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#include "qemu-common.h"
25#include "block_int.h"
26#include "module.h"
27#include <zlib.h>
28#include "aes.h"
29#include "block/qcow2.h"
30
31/*
32  Differences with QCOW:
33
34  - Support for multiple incremental snapshots.
35  - Memory management by reference counts.
36  - Clusters which have a reference count of one have the bit
37    QCOW_OFLAG_COPIED to optimize write performance.
38  - Size of compressed clusters is stored in sectors to reduce bit usage
39    in the cluster offsets.
40  - Support for storing additional data (such as the VM state) in the
41    snapshots.
42  - If a backing store is used, the cluster size is not constrained
43    (could be backported to QCOW).
44  - L2 tables have always a size of one cluster.
45*/
46
47
48typedef struct {
49    uint32_t magic;
50    uint32_t len;
51} QCowExtension;
52#define  QCOW_EXT_MAGIC_END 0
53#define  QCOW_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
54
55static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
56{
57    const QCowHeader *cow_header = (const void *)buf;
58
59    if (buf_size >= sizeof(QCowHeader) &&
60        be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
61        be32_to_cpu(cow_header->version) == QCOW_VERSION)
62        return 100;
63    else
64        return 0;
65}
66
67
68/*
69 * read qcow2 extension and fill bs
70 * start reading from start_offset
71 * finish reading upon magic of value 0 or when end_offset reached
72 * unknown magic is skipped (future extension this version knows nothing about)
73 * return 0 upon success, non-0 otherwise
74 */
75static int qcow_read_extensions(BlockDriverState *bs, uint64_t start_offset,
76                                uint64_t end_offset)
77{
78    QCowExtension ext;
79    uint64_t offset;
80
81#ifdef DEBUG_EXT
82    printf("qcow_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
83#endif
84    offset = start_offset;
85    while (offset < end_offset) {
86
87#ifdef DEBUG_EXT
88        /* Sanity check */
89        if (offset > s->cluster_size)
90            printf("qcow_handle_extension: suspicious offset %lu\n", offset);
91
92        printf("attemting to read extended header in offset %lu\n", offset);
93#endif
94
95        if (bdrv_pread(bs->file, offset, &ext, sizeof(ext)) != sizeof(ext)) {
96            fprintf(stderr, "qcow_handle_extension: ERROR: "
97                    "pread fail from offset %" PRIu64 "\n",
98                    offset);
99            return 1;
100        }
101        be32_to_cpus(&ext.magic);
102        be32_to_cpus(&ext.len);
103        offset += sizeof(ext);
104#ifdef DEBUG_EXT
105        printf("ext.magic = 0x%x\n", ext.magic);
106#endif
107        switch (ext.magic) {
108        case QCOW_EXT_MAGIC_END:
109            return 0;
110
111        case QCOW_EXT_MAGIC_BACKING_FORMAT:
112            if (ext.len >= sizeof(bs->backing_format)) {
113                fprintf(stderr, "ERROR: ext_backing_format: len=%u too large"
114                        " (>=%zu)\n",
115                        ext.len, sizeof(bs->backing_format));
116                return 2;
117            }
118            if (bdrv_pread(bs->file, offset , bs->backing_format,
119                           ext.len) != ext.len)
120                return 3;
121            bs->backing_format[ext.len] = '\0';
122#ifdef DEBUG_EXT
123            printf("Qcow2: Got format extension %s\n", bs->backing_format);
124#endif
125            offset = ((offset + ext.len + 7) & ~7);
126            break;
127
128        default:
129            /* unknown magic -- just skip it */
130            offset = ((offset + ext.len + 7) & ~7);
131            break;
132        }
133    }
134
135    return 0;
136}
137
138
139static int qcow_open(BlockDriverState *bs, int flags)
140{
141    BDRVQcowState *s = bs->opaque;
142    int len, i;
143    QCowHeader header;
144    uint64_t ext_end;
145
146    if (bdrv_pread(bs->file, 0, &header, sizeof(header)) != sizeof(header))
147        goto fail;
148    be32_to_cpus(&header.magic);
149    be32_to_cpus(&header.version);
150    be64_to_cpus(&header.backing_file_offset);
151    be32_to_cpus(&header.backing_file_size);
152    be64_to_cpus(&header.size);
153    be32_to_cpus(&header.cluster_bits);
154    be32_to_cpus(&header.crypt_method);
155    be64_to_cpus(&header.l1_table_offset);
156    be32_to_cpus(&header.l1_size);
157    be64_to_cpus(&header.refcount_table_offset);
158    be32_to_cpus(&header.refcount_table_clusters);
159    be64_to_cpus(&header.snapshots_offset);
160    be32_to_cpus(&header.nb_snapshots);
161
162    if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
163        goto fail;
164    if (header.cluster_bits < MIN_CLUSTER_BITS ||
165        header.cluster_bits > MAX_CLUSTER_BITS)
166        goto fail;
167    if (header.crypt_method > QCOW_CRYPT_AES)
168        goto fail;
169    s->crypt_method_header = header.crypt_method;
170    if (s->crypt_method_header)
171        bs->encrypted = 1;
172    s->cluster_bits = header.cluster_bits;
173    s->cluster_size = 1 << s->cluster_bits;
174    s->cluster_sectors = 1 << (s->cluster_bits - 9);
175    s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
176    s->l2_size = 1 << s->l2_bits;
177    bs->total_sectors = header.size / 512;
178    s->csize_shift = (62 - (s->cluster_bits - 8));
179    s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
180    s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
181    s->refcount_table_offset = header.refcount_table_offset;
182    s->refcount_table_size =
183        header.refcount_table_clusters << (s->cluster_bits - 3);
184
185    s->snapshots_offset = header.snapshots_offset;
186    s->nb_snapshots = header.nb_snapshots;
187
188    /* read the level 1 table */
189    s->l1_size = header.l1_size;
190    s->l1_vm_state_index = size_to_l1(s, header.size);
191    /* the L1 table must contain at least enough entries to put
192       header.size bytes */
193    if (s->l1_size < s->l1_vm_state_index)
194        goto fail;
195    s->l1_table_offset = header.l1_table_offset;
196    if (s->l1_size > 0) {
197        s->l1_table = qemu_mallocz(
198            align_offset(s->l1_size * sizeof(uint64_t), 512));
199        if (bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
200            s->l1_size * sizeof(uint64_t))
201            goto fail;
202        for(i = 0;i < s->l1_size; i++) {
203            be64_to_cpus(&s->l1_table[i]);
204        }
205    }
206    /* alloc L2 cache */
207    s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
208    s->cluster_cache = qemu_malloc(s->cluster_size);
209    /* one more sector for decompressed data alignment */
210    s->cluster_data = qemu_malloc(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
211                                  + 512);
212    s->cluster_cache_offset = -1;
213
214    if (qcow2_refcount_init(bs) < 0)
215        goto fail;
216
217    QLIST_INIT(&s->cluster_allocs);
218
219    /* read qcow2 extensions */
220    if (header.backing_file_offset)
221        ext_end = header.backing_file_offset;
222    else
223        ext_end = s->cluster_size;
224    if (qcow_read_extensions(bs, sizeof(header), ext_end))
225        goto fail;
226
227    /* read the backing file name */
228    if (header.backing_file_offset != 0) {
229        len = header.backing_file_size;
230        if (len > 1023)
231            len = 1023;
232        if (bdrv_pread(bs->file, header.backing_file_offset, bs->backing_file, len) != len)
233            goto fail;
234        bs->backing_file[len] = '\0';
235    }
236    if (qcow2_read_snapshots(bs) < 0)
237        goto fail;
238
239#ifdef DEBUG_ALLOC
240    qcow2_check_refcounts(bs);
241#endif
242    return 0;
243
244 fail:
245    qcow2_free_snapshots(bs);
246    qcow2_refcount_close(bs);
247    qemu_free(s->l1_table);
248    qemu_free(s->l2_cache);
249    qemu_free(s->cluster_cache);
250    qemu_free(s->cluster_data);
251    return -1;
252}
253
254static int qcow_set_key(BlockDriverState *bs, const char *key)
255{
256    BDRVQcowState *s = bs->opaque;
257    uint8_t keybuf[16];
258    int len, i;
259
260    memset(keybuf, 0, 16);
261    len = strlen(key);
262    if (len > 16)
263        len = 16;
264    /* XXX: we could compress the chars to 7 bits to increase
265       entropy */
266    for(i = 0;i < len;i++) {
267        keybuf[i] = key[i];
268    }
269    s->crypt_method = s->crypt_method_header;
270
271    if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
272        return -1;
273    if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
274        return -1;
275#if 0
276    /* test */
277    {
278        uint8_t in[16];
279        uint8_t out[16];
280        uint8_t tmp[16];
281        for(i=0;i<16;i++)
282            in[i] = i;
283        AES_encrypt(in, tmp, &s->aes_encrypt_key);
284        AES_decrypt(tmp, out, &s->aes_decrypt_key);
285        for(i = 0; i < 16; i++)
286            printf(" %02x", tmp[i]);
287        printf("\n");
288        for(i = 0; i < 16; i++)
289            printf(" %02x", out[i]);
290        printf("\n");
291    }
292#endif
293    return 0;
294}
295
296static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
297                             int nb_sectors, int *pnum)
298{
299    uint64_t cluster_offset;
300    int ret;
301
302    *pnum = nb_sectors;
303    /* FIXME We can get errors here, but the bdrv_is_allocated interface can't
304     * pass them on today */
305    ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset);
306    if (ret < 0) {
307        *pnum = 0;
308    }
309
310    return (cluster_offset != 0);
311}
312
313/* handle reading after the end of the backing file */
314int qcow2_backing_read1(BlockDriverState *bs,
315                  int64_t sector_num, uint8_t *buf, int nb_sectors)
316{
317    int n1;
318    if ((sector_num + nb_sectors) <= bs->total_sectors)
319        return nb_sectors;
320    if (sector_num >= bs->total_sectors)
321        n1 = 0;
322    else
323        n1 = bs->total_sectors - sector_num;
324    memset(buf + n1 * 512, 0, 512 * (nb_sectors - n1));
325    return n1;
326}
327
328typedef struct QCowAIOCB {
329    BlockDriverAIOCB common;
330    int64_t sector_num;
331    QEMUIOVector *qiov;
332    uint8_t *buf;
333    void *orig_buf;
334    int remaining_sectors;
335    int cur_nr_sectors;	/* number of sectors in current iteration */
336    uint64_t cluster_offset;
337    uint8_t *cluster_data;
338    BlockDriverAIOCB *hd_aiocb;
339    struct iovec hd_iov;
340    QEMUIOVector hd_qiov;
341    QEMUBH *bh;
342    QCowL2Meta l2meta;
343    QLIST_ENTRY(QCowAIOCB) next_depend;
344} QCowAIOCB;
345
346static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
347{
348    QCowAIOCB *acb = container_of(blockacb, QCowAIOCB, common);
349    if (acb->hd_aiocb)
350        bdrv_aio_cancel(acb->hd_aiocb);
351    qemu_aio_release(acb);
352}
353
354static AIOPool qcow_aio_pool = {
355    .aiocb_size         = sizeof(QCowAIOCB),
356    .cancel             = qcow_aio_cancel,
357};
358
359static void qcow_aio_read_cb(void *opaque, int ret);
360static void qcow_aio_read_bh(void *opaque)
361{
362    QCowAIOCB *acb = opaque;
363    qemu_bh_delete(acb->bh);
364    acb->bh = NULL;
365    qcow_aio_read_cb(opaque, 0);
366}
367
368static int qcow_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb)
369{
370    if (acb->bh)
371        return -EIO;
372
373    acb->bh = qemu_bh_new(cb, acb);
374    if (!acb->bh)
375        return -EIO;
376
377    qemu_bh_schedule(acb->bh);
378
379    return 0;
380}
381
382static void qcow_aio_read_cb(void *opaque, int ret)
383{
384    QCowAIOCB *acb = opaque;
385    BlockDriverState *bs = acb->common.bs;
386    BDRVQcowState *s = bs->opaque;
387    int index_in_cluster, n1;
388
389    acb->hd_aiocb = NULL;
390    if (ret < 0)
391        goto done;
392
393    /* post process the read buffer */
394    if (!acb->cluster_offset) {
395        /* nothing to do */
396    } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
397        /* nothing to do */
398    } else {
399        if (s->crypt_method) {
400            qcow2_encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
401                            acb->cur_nr_sectors, 0,
402                            &s->aes_decrypt_key);
403        }
404    }
405
406    acb->remaining_sectors -= acb->cur_nr_sectors;
407    acb->sector_num += acb->cur_nr_sectors;
408    acb->buf += acb->cur_nr_sectors * 512;
409
410    if (acb->remaining_sectors == 0) {
411        /* request completed */
412        ret = 0;
413        goto done;
414    }
415
416    /* prepare next AIO request */
417    acb->cur_nr_sectors = acb->remaining_sectors;
418    ret = qcow2_get_cluster_offset(bs, acb->sector_num << 9,
419        &acb->cur_nr_sectors, &acb->cluster_offset);
420    if (ret < 0) {
421        goto done;
422    }
423
424    index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
425
426    if (!acb->cluster_offset) {
427        if (bs->backing_hd) {
428            /* read from the base image */
429            n1 = qcow2_backing_read1(bs->backing_hd, acb->sector_num,
430                               acb->buf, acb->cur_nr_sectors);
431            if (n1 > 0) {
432                acb->hd_iov.iov_base = (void *)acb->buf;
433                acb->hd_iov.iov_len = acb->cur_nr_sectors * 512;
434                qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
435                BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
436                acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num,
437                                    &acb->hd_qiov, acb->cur_nr_sectors,
438				    qcow_aio_read_cb, acb);
439                if (acb->hd_aiocb == NULL)
440                    goto done;
441            } else {
442                ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
443                if (ret < 0)
444                    goto done;
445            }
446        } else {
447            /* Note: in this case, no need to wait */
448            memset(acb->buf, 0, 512 * acb->cur_nr_sectors);
449            ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
450            if (ret < 0)
451                goto done;
452        }
453    } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
454        /* add AIO support for compressed blocks ? */
455        if (qcow2_decompress_cluster(bs, acb->cluster_offset) < 0)
456            goto done;
457        memcpy(acb->buf, s->cluster_cache + index_in_cluster * 512,
458               512 * acb->cur_nr_sectors);
459        ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
460        if (ret < 0)
461            goto done;
462    } else {
463        if ((acb->cluster_offset & 511) != 0) {
464            ret = -EIO;
465            goto done;
466        }
467
468        acb->hd_iov.iov_base = (void *)acb->buf;
469        acb->hd_iov.iov_len = acb->cur_nr_sectors * 512;
470        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
471        BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
472        acb->hd_aiocb = bdrv_aio_readv(bs->file,
473                            (acb->cluster_offset >> 9) + index_in_cluster,
474                            &acb->hd_qiov, acb->cur_nr_sectors,
475                            qcow_aio_read_cb, acb);
476        if (acb->hd_aiocb == NULL) {
477            ret = -EIO;
478            goto done;
479        }
480    }
481
482    return;
483done:
484    if (acb->qiov->niov > 1) {
485        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
486        qemu_vfree(acb->orig_buf);
487    }
488    acb->common.cb(acb->common.opaque, ret);
489    qemu_aio_release(acb);
490}
491
492static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs,
493        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
494        BlockDriverCompletionFunc *cb, void *opaque, int is_write)
495{
496    QCowAIOCB *acb;
497
498    acb = qemu_aio_get(&qcow_aio_pool, bs, cb, opaque);
499    if (!acb)
500        return NULL;
501    acb->hd_aiocb = NULL;
502    acb->sector_num = sector_num;
503    acb->qiov = qiov;
504    if (qiov->niov > 1) {
505        acb->buf = acb->orig_buf = qemu_blockalign(bs, qiov->size);
506        if (is_write)
507            qemu_iovec_to_buffer(qiov, acb->buf);
508    } else {
509        acb->buf = (uint8_t *)qiov->iov->iov_base;
510    }
511    acb->remaining_sectors = nb_sectors;
512    acb->cur_nr_sectors = 0;
513    acb->cluster_offset = 0;
514    acb->l2meta.nb_clusters = 0;
515    QLIST_INIT(&acb->l2meta.dependent_requests);
516    return acb;
517}
518
519static BlockDriverAIOCB *qcow_aio_readv(BlockDriverState *bs,
520        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
521        BlockDriverCompletionFunc *cb, void *opaque)
522{
523    QCowAIOCB *acb;
524
525    acb = qcow_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
526    if (!acb)
527        return NULL;
528
529    qcow_aio_read_cb(acb, 0);
530    return &acb->common;
531}
532
533static void qcow_aio_write_cb(void *opaque, int ret);
534
535static void run_dependent_requests(QCowL2Meta *m)
536{
537    QCowAIOCB *req;
538    QCowAIOCB *next;
539
540    /* Take the request off the list of running requests */
541    if (m->nb_clusters != 0) {
542        QLIST_REMOVE(m, next_in_flight);
543    }
544
545    /* Restart all dependent requests */
546    QLIST_FOREACH_SAFE(req, &m->dependent_requests, next_depend, next) {
547        qcow_aio_write_cb(req, 0);
548    }
549
550    /* Empty the list for the next part of the request */
551    QLIST_INIT(&m->dependent_requests);
552}
553
554static void qcow_aio_write_cb(void *opaque, int ret)
555{
556    QCowAIOCB *acb = opaque;
557    BlockDriverState *bs = acb->common.bs;
558    BDRVQcowState *s = bs->opaque;
559    int index_in_cluster;
560    const uint8_t *src_buf;
561    int n_end;
562
563    acb->hd_aiocb = NULL;
564
565    if (ret >= 0) {
566        ret = qcow2_alloc_cluster_link_l2(bs, &acb->l2meta);
567    }
568
569    run_dependent_requests(&acb->l2meta);
570
571    if (ret < 0)
572        goto done;
573
574    acb->remaining_sectors -= acb->cur_nr_sectors;
575    acb->sector_num += acb->cur_nr_sectors;
576    acb->buf += acb->cur_nr_sectors * 512;
577
578    if (acb->remaining_sectors == 0) {
579        /* request completed */
580        ret = 0;
581        goto done;
582    }
583
584    index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
585    n_end = index_in_cluster + acb->remaining_sectors;
586    if (s->crypt_method &&
587        n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
588        n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
589
590    ret = qcow2_alloc_cluster_offset(bs, acb->sector_num << 9,
591        index_in_cluster, n_end, &acb->cur_nr_sectors, &acb->l2meta);
592    if (ret < 0) {
593        goto done;
594    }
595
596    acb->cluster_offset = acb->l2meta.cluster_offset;
597
598    /* Need to wait for another request? If so, we are done for now. */
599    if (acb->l2meta.nb_clusters == 0 && acb->l2meta.depends_on != NULL) {
600        QLIST_INSERT_HEAD(&acb->l2meta.depends_on->dependent_requests,
601            acb, next_depend);
602        return;
603    }
604
605    assert((acb->cluster_offset & 511) == 0);
606
607    if (s->crypt_method) {
608        if (!acb->cluster_data) {
609            acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS *
610                                             s->cluster_size);
611        }
612        qcow2_encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
613                        acb->cur_nr_sectors, 1, &s->aes_encrypt_key);
614        src_buf = acb->cluster_data;
615    } else {
616        src_buf = acb->buf;
617    }
618    acb->hd_iov.iov_base = (void *)src_buf;
619    acb->hd_iov.iov_len = acb->cur_nr_sectors * 512;
620    qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
621    BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
622    acb->hd_aiocb = bdrv_aio_writev(bs->file,
623                                    (acb->cluster_offset >> 9) + index_in_cluster,
624                                    &acb->hd_qiov, acb->cur_nr_sectors,
625                                    qcow_aio_write_cb, acb);
626    if (acb->hd_aiocb == NULL) {
627        ret = -EIO;
628        goto fail;
629    }
630
631    return;
632
633fail:
634    if (acb->l2meta.nb_clusters != 0) {
635        QLIST_REMOVE(&acb->l2meta, next_in_flight);
636    }
637done:
638    if (acb->qiov->niov > 1)
639        qemu_vfree(acb->orig_buf);
640    acb->common.cb(acb->common.opaque, ret);
641    qemu_aio_release(acb);
642}
643
644static BlockDriverAIOCB *qcow_aio_writev(BlockDriverState *bs,
645        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
646        BlockDriverCompletionFunc *cb, void *opaque)
647{
648    BDRVQcowState *s = bs->opaque;
649    QCowAIOCB *acb;
650
651    s->cluster_cache_offset = -1; /* disable compressed cache */
652
653    acb = qcow_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
654    if (!acb)
655        return NULL;
656
657    qcow_aio_write_cb(acb, 0);
658    return &acb->common;
659}
660
661static void qcow_close(BlockDriverState *bs)
662{
663    BDRVQcowState *s = bs->opaque;
664    qemu_free(s->l1_table);
665    qemu_free(s->l2_cache);
666    qemu_free(s->cluster_cache);
667    qemu_free(s->cluster_data);
668    qcow2_refcount_close(bs);
669}
670
671/*
672 * Updates the variable length parts of the qcow2 header, i.e. the backing file
673 * name and all extensions. qcow2 was not designed to allow such changes, so if
674 * we run out of space (we can only use the first cluster) this function may
675 * fail.
676 *
677 * Returns 0 on success, -errno in error cases.
678 */
679static int qcow2_update_ext_header(BlockDriverState *bs,
680    const char *backing_file, const char *backing_fmt)
681{
682    size_t backing_file_len = 0;
683    size_t backing_fmt_len = 0;
684    BDRVQcowState *s = bs->opaque;
685    QCowExtension ext_backing_fmt = {0, 0};
686    int ret;
687
688    /* Backing file format doesn't make sense without a backing file */
689    if (backing_fmt && !backing_file) {
690        return -EINVAL;
691    }
692
693    /* Prepare the backing file format extension if needed */
694    if (backing_fmt) {
695        ext_backing_fmt.len = cpu_to_be32(strlen(backing_fmt));
696        ext_backing_fmt.magic = cpu_to_be32(QCOW_EXT_MAGIC_BACKING_FORMAT);
697        backing_fmt_len = ((sizeof(ext_backing_fmt)
698            + strlen(backing_fmt) + 7) & ~7);
699    }
700
701    /* Check if we can fit the new header into the first cluster */
702    if (backing_file) {
703        backing_file_len = strlen(backing_file);
704    }
705
706    size_t header_size = sizeof(QCowHeader) + backing_file_len
707        + backing_fmt_len;
708
709    if (header_size > s->cluster_size) {
710        return -ENOSPC;
711    }
712
713    /* Rewrite backing file name and qcow2 extensions */
714    size_t ext_size = header_size - sizeof(QCowHeader);
715    uint8_t buf[ext_size];
716    size_t offset = 0;
717    size_t backing_file_offset = 0;
718
719    if (backing_file) {
720        if (backing_fmt) {
721            int padding = backing_fmt_len -
722                (sizeof(ext_backing_fmt) + strlen(backing_fmt));
723
724            memcpy(buf + offset, &ext_backing_fmt, sizeof(ext_backing_fmt));
725            offset += sizeof(ext_backing_fmt);
726
727            memcpy(buf + offset, backing_fmt, strlen(backing_fmt));
728            offset += strlen(backing_fmt);
729
730            memset(buf + offset, 0, padding);
731            offset += padding;
732        }
733
734        memcpy(buf + offset, backing_file, backing_file_len);
735        backing_file_offset = sizeof(QCowHeader) + offset;
736    }
737
738    ret = bdrv_pwrite_sync(bs->file, sizeof(QCowHeader), buf, ext_size);
739    if (ret < 0) {
740        goto fail;
741    }
742
743    /* Update header fields */
744    uint64_t be_backing_file_offset = cpu_to_be64(backing_file_offset);
745    uint32_t be_backing_file_size = cpu_to_be32(backing_file_len);
746
747    ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_offset),
748        &be_backing_file_offset, sizeof(uint64_t));
749    if (ret < 0) {
750        goto fail;
751    }
752
753    ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_size),
754        &be_backing_file_size, sizeof(uint32_t));
755    if (ret < 0) {
756        goto fail;
757    }
758
759    ret = 0;
760fail:
761    return ret;
762}
763
764static int qcow2_change_backing_file(BlockDriverState *bs,
765    const char *backing_file, const char *backing_fmt)
766{
767    return qcow2_update_ext_header(bs, backing_file, backing_fmt);
768}
769
770static int get_bits_from_size(size_t size)
771{
772    int res = 0;
773
774    if (size == 0) {
775        return -1;
776    }
777
778    while (size != 1) {
779        /* Not a power of two */
780        if (size & 1) {
781            return -1;
782        }
783
784        size >>= 1;
785        res++;
786    }
787
788    return res;
789}
790
791
792static int preallocate(BlockDriverState *bs)
793{
794    uint64_t nb_sectors;
795    uint64_t offset;
796    int num;
797    int ret;
798    QCowL2Meta meta;
799
800    nb_sectors = bdrv_getlength(bs) >> 9;
801    offset = 0;
802    QLIST_INIT(&meta.dependent_requests);
803    meta.cluster_offset = 0;
804
805    while (nb_sectors) {
806        num = MIN(nb_sectors, INT_MAX >> 9);
807        ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta);
808        if (ret < 0) {
809            return ret;
810        }
811
812        ret = qcow2_alloc_cluster_link_l2(bs, &meta);
813        if (ret < 0) {
814            qcow2_free_any_clusters(bs, meta.cluster_offset, meta.nb_clusters);
815            return ret;
816        }
817
818        /* There are no dependent requests, but we need to remove our request
819         * from the list of in-flight requests */
820        run_dependent_requests(&meta);
821
822        /* TODO Preallocate data if requested */
823
824        nb_sectors -= num;
825        offset += num << 9;
826    }
827
828    /*
829     * It is expected that the image file is large enough to actually contain
830     * all of the allocated clusters (otherwise we get failing reads after
831     * EOF). Extend the image to the last allocated sector.
832     */
833    if (meta.cluster_offset != 0) {
834        uint8_t buf[512];
835        memset(buf, 0, 512);
836        ret = bdrv_write(bs->file, (meta.cluster_offset >> 9) + num - 1, buf, 1);
837        if (ret < 0) {
838            return ret;
839        }
840    }
841
842    return 0;
843}
844
845static int qcow_create2(const char *filename, int64_t total_size,
846                        const char *backing_file, const char *backing_format,
847                        int flags, size_t cluster_size, int prealloc)
848{
849
850    int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits;
851    int ref_clusters, reftable_clusters, backing_format_len = 0;
852    int rounded_ext_bf_len = 0;
853    QCowHeader header;
854    uint64_t tmp, offset;
855    uint64_t old_ref_clusters;
856    QCowCreateState s1, *s = &s1;
857    QCowExtension ext_bf = {0, 0};
858    int ret;
859
860    memset(s, 0, sizeof(*s));
861
862    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
863    if (fd < 0)
864        return -errno;
865    memset(&header, 0, sizeof(header));
866    header.magic = cpu_to_be32(QCOW_MAGIC);
867    header.version = cpu_to_be32(QCOW_VERSION);
868    header.size = cpu_to_be64(total_size * 512);
869    header_size = sizeof(header);
870    backing_filename_len = 0;
871    if (backing_file) {
872        if (backing_format) {
873            ext_bf.magic = QCOW_EXT_MAGIC_BACKING_FORMAT;
874            backing_format_len = strlen(backing_format);
875            ext_bf.len = backing_format_len;
876            rounded_ext_bf_len = (sizeof(ext_bf) + ext_bf.len + 7) & ~7;
877            header_size += rounded_ext_bf_len;
878        }
879        header.backing_file_offset = cpu_to_be64(header_size);
880        backing_filename_len = strlen(backing_file);
881        header.backing_file_size = cpu_to_be32(backing_filename_len);
882        header_size += backing_filename_len;
883    }
884
885    /* Cluster size */
886    s->cluster_bits = get_bits_from_size(cluster_size);
887    if (s->cluster_bits < MIN_CLUSTER_BITS ||
888        s->cluster_bits > MAX_CLUSTER_BITS)
889    {
890        fprintf(stderr, "Cluster size must be a power of two between "
891            "%d and %dk\n",
892            1 << MIN_CLUSTER_BITS,
893            1 << (MAX_CLUSTER_BITS - 10));
894        return -EINVAL;
895    }
896    s->cluster_size = 1 << s->cluster_bits;
897
898    header.cluster_bits = cpu_to_be32(s->cluster_bits);
899    header_size = (header_size + 7) & ~7;
900    if (flags & BLOCK_FLAG_ENCRYPT) {
901        header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
902    } else {
903        header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
904    }
905    l2_bits = s->cluster_bits - 3;
906    shift = s->cluster_bits + l2_bits;
907    l1_size = (((total_size * 512) + (1LL << shift) - 1) >> shift);
908    offset = align_offset(header_size, s->cluster_size);
909    s->l1_table_offset = offset;
910    header.l1_table_offset = cpu_to_be64(s->l1_table_offset);
911    header.l1_size = cpu_to_be32(l1_size);
912    offset += align_offset(l1_size * sizeof(uint64_t), s->cluster_size);
913
914    /* count how many refcount blocks needed */
915
916#define NUM_CLUSTERS(bytes) \
917    (((bytes) + (s->cluster_size) - 1) / (s->cluster_size))
918
919    ref_clusters = NUM_CLUSTERS(NUM_CLUSTERS(offset) * sizeof(uint16_t));
920
921    do {
922        uint64_t image_clusters;
923        old_ref_clusters = ref_clusters;
924
925        /* Number of clusters used for the refcount table */
926        reftable_clusters = NUM_CLUSTERS(ref_clusters * sizeof(uint64_t));
927
928        /* Number of clusters that the whole image will have */
929        image_clusters = NUM_CLUSTERS(offset) + ref_clusters
930            + reftable_clusters;
931
932        /* Number of refcount blocks needed for the image */
933        ref_clusters = NUM_CLUSTERS(image_clusters * sizeof(uint16_t));
934
935    } while (ref_clusters != old_ref_clusters);
936
937    s->refcount_table = qemu_mallocz(reftable_clusters * s->cluster_size);
938
939    s->refcount_table_offset = offset;
940    header.refcount_table_offset = cpu_to_be64(offset);
941    header.refcount_table_clusters = cpu_to_be32(reftable_clusters);
942    offset += (reftable_clusters * s->cluster_size);
943    s->refcount_block_offset = offset;
944
945    for (i=0; i < ref_clusters; i++) {
946        s->refcount_table[i] = cpu_to_be64(offset);
947        offset += s->cluster_size;
948    }
949
950    s->refcount_block = qemu_mallocz(ref_clusters * s->cluster_size);
951
952    /* update refcounts */
953    qcow2_create_refcount_update(s, 0, header_size);
954    qcow2_create_refcount_update(s, s->l1_table_offset,
955        l1_size * sizeof(uint64_t));
956    qcow2_create_refcount_update(s, s->refcount_table_offset,
957        reftable_clusters * s->cluster_size);
958    qcow2_create_refcount_update(s, s->refcount_block_offset,
959        ref_clusters * s->cluster_size);
960
961    /* write all the data */
962    ret = qemu_write_full(fd, &header, sizeof(header));
963    if (ret != sizeof(header)) {
964        ret = -errno;
965        goto exit;
966    }
967    if (backing_file) {
968        if (backing_format_len) {
969            char zero[16];
970            int padding = rounded_ext_bf_len - (ext_bf.len + sizeof(ext_bf));
971
972            memset(zero, 0, sizeof(zero));
973            cpu_to_be32s(&ext_bf.magic);
974            cpu_to_be32s(&ext_bf.len);
975            ret = qemu_write_full(fd, &ext_bf, sizeof(ext_bf));
976            if (ret != sizeof(ext_bf)) {
977                ret = -errno;
978                goto exit;
979            }
980            ret = qemu_write_full(fd, backing_format, backing_format_len);
981            if (ret != backing_format_len) {
982                ret = -errno;
983                goto exit;
984            }
985            if (padding > 0) {
986                ret = qemu_write_full(fd, zero, padding);
987                if (ret != padding) {
988                    ret = -errno;
989                    goto exit;
990                }
991            }
992        }
993        ret = qemu_write_full(fd, backing_file, backing_filename_len);
994        if (ret != backing_filename_len) {
995            ret = -errno;
996            goto exit;
997        }
998    }
999    lseek(fd, s->l1_table_offset, SEEK_SET);
1000    tmp = 0;
1001    for(i = 0;i < l1_size; i++) {
1002        ret = qemu_write_full(fd, &tmp, sizeof(tmp));
1003        if (ret != sizeof(tmp)) {
1004            ret = -errno;
1005            goto exit;
1006        }
1007    }
1008    lseek(fd, s->refcount_table_offset, SEEK_SET);
1009    ret = qemu_write_full(fd, s->refcount_table,
1010        reftable_clusters * s->cluster_size);
1011    if (ret != reftable_clusters * s->cluster_size) {
1012        ret = -errno;
1013        goto exit;
1014    }
1015
1016    lseek(fd, s->refcount_block_offset, SEEK_SET);
1017    ret = qemu_write_full(fd, s->refcount_block,
1018		    ref_clusters * s->cluster_size);
1019    if (ret != ref_clusters * s->cluster_size) {
1020        ret = -errno;
1021        goto exit;
1022    }
1023
1024    ret = 0;
1025exit:
1026    qemu_free(s->refcount_table);
1027    qemu_free(s->refcount_block);
1028    close(fd);
1029
1030    /* Preallocate metadata */
1031    if (ret == 0 && prealloc) {
1032        BlockDriverState *bs;
1033        BlockDriver *drv = bdrv_find_format("qcow2");
1034        bs = bdrv_new("");
1035        bdrv_open(bs, filename, BDRV_O_CACHE_WB | BDRV_O_RDWR, drv);
1036        ret = preallocate(bs);
1037        bdrv_close(bs);
1038    }
1039
1040    return ret;
1041}
1042
1043static int qcow_create(const char *filename, QEMUOptionParameter *options)
1044{
1045    const char *backing_file = NULL;
1046    const char *backing_fmt = NULL;
1047    uint64_t sectors = 0;
1048    int flags = 0;
1049    size_t cluster_size = 65536;
1050    int prealloc = 0;
1051
1052    /* Read out options */
1053    while (options && options->name) {
1054        if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
1055            sectors = options->value.n / 512;
1056        } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
1057            backing_file = options->value.s;
1058        } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
1059            backing_fmt = options->value.s;
1060        } else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) {
1061            flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0;
1062        } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
1063            if (options->value.n) {
1064                cluster_size = options->value.n;
1065            }
1066        } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
1067            if (!options->value.s || !strcmp(options->value.s, "off")) {
1068                prealloc = 0;
1069            } else if (!strcmp(options->value.s, "metadata")) {
1070                prealloc = 1;
1071            } else {
1072                fprintf(stderr, "Invalid preallocation mode: '%s'\n",
1073                    options->value.s);
1074                return -EINVAL;
1075            }
1076        }
1077        options++;
1078    }
1079
1080    if (backing_file && prealloc) {
1081        fprintf(stderr, "Backing file and preallocation cannot be used at "
1082            "the same time\n");
1083        return -EINVAL;
1084    }
1085
1086    return qcow_create2(filename, sectors, backing_file, backing_fmt, flags,
1087        cluster_size, prealloc);
1088}
1089
1090static int qcow_make_empty(BlockDriverState *bs)
1091{
1092#if 0
1093    /* XXX: not correct */
1094    BDRVQcowState *s = bs->opaque;
1095    uint32_t l1_length = s->l1_size * sizeof(uint64_t);
1096    int ret;
1097
1098    memset(s->l1_table, 0, l1_length);
1099    if (bdrv_pwrite(bs->file, s->l1_table_offset, s->l1_table, l1_length) < 0)
1100        return -1;
1101    ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length);
1102    if (ret < 0)
1103        return ret;
1104
1105    l2_cache_reset(bs);
1106#endif
1107    return 0;
1108}
1109
1110static int qcow2_truncate(BlockDriverState *bs, int64_t offset)
1111{
1112    BDRVQcowState *s = bs->opaque;
1113    int ret, new_l1_size;
1114
1115    if (offset & 511) {
1116        return -EINVAL;
1117    }
1118
1119    /* cannot proceed if image has snapshots */
1120    if (s->nb_snapshots) {
1121        return -ENOTSUP;
1122    }
1123
1124    /* shrinking is currently not supported */
1125    if (offset < bs->total_sectors * 512) {
1126        return -ENOTSUP;
1127    }
1128
1129    new_l1_size = size_to_l1(s, offset);
1130    ret = qcow2_grow_l1_table(bs, new_l1_size);
1131    if (ret < 0) {
1132        return ret;
1133    }
1134
1135    /* write updated header.size */
1136    offset = cpu_to_be64(offset);
1137    ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
1138                           &offset, sizeof(uint64_t));
1139    if (ret < 0) {
1140        return ret;
1141    }
1142
1143    s->l1_vm_state_index = new_l1_size;
1144    return 0;
1145}
1146
1147/* XXX: put compressed sectors first, then all the cluster aligned
1148   tables to avoid losing bytes in alignment */
1149static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
1150                                 const uint8_t *buf, int nb_sectors)
1151{
1152    BDRVQcowState *s = bs->opaque;
1153    z_stream strm;
1154    int ret, out_len;
1155    uint8_t *out_buf;
1156    uint64_t cluster_offset;
1157
1158    if (nb_sectors == 0) {
1159        /* align end of file to a sector boundary to ease reading with
1160           sector based I/Os */
1161        cluster_offset = bdrv_getlength(bs->file);
1162        cluster_offset = (cluster_offset + 511) & ~511;
1163        bdrv_truncate(bs->file, cluster_offset);
1164        return 0;
1165    }
1166
1167    if (nb_sectors != s->cluster_sectors)
1168        return -EINVAL;
1169
1170    out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
1171
1172    /* best compression, small window, no zlib header */
1173    memset(&strm, 0, sizeof(strm));
1174    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
1175                       Z_DEFLATED, -12,
1176                       9, Z_DEFAULT_STRATEGY);
1177    if (ret != 0) {
1178        qemu_free(out_buf);
1179        return -1;
1180    }
1181
1182    strm.avail_in = s->cluster_size;
1183    strm.next_in = (uint8_t *)buf;
1184    strm.avail_out = s->cluster_size;
1185    strm.next_out = out_buf;
1186
1187    ret = deflate(&strm, Z_FINISH);
1188    if (ret != Z_STREAM_END && ret != Z_OK) {
1189        qemu_free(out_buf);
1190        deflateEnd(&strm);
1191        return -1;
1192    }
1193    out_len = strm.next_out - out_buf;
1194
1195    deflateEnd(&strm);
1196
1197    if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
1198        /* could not compress: write normal cluster */
1199        bdrv_write(bs, sector_num, buf, s->cluster_sectors);
1200    } else {
1201        cluster_offset = qcow2_alloc_compressed_cluster_offset(bs,
1202            sector_num << 9, out_len);
1203        if (!cluster_offset)
1204            return -1;
1205        cluster_offset &= s->cluster_offset_mask;
1206        BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
1207        if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len) != out_len) {
1208            qemu_free(out_buf);
1209            return -1;
1210        }
1211    }
1212
1213    qemu_free(out_buf);
1214    return 0;
1215}
1216
1217static void qcow_flush(BlockDriverState *bs)
1218{
1219    bdrv_flush(bs->file);
1220}
1221
1222static BlockDriverAIOCB *qcow_aio_flush(BlockDriverState *bs,
1223         BlockDriverCompletionFunc *cb, void *opaque)
1224{
1225    return bdrv_aio_flush(bs->file, cb, opaque);
1226}
1227
1228static int64_t qcow_vm_state_offset(BDRVQcowState *s)
1229{
1230	return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits);
1231}
1232
1233static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
1234{
1235    BDRVQcowState *s = bs->opaque;
1236    bdi->cluster_size = s->cluster_size;
1237    bdi->vm_state_offset = qcow_vm_state_offset(s);
1238    return 0;
1239}
1240
1241
1242static int qcow_check(BlockDriverState *bs, BdrvCheckResult *result)
1243{
1244    return qcow2_check_refcounts(bs, result);
1245}
1246
1247#if 0
1248static void dump_refcounts(BlockDriverState *bs)
1249{
1250    BDRVQcowState *s = bs->opaque;
1251    int64_t nb_clusters, k, k1, size;
1252    int refcount;
1253
1254    size = bdrv_getlength(bs->file);
1255    nb_clusters = size_to_clusters(s, size);
1256    for(k = 0; k < nb_clusters;) {
1257        k1 = k;
1258        refcount = get_refcount(bs, k);
1259        k++;
1260        while (k < nb_clusters && get_refcount(bs, k) == refcount)
1261            k++;
1262        printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount,
1263               k - k1);
1264    }
1265}
1266#endif
1267
1268static int qcow_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
1269                           int64_t pos, int size)
1270{
1271    BDRVQcowState *s = bs->opaque;
1272    int growable = bs->growable;
1273    int ret;
1274
1275    BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
1276    bs->growable = 1;
1277    ret = bdrv_pwrite(bs, qcow_vm_state_offset(s) + pos, buf, size);
1278    bs->growable = growable;
1279
1280    return ret;
1281}
1282
1283static int qcow_load_vmstate(BlockDriverState *bs, uint8_t *buf,
1284                           int64_t pos, int size)
1285{
1286    BDRVQcowState *s = bs->opaque;
1287    int growable = bs->growable;
1288    int ret;
1289
1290    BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
1291    bs->growable = 1;
1292    ret = bdrv_pread(bs, qcow_vm_state_offset(s) + pos, buf, size);
1293    bs->growable = growable;
1294
1295    return ret;
1296}
1297
1298static QEMUOptionParameter qcow_create_options[] = {
1299    {
1300        .name = BLOCK_OPT_SIZE,
1301        .type = OPT_SIZE,
1302        .help = "Virtual disk size"
1303    },
1304    {
1305        .name = BLOCK_OPT_BACKING_FILE,
1306        .type = OPT_STRING,
1307        .help = "File name of a base image"
1308    },
1309    {
1310        .name = BLOCK_OPT_BACKING_FMT,
1311        .type = OPT_STRING,
1312        .help = "Image format of the base image"
1313    },
1314    {
1315        .name = BLOCK_OPT_ENCRYPT,
1316        .type = OPT_FLAG,
1317        .help = "Encrypt the image"
1318    },
1319    {
1320        .name = BLOCK_OPT_CLUSTER_SIZE,
1321        .type = OPT_SIZE,
1322        .help = "qcow2 cluster size"
1323    },
1324    {
1325        .name = BLOCK_OPT_PREALLOC,
1326        .type = OPT_STRING,
1327        .help = "Preallocation mode (allowed values: off, metadata)"
1328    },
1329    { NULL }
1330};
1331
1332static BlockDriver bdrv_qcow2 = {
1333    .format_name	= "qcow2",
1334    .instance_size	= sizeof(BDRVQcowState),
1335    .bdrv_probe		= qcow_probe,
1336    .bdrv_open		= qcow_open,
1337    .bdrv_close		= qcow_close,
1338    .bdrv_create	= qcow_create,
1339    .bdrv_flush		= qcow_flush,
1340    .bdrv_is_allocated	= qcow_is_allocated,
1341    .bdrv_set_key	= qcow_set_key,
1342    .bdrv_make_empty	= qcow_make_empty,
1343
1344    .bdrv_aio_readv	= qcow_aio_readv,
1345    .bdrv_aio_writev	= qcow_aio_writev,
1346    .bdrv_aio_flush	= qcow_aio_flush,
1347
1348    .bdrv_truncate          = qcow2_truncate,
1349    .bdrv_write_compressed  = qcow_write_compressed,
1350
1351    .bdrv_snapshot_create   = qcow2_snapshot_create,
1352    .bdrv_snapshot_goto     = qcow2_snapshot_goto,
1353    .bdrv_snapshot_delete   = qcow2_snapshot_delete,
1354    .bdrv_snapshot_list     = qcow2_snapshot_list,
1355    .bdrv_get_info	= qcow_get_info,
1356
1357    .bdrv_save_vmstate    = qcow_save_vmstate,
1358    .bdrv_load_vmstate    = qcow_load_vmstate,
1359
1360    .bdrv_change_backing_file   = qcow2_change_backing_file,
1361
1362    .create_options = qcow_create_options,
1363    .bdrv_check = qcow_check,
1364};
1365
1366static void bdrv_qcow2_init(void)
1367{
1368    bdrv_register(&bdrv_qcow2);
1369}
1370
1371block_init(bdrv_qcow2_init);
1372