case TAPDISK_MESSAGE_CLOSE:
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return "close";
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case TAPDISK_MESSAGE_CLOSE_RSP:
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return "close response";
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case TAPDISK_MESSAGE_EXIT:
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return "exit";
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default:
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return "unknown";
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}
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}
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#endif
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