xref: /openbmc/qemu/block/nfs.c (revision 1580b897)
1 /*
2  * QEMU Block driver for native access to files on NFS shares
3  *
4  * Copyright (c) 2014-2017 Peter Lieven <pl@kamp.de>
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/osdep.h"
26 
27 #if !defined(_WIN32)
28 #include <poll.h>
29 #endif
30 #include "qemu/config-file.h"
31 #include "qemu/error-report.h"
32 #include "qapi/error.h"
33 #include "block/block_int.h"
34 #include "block/qdict.h"
35 #include "trace.h"
36 #include "qemu/iov.h"
37 #include "qemu/main-loop.h"
38 #include "qemu/module.h"
39 #include "qemu/option.h"
40 #include "qemu/uri.h"
41 #include "qemu/cutils.h"
42 #include "sysemu/replay.h"
43 #include "qapi/qapi-visit-block-core.h"
44 #include "qapi/qmp/qdict.h"
45 #include "qapi/qmp/qstring.h"
46 #include "qapi/qobject-input-visitor.h"
47 #include "qapi/qobject-output-visitor.h"
48 #include <nfsc/libnfs.h>
49 
50 
51 #define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
52 #define QEMU_NFS_MAX_PAGECACHE_SIZE (8388608 / NFS_BLKSIZE)
53 #define QEMU_NFS_MAX_DEBUG_LEVEL 2
54 
55 typedef struct NFSClient {
56     struct nfs_context *context;
57     struct nfsfh *fh;
58     int events;
59     bool has_zero_init;
60     AioContext *aio_context;
61     QemuMutex mutex;
62     uint64_t st_blocks;
63     bool cache_used;
64     NFSServer *server;
65     char *path;
66     int64_t uid, gid, tcp_syncnt, readahead, pagecache, debug;
67 } NFSClient;
68 
69 typedef struct NFSRPC {
70     BlockDriverState *bs;
71     int ret;
72     int complete;
73     QEMUIOVector *iov;
74     struct stat *st;
75     Coroutine *co;
76     NFSClient *client;
77 } NFSRPC;
78 
79 static int nfs_parse_uri(const char *filename, QDict *options, Error **errp)
80 {
81     URI *uri = NULL;
82     QueryParams *qp = NULL;
83     int ret = -EINVAL, i;
84 
85     uri = uri_parse(filename);
86     if (!uri) {
87         error_setg(errp, "Invalid URI specified");
88         goto out;
89     }
90     if (g_strcmp0(uri->scheme, "nfs") != 0) {
91         error_setg(errp, "URI scheme must be 'nfs'");
92         goto out;
93     }
94 
95     if (!uri->server) {
96         error_setg(errp, "missing hostname in URI");
97         goto out;
98     }
99 
100     if (!uri->path) {
101         error_setg(errp, "missing file path in URI");
102         goto out;
103     }
104 
105     qp = query_params_parse(uri->query);
106     if (!qp) {
107         error_setg(errp, "could not parse query parameters");
108         goto out;
109     }
110 
111     qdict_put_str(options, "server.host", uri->server);
112     qdict_put_str(options, "server.type", "inet");
113     qdict_put_str(options, "path", uri->path);
114 
115     for (i = 0; i < qp->n; i++) {
116         unsigned long long val;
117         if (!qp->p[i].value) {
118             error_setg(errp, "Value for NFS parameter expected: %s",
119                        qp->p[i].name);
120             goto out;
121         }
122         if (parse_uint_full(qp->p[i].value, &val, 0)) {
123             error_setg(errp, "Illegal value for NFS parameter: %s",
124                        qp->p[i].name);
125             goto out;
126         }
127         if (!strcmp(qp->p[i].name, "uid")) {
128             qdict_put_str(options, "user", qp->p[i].value);
129         } else if (!strcmp(qp->p[i].name, "gid")) {
130             qdict_put_str(options, "group", qp->p[i].value);
131         } else if (!strcmp(qp->p[i].name, "tcp-syncnt")) {
132             qdict_put_str(options, "tcp-syn-count", qp->p[i].value);
133         } else if (!strcmp(qp->p[i].name, "readahead")) {
134             qdict_put_str(options, "readahead-size", qp->p[i].value);
135         } else if (!strcmp(qp->p[i].name, "pagecache")) {
136             qdict_put_str(options, "page-cache-size", qp->p[i].value);
137         } else if (!strcmp(qp->p[i].name, "debug")) {
138             qdict_put_str(options, "debug", qp->p[i].value);
139         } else {
140             error_setg(errp, "Unknown NFS parameter name: %s",
141                        qp->p[i].name);
142             goto out;
143         }
144     }
145     ret = 0;
146 out:
147     if (qp) {
148         query_params_free(qp);
149     }
150     uri_free(uri);
151     return ret;
152 }
153 
154 static bool nfs_has_filename_options_conflict(QDict *options, Error **errp)
155 {
156     const QDictEntry *qe;
157 
158     for (qe = qdict_first(options); qe; qe = qdict_next(options, qe)) {
159         if (!strcmp(qe->key, "host") ||
160             !strcmp(qe->key, "path") ||
161             !strcmp(qe->key, "user") ||
162             !strcmp(qe->key, "group") ||
163             !strcmp(qe->key, "tcp-syn-count") ||
164             !strcmp(qe->key, "readahead-size") ||
165             !strcmp(qe->key, "page-cache-size") ||
166             !strcmp(qe->key, "debug") ||
167             strstart(qe->key, "server.", NULL))
168         {
169             error_setg(errp, "Option %s cannot be used with a filename",
170                        qe->key);
171             return true;
172         }
173     }
174 
175     return false;
176 }
177 
178 static void nfs_parse_filename(const char *filename, QDict *options,
179                                Error **errp)
180 {
181     if (nfs_has_filename_options_conflict(options, errp)) {
182         return;
183     }
184 
185     nfs_parse_uri(filename, options, errp);
186 }
187 
188 static void nfs_process_read(void *arg);
189 static void nfs_process_write(void *arg);
190 
191 /* Called with QemuMutex held.  */
192 static void nfs_set_events(NFSClient *client)
193 {
194     int ev = nfs_which_events(client->context);
195     if (ev != client->events) {
196         aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
197                            false,
198                            (ev & POLLIN) ? nfs_process_read : NULL,
199                            (ev & POLLOUT) ? nfs_process_write : NULL,
200                            NULL, client);
201 
202     }
203     client->events = ev;
204 }
205 
206 static void nfs_process_read(void *arg)
207 {
208     NFSClient *client = arg;
209 
210     qemu_mutex_lock(&client->mutex);
211     nfs_service(client->context, POLLIN);
212     nfs_set_events(client);
213     qemu_mutex_unlock(&client->mutex);
214 }
215 
216 static void nfs_process_write(void *arg)
217 {
218     NFSClient *client = arg;
219 
220     qemu_mutex_lock(&client->mutex);
221     nfs_service(client->context, POLLOUT);
222     nfs_set_events(client);
223     qemu_mutex_unlock(&client->mutex);
224 }
225 
226 static void nfs_co_init_task(BlockDriverState *bs, NFSRPC *task)
227 {
228     *task = (NFSRPC) {
229         .co             = qemu_coroutine_self(),
230         .bs             = bs,
231         .client         = bs->opaque,
232     };
233 }
234 
235 static void nfs_co_generic_bh_cb(void *opaque)
236 {
237     NFSRPC *task = opaque;
238 
239     task->complete = 1;
240     aio_co_wake(task->co);
241 }
242 
243 /* Called (via nfs_service) with QemuMutex held.  */
244 static void
245 nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data,
246                   void *private_data)
247 {
248     NFSRPC *task = private_data;
249     task->ret = ret;
250     assert(!task->st);
251     if (task->ret > 0 && task->iov) {
252         if (task->ret <= task->iov->size) {
253             qemu_iovec_from_buf(task->iov, 0, data, task->ret);
254         } else {
255             task->ret = -EIO;
256         }
257     }
258     if (task->ret < 0) {
259         error_report("NFS Error: %s", nfs_get_error(nfs));
260     }
261     replay_bh_schedule_oneshot_event(task->client->aio_context,
262                                      nfs_co_generic_bh_cb, task);
263 }
264 
265 static int coroutine_fn nfs_co_preadv(BlockDriverState *bs, uint64_t offset,
266                                       uint64_t bytes, QEMUIOVector *iov,
267                                       int flags)
268 {
269     NFSClient *client = bs->opaque;
270     NFSRPC task;
271 
272     nfs_co_init_task(bs, &task);
273     task.iov = iov;
274 
275     WITH_QEMU_LOCK_GUARD(&client->mutex) {
276         if (nfs_pread_async(client->context, client->fh,
277                             offset, bytes, nfs_co_generic_cb, &task) != 0) {
278             return -ENOMEM;
279         }
280 
281         nfs_set_events(client);
282     }
283     while (!task.complete) {
284         qemu_coroutine_yield();
285     }
286 
287     if (task.ret < 0) {
288         return task.ret;
289     }
290 
291     /* zero pad short reads */
292     if (task.ret < iov->size) {
293         qemu_iovec_memset(iov, task.ret, 0, iov->size - task.ret);
294     }
295 
296     return 0;
297 }
298 
299 static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, uint64_t offset,
300                                        uint64_t bytes, QEMUIOVector *iov,
301                                        int flags)
302 {
303     NFSClient *client = bs->opaque;
304     NFSRPC task;
305     char *buf = NULL;
306     bool my_buffer = false;
307 
308     nfs_co_init_task(bs, &task);
309 
310     if (iov->niov != 1) {
311         buf = g_try_malloc(bytes);
312         if (bytes && buf == NULL) {
313             return -ENOMEM;
314         }
315         qemu_iovec_to_buf(iov, 0, buf, bytes);
316         my_buffer = true;
317     } else {
318         buf = iov->iov[0].iov_base;
319     }
320 
321     WITH_QEMU_LOCK_GUARD(&client->mutex) {
322         if (nfs_pwrite_async(client->context, client->fh,
323                              offset, bytes, buf,
324                              nfs_co_generic_cb, &task) != 0) {
325             if (my_buffer) {
326                 g_free(buf);
327             }
328             return -ENOMEM;
329         }
330 
331         nfs_set_events(client);
332     }
333     while (!task.complete) {
334         qemu_coroutine_yield();
335     }
336 
337     if (my_buffer) {
338         g_free(buf);
339     }
340 
341     if (task.ret != bytes) {
342         return task.ret < 0 ? task.ret : -EIO;
343     }
344 
345     return 0;
346 }
347 
348 static int coroutine_fn nfs_co_flush(BlockDriverState *bs)
349 {
350     NFSClient *client = bs->opaque;
351     NFSRPC task;
352 
353     nfs_co_init_task(bs, &task);
354 
355     WITH_QEMU_LOCK_GUARD(&client->mutex) {
356         if (nfs_fsync_async(client->context, client->fh, nfs_co_generic_cb,
357                             &task) != 0) {
358             return -ENOMEM;
359         }
360 
361         nfs_set_events(client);
362     }
363     while (!task.complete) {
364         qemu_coroutine_yield();
365     }
366 
367     return task.ret;
368 }
369 
370 static void nfs_detach_aio_context(BlockDriverState *bs)
371 {
372     NFSClient *client = bs->opaque;
373 
374     aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
375                        false, NULL, NULL, NULL, NULL);
376     client->events = 0;
377 }
378 
379 static void nfs_attach_aio_context(BlockDriverState *bs,
380                                    AioContext *new_context)
381 {
382     NFSClient *client = bs->opaque;
383 
384     client->aio_context = new_context;
385     nfs_set_events(client);
386 }
387 
388 static void nfs_client_close(NFSClient *client)
389 {
390     if (client->context) {
391         qemu_mutex_lock(&client->mutex);
392         aio_set_fd_handler(client->aio_context, nfs_get_fd(client->context),
393                            false, NULL, NULL, NULL, NULL);
394         qemu_mutex_unlock(&client->mutex);
395         if (client->fh) {
396             nfs_close(client->context, client->fh);
397             client->fh = NULL;
398         }
399 #ifdef LIBNFS_FEATURE_UMOUNT
400         nfs_umount(client->context);
401 #endif
402         nfs_destroy_context(client->context);
403         client->context = NULL;
404     }
405     g_free(client->path);
406     qemu_mutex_destroy(&client->mutex);
407     qapi_free_NFSServer(client->server);
408     client->server = NULL;
409 }
410 
411 static void nfs_file_close(BlockDriverState *bs)
412 {
413     NFSClient *client = bs->opaque;
414     nfs_client_close(client);
415 }
416 
417 static int64_t nfs_client_open(NFSClient *client, BlockdevOptionsNfs *opts,
418                                int flags, int open_flags, Error **errp)
419 {
420     int64_t ret = -EINVAL;
421     struct stat st;
422     char *file = NULL, *strp = NULL;
423 
424     qemu_mutex_init(&client->mutex);
425 
426     client->path = g_strdup(opts->path);
427 
428     strp = strrchr(client->path, '/');
429     if (strp == NULL) {
430         error_setg(errp, "Invalid URL specified");
431         goto fail;
432     }
433     file = g_strdup(strp);
434     *strp = 0;
435 
436     /* Steal the NFSServer object from opts; set the original pointer to NULL
437      * to avoid use after free and double free. */
438     client->server = opts->server;
439     opts->server = NULL;
440 
441     client->context = nfs_init_context();
442     if (client->context == NULL) {
443         error_setg(errp, "Failed to init NFS context");
444         goto fail;
445     }
446 
447     if (opts->has_user) {
448         client->uid = opts->user;
449         nfs_set_uid(client->context, client->uid);
450     }
451 
452     if (opts->has_group) {
453         client->gid = opts->group;
454         nfs_set_gid(client->context, client->gid);
455     }
456 
457     if (opts->has_tcp_syn_count) {
458         client->tcp_syncnt = opts->tcp_syn_count;
459         nfs_set_tcp_syncnt(client->context, client->tcp_syncnt);
460     }
461 
462 #ifdef LIBNFS_FEATURE_READAHEAD
463     if (opts->has_readahead_size) {
464         if (open_flags & BDRV_O_NOCACHE) {
465             error_setg(errp, "Cannot enable NFS readahead "
466                              "if cache.direct = on");
467             goto fail;
468         }
469         client->readahead = opts->readahead_size;
470         if (client->readahead > QEMU_NFS_MAX_READAHEAD_SIZE) {
471             warn_report("Truncating NFS readahead size to %d",
472                         QEMU_NFS_MAX_READAHEAD_SIZE);
473             client->readahead = QEMU_NFS_MAX_READAHEAD_SIZE;
474         }
475         nfs_set_readahead(client->context, client->readahead);
476 #ifdef LIBNFS_FEATURE_PAGECACHE
477         nfs_set_pagecache_ttl(client->context, 0);
478 #endif
479         client->cache_used = true;
480     }
481 #endif
482 
483 #ifdef LIBNFS_FEATURE_PAGECACHE
484     if (opts->has_page_cache_size) {
485         if (open_flags & BDRV_O_NOCACHE) {
486             error_setg(errp, "Cannot enable NFS pagecache "
487                              "if cache.direct = on");
488             goto fail;
489         }
490         client->pagecache = opts->page_cache_size;
491         if (client->pagecache > QEMU_NFS_MAX_PAGECACHE_SIZE) {
492             warn_report("Truncating NFS pagecache size to %d pages",
493                         QEMU_NFS_MAX_PAGECACHE_SIZE);
494             client->pagecache = QEMU_NFS_MAX_PAGECACHE_SIZE;
495         }
496         nfs_set_pagecache(client->context, client->pagecache);
497         nfs_set_pagecache_ttl(client->context, 0);
498         client->cache_used = true;
499     }
500 #endif
501 
502 #ifdef LIBNFS_FEATURE_DEBUG
503     if (opts->has_debug) {
504         client->debug = opts->debug;
505         /* limit the maximum debug level to avoid potential flooding
506          * of our log files. */
507         if (client->debug > QEMU_NFS_MAX_DEBUG_LEVEL) {
508             warn_report("Limiting NFS debug level to %d",
509                         QEMU_NFS_MAX_DEBUG_LEVEL);
510             client->debug = QEMU_NFS_MAX_DEBUG_LEVEL;
511         }
512         nfs_set_debug(client->context, client->debug);
513     }
514 #endif
515 
516     ret = nfs_mount(client->context, client->server->host, client->path);
517     if (ret < 0) {
518         error_setg(errp, "Failed to mount nfs share: %s",
519                    nfs_get_error(client->context));
520         goto fail;
521     }
522 
523     if (flags & O_CREAT) {
524         ret = nfs_creat(client->context, file, 0600, &client->fh);
525         if (ret < 0) {
526             error_setg(errp, "Failed to create file: %s",
527                        nfs_get_error(client->context));
528             goto fail;
529         }
530     } else {
531         ret = nfs_open(client->context, file, flags, &client->fh);
532         if (ret < 0) {
533             error_setg(errp, "Failed to open file : %s",
534                        nfs_get_error(client->context));
535             goto fail;
536         }
537     }
538 
539     ret = nfs_fstat(client->context, client->fh, &st);
540     if (ret < 0) {
541         error_setg(errp, "Failed to fstat file: %s",
542                    nfs_get_error(client->context));
543         goto fail;
544     }
545 
546     ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
547 #if !defined(_WIN32)
548     client->st_blocks = st.st_blocks;
549 #endif
550     client->has_zero_init = S_ISREG(st.st_mode);
551     *strp = '/';
552     goto out;
553 
554 fail:
555     nfs_client_close(client);
556 out:
557     g_free(file);
558     return ret;
559 }
560 
561 static BlockdevOptionsNfs *nfs_options_qdict_to_qapi(QDict *options,
562                                                      Error **errp)
563 {
564     BlockdevOptionsNfs *opts = NULL;
565     Visitor *v;
566     const QDictEntry *e;
567 
568     v = qobject_input_visitor_new_flat_confused(options, errp);
569     if (!v) {
570         return NULL;
571     }
572 
573     visit_type_BlockdevOptionsNfs(v, NULL, &opts, errp);
574     visit_free(v);
575     if (!opts) {
576         return NULL;
577     }
578 
579     /* Remove the processed options from the QDict (the visitor processes
580      * _all_ options in the QDict) */
581     while ((e = qdict_first(options))) {
582         qdict_del(options, e->key);
583     }
584 
585     return opts;
586 }
587 
588 static int64_t nfs_client_open_qdict(NFSClient *client, QDict *options,
589                                      int flags, int open_flags, Error **errp)
590 {
591     BlockdevOptionsNfs *opts;
592     int64_t ret;
593 
594     opts = nfs_options_qdict_to_qapi(options, errp);
595     if (opts == NULL) {
596         ret = -EINVAL;
597         goto fail;
598     }
599 
600     ret = nfs_client_open(client, opts, flags, open_flags, errp);
601 fail:
602     qapi_free_BlockdevOptionsNfs(opts);
603     return ret;
604 }
605 
606 static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
607                          Error **errp) {
608     NFSClient *client = bs->opaque;
609     int64_t ret;
610 
611     client->aio_context = bdrv_get_aio_context(bs);
612 
613     ret = nfs_client_open_qdict(client, options,
614                                 (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
615                                 bs->open_flags, errp);
616     if (ret < 0) {
617         return ret;
618     }
619 
620     bs->total_sectors = ret;
621     if (client->has_zero_init) {
622         bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
623     }
624     return 0;
625 }
626 
627 static QemuOptsList nfs_create_opts = {
628     .name = "nfs-create-opts",
629     .head = QTAILQ_HEAD_INITIALIZER(nfs_create_opts.head),
630     .desc = {
631         {
632             .name = BLOCK_OPT_SIZE,
633             .type = QEMU_OPT_SIZE,
634             .help = "Virtual disk size"
635         },
636         { /* end of list */ }
637     }
638 };
639 
640 static int nfs_file_co_create(BlockdevCreateOptions *options, Error **errp)
641 {
642     BlockdevCreateOptionsNfs *opts = &options->u.nfs;
643     NFSClient *client = g_new0(NFSClient, 1);
644     int ret;
645 
646     assert(options->driver == BLOCKDEV_DRIVER_NFS);
647 
648     client->aio_context = qemu_get_aio_context();
649 
650     ret = nfs_client_open(client, opts->location, O_CREAT, 0, errp);
651     if (ret < 0) {
652         goto out;
653     }
654     ret = nfs_ftruncate(client->context, client->fh, opts->size);
655     nfs_client_close(client);
656 
657 out:
658     g_free(client);
659     return ret;
660 }
661 
662 static int coroutine_fn nfs_file_co_create_opts(BlockDriver *drv,
663                                                 const char *url,
664                                                 QemuOpts *opts,
665                                                 Error **errp)
666 {
667     BlockdevCreateOptions *create_options;
668     BlockdevCreateOptionsNfs *nfs_opts;
669     QDict *options;
670     int ret;
671 
672     create_options = g_new0(BlockdevCreateOptions, 1);
673     create_options->driver = BLOCKDEV_DRIVER_NFS;
674     nfs_opts = &create_options->u.nfs;
675 
676     /* Read out options */
677     nfs_opts->size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
678                               BDRV_SECTOR_SIZE);
679 
680     options = qdict_new();
681     ret = nfs_parse_uri(url, options, errp);
682     if (ret < 0) {
683         goto out;
684     }
685 
686     nfs_opts->location = nfs_options_qdict_to_qapi(options, errp);
687     if (nfs_opts->location == NULL) {
688         ret = -EINVAL;
689         goto out;
690     }
691 
692     ret = nfs_file_co_create(create_options, errp);
693     if (ret < 0) {
694         goto out;
695     }
696 
697     ret = 0;
698 out:
699     qobject_unref(options);
700     qapi_free_BlockdevCreateOptions(create_options);
701     return ret;
702 }
703 
704 static int nfs_has_zero_init(BlockDriverState *bs)
705 {
706     NFSClient *client = bs->opaque;
707     return client->has_zero_init;
708 }
709 
710 #if !defined(_WIN32)
711 /* Called (via nfs_service) with QemuMutex held.  */
712 static void
713 nfs_get_allocated_file_size_cb(int ret, struct nfs_context *nfs, void *data,
714                                void *private_data)
715 {
716     NFSRPC *task = private_data;
717     task->ret = ret;
718     if (task->ret == 0) {
719         memcpy(task->st, data, sizeof(struct stat));
720     }
721     if (task->ret < 0) {
722         error_report("NFS Error: %s", nfs_get_error(nfs));
723     }
724 
725     /* Set task->complete before reading bs->wakeup.  */
726     qatomic_mb_set(&task->complete, 1);
727     bdrv_wakeup(task->bs);
728 }
729 
730 static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
731 {
732     NFSClient *client = bs->opaque;
733     NFSRPC task = {0};
734     struct stat st;
735 
736     if (bdrv_is_read_only(bs) &&
737         !(bs->open_flags & BDRV_O_NOCACHE)) {
738         return client->st_blocks * 512;
739     }
740 
741     task.bs = bs;
742     task.st = &st;
743     if (nfs_fstat_async(client->context, client->fh, nfs_get_allocated_file_size_cb,
744                         &task) != 0) {
745         return -ENOMEM;
746     }
747 
748     nfs_set_events(client);
749     BDRV_POLL_WHILE(bs, !task.complete);
750 
751     return (task.ret < 0 ? task.ret : st.st_blocks * 512);
752 }
753 #endif
754 
755 static int coroutine_fn
756 nfs_file_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
757                      PreallocMode prealloc, BdrvRequestFlags flags,
758                      Error **errp)
759 {
760     NFSClient *client = bs->opaque;
761     int ret;
762 
763     if (prealloc != PREALLOC_MODE_OFF) {
764         error_setg(errp, "Unsupported preallocation mode '%s'",
765                    PreallocMode_str(prealloc));
766         return -ENOTSUP;
767     }
768 
769     ret = nfs_ftruncate(client->context, client->fh, offset);
770     if (ret < 0) {
771         error_setg_errno(errp, -ret, "Failed to truncate file");
772         return ret;
773     }
774 
775     return 0;
776 }
777 
778 /* Note that this will not re-establish a connection with the NFS server
779  * - it is effectively a NOP.  */
780 static int nfs_reopen_prepare(BDRVReopenState *state,
781                               BlockReopenQueue *queue, Error **errp)
782 {
783     NFSClient *client = state->bs->opaque;
784     struct stat st;
785     int ret = 0;
786 
787     if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
788         error_setg(errp, "Cannot open a read-only mount as read-write");
789         return -EACCES;
790     }
791 
792     if ((state->flags & BDRV_O_NOCACHE) && client->cache_used) {
793         error_setg(errp, "Cannot disable cache if libnfs readahead or"
794                          " pagecache is enabled");
795         return -EINVAL;
796     }
797 
798     /* Update cache for read-only reopens */
799     if (!(state->flags & BDRV_O_RDWR)) {
800         ret = nfs_fstat(client->context, client->fh, &st);
801         if (ret < 0) {
802             error_setg(errp, "Failed to fstat file: %s",
803                        nfs_get_error(client->context));
804             return ret;
805         }
806 #if !defined(_WIN32)
807         client->st_blocks = st.st_blocks;
808 #endif
809     }
810 
811     return 0;
812 }
813 
814 static void nfs_refresh_filename(BlockDriverState *bs)
815 {
816     NFSClient *client = bs->opaque;
817 
818     if (client->uid && !client->gid) {
819         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
820                  "nfs://%s%s?uid=%" PRId64, client->server->host, client->path,
821                  client->uid);
822     } else if (!client->uid && client->gid) {
823         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
824                  "nfs://%s%s?gid=%" PRId64, client->server->host, client->path,
825                  client->gid);
826     } else if (client->uid && client->gid) {
827         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
828                  "nfs://%s%s?uid=%" PRId64 "&gid=%" PRId64,
829                  client->server->host, client->path, client->uid, client->gid);
830     } else {
831         snprintf(bs->exact_filename, sizeof(bs->exact_filename),
832                  "nfs://%s%s", client->server->host, client->path);
833     }
834 }
835 
836 static char *nfs_dirname(BlockDriverState *bs, Error **errp)
837 {
838     NFSClient *client = bs->opaque;
839 
840     if (client->uid || client->gid) {
841         bdrv_refresh_filename(bs);
842         error_setg(errp, "Cannot generate a base directory for NFS node '%s'",
843                    bs->filename);
844         return NULL;
845     }
846 
847     return g_strdup_printf("nfs://%s%s/", client->server->host, client->path);
848 }
849 
850 #ifdef LIBNFS_FEATURE_PAGECACHE
851 static void coroutine_fn nfs_co_invalidate_cache(BlockDriverState *bs,
852                                                  Error **errp)
853 {
854     NFSClient *client = bs->opaque;
855     nfs_pagecache_invalidate(client->context, client->fh);
856 }
857 #endif
858 
859 static const char *nfs_strong_runtime_opts[] = {
860     "path",
861     "user",
862     "group",
863     "server.",
864 
865     NULL
866 };
867 
868 static BlockDriver bdrv_nfs = {
869     .format_name                    = "nfs",
870     .protocol_name                  = "nfs",
871 
872     .instance_size                  = sizeof(NFSClient),
873     .bdrv_parse_filename            = nfs_parse_filename,
874     .create_opts                    = &nfs_create_opts,
875 
876     .bdrv_has_zero_init             = nfs_has_zero_init,
877 /* libnfs does not provide the allocated filesize of a file on win32. */
878 #if !defined(_WIN32)
879     .bdrv_get_allocated_file_size   = nfs_get_allocated_file_size,
880 #endif
881     .bdrv_co_truncate               = nfs_file_co_truncate,
882 
883     .bdrv_file_open                 = nfs_file_open,
884     .bdrv_close                     = nfs_file_close,
885     .bdrv_co_create                 = nfs_file_co_create,
886     .bdrv_co_create_opts            = nfs_file_co_create_opts,
887     .bdrv_reopen_prepare            = nfs_reopen_prepare,
888 
889     .bdrv_co_preadv                 = nfs_co_preadv,
890     .bdrv_co_pwritev                = nfs_co_pwritev,
891     .bdrv_co_flush_to_disk          = nfs_co_flush,
892 
893     .bdrv_detach_aio_context        = nfs_detach_aio_context,
894     .bdrv_attach_aio_context        = nfs_attach_aio_context,
895     .bdrv_refresh_filename          = nfs_refresh_filename,
896     .bdrv_dirname                   = nfs_dirname,
897 
898     .strong_runtime_opts            = nfs_strong_runtime_opts,
899 
900 #ifdef LIBNFS_FEATURE_PAGECACHE
901     .bdrv_co_invalidate_cache       = nfs_co_invalidate_cache,
902 #endif
903 };
904 
905 static void nfs_block_init(void)
906 {
907     bdrv_register(&bdrv_nfs);
908 }
909 
910 block_init(nfs_block_init);
911