xref: /openbmc/qemu/block/rbd.c (revision a697d240)
1 /*
2  * QEMU Block driver for RADOS (Ceph)
3  *
4  * Copyright (C) 2010-2011 Christian Brunner <chb@muc.de>,
5  *                         Josh Durgin <josh.durgin@dreamhost.com>
6  *
7  * This work is licensed under the terms of the GNU GPL, version 2.  See
8  * the COPYING file in the top-level directory.
9  *
10  * Contributions after 2012-01-13 are licensed under the terms of the
11  * GNU GPL, version 2 or (at your option) any later version.
12  */
13 
14 #include <inttypes.h>
15 
16 #include "qemu-common.h"
17 #include "qemu/error-report.h"
18 #include "block/block_int.h"
19 
20 #include <rbd/librbd.h>
21 
22 /*
23  * When specifying the image filename use:
24  *
25  * rbd:poolname/devicename[@snapshotname][:option1=value1[:option2=value2...]]
26  *
27  * poolname must be the name of an existing rados pool.
28  *
29  * devicename is the name of the rbd image.
30  *
31  * Each option given is used to configure rados, and may be any valid
32  * Ceph option, "id", or "conf".
33  *
34  * The "id" option indicates what user we should authenticate as to
35  * the Ceph cluster.  If it is excluded we will use the Ceph default
36  * (normally 'admin').
37  *
38  * The "conf" option specifies a Ceph configuration file to read.  If
39  * it is not specified, we will read from the default Ceph locations
40  * (e.g., /etc/ceph/ceph.conf).  To avoid reading _any_ configuration
41  * file, specify conf=/dev/null.
42  *
43  * Configuration values containing :, @, or = can be escaped with a
44  * leading "\".
45  */
46 
47 /* rbd_aio_discard added in 0.1.2 */
48 #if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 2)
49 #define LIBRBD_SUPPORTS_DISCARD
50 #else
51 #undef LIBRBD_SUPPORTS_DISCARD
52 #endif
53 
54 #define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)
55 
56 #define RBD_MAX_CONF_NAME_SIZE 128
57 #define RBD_MAX_CONF_VAL_SIZE 512
58 #define RBD_MAX_CONF_SIZE 1024
59 #define RBD_MAX_POOL_NAME_SIZE 128
60 #define RBD_MAX_SNAP_NAME_SIZE 128
61 #define RBD_MAX_SNAPS 100
62 
63 typedef enum {
64     RBD_AIO_READ,
65     RBD_AIO_WRITE,
66     RBD_AIO_DISCARD,
67     RBD_AIO_FLUSH
68 } RBDAIOCmd;
69 
70 typedef struct RBDAIOCB {
71     BlockDriverAIOCB common;
72     QEMUBH *bh;
73     int64_t ret;
74     QEMUIOVector *qiov;
75     char *bounce;
76     RBDAIOCmd cmd;
77     int64_t sector_num;
78     int error;
79     struct BDRVRBDState *s;
80     int cancelled;
81     int status;
82 } RBDAIOCB;
83 
84 typedef struct RADOSCB {
85     int rcbid;
86     RBDAIOCB *acb;
87     struct BDRVRBDState *s;
88     int done;
89     int64_t size;
90     char *buf;
91     int64_t ret;
92 } RADOSCB;
93 
94 #define RBD_FD_READ 0
95 #define RBD_FD_WRITE 1
96 
97 typedef struct BDRVRBDState {
98     rados_t cluster;
99     rados_ioctx_t io_ctx;
100     rbd_image_t image;
101     char name[RBD_MAX_IMAGE_NAME_SIZE];
102     char *snap;
103 } BDRVRBDState;
104 
105 static int qemu_rbd_next_tok(char *dst, int dst_len,
106                              char *src, char delim,
107                              const char *name,
108                              char **p, Error **errp)
109 {
110     int l;
111     char *end;
112 
113     *p = NULL;
114 
115     if (delim != '\0') {
116         for (end = src; *end; ++end) {
117             if (*end == delim) {
118                 break;
119             }
120             if (*end == '\\' && end[1] != '\0') {
121                 end++;
122             }
123         }
124         if (*end == delim) {
125             *p = end + 1;
126             *end = '\0';
127         }
128     }
129     l = strlen(src);
130     if (l >= dst_len) {
131         error_setg(errp, "%s too long", name);
132         return -EINVAL;
133     } else if (l == 0) {
134         error_setg(errp, "%s too short", name);
135         return -EINVAL;
136     }
137 
138     pstrcpy(dst, dst_len, src);
139 
140     return 0;
141 }
142 
143 static void qemu_rbd_unescape(char *src)
144 {
145     char *p;
146 
147     for (p = src; *src; ++src, ++p) {
148         if (*src == '\\' && src[1] != '\0') {
149             src++;
150         }
151         *p = *src;
152     }
153     *p = '\0';
154 }
155 
156 static int qemu_rbd_parsename(const char *filename,
157                               char *pool, int pool_len,
158                               char *snap, int snap_len,
159                               char *name, int name_len,
160                               char *conf, int conf_len,
161                               Error **errp)
162 {
163     const char *start;
164     char *p, *buf;
165     int ret;
166 
167     if (!strstart(filename, "rbd:", &start)) {
168         error_setg(errp, "File name must start with 'rbd:'");
169         return -EINVAL;
170     }
171 
172     buf = g_strdup(start);
173     p = buf;
174     *snap = '\0';
175     *conf = '\0';
176 
177     ret = qemu_rbd_next_tok(pool, pool_len, p,
178                             '/', "pool name", &p, errp);
179     if (ret < 0 || !p) {
180         ret = -EINVAL;
181         goto done;
182     }
183     qemu_rbd_unescape(pool);
184 
185     if (strchr(p, '@')) {
186         ret = qemu_rbd_next_tok(name, name_len, p,
187                                 '@', "object name", &p, errp);
188         if (ret < 0) {
189             goto done;
190         }
191         ret = qemu_rbd_next_tok(snap, snap_len, p,
192                                 ':', "snap name", &p, errp);
193         qemu_rbd_unescape(snap);
194     } else {
195         ret = qemu_rbd_next_tok(name, name_len, p,
196                                 ':', "object name", &p, errp);
197     }
198     qemu_rbd_unescape(name);
199     if (ret < 0 || !p) {
200         goto done;
201     }
202 
203     ret = qemu_rbd_next_tok(conf, conf_len, p,
204                             '\0', "configuration", &p, errp);
205 
206 done:
207     g_free(buf);
208     return ret;
209 }
210 
211 static char *qemu_rbd_parse_clientname(const char *conf, char *clientname)
212 {
213     const char *p = conf;
214 
215     while (*p) {
216         int len;
217         const char *end = strchr(p, ':');
218 
219         if (end) {
220             len = end - p;
221         } else {
222             len = strlen(p);
223         }
224 
225         if (strncmp(p, "id=", 3) == 0) {
226             len -= 3;
227             strncpy(clientname, p + 3, len);
228             clientname[len] = '\0';
229             return clientname;
230         }
231         if (end == NULL) {
232             break;
233         }
234         p = end + 1;
235     }
236     return NULL;
237 }
238 
239 static int qemu_rbd_set_conf(rados_t cluster, const char *conf, Error **errp)
240 {
241     char *p, *buf;
242     char name[RBD_MAX_CONF_NAME_SIZE];
243     char value[RBD_MAX_CONF_VAL_SIZE];
244     int ret = 0;
245 
246     buf = g_strdup(conf);
247     p = buf;
248 
249     while (p) {
250         ret = qemu_rbd_next_tok(name, sizeof(name), p,
251                                 '=', "conf option name", &p, errp);
252         if (ret < 0) {
253             break;
254         }
255         qemu_rbd_unescape(name);
256 
257         if (!p) {
258             error_setg(errp, "conf option %s has no value", name);
259             ret = -EINVAL;
260             break;
261         }
262 
263         ret = qemu_rbd_next_tok(value, sizeof(value), p,
264                                 ':', "conf option value", &p, errp);
265         if (ret < 0) {
266             break;
267         }
268         qemu_rbd_unescape(value);
269 
270         if (strcmp(name, "conf") == 0) {
271             ret = rados_conf_read_file(cluster, value);
272             if (ret < 0) {
273                 error_setg(errp, "error reading conf file %s", value);
274                 break;
275             }
276         } else if (strcmp(name, "id") == 0) {
277             /* ignore, this is parsed by qemu_rbd_parse_clientname() */
278         } else {
279             ret = rados_conf_set(cluster, name, value);
280             if (ret < 0) {
281                 error_setg(errp, "invalid conf option %s", name);
282                 ret = -EINVAL;
283                 break;
284             }
285         }
286     }
287 
288     g_free(buf);
289     return ret;
290 }
291 
292 static int qemu_rbd_create(const char *filename, QemuOpts *opts, Error **errp)
293 {
294     Error *local_err = NULL;
295     int64_t bytes = 0;
296     int64_t objsize;
297     int obj_order = 0;
298     char pool[RBD_MAX_POOL_NAME_SIZE];
299     char name[RBD_MAX_IMAGE_NAME_SIZE];
300     char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
301     char conf[RBD_MAX_CONF_SIZE];
302     char clientname_buf[RBD_MAX_CONF_SIZE];
303     char *clientname;
304     rados_t cluster;
305     rados_ioctx_t io_ctx;
306     int ret;
307 
308     if (qemu_rbd_parsename(filename, pool, sizeof(pool),
309                            snap_buf, sizeof(snap_buf),
310                            name, sizeof(name),
311                            conf, sizeof(conf), &local_err) < 0) {
312         error_propagate(errp, local_err);
313         return -EINVAL;
314     }
315 
316     /* Read out options */
317     bytes = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
318                      BDRV_SECTOR_SIZE);
319     objsize = qemu_opt_get_size_del(opts, BLOCK_OPT_CLUSTER_SIZE, 0);
320     if (objsize) {
321         if ((objsize - 1) & objsize) {    /* not a power of 2? */
322             error_setg(errp, "obj size needs to be power of 2");
323             return -EINVAL;
324         }
325         if (objsize < 4096) {
326             error_setg(errp, "obj size too small");
327             return -EINVAL;
328         }
329         obj_order = ffs(objsize) - 1;
330     }
331 
332     clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
333     if (rados_create(&cluster, clientname) < 0) {
334         error_setg(errp, "error initializing");
335         return -EIO;
336     }
337 
338     if (strstr(conf, "conf=") == NULL) {
339         /* try default location, but ignore failure */
340         rados_conf_read_file(cluster, NULL);
341     }
342 
343     if (conf[0] != '\0' &&
344         qemu_rbd_set_conf(cluster, conf, &local_err) < 0) {
345         rados_shutdown(cluster);
346         error_propagate(errp, local_err);
347         return -EIO;
348     }
349 
350     if (rados_connect(cluster) < 0) {
351         error_setg(errp, "error connecting");
352         rados_shutdown(cluster);
353         return -EIO;
354     }
355 
356     if (rados_ioctx_create(cluster, pool, &io_ctx) < 0) {
357         error_setg(errp, "error opening pool %s", pool);
358         rados_shutdown(cluster);
359         return -EIO;
360     }
361 
362     ret = rbd_create(io_ctx, name, bytes, &obj_order);
363     rados_ioctx_destroy(io_ctx);
364     rados_shutdown(cluster);
365 
366     return ret;
367 }
368 
369 /*
370  * This aio completion is being called from rbd_finish_bh() and runs in qemu
371  * BH context.
372  */
373 static void qemu_rbd_complete_aio(RADOSCB *rcb)
374 {
375     RBDAIOCB *acb = rcb->acb;
376     int64_t r;
377 
378     r = rcb->ret;
379 
380     if (acb->cmd != RBD_AIO_READ) {
381         if (r < 0) {
382             acb->ret = r;
383             acb->error = 1;
384         } else if (!acb->error) {
385             acb->ret = rcb->size;
386         }
387     } else {
388         if (r < 0) {
389             memset(rcb->buf, 0, rcb->size);
390             acb->ret = r;
391             acb->error = 1;
392         } else if (r < rcb->size) {
393             memset(rcb->buf + r, 0, rcb->size - r);
394             if (!acb->error) {
395                 acb->ret = rcb->size;
396             }
397         } else if (!acb->error) {
398             acb->ret = r;
399         }
400     }
401 
402     g_free(rcb);
403 
404     if (acb->cmd == RBD_AIO_READ) {
405         qemu_iovec_from_buf(acb->qiov, 0, acb->bounce, acb->qiov->size);
406     }
407     qemu_vfree(acb->bounce);
408     acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
409     acb->status = 0;
410 
411     if (!acb->cancelled) {
412         qemu_aio_release(acb);
413     }
414 }
415 
416 /* TODO Convert to fine grained options */
417 static QemuOptsList runtime_opts = {
418     .name = "rbd",
419     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
420     .desc = {
421         {
422             .name = "filename",
423             .type = QEMU_OPT_STRING,
424             .help = "Specification of the rbd image",
425         },
426         { /* end of list */ }
427     },
428 };
429 
430 static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
431                          Error **errp)
432 {
433     BDRVRBDState *s = bs->opaque;
434     char pool[RBD_MAX_POOL_NAME_SIZE];
435     char snap_buf[RBD_MAX_SNAP_NAME_SIZE];
436     char conf[RBD_MAX_CONF_SIZE];
437     char clientname_buf[RBD_MAX_CONF_SIZE];
438     char *clientname;
439     QemuOpts *opts;
440     Error *local_err = NULL;
441     const char *filename;
442     int r;
443 
444     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
445     qemu_opts_absorb_qdict(opts, options, &local_err);
446     if (local_err) {
447         error_propagate(errp, local_err);
448         qemu_opts_del(opts);
449         return -EINVAL;
450     }
451 
452     filename = qemu_opt_get(opts, "filename");
453 
454     if (qemu_rbd_parsename(filename, pool, sizeof(pool),
455                            snap_buf, sizeof(snap_buf),
456                            s->name, sizeof(s->name),
457                            conf, sizeof(conf), errp) < 0) {
458         r = -EINVAL;
459         goto failed_opts;
460     }
461 
462     clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
463     r = rados_create(&s->cluster, clientname);
464     if (r < 0) {
465         error_setg(&local_err, "error initializing");
466         goto failed_opts;
467     }
468 
469     s->snap = NULL;
470     if (snap_buf[0] != '\0') {
471         s->snap = g_strdup(snap_buf);
472     }
473 
474     /*
475      * Fallback to more conservative semantics if setting cache
476      * options fails. Ignore errors from setting rbd_cache because the
477      * only possible error is that the option does not exist, and
478      * librbd defaults to no caching. If write through caching cannot
479      * be set up, fall back to no caching.
480      */
481     if (flags & BDRV_O_NOCACHE) {
482         rados_conf_set(s->cluster, "rbd_cache", "false");
483     } else {
484         rados_conf_set(s->cluster, "rbd_cache", "true");
485     }
486 
487     if (strstr(conf, "conf=") == NULL) {
488         /* try default location, but ignore failure */
489         rados_conf_read_file(s->cluster, NULL);
490     }
491 
492     if (conf[0] != '\0') {
493         r = qemu_rbd_set_conf(s->cluster, conf, errp);
494         if (r < 0) {
495             goto failed_shutdown;
496         }
497     }
498 
499     r = rados_connect(s->cluster);
500     if (r < 0) {
501         error_setg(&local_err, "error connecting");
502         goto failed_shutdown;
503     }
504 
505     r = rados_ioctx_create(s->cluster, pool, &s->io_ctx);
506     if (r < 0) {
507         error_setg(&local_err, "error opening pool %s", pool);
508         goto failed_shutdown;
509     }
510 
511     r = rbd_open(s->io_ctx, s->name, &s->image, s->snap);
512     if (r < 0) {
513         error_setg(&local_err, "error reading header from %s", s->name);
514         goto failed_open;
515     }
516 
517     bs->read_only = (s->snap != NULL);
518 
519     qemu_opts_del(opts);
520     return 0;
521 
522 failed_open:
523     rados_ioctx_destroy(s->io_ctx);
524 failed_shutdown:
525     rados_shutdown(s->cluster);
526     g_free(s->snap);
527 failed_opts:
528     qemu_opts_del(opts);
529     return r;
530 }
531 
532 static void qemu_rbd_close(BlockDriverState *bs)
533 {
534     BDRVRBDState *s = bs->opaque;
535 
536     rbd_close(s->image);
537     rados_ioctx_destroy(s->io_ctx);
538     g_free(s->snap);
539     rados_shutdown(s->cluster);
540 }
541 
542 /*
543  * Cancel aio. Since we don't reference acb in a non qemu threads,
544  * it is safe to access it here.
545  */
546 static void qemu_rbd_aio_cancel(BlockDriverAIOCB *blockacb)
547 {
548     RBDAIOCB *acb = (RBDAIOCB *) blockacb;
549     acb->cancelled = 1;
550 
551     while (acb->status == -EINPROGRESS) {
552         aio_poll(bdrv_get_aio_context(acb->common.bs), true);
553     }
554 
555     qemu_aio_release(acb);
556 }
557 
558 static const AIOCBInfo rbd_aiocb_info = {
559     .aiocb_size = sizeof(RBDAIOCB),
560     .cancel = qemu_rbd_aio_cancel,
561 };
562 
563 static void rbd_finish_bh(void *opaque)
564 {
565     RADOSCB *rcb = opaque;
566     qemu_bh_delete(rcb->acb->bh);
567     qemu_rbd_complete_aio(rcb);
568 }
569 
570 /*
571  * This is the callback function for rbd_aio_read and _write
572  *
573  * Note: this function is being called from a non qemu thread so
574  * we need to be careful about what we do here. Generally we only
575  * schedule a BH, and do the rest of the io completion handling
576  * from rbd_finish_bh() which runs in a qemu context.
577  */
578 static void rbd_finish_aiocb(rbd_completion_t c, RADOSCB *rcb)
579 {
580     RBDAIOCB *acb = rcb->acb;
581 
582     rcb->ret = rbd_aio_get_return_value(c);
583     rbd_aio_release(c);
584 
585     acb->bh = aio_bh_new(bdrv_get_aio_context(acb->common.bs),
586                          rbd_finish_bh, rcb);
587     qemu_bh_schedule(acb->bh);
588 }
589 
590 static int rbd_aio_discard_wrapper(rbd_image_t image,
591                                    uint64_t off,
592                                    uint64_t len,
593                                    rbd_completion_t comp)
594 {
595 #ifdef LIBRBD_SUPPORTS_DISCARD
596     return rbd_aio_discard(image, off, len, comp);
597 #else
598     return -ENOTSUP;
599 #endif
600 }
601 
602 static int rbd_aio_flush_wrapper(rbd_image_t image,
603                                  rbd_completion_t comp)
604 {
605 #ifdef LIBRBD_SUPPORTS_AIO_FLUSH
606     return rbd_aio_flush(image, comp);
607 #else
608     return -ENOTSUP;
609 #endif
610 }
611 
612 static BlockDriverAIOCB *rbd_start_aio(BlockDriverState *bs,
613                                        int64_t sector_num,
614                                        QEMUIOVector *qiov,
615                                        int nb_sectors,
616                                        BlockDriverCompletionFunc *cb,
617                                        void *opaque,
618                                        RBDAIOCmd cmd)
619 {
620     RBDAIOCB *acb;
621     RADOSCB *rcb = NULL;
622     rbd_completion_t c;
623     int64_t off, size;
624     char *buf;
625     int r;
626 
627     BDRVRBDState *s = bs->opaque;
628 
629     acb = qemu_aio_get(&rbd_aiocb_info, bs, cb, opaque);
630     acb->cmd = cmd;
631     acb->qiov = qiov;
632     if (cmd == RBD_AIO_DISCARD || cmd == RBD_AIO_FLUSH) {
633         acb->bounce = NULL;
634     } else {
635         acb->bounce = qemu_try_blockalign(bs, qiov->size);
636         if (acb->bounce == NULL) {
637             goto failed;
638         }
639     }
640     acb->ret = 0;
641     acb->error = 0;
642     acb->s = s;
643     acb->cancelled = 0;
644     acb->bh = NULL;
645     acb->status = -EINPROGRESS;
646 
647     if (cmd == RBD_AIO_WRITE) {
648         qemu_iovec_to_buf(acb->qiov, 0, acb->bounce, qiov->size);
649     }
650 
651     buf = acb->bounce;
652 
653     off = sector_num * BDRV_SECTOR_SIZE;
654     size = nb_sectors * BDRV_SECTOR_SIZE;
655 
656     rcb = g_new(RADOSCB, 1);
657     rcb->done = 0;
658     rcb->acb = acb;
659     rcb->buf = buf;
660     rcb->s = acb->s;
661     rcb->size = size;
662     r = rbd_aio_create_completion(rcb, (rbd_callback_t) rbd_finish_aiocb, &c);
663     if (r < 0) {
664         goto failed;
665     }
666 
667     switch (cmd) {
668     case RBD_AIO_WRITE:
669         r = rbd_aio_write(s->image, off, size, buf, c);
670         break;
671     case RBD_AIO_READ:
672         r = rbd_aio_read(s->image, off, size, buf, c);
673         break;
674     case RBD_AIO_DISCARD:
675         r = rbd_aio_discard_wrapper(s->image, off, size, c);
676         break;
677     case RBD_AIO_FLUSH:
678         r = rbd_aio_flush_wrapper(s->image, c);
679         break;
680     default:
681         r = -EINVAL;
682     }
683 
684     if (r < 0) {
685         goto failed_completion;
686     }
687 
688     return &acb->common;
689 
690 failed_completion:
691     rbd_aio_release(c);
692 failed:
693     g_free(rcb);
694     qemu_vfree(acb->bounce);
695     qemu_aio_release(acb);
696     return NULL;
697 }
698 
699 static BlockDriverAIOCB *qemu_rbd_aio_readv(BlockDriverState *bs,
700                                             int64_t sector_num,
701                                             QEMUIOVector *qiov,
702                                             int nb_sectors,
703                                             BlockDriverCompletionFunc *cb,
704                                             void *opaque)
705 {
706     return rbd_start_aio(bs, sector_num, qiov, nb_sectors, cb, opaque,
707                          RBD_AIO_READ);
708 }
709 
710 static BlockDriverAIOCB *qemu_rbd_aio_writev(BlockDriverState *bs,
711                                              int64_t sector_num,
712                                              QEMUIOVector *qiov,
713                                              int nb_sectors,
714                                              BlockDriverCompletionFunc *cb,
715                                              void *opaque)
716 {
717     return rbd_start_aio(bs, sector_num, qiov, nb_sectors, cb, opaque,
718                          RBD_AIO_WRITE);
719 }
720 
721 #ifdef LIBRBD_SUPPORTS_AIO_FLUSH
722 static BlockDriverAIOCB *qemu_rbd_aio_flush(BlockDriverState *bs,
723                                             BlockDriverCompletionFunc *cb,
724                                             void *opaque)
725 {
726     return rbd_start_aio(bs, 0, NULL, 0, cb, opaque, RBD_AIO_FLUSH);
727 }
728 
729 #else
730 
731 static int qemu_rbd_co_flush(BlockDriverState *bs)
732 {
733 #if LIBRBD_VERSION_CODE >= LIBRBD_VERSION(0, 1, 1)
734     /* rbd_flush added in 0.1.1 */
735     BDRVRBDState *s = bs->opaque;
736     return rbd_flush(s->image);
737 #else
738     return 0;
739 #endif
740 }
741 #endif
742 
743 static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
744 {
745     BDRVRBDState *s = bs->opaque;
746     rbd_image_info_t info;
747     int r;
748 
749     r = rbd_stat(s->image, &info, sizeof(info));
750     if (r < 0) {
751         return r;
752     }
753 
754     bdi->cluster_size = info.obj_size;
755     return 0;
756 }
757 
758 static int64_t qemu_rbd_getlength(BlockDriverState *bs)
759 {
760     BDRVRBDState *s = bs->opaque;
761     rbd_image_info_t info;
762     int r;
763 
764     r = rbd_stat(s->image, &info, sizeof(info));
765     if (r < 0) {
766         return r;
767     }
768 
769     return info.size;
770 }
771 
772 static int qemu_rbd_truncate(BlockDriverState *bs, int64_t offset)
773 {
774     BDRVRBDState *s = bs->opaque;
775     int r;
776 
777     r = rbd_resize(s->image, offset);
778     if (r < 0) {
779         return r;
780     }
781 
782     return 0;
783 }
784 
785 static int qemu_rbd_snap_create(BlockDriverState *bs,
786                                 QEMUSnapshotInfo *sn_info)
787 {
788     BDRVRBDState *s = bs->opaque;
789     int r;
790 
791     if (sn_info->name[0] == '\0') {
792         return -EINVAL; /* we need a name for rbd snapshots */
793     }
794 
795     /*
796      * rbd snapshots are using the name as the user controlled unique identifier
797      * we can't use the rbd snapid for that purpose, as it can't be set
798      */
799     if (sn_info->id_str[0] != '\0' &&
800         strcmp(sn_info->id_str, sn_info->name) != 0) {
801         return -EINVAL;
802     }
803 
804     if (strlen(sn_info->name) >= sizeof(sn_info->id_str)) {
805         return -ERANGE;
806     }
807 
808     r = rbd_snap_create(s->image, sn_info->name);
809     if (r < 0) {
810         error_report("failed to create snap: %s", strerror(-r));
811         return r;
812     }
813 
814     return 0;
815 }
816 
817 static int qemu_rbd_snap_remove(BlockDriverState *bs,
818                                 const char *snapshot_id,
819                                 const char *snapshot_name,
820                                 Error **errp)
821 {
822     BDRVRBDState *s = bs->opaque;
823     int r;
824 
825     if (!snapshot_name) {
826         error_setg(errp, "rbd need a valid snapshot name");
827         return -EINVAL;
828     }
829 
830     /* If snapshot_id is specified, it must be equal to name, see
831        qemu_rbd_snap_list() */
832     if (snapshot_id && strcmp(snapshot_id, snapshot_name)) {
833         error_setg(errp,
834                    "rbd do not support snapshot id, it should be NULL or "
835                    "equal to snapshot name");
836         return -EINVAL;
837     }
838 
839     r = rbd_snap_remove(s->image, snapshot_name);
840     if (r < 0) {
841         error_setg_errno(errp, -r, "Failed to remove the snapshot");
842     }
843     return r;
844 }
845 
846 static int qemu_rbd_snap_rollback(BlockDriverState *bs,
847                                   const char *snapshot_name)
848 {
849     BDRVRBDState *s = bs->opaque;
850     int r;
851 
852     r = rbd_snap_rollback(s->image, snapshot_name);
853     return r;
854 }
855 
856 static int qemu_rbd_snap_list(BlockDriverState *bs,
857                               QEMUSnapshotInfo **psn_tab)
858 {
859     BDRVRBDState *s = bs->opaque;
860     QEMUSnapshotInfo *sn_info, *sn_tab = NULL;
861     int i, snap_count;
862     rbd_snap_info_t *snaps;
863     int max_snaps = RBD_MAX_SNAPS;
864 
865     do {
866         snaps = g_new(rbd_snap_info_t, max_snaps);
867         snap_count = rbd_snap_list(s->image, snaps, &max_snaps);
868         if (snap_count <= 0) {
869             g_free(snaps);
870         }
871     } while (snap_count == -ERANGE);
872 
873     if (snap_count <= 0) {
874         goto done;
875     }
876 
877     sn_tab = g_new0(QEMUSnapshotInfo, snap_count);
878 
879     for (i = 0; i < snap_count; i++) {
880         const char *snap_name = snaps[i].name;
881 
882         sn_info = sn_tab + i;
883         pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), snap_name);
884         pstrcpy(sn_info->name, sizeof(sn_info->name), snap_name);
885 
886         sn_info->vm_state_size = snaps[i].size;
887         sn_info->date_sec = 0;
888         sn_info->date_nsec = 0;
889         sn_info->vm_clock_nsec = 0;
890     }
891     rbd_snap_list_end(snaps);
892     g_free(snaps);
893 
894  done:
895     *psn_tab = sn_tab;
896     return snap_count;
897 }
898 
899 #ifdef LIBRBD_SUPPORTS_DISCARD
900 static BlockDriverAIOCB* qemu_rbd_aio_discard(BlockDriverState *bs,
901                                               int64_t sector_num,
902                                               int nb_sectors,
903                                               BlockDriverCompletionFunc *cb,
904                                               void *opaque)
905 {
906     return rbd_start_aio(bs, sector_num, NULL, nb_sectors, cb, opaque,
907                          RBD_AIO_DISCARD);
908 }
909 #endif
910 
911 static QemuOptsList qemu_rbd_create_opts = {
912     .name = "rbd-create-opts",
913     .head = QTAILQ_HEAD_INITIALIZER(qemu_rbd_create_opts.head),
914     .desc = {
915         {
916             .name = BLOCK_OPT_SIZE,
917             .type = QEMU_OPT_SIZE,
918             .help = "Virtual disk size"
919         },
920         {
921             .name = BLOCK_OPT_CLUSTER_SIZE,
922             .type = QEMU_OPT_SIZE,
923             .help = "RBD object size"
924         },
925         { /* end of list */ }
926     }
927 };
928 
929 static BlockDriver bdrv_rbd = {
930     .format_name        = "rbd",
931     .instance_size      = sizeof(BDRVRBDState),
932     .bdrv_needs_filename = true,
933     .bdrv_file_open     = qemu_rbd_open,
934     .bdrv_close         = qemu_rbd_close,
935     .bdrv_create        = qemu_rbd_create,
936     .bdrv_has_zero_init = bdrv_has_zero_init_1,
937     .bdrv_get_info      = qemu_rbd_getinfo,
938     .create_opts        = &qemu_rbd_create_opts,
939     .bdrv_getlength     = qemu_rbd_getlength,
940     .bdrv_truncate      = qemu_rbd_truncate,
941     .protocol_name      = "rbd",
942 
943     .bdrv_aio_readv         = qemu_rbd_aio_readv,
944     .bdrv_aio_writev        = qemu_rbd_aio_writev,
945 
946 #ifdef LIBRBD_SUPPORTS_AIO_FLUSH
947     .bdrv_aio_flush         = qemu_rbd_aio_flush,
948 #else
949     .bdrv_co_flush_to_disk  = qemu_rbd_co_flush,
950 #endif
951 
952 #ifdef LIBRBD_SUPPORTS_DISCARD
953     .bdrv_aio_discard       = qemu_rbd_aio_discard,
954 #endif
955 
956     .bdrv_snapshot_create   = qemu_rbd_snap_create,
957     .bdrv_snapshot_delete   = qemu_rbd_snap_remove,
958     .bdrv_snapshot_list     = qemu_rbd_snap_list,
959     .bdrv_snapshot_goto     = qemu_rbd_snap_rollback,
960 };
961 
962 static void bdrv_rbd_init(void)
963 {
964     bdrv_register(&bdrv_rbd);
965 }
966 
967 block_init(bdrv_rbd_init);
968