debuggers.hg

view tools/ioemu/block-bochs.c @ 10969:3ea0a6847198

[qemu] Make sure disk writes really made it to disk before we report I/O
completion to the guest domain. The DMA_MULTI_THREAD functionality
from the qemu-dm IDE emulation should make the performance overhead
of synchronous writes bearable, or at least comparable to native
hardware.

Signed-off-by: Rik van Riel <riel@redhat.com>
author chris@kneesaa.uk.xensource.com
date Fri Aug 04 10:28:51 2006 +0100 (2006-08-04)
parents b450f21472a0
children 9bb6c1c1890a
line source
1 /*
2 * Block driver for the various disk image formats used by Bochs
3 * Currently only for "growing" type in read-only mode
4 *
5 * Copyright (c) 2005 Alex Beregszaszi
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25 #include "vl.h"
26 #include "block_int.h"
28 /**************************************************************/
30 #define HEADER_MAGIC "Bochs Virtual HD Image"
31 #define HEADER_VERSION 0x00010000
32 #define HEADER_SIZE 512
34 #define REDOLOG_TYPE "Redolog"
35 #define GROWING_TYPE "Growing"
37 // not allocated: 0xffffffff
39 // always little-endian
40 struct bochs_header {
41 char magic[32]; // "Bochs Virtual HD Image"
42 char type[16]; // "Redolog"
43 char subtype[16]; // "Undoable" / "Volatile" / "Growing"
44 uint32_t version;
45 uint32_t header; // size of header
47 union {
48 struct {
49 uint32_t catalog; // num of entries
50 uint32_t bitmap; // bitmap size
51 uint32_t extent; // extent size
52 uint64_t disk; // disk size
53 char padding[HEADER_SIZE - 64 - 8 - 20];
54 } redolog;
55 char padding[HEADER_SIZE - 64 - 8];
56 } extra;
57 };
59 typedef struct BDRVBochsState {
60 int fd;
62 uint32_t *catalog_bitmap;
63 int catalog_size;
65 int data_offset;
67 int bitmap_blocks;
68 int extent_blocks;
69 int extent_size;
70 } BDRVBochsState;
72 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
73 {
74 const struct bochs_header *bochs = (const void *)buf;
76 if (buf_size < HEADER_SIZE)
77 return 0;
79 if (!strcmp(bochs->magic, HEADER_MAGIC) &&
80 !strcmp(bochs->type, REDOLOG_TYPE) &&
81 !strcmp(bochs->subtype, GROWING_TYPE) &&
82 (le32_to_cpu(bochs->version) == HEADER_VERSION))
83 return 100;
85 return 0;
86 }
88 static int bochs_open(BlockDriverState *bs, const char *filename)
89 {
90 BDRVBochsState *s = bs->opaque;
91 int fd, i;
92 struct bochs_header bochs;
94 fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE | O_SYNC);
95 if (fd < 0) {
96 fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
97 if (fd < 0)
98 return -1;
99 }
101 bs->read_only = 1; // no write support yet
103 s->fd = fd;
105 if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
106 goto fail;
107 }
109 if (strcmp(bochs.magic, HEADER_MAGIC) ||
110 strcmp(bochs.type, REDOLOG_TYPE) ||
111 strcmp(bochs.subtype, GROWING_TYPE) ||
112 (le32_to_cpu(bochs.version) != HEADER_VERSION)) {
113 goto fail;
114 }
116 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
118 lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);
120 s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
121 s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
122 if (!s->catalog_bitmap)
123 goto fail;
124 if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
125 s->catalog_size * 4)
126 goto fail;
127 for (i = 0; i < s->catalog_size; i++)
128 le32_to_cpus(&s->catalog_bitmap[i]);
130 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
132 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
133 s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
135 s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
137 return 0;
138 fail:
139 close(fd);
140 return -1;
141 }
143 static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
144 {
145 BDRVBochsState *s = bs->opaque;
146 int64_t offset = sector_num * 512;
147 int64_t extent_index, extent_offset, bitmap_offset, block_offset;
148 char bitmap_entry;
150 // seek to sector
151 extent_index = offset / s->extent_size;
152 extent_offset = (offset % s->extent_size) / 512;
154 if (s->catalog_bitmap[extent_index] == 0xffffffff)
155 {
156 // fprintf(stderr, "page not allocated [%x - %x:%x]\n",
157 // sector_num, extent_index, extent_offset);
158 return -1; // not allocated
159 }
161 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
162 (s->extent_blocks + s->bitmap_blocks));
163 block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
165 // fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
166 // sector_num, extent_index, extent_offset,
167 // le32_to_cpu(s->catalog_bitmap[extent_index]),
168 // bitmap_offset, block_offset);
170 // read in bitmap for current extent
171 lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
173 read(s->fd, &bitmap_entry, 1);
175 if (!((bitmap_entry >> (extent_offset % 8)) & 1))
176 {
177 // fprintf(stderr, "sector (%x) in bitmap not allocated\n",
178 // sector_num);
179 return -1; // not allocated
180 }
182 lseek(s->fd, block_offset, SEEK_SET);
184 return 0;
185 }
187 static int bochs_read(BlockDriverState *bs, int64_t sector_num,
188 uint8_t *buf, int nb_sectors)
189 {
190 BDRVBochsState *s = bs->opaque;
191 int ret;
193 while (nb_sectors > 0) {
194 if (!seek_to_sector(bs, sector_num))
195 {
196 ret = read(s->fd, buf, 512);
197 if (ret != 512)
198 return -1;
199 }
200 else
201 memset(buf, 0, 512);
202 nb_sectors--;
203 sector_num++;
204 buf += 512;
205 }
206 return 0;
207 }
209 static void bochs_close(BlockDriverState *bs)
210 {
211 BDRVBochsState *s = bs->opaque;
212 qemu_free(s->catalog_bitmap);
213 close(s->fd);
214 }
216 BlockDriver bdrv_bochs = {
217 "bochs",
218 sizeof(BDRVBochsState),
219 bochs_probe,
220 bochs_open,
221 bochs_read,
222 NULL,
223 bochs_close,
224 };