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1.1 root 1: /*
2: * Block driver for the QCOW version 2 format
3: *
4: * Copyright (c) 2004-2006 Fabrice Bellard
5: *
6: * Permission is hereby granted, free of charge, to any person obtaining a copy
7: * of this software and associated documentation files (the "Software"), to deal
8: * in the Software without restriction, including without limitation the rights
9: * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10: * copies of the Software, and to permit persons to whom the Software is
11: * furnished to do so, subject to the following conditions:
12: *
13: * The above copyright notice and this permission notice shall be included in
14: * all copies or substantial portions of the Software.
15: *
16: * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17: * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18: * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19: * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20: * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21: * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22: * THE SOFTWARE.
23: */
24:
25: #include "qemu-common.h"
26: #include "block_int.h"
27: #include "block/qcow2.h"
28:
29: typedef struct __attribute__((packed)) QCowSnapshotHeader {
30: /* header is 8 byte aligned */
31: uint64_t l1_table_offset;
32:
33: uint32_t l1_size;
34: uint16_t id_str_size;
35: uint16_t name_size;
36:
37: uint32_t date_sec;
38: uint32_t date_nsec;
39:
40: uint64_t vm_clock_nsec;
41:
42: uint32_t vm_state_size;
43: uint32_t extra_data_size; /* for extension */
44: /* extra data follows */
45: /* id_str follows */
46: /* name follows */
47: } QCowSnapshotHeader;
48:
49: void qcow2_free_snapshots(BlockDriverState *bs)
50: {
51: BDRVQcowState *s = bs->opaque;
52: int i;
53:
54: for(i = 0; i < s->nb_snapshots; i++) {
55: qemu_free(s->snapshots[i].name);
56: qemu_free(s->snapshots[i].id_str);
57: }
58: qemu_free(s->snapshots);
59: s->snapshots = NULL;
60: s->nb_snapshots = 0;
61: }
62:
63: int qcow2_read_snapshots(BlockDriverState *bs)
64: {
65: BDRVQcowState *s = bs->opaque;
66: QCowSnapshotHeader h;
67: QCowSnapshot *sn;
68: int i, id_str_size, name_size;
69: int64_t offset;
70: uint32_t extra_data_size;
71:
72: if (!s->nb_snapshots) {
73: s->snapshots = NULL;
74: s->snapshots_size = 0;
75: return 0;
76: }
77:
78: offset = s->snapshots_offset;
79: s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
80: for(i = 0; i < s->nb_snapshots; i++) {
81: offset = align_offset(offset, 8);
82: if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h))
83: goto fail;
84: offset += sizeof(h);
85: sn = s->snapshots + i;
86: sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
87: sn->l1_size = be32_to_cpu(h.l1_size);
88: sn->vm_state_size = be32_to_cpu(h.vm_state_size);
89: sn->date_sec = be32_to_cpu(h.date_sec);
90: sn->date_nsec = be32_to_cpu(h.date_nsec);
91: sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
92: extra_data_size = be32_to_cpu(h.extra_data_size);
93:
94: id_str_size = be16_to_cpu(h.id_str_size);
95: name_size = be16_to_cpu(h.name_size);
96:
97: offset += extra_data_size;
98:
99: sn->id_str = qemu_malloc(id_str_size + 1);
100: if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
101: goto fail;
102: offset += id_str_size;
103: sn->id_str[id_str_size] = '\0';
104:
105: sn->name = qemu_malloc(name_size + 1);
106: if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
107: goto fail;
108: offset += name_size;
109: sn->name[name_size] = '\0';
110: }
111: s->snapshots_size = offset - s->snapshots_offset;
112: return 0;
113: fail:
114: qcow2_free_snapshots(bs);
115: return -1;
116: }
117:
118: /* add at the end of the file a new list of snapshots */
119: static int qcow_write_snapshots(BlockDriverState *bs)
120: {
121: BDRVQcowState *s = bs->opaque;
122: QCowSnapshot *sn;
123: QCowSnapshotHeader h;
124: int i, name_size, id_str_size, snapshots_size;
125: uint64_t data64;
126: uint32_t data32;
127: int64_t offset, snapshots_offset;
128:
129: /* compute the size of the snapshots */
130: offset = 0;
131: for(i = 0; i < s->nb_snapshots; i++) {
132: sn = s->snapshots + i;
133: offset = align_offset(offset, 8);
134: offset += sizeof(h);
135: offset += strlen(sn->id_str);
136: offset += strlen(sn->name);
137: }
138: snapshots_size = offset;
139:
140: snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
141: offset = snapshots_offset;
142:
143: for(i = 0; i < s->nb_snapshots; i++) {
144: sn = s->snapshots + i;
145: memset(&h, 0, sizeof(h));
146: h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
147: h.l1_size = cpu_to_be32(sn->l1_size);
148: h.vm_state_size = cpu_to_be32(sn->vm_state_size);
149: h.date_sec = cpu_to_be32(sn->date_sec);
150: h.date_nsec = cpu_to_be32(sn->date_nsec);
151: h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
152:
153: id_str_size = strlen(sn->id_str);
154: name_size = strlen(sn->name);
155: h.id_str_size = cpu_to_be16(id_str_size);
156: h.name_size = cpu_to_be16(name_size);
157: offset = align_offset(offset, 8);
158: if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
159: goto fail;
160: offset += sizeof(h);
161: if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
162: goto fail;
163: offset += id_str_size;
164: if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
165: goto fail;
166: offset += name_size;
167: }
168:
169: /* update the various header fields */
170: data64 = cpu_to_be64(snapshots_offset);
171: if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
172: &data64, sizeof(data64)) != sizeof(data64))
173: goto fail;
174: data32 = cpu_to_be32(s->nb_snapshots);
175: if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
176: &data32, sizeof(data32)) != sizeof(data32))
177: goto fail;
178:
179: /* free the old snapshot table */
180: qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
181: s->snapshots_offset = snapshots_offset;
182: s->snapshots_size = snapshots_size;
183: return 0;
184: fail:
185: return -1;
186: }
187:
188: static void find_new_snapshot_id(BlockDriverState *bs,
189: char *id_str, int id_str_size)
190: {
191: BDRVQcowState *s = bs->opaque;
192: QCowSnapshot *sn;
193: int i, id, id_max = 0;
194:
195: for(i = 0; i < s->nb_snapshots; i++) {
196: sn = s->snapshots + i;
197: id = strtoul(sn->id_str, NULL, 10);
198: if (id > id_max)
199: id_max = id;
200: }
201: snprintf(id_str, id_str_size, "%d", id_max + 1);
202: }
203:
204: static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
205: {
206: BDRVQcowState *s = bs->opaque;
207: int i;
208:
209: for(i = 0; i < s->nb_snapshots; i++) {
210: if (!strcmp(s->snapshots[i].id_str, id_str))
211: return i;
212: }
213: return -1;
214: }
215:
216: static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
217: {
218: BDRVQcowState *s = bs->opaque;
219: int i, ret;
220:
221: ret = find_snapshot_by_id(bs, name);
222: if (ret >= 0)
223: return ret;
224: for(i = 0; i < s->nb_snapshots; i++) {
225: if (!strcmp(s->snapshots[i].name, name))
226: return i;
227: }
228: return -1;
229: }
230:
231: /* if no id is provided, a new one is constructed */
232: int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
233: {
234: BDRVQcowState *s = bs->opaque;
235: QCowSnapshot *snapshots1, sn1, *sn = &sn1;
236: int i, ret;
237: uint64_t *l1_table = NULL;
238:
239: memset(sn, 0, sizeof(*sn));
240:
241: if (sn_info->id_str[0] == '\0') {
242: /* compute a new id */
243: find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
244: }
245:
246: /* check that the ID is unique */
247: if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
248: return -ENOENT;
249:
250: sn->id_str = qemu_strdup(sn_info->id_str);
251: if (!sn->id_str)
252: goto fail;
253: sn->name = qemu_strdup(sn_info->name);
254: if (!sn->name)
255: goto fail;
256: sn->vm_state_size = sn_info->vm_state_size;
257: sn->date_sec = sn_info->date_sec;
258: sn->date_nsec = sn_info->date_nsec;
259: sn->vm_clock_nsec = sn_info->vm_clock_nsec;
260:
261: ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
262: if (ret < 0)
263: goto fail;
264:
265: /* create the L1 table of the snapshot */
266: sn->l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
267: sn->l1_size = s->l1_size;
268:
269: l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
270: for(i = 0; i < s->l1_size; i++) {
271: l1_table[i] = cpu_to_be64(s->l1_table[i]);
272: }
273: if (bdrv_pwrite(s->hd, sn->l1_table_offset,
274: l1_table, s->l1_size * sizeof(uint64_t)) !=
275: (s->l1_size * sizeof(uint64_t)))
276: goto fail;
277: qemu_free(l1_table);
278: l1_table = NULL;
279:
280: snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
281: if (s->snapshots) {
282: memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
283: qemu_free(s->snapshots);
284: }
285: s->snapshots = snapshots1;
286: s->snapshots[s->nb_snapshots++] = *sn;
287:
288: if (qcow_write_snapshots(bs) < 0)
289: goto fail;
290: #ifdef DEBUG_ALLOC
291: qcow2_check_refcounts(bs);
292: #endif
293: return 0;
294: fail:
295: qemu_free(sn->name);
296: qemu_free(l1_table);
297: return -1;
298: }
299:
300: /* copy the snapshot 'snapshot_name' into the current disk image */
301: int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
302: {
303: BDRVQcowState *s = bs->opaque;
304: QCowSnapshot *sn;
305: int i, snapshot_index, l1_size2;
306:
307: snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
308: if (snapshot_index < 0)
309: return -ENOENT;
310: sn = &s->snapshots[snapshot_index];
311:
312: if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
313: goto fail;
314:
315: if (qcow2_grow_l1_table(bs, sn->l1_size) < 0)
316: goto fail;
317:
318: s->l1_size = sn->l1_size;
319: l1_size2 = s->l1_size * sizeof(uint64_t);
320: /* copy the snapshot l1 table to the current l1 table */
321: if (bdrv_pread(s->hd, sn->l1_table_offset,
322: s->l1_table, l1_size2) != l1_size2)
323: goto fail;
324: if (bdrv_pwrite(s->hd, s->l1_table_offset,
325: s->l1_table, l1_size2) != l1_size2)
326: goto fail;
327: for(i = 0;i < s->l1_size; i++) {
328: be64_to_cpus(&s->l1_table[i]);
329: }
330:
331: if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
332: goto fail;
333:
334: #ifdef DEBUG_ALLOC
335: qcow2_check_refcounts(bs);
336: #endif
337: return 0;
338: fail:
339: return -EIO;
340: }
341:
342: int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
343: {
344: BDRVQcowState *s = bs->opaque;
345: QCowSnapshot *sn;
346: int snapshot_index, ret;
347:
348: snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
349: if (snapshot_index < 0)
350: return -ENOENT;
351: sn = &s->snapshots[snapshot_index];
352:
353: ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
354: if (ret < 0)
355: return ret;
356: /* must update the copied flag on the current cluster offsets */
357: ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
358: if (ret < 0)
359: return ret;
360: qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
361:
362: qemu_free(sn->id_str);
363: qemu_free(sn->name);
364: memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
365: s->nb_snapshots--;
366: ret = qcow_write_snapshots(bs);
367: if (ret < 0) {
368: /* XXX: restore snapshot if error ? */
369: return ret;
370: }
371: #ifdef DEBUG_ALLOC
372: qcow2_check_refcounts(bs);
373: #endif
374: return 0;
375: }
376:
377: int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
378: {
379: BDRVQcowState *s = bs->opaque;
380: QEMUSnapshotInfo *sn_tab, *sn_info;
381: QCowSnapshot *sn;
382: int i;
383:
384: if (!s->nb_snapshots) {
385: *psn_tab = NULL;
386: return s->nb_snapshots;
387: }
388:
389: sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
390: for(i = 0; i < s->nb_snapshots; i++) {
391: sn_info = sn_tab + i;
392: sn = s->snapshots + i;
393: pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
394: sn->id_str);
395: pstrcpy(sn_info->name, sizeof(sn_info->name),
396: sn->name);
397: sn_info->vm_state_size = sn->vm_state_size;
398: sn_info->date_sec = sn->date_sec;
399: sn_info->date_nsec = sn->date_nsec;
400: sn_info->vm_clock_nsec = sn->vm_clock_nsec;
401: }
402: *psn_tab = sn_tab;
403: return s->nb_snapshots;
404: }
405:
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