xref: /openbmc/qemu/block/blklogwrites.c (revision a26d018c)
1 /*
2  * Write logging blk driver based on blkverify and blkdebug.
3  *
4  * Copyright (c) 2017 Tuomas Tynkkynen <tuomas@tuxera.com>
5  * Copyright (c) 2018 Aapo Vienamo <aapo@tuxera.com>
6  * Copyright (c) 2018-2024 Ari Sundholm <ari@tuxera.com>
7  *
8  * This work is licensed under the terms of the GNU GPL, version 2 or later.
9  * See the COPYING file in the top-level directory.
10  */
11 
12 #include "qemu/osdep.h"
13 #include "qapi/error.h"
14 #include "qemu/sockets.h" /* for EINPROGRESS on Windows */
15 #include "block/block-io.h"
16 #include "block/block_int.h"
17 #include "qapi/qmp/qdict.h"
18 #include "qapi/qmp/qstring.h"
19 #include "qemu/cutils.h"
20 #include "qemu/module.h"
21 #include "qemu/option.h"
22 
23 /* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
24 
25 #define LOG_FLUSH_FLAG   (1 << 0)
26 #define LOG_FUA_FLAG     (1 << 1)
27 #define LOG_DISCARD_FLAG (1 << 2)
28 #define LOG_MARK_FLAG    (1 << 3)
29 #define LOG_FLAG_MASK    (LOG_FLUSH_FLAG \
30                          | LOG_FUA_FLAG \
31                          | LOG_DISCARD_FLAG \
32                          | LOG_MARK_FLAG)
33 
34 #define WRITE_LOG_VERSION 1ULL
35 #define WRITE_LOG_MAGIC 0x6a736677736872ULL
36 
37 /* All fields are little-endian. */
38 struct log_write_super {
39     uint64_t magic;
40     uint64_t version;
41     uint64_t nr_entries;
42     uint32_t sectorsize;
43 } QEMU_PACKED;
44 
45 struct log_write_entry {
46     uint64_t sector;
47     uint64_t nr_sectors;
48     uint64_t flags;
49     uint64_t data_len;
50 } QEMU_PACKED;
51 
52 /* End of disk format structures. */
53 
54 typedef struct {
55     BdrvChild *log_file;
56     uint32_t sectorsize;
57     uint32_t sectorbits;
58     uint64_t update_interval;
59 
60     /*
61      * The mutable state of the driver, consisting of the current log sector
62      * and the number of log entries.
63      *
64      * May be read and/or written from multiple threads, and the mutex must be
65      * held when accessing these fields.
66      */
67     uint64_t cur_log_sector;
68     uint64_t nr_entries;
69     QemuMutex mutex;
70 
71     /*
72      * The super block sequence number. Non-zero if a super block update is in
73      * progress.
74      *
75      * The mutex must be held when accessing this field.
76      */
77     uint64_t super_update_seq;
78 
79     /*
80      * A coroutine-aware queue to serialize super block updates.
81      *
82      * Used with the mutex to ensure that only one thread be updating the super
83      * block at a time.
84      */
85     CoQueue super_update_queue;
86 } BDRVBlkLogWritesState;
87 
88 static QemuOptsList runtime_opts = {
89     .name = "blklogwrites",
90     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
91     .desc = {
92         {
93             .name = "log-append",
94             .type = QEMU_OPT_BOOL,
95             .help = "Append to an existing log",
96         },
97         {
98             .name = "log-sector-size",
99             .type = QEMU_OPT_SIZE,
100             .help = "Log sector size",
101         },
102         {
103             .name = "log-super-update-interval",
104             .type = QEMU_OPT_NUMBER,
105             .help = "Log superblock update interval (# of write requests)",
106         },
107         { /* end of list */ }
108     },
109 };
110 
blk_log_writes_log2(uint32_t value)111 static inline uint32_t blk_log_writes_log2(uint32_t value)
112 {
113     assert(value > 0);
114     return 31 - clz32(value);
115 }
116 
blk_log_writes_sector_size_valid(uint32_t sector_size)117 static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size)
118 {
119     return is_power_of_2(sector_size) &&
120         sector_size >= sizeof(struct log_write_super) &&
121         sector_size >= sizeof(struct log_write_entry) &&
122         sector_size < (1ull << 24);
123 }
124 
blk_log_writes_find_cur_log_sector(BdrvChild * log,uint32_t sector_size,uint64_t nr_entries,Error ** errp)125 static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log,
126                                                    uint32_t sector_size,
127                                                    uint64_t nr_entries,
128                                                    Error **errp)
129 {
130     uint64_t cur_sector = 1;
131     uint64_t cur_idx = 0;
132     uint32_t sector_bits = blk_log_writes_log2(sector_size);
133     struct log_write_entry cur_entry;
134 
135     while (cur_idx < nr_entries) {
136         int read_ret = bdrv_pread(log, cur_sector << sector_bits,
137                                   sizeof(cur_entry), &cur_entry, 0);
138         if (read_ret < 0) {
139             error_setg_errno(errp, -read_ret,
140                              "Failed to read log entry %"PRIu64, cur_idx);
141             return (uint64_t)-1ull;
142         }
143 
144         if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) {
145             error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64,
146                        le64_to_cpu(cur_entry.flags), cur_idx);
147             return (uint64_t)-1ull;
148         }
149 
150         /* Account for the sector of the entry itself */
151         ++cur_sector;
152 
153         /*
154          * Account for the data of the write.
155          * For discards, this data is not present.
156          */
157         if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) {
158             cur_sector += le64_to_cpu(cur_entry.nr_sectors);
159         }
160 
161         ++cur_idx;
162     }
163 
164     return cur_sector;
165 }
166 
blk_log_writes_open(BlockDriverState * bs,QDict * options,int flags,Error ** errp)167 static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
168                                Error **errp)
169 {
170     BDRVBlkLogWritesState *s = bs->opaque;
171     QemuOpts *opts;
172     Error *local_err = NULL;
173     int ret;
174     uint64_t log_sector_size;
175     bool log_append;
176 
177     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
178     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
179         ret = -EINVAL;
180         goto fail;
181     }
182 
183     /* Open the file */
184     ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
185     if (ret < 0) {
186         goto fail;
187     }
188 
189     /* Open the log file */
190     s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_of_bds,
191                                   BDRV_CHILD_METADATA, false, errp);
192     if (!s->log_file) {
193         ret = -EINVAL;
194         goto fail;
195     }
196 
197     qemu_mutex_init(&s->mutex);
198     qemu_co_queue_init(&s->super_update_queue);
199 
200     log_append = qemu_opt_get_bool(opts, "log-append", false);
201 
202     if (log_append) {
203         struct log_write_super log_sb = { 0, 0, 0, 0 };
204 
205         if (qemu_opt_find(opts, "log-sector-size")) {
206             ret = -EINVAL;
207             error_setg(errp, "log-append and log-sector-size are mutually "
208                        "exclusive");
209             goto fail_log;
210         }
211 
212         /* Read log superblock or fake one for an empty log */
213         if (!bdrv_getlength(s->log_file->bs)) {
214             log_sb.magic      = cpu_to_le64(WRITE_LOG_MAGIC);
215             log_sb.version    = cpu_to_le64(WRITE_LOG_VERSION);
216             log_sb.nr_entries = cpu_to_le64(0);
217             log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
218         } else {
219             ret = bdrv_pread(s->log_file, 0, sizeof(log_sb), &log_sb, 0);
220             if (ret < 0) {
221                 error_setg_errno(errp, -ret, "Could not read log superblock");
222                 goto fail_log;
223             }
224         }
225 
226         if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
227             ret = -EINVAL;
228             error_setg(errp, "Invalid log superblock magic");
229             goto fail_log;
230         }
231 
232         if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
233             ret = -EINVAL;
234             error_setg(errp, "Unsupported log version %"PRIu64,
235                        le64_to_cpu(log_sb.version));
236             goto fail_log;
237         }
238 
239         log_sector_size = le32_to_cpu(log_sb.sectorsize);
240         s->cur_log_sector = 1;
241         s->nr_entries = 0;
242 
243         if (blk_log_writes_sector_size_valid(log_sector_size)) {
244             s->cur_log_sector =
245                 blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
246                                     le64_to_cpu(log_sb.nr_entries), &local_err);
247             if (local_err) {
248                 ret = -EINVAL;
249                 error_propagate(errp, local_err);
250                 goto fail_log;
251             }
252 
253             s->nr_entries = le64_to_cpu(log_sb.nr_entries);
254         }
255     } else {
256         log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
257                                             BDRV_SECTOR_SIZE);
258         s->cur_log_sector = 1;
259         s->nr_entries = 0;
260     }
261 
262     s->super_update_seq = 0;
263 
264     if (!blk_log_writes_sector_size_valid(log_sector_size)) {
265         ret = -EINVAL;
266         error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
267         goto fail_log;
268     }
269 
270     s->sectorsize = log_sector_size;
271     s->sectorbits = blk_log_writes_log2(log_sector_size);
272     s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval",
273                                              4096);
274     if (!s->update_interval) {
275         ret = -EINVAL;
276         error_setg(errp, "Invalid log superblock update interval %"PRIu64,
277                    s->update_interval);
278         goto fail_log;
279     }
280 
281     ret = 0;
282 fail_log:
283     if (ret < 0) {
284         bdrv_graph_wrlock();
285         bdrv_unref_child(bs, s->log_file);
286         bdrv_graph_wrunlock();
287         s->log_file = NULL;
288         qemu_mutex_destroy(&s->mutex);
289     }
290 fail:
291     qemu_opts_del(opts);
292     return ret;
293 }
294 
blk_log_writes_close(BlockDriverState * bs)295 static void blk_log_writes_close(BlockDriverState *bs)
296 {
297     BDRVBlkLogWritesState *s = bs->opaque;
298 
299     bdrv_graph_wrlock();
300     bdrv_unref_child(bs, s->log_file);
301     s->log_file = NULL;
302     bdrv_graph_wrunlock();
303     qemu_mutex_destroy(&s->mutex);
304 }
305 
306 static int64_t coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_getlength(BlockDriverState * bs)307 blk_log_writes_co_getlength(BlockDriverState *bs)
308 {
309     return bdrv_co_getlength(bs->file->bs);
310 }
311 
blk_log_writes_child_perm(BlockDriverState * bs,BdrvChild * c,BdrvChildRole role,BlockReopenQueue * ro_q,uint64_t perm,uint64_t shrd,uint64_t * nperm,uint64_t * nshrd)312 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
313                                       BdrvChildRole role,
314                                       BlockReopenQueue *ro_q,
315                                       uint64_t perm, uint64_t shrd,
316                                       uint64_t *nperm, uint64_t *nshrd)
317 {
318     if (!c) {
319         *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
320         *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
321         return;
322     }
323 
324     bdrv_default_perms(bs, c, role, ro_q, perm, shrd,
325                        nperm, nshrd);
326 }
327 
blk_log_writes_refresh_limits(BlockDriverState * bs,Error ** errp)328 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
329 {
330     const BDRVBlkLogWritesState *s = bs->opaque;
331     bs->bl.request_alignment = s->sectorsize;
332 }
333 
334 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_preadv(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,BdrvRequestFlags flags)335 blk_log_writes_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
336                          QEMUIOVector *qiov, BdrvRequestFlags flags)
337 {
338     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
339 }
340 
341 typedef struct BlkLogWritesFileReq {
342     BlockDriverState *bs;
343     uint64_t offset;
344     uint64_t bytes;
345     int file_flags;
346     QEMUIOVector *qiov;
347     int GRAPH_RDLOCK_PTR (*func)(struct BlkLogWritesFileReq *r);
348     int file_ret;
349 } BlkLogWritesFileReq;
350 
351 typedef struct {
352     BlockDriverState *bs;
353     QEMUIOVector *qiov;
354     struct log_write_entry entry;
355     uint64_t zero_size;
356     int log_ret;
357 } BlkLogWritesLogReq;
358 
359 static void coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_log(BlkLogWritesLogReq * lr)360 blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
361 {
362     BDRVBlkLogWritesState *s = lr->bs->opaque;
363 
364     /*
365      * Determine the offsets and sizes of different parts of the entry, and
366      * update the state of the driver.
367      *
368      * This needs to be done in one go, before any actual I/O is done, as the
369      * log entry may have to be written in two parts, and the state of the
370      * driver may be modified by other driver operations while waiting for the
371      * I/O to complete.
372      */
373     qemu_mutex_lock(&s->mutex);
374     const uint64_t entry_start_sector = s->cur_log_sector;
375     const uint64_t entry_offset = entry_start_sector << s->sectorbits;
376     const uint64_t qiov_aligned_size = ROUND_UP(lr->qiov->size, s->sectorsize);
377     const uint64_t entry_aligned_size = qiov_aligned_size +
378         ROUND_UP(lr->zero_size, s->sectorsize);
379     const uint64_t entry_nr_sectors = entry_aligned_size >> s->sectorbits;
380     const uint64_t entry_seq = s->nr_entries + 1;
381 
382     s->nr_entries = entry_seq;
383     s->cur_log_sector += entry_nr_sectors;
384     qemu_mutex_unlock(&s->mutex);
385 
386     /*
387      * Write the log entry. Note that if this is a "write zeroes" operation,
388      * only the entry header is written here, with the zeroing being done
389      * separately below.
390      */
391     lr->log_ret = bdrv_co_pwritev(s->log_file, entry_offset, lr->qiov->size,
392                                   lr->qiov, 0);
393 
394     /* Logging for the "write zeroes" operation */
395     if (lr->log_ret == 0 && lr->zero_size) {
396         const uint64_t zeroes_offset = entry_offset + qiov_aligned_size;
397 
398         lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, zeroes_offset,
399                                             lr->zero_size, 0);
400     }
401 
402     /* Update super block on flush or every update interval */
403     if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
404         || (entry_seq % s->update_interval == 0)))
405     {
406         struct log_write_super super = {
407             .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
408             .version    = cpu_to_le64(WRITE_LOG_VERSION),
409             .nr_entries = 0, /* updated below */
410             .sectorsize = cpu_to_le32(s->sectorsize),
411         };
412         void *zeroes;
413         QEMUIOVector qiov;
414 
415         /*
416          * Wait if a super block update is already in progress.
417          * Bail out if a newer update got its turn before us.
418          */
419         WITH_QEMU_LOCK_GUARD(&s->mutex) {
420             CoQueueWaitFlags wait_flags = 0;
421             while (s->super_update_seq) {
422                 if (entry_seq < s->super_update_seq) {
423                     return;
424                 }
425                 qemu_co_queue_wait_flags(&s->super_update_queue,
426                     &s->mutex, wait_flags);
427 
428                 /*
429                  * In case the wait condition remains true after wakeup,
430                  * to avoid starvation, make sure that this request is
431                  * scheduled to rerun next by pushing it to the front of the
432                  * queue.
433                  */
434                 wait_flags = CO_QUEUE_WAIT_FRONT;
435             }
436             s->super_update_seq = entry_seq;
437             super.nr_entries = cpu_to_le64(s->nr_entries);
438         }
439 
440         zeroes = g_malloc0(s->sectorsize - sizeof(super));
441 
442         qemu_iovec_init(&qiov, 2);
443         qemu_iovec_add(&qiov, &super, sizeof(super));
444         qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
445 
446         lr->log_ret =
447             bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
448         if (lr->log_ret == 0) {
449             lr->log_ret = bdrv_co_flush(s->log_file->bs);
450         }
451 
452         /* The super block has been updated. Let another request have a go. */
453         qemu_mutex_lock(&s->mutex);
454         s->super_update_seq = 0;
455         (void) qemu_co_queue_next(&s->super_update_queue);
456         qemu_mutex_unlock(&s->mutex);
457 
458         qemu_iovec_destroy(&qiov);
459         g_free(zeroes);
460     }
461 }
462 
463 static void coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_file(BlkLogWritesFileReq * fr)464 blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
465 {
466     fr->file_ret = fr->func(fr);
467 }
468 
469 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_log(BlockDriverState * bs,uint64_t offset,uint64_t bytes,QEMUIOVector * qiov,int flags,int (* file_func)(BlkLogWritesFileReq * r),uint64_t entry_flags,bool is_zero_write)470 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
471                       QEMUIOVector *qiov, int flags,
472                       int /*GRAPH_RDLOCK*/ (*file_func)(BlkLogWritesFileReq *r),
473                       uint64_t entry_flags, bool is_zero_write)
474 {
475     QEMUIOVector log_qiov;
476     size_t niov = qiov ? qiov->niov : 0;
477     const BDRVBlkLogWritesState *s = bs->opaque;
478     BlkLogWritesFileReq fr = {
479         .bs         = bs,
480         .offset     = offset,
481         .bytes      = bytes,
482         .file_flags = flags,
483         .qiov       = qiov,
484         .func       = file_func,
485     };
486     BlkLogWritesLogReq lr = {
487         .bs             = bs,
488         .qiov           = &log_qiov,
489         .entry = {
490             .sector     = cpu_to_le64(offset >> s->sectorbits),
491             .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
492             .flags      = cpu_to_le64(entry_flags),
493             .data_len   = 0,
494         },
495         .zero_size = is_zero_write ? bytes : 0,
496     };
497     void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
498 
499     assert((1 << s->sectorbits) == s->sectorsize);
500     assert(bs->bl.request_alignment == s->sectorsize);
501     assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
502     assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
503 
504     qemu_iovec_init(&log_qiov, niov + 2);
505     qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
506     qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
507     if (qiov) {
508         qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
509     }
510 
511     blk_log_writes_co_do_file(&fr);
512     blk_log_writes_co_do_log(&lr);
513 
514     qemu_iovec_destroy(&log_qiov);
515     g_free(zeroes);
516 
517     if (lr.log_ret < 0) {
518         return lr.log_ret;
519     }
520 
521     return fr.file_ret;
522 }
523 
524 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq * fr)525 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
526 {
527     return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
528                            fr->qiov, fr->file_flags);
529 }
530 
531 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq * fr)532 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
533 {
534     return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
535                                  fr->file_flags);
536 }
537 
538 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_file_flush(BlkLogWritesFileReq * fr)539 blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
540 {
541     return bdrv_co_flush(fr->bs->file->bs);
542 }
543 
544 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq * fr)545 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
546 {
547     return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes);
548 }
549 
550 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_pwritev(BlockDriverState * bs,int64_t offset,int64_t bytes,QEMUIOVector * qiov,BdrvRequestFlags flags)551 blk_log_writes_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
552                           QEMUIOVector *qiov, BdrvRequestFlags flags)
553 {
554     return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
555                                  blk_log_writes_co_do_file_pwritev, 0, false);
556 }
557 
558 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_pwrite_zeroes(BlockDriverState * bs,int64_t offset,int64_t bytes,BdrvRequestFlags flags)559 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
560                                 int64_t bytes, BdrvRequestFlags flags)
561 {
562     return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
563                                  blk_log_writes_co_do_file_pwrite_zeroes, 0,
564                                  true);
565 }
566 
567 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_flush_to_disk(BlockDriverState * bs)568 blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
569 {
570     return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
571                                  blk_log_writes_co_do_file_flush,
572                                  LOG_FLUSH_FLAG, false);
573 }
574 
575 static int coroutine_fn GRAPH_RDLOCK
blk_log_writes_co_pdiscard(BlockDriverState * bs,int64_t offset,int64_t bytes)576 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
577 {
578     return blk_log_writes_co_log(bs, offset, bytes, NULL, 0,
579                                  blk_log_writes_co_do_file_pdiscard,
580                                  LOG_DISCARD_FLAG, false);
581 }
582 
583 static const char *const blk_log_writes_strong_runtime_opts[] = {
584     "log-append",
585     "log-sector-size",
586 
587     NULL
588 };
589 
590 static BlockDriver bdrv_blk_log_writes = {
591     .format_name            = "blklogwrites",
592     .instance_size          = sizeof(BDRVBlkLogWritesState),
593 
594     .bdrv_open              = blk_log_writes_open,
595     .bdrv_close             = blk_log_writes_close,
596     .bdrv_co_getlength      = blk_log_writes_co_getlength,
597     .bdrv_child_perm        = blk_log_writes_child_perm,
598     .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
599 
600     .bdrv_co_preadv         = blk_log_writes_co_preadv,
601     .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
602     .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
603     .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
604     .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
605 
606     .is_filter              = true,
607     .strong_runtime_opts    = blk_log_writes_strong_runtime_opts,
608 };
609 
bdrv_blk_log_writes_init(void)610 static void bdrv_blk_log_writes_init(void)
611 {
612     bdrv_register(&bdrv_blk_log_writes);
613 }
614 
615 block_init(bdrv_blk_log_writes_init);
616