ia64/linux-2.6.18-xen.hg

view drivers/xen/blkback/common.h @ 878:eba6fe6d8d53

blktap2: a completely rewritten blktap implementation

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>
author Keir Fraser <keir.fraser@citrix.com>
date Tue May 26 11:23:16 2009 +0100 (2009-05-26)
parents e5f0712d7520
children 4e5cd2fc45a7
line source
1 /*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License version 2
4 * as published by the Free Software Foundation; or, when distributed
5 * separately from the Linux kernel or incorporated into other
6 * software packages, subject to the following license:
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this source file (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use, copy, modify,
11 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
12 * and to permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 */
27 #ifndef __BLKIF__BACKEND__COMMON_H__
28 #define __BLKIF__BACKEND__COMMON_H__
30 #include <linux/version.h>
31 #include <linux/module.h>
32 #include <linux/interrupt.h>
33 #include <linux/slab.h>
34 #include <linux/blkdev.h>
35 #include <linux/vmalloc.h>
36 #include <linux/wait.h>
37 #include <asm/io.h>
38 #include <asm/setup.h>
39 #include <asm/pgalloc.h>
40 #include <xen/evtchn.h>
41 #include <asm/hypervisor.h>
42 #include <xen/blkif.h>
43 #include <xen/gnttab.h>
44 #include <xen/driver_util.h>
45 #include <xen/xenbus.h>
46 #include "blkback-pagemap.h"
49 #define DPRINTK(_f, _a...) \
50 pr_debug("(file=%s, line=%d) " _f, \
51 __FILE__ , __LINE__ , ## _a )
53 struct vbd {
54 blkif_vdev_t handle; /* what the domain refers to this vbd as */
55 unsigned char readonly; /* Non-zero -> read-only */
56 unsigned char type; /* VDISK_xxx */
57 u32 pdevice; /* phys device that this vbd maps to */
58 struct block_device *bdev;
59 };
61 struct backend_info;
63 typedef struct blkif_st {
64 /* Unique identifier for this interface. */
65 domid_t domid;
66 unsigned int handle;
67 /* Physical parameters of the comms window. */
68 unsigned int irq;
69 /* Comms information. */
70 enum blkif_protocol blk_protocol;
71 blkif_back_rings_t blk_rings;
72 struct vm_struct *blk_ring_area;
73 /* The VBD attached to this interface. */
74 struct vbd vbd;
75 /* Back pointer to the backend_info. */
76 struct backend_info *be;
77 /* Private fields. */
78 spinlock_t blk_ring_lock;
79 atomic_t refcnt;
81 wait_queue_head_t wq;
82 struct task_struct *xenblkd;
83 unsigned int waiting_reqs;
84 request_queue_t *plug;
86 /* statistics */
87 unsigned long st_print;
88 int st_rd_req;
89 int st_wr_req;
90 int st_oo_req;
91 int st_br_req;
92 int st_rd_sect;
93 int st_wr_sect;
95 wait_queue_head_t waiting_to_free;
97 grant_handle_t shmem_handle;
98 grant_ref_t shmem_ref;
99 } blkif_t;
101 blkif_t *blkif_alloc(domid_t domid);
102 void blkif_disconnect(blkif_t *blkif);
103 void blkif_free(blkif_t *blkif);
104 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn);
106 #define blkif_get(_b) (atomic_inc(&(_b)->refcnt))
107 #define blkif_put(_b) \
108 do { \
109 if (atomic_dec_and_test(&(_b)->refcnt)) \
110 wake_up(&(_b)->waiting_to_free);\
111 } while (0)
113 /* Create a vbd. */
114 int vbd_create(blkif_t *blkif, blkif_vdev_t vdevice, unsigned major,
115 unsigned minor, int readonly, int cdrom);
116 void vbd_free(struct vbd *vbd);
118 unsigned long long vbd_size(struct vbd *vbd);
119 unsigned int vbd_info(struct vbd *vbd);
120 unsigned long vbd_secsize(struct vbd *vbd);
122 struct phys_req {
123 unsigned short dev;
124 unsigned short nr_sects;
125 struct block_device *bdev;
126 blkif_sector_t sector_number;
127 };
129 int vbd_translate(struct phys_req *req, blkif_t *blkif, int operation);
131 void blkif_interface_init(void);
133 void blkif_xenbus_init(void);
135 irqreturn_t blkif_be_int(int irq, void *dev_id, struct pt_regs *regs);
136 int blkif_schedule(void *arg);
138 int blkback_barrier(struct xenbus_transaction xbt,
139 struct backend_info *be, int state);
141 int blkback_pagemap_init(int);
142 void blkback_pagemap_set(int, struct page *, domid_t, busid_t, grant_ref_t);
143 void blkback_pagemap_clear(struct page *);
145 #endif /* __BLKIF__BACKEND__COMMON_H__ */