xref: /openbmc/qemu/block/blklogwrites.c (revision 0e8e77d4)
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 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_int.h"
16 #include "qapi/qmp/qdict.h"
17 #include "qapi/qmp/qstring.h"
18 #include "qemu/cutils.h"
19 #include "qemu/module.h"
20 #include "qemu/option.h"
21 
22 /* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
23 
24 #define LOG_FLUSH_FLAG   (1 << 0)
25 #define LOG_FUA_FLAG     (1 << 1)
26 #define LOG_DISCARD_FLAG (1 << 2)
27 #define LOG_MARK_FLAG    (1 << 3)
28 #define LOG_FLAG_MASK    (LOG_FLUSH_FLAG \
29                          | LOG_FUA_FLAG \
30                          | LOG_DISCARD_FLAG \
31                          | LOG_MARK_FLAG)
32 
33 #define WRITE_LOG_VERSION 1ULL
34 #define WRITE_LOG_MAGIC 0x6a736677736872ULL
35 
36 /* All fields are little-endian. */
37 struct log_write_super {
38     uint64_t magic;
39     uint64_t version;
40     uint64_t nr_entries;
41     uint32_t sectorsize;
42 } QEMU_PACKED;
43 
44 struct log_write_entry {
45     uint64_t sector;
46     uint64_t nr_sectors;
47     uint64_t flags;
48     uint64_t data_len;
49 } QEMU_PACKED;
50 
51 /* End of disk format structures. */
52 
53 typedef struct {
54     BdrvChild *log_file;
55     uint32_t sectorsize;
56     uint32_t sectorbits;
57     uint64_t cur_log_sector;
58     uint64_t nr_entries;
59     uint64_t update_interval;
60 } BDRVBlkLogWritesState;
61 
62 static QemuOptsList runtime_opts = {
63     .name = "blklogwrites",
64     .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
65     .desc = {
66         {
67             .name = "log-append",
68             .type = QEMU_OPT_BOOL,
69             .help = "Append to an existing log",
70         },
71         {
72             .name = "log-sector-size",
73             .type = QEMU_OPT_SIZE,
74             .help = "Log sector size",
75         },
76         {
77             .name = "log-super-update-interval",
78             .type = QEMU_OPT_NUMBER,
79             .help = "Log superblock update interval (# of write requests)",
80         },
81         { /* end of list */ }
82     },
83 };
84 
85 static inline uint32_t blk_log_writes_log2(uint32_t value)
86 {
87     assert(value > 0);
88     return 31 - clz32(value);
89 }
90 
91 static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size)
92 {
93     return is_power_of_2(sector_size) &&
94         sector_size >= sizeof(struct log_write_super) &&
95         sector_size >= sizeof(struct log_write_entry) &&
96         sector_size < (1ull << 24);
97 }
98 
99 static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log,
100                                                    uint32_t sector_size,
101                                                    uint64_t nr_entries,
102                                                    Error **errp)
103 {
104     uint64_t cur_sector = 1;
105     uint64_t cur_idx = 0;
106     uint32_t sector_bits = blk_log_writes_log2(sector_size);
107     struct log_write_entry cur_entry;
108 
109     while (cur_idx < nr_entries) {
110         int read_ret = bdrv_pread(log, cur_sector << sector_bits, &cur_entry,
111                                   sizeof(cur_entry));
112         if (read_ret < 0) {
113             error_setg_errno(errp, -read_ret,
114                              "Failed to read log entry %"PRIu64, cur_idx);
115             return (uint64_t)-1ull;
116         }
117 
118         if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) {
119             error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64,
120                        le64_to_cpu(cur_entry.flags), cur_idx);
121             return (uint64_t)-1ull;
122         }
123 
124         /* Account for the sector of the entry itself */
125         ++cur_sector;
126 
127         /*
128          * Account for the data of the write.
129          * For discards, this data is not present.
130          */
131         if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) {
132             cur_sector += le64_to_cpu(cur_entry.nr_sectors);
133         }
134 
135         ++cur_idx;
136     }
137 
138     return cur_sector;
139 }
140 
141 static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
142                                Error **errp)
143 {
144     BDRVBlkLogWritesState *s = bs->opaque;
145     QemuOpts *opts;
146     Error *local_err = NULL;
147     int ret;
148     uint64_t log_sector_size;
149     bool log_append;
150 
151     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
152     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
153         ret = -EINVAL;
154         goto fail;
155     }
156 
157     /* Open the file */
158     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
159                                BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false,
160                                &local_err);
161     if (local_err) {
162         ret = -EINVAL;
163         error_propagate(errp, local_err);
164         goto fail;
165     }
166 
167     /* Open the log file */
168     s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_of_bds,
169                                   BDRV_CHILD_METADATA, false, &local_err);
170     if (local_err) {
171         ret = -EINVAL;
172         error_propagate(errp, local_err);
173         goto fail;
174     }
175 
176     log_append = qemu_opt_get_bool(opts, "log-append", false);
177 
178     if (log_append) {
179         struct log_write_super log_sb = { 0, 0, 0, 0 };
180 
181         if (qemu_opt_find(opts, "log-sector-size")) {
182             ret = -EINVAL;
183             error_setg(errp, "log-append and log-sector-size are mutually "
184                        "exclusive");
185             goto fail_log;
186         }
187 
188         /* Read log superblock or fake one for an empty log */
189         if (!bdrv_getlength(s->log_file->bs)) {
190             log_sb.magic      = cpu_to_le64(WRITE_LOG_MAGIC);
191             log_sb.version    = cpu_to_le64(WRITE_LOG_VERSION);
192             log_sb.nr_entries = cpu_to_le64(0);
193             log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
194         } else {
195             ret = bdrv_pread(s->log_file, 0, &log_sb, sizeof(log_sb));
196             if (ret < 0) {
197                 error_setg_errno(errp, -ret, "Could not read log superblock");
198                 goto fail_log;
199             }
200         }
201 
202         if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
203             ret = -EINVAL;
204             error_setg(errp, "Invalid log superblock magic");
205             goto fail_log;
206         }
207 
208         if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
209             ret = -EINVAL;
210             error_setg(errp, "Unsupported log version %"PRIu64,
211                        le64_to_cpu(log_sb.version));
212             goto fail_log;
213         }
214 
215         log_sector_size = le32_to_cpu(log_sb.sectorsize);
216         s->cur_log_sector = 1;
217         s->nr_entries = 0;
218 
219         if (blk_log_writes_sector_size_valid(log_sector_size)) {
220             s->cur_log_sector =
221                 blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
222                                     le64_to_cpu(log_sb.nr_entries), &local_err);
223             if (local_err) {
224                 ret = -EINVAL;
225                 error_propagate(errp, local_err);
226                 goto fail_log;
227             }
228 
229             s->nr_entries = le64_to_cpu(log_sb.nr_entries);
230         }
231     } else {
232         log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
233                                             BDRV_SECTOR_SIZE);
234         s->cur_log_sector = 1;
235         s->nr_entries = 0;
236     }
237 
238     if (!blk_log_writes_sector_size_valid(log_sector_size)) {
239         ret = -EINVAL;
240         error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
241         goto fail_log;
242     }
243 
244     s->sectorsize = log_sector_size;
245     s->sectorbits = blk_log_writes_log2(log_sector_size);
246     s->update_interval = qemu_opt_get_number(opts, "log-super-update-interval",
247                                              4096);
248     if (!s->update_interval) {
249         ret = -EINVAL;
250         error_setg(errp, "Invalid log superblock update interval %"PRIu64,
251                    s->update_interval);
252         goto fail_log;
253     }
254 
255     ret = 0;
256 fail_log:
257     if (ret < 0) {
258         bdrv_unref_child(bs, s->log_file);
259         s->log_file = NULL;
260     }
261 fail:
262     if (ret < 0) {
263         bdrv_unref_child(bs, bs->file);
264         bs->file = NULL;
265     }
266     qemu_opts_del(opts);
267     return ret;
268 }
269 
270 static void blk_log_writes_close(BlockDriverState *bs)
271 {
272     BDRVBlkLogWritesState *s = bs->opaque;
273 
274     bdrv_unref_child(bs, s->log_file);
275     s->log_file = NULL;
276 }
277 
278 static int64_t blk_log_writes_getlength(BlockDriverState *bs)
279 {
280     return bdrv_getlength(bs->file->bs);
281 }
282 
283 static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
284                                       BdrvChildRole role,
285                                       BlockReopenQueue *ro_q,
286                                       uint64_t perm, uint64_t shrd,
287                                       uint64_t *nperm, uint64_t *nshrd)
288 {
289     if (!c) {
290         *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
291         *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
292         return;
293     }
294 
295     bdrv_default_perms(bs, c, role, ro_q, perm, shrd,
296                        nperm, nshrd);
297 }
298 
299 static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
300 {
301     BDRVBlkLogWritesState *s = bs->opaque;
302     bs->bl.request_alignment = s->sectorsize;
303 }
304 
305 static int coroutine_fn
306 blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
307                          QEMUIOVector *qiov, int flags)
308 {
309     return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
310 }
311 
312 typedef struct BlkLogWritesFileReq {
313     BlockDriverState *bs;
314     uint64_t offset;
315     uint64_t bytes;
316     int file_flags;
317     QEMUIOVector *qiov;
318     int (*func)(struct BlkLogWritesFileReq *r);
319     int file_ret;
320 } BlkLogWritesFileReq;
321 
322 typedef struct {
323     BlockDriverState *bs;
324     QEMUIOVector *qiov;
325     struct log_write_entry entry;
326     uint64_t zero_size;
327     int log_ret;
328 } BlkLogWritesLogReq;
329 
330 static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
331 {
332     BDRVBlkLogWritesState *s = lr->bs->opaque;
333     uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
334 
335     s->nr_entries++;
336     s->cur_log_sector +=
337             ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
338 
339     lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
340                                   lr->qiov, 0);
341 
342     /* Logging for the "write zeroes" operation */
343     if (lr->log_ret == 0 && lr->zero_size) {
344         cur_log_offset = s->cur_log_sector << s->sectorbits;
345         s->cur_log_sector +=
346                 ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
347 
348         lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
349                                             lr->zero_size, 0);
350     }
351 
352     /* Update super block on flush or every update interval */
353     if (lr->log_ret == 0 && ((lr->entry.flags & LOG_FLUSH_FLAG)
354         || (s->nr_entries % s->update_interval == 0)))
355     {
356         struct log_write_super super = {
357             .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
358             .version    = cpu_to_le64(WRITE_LOG_VERSION),
359             .nr_entries = cpu_to_le64(s->nr_entries),
360             .sectorsize = cpu_to_le32(s->sectorsize),
361         };
362         void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
363         QEMUIOVector qiov;
364 
365         qemu_iovec_init(&qiov, 2);
366         qemu_iovec_add(&qiov, &super, sizeof(super));
367         qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
368 
369         lr->log_ret =
370             bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
371         if (lr->log_ret == 0) {
372             lr->log_ret = bdrv_co_flush(s->log_file->bs);
373         }
374         qemu_iovec_destroy(&qiov);
375         g_free(zeroes);
376     }
377 }
378 
379 static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
380 {
381     fr->file_ret = fr->func(fr);
382 }
383 
384 static int coroutine_fn
385 blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
386                       QEMUIOVector *qiov, int flags,
387                       int (*file_func)(BlkLogWritesFileReq *r),
388                       uint64_t entry_flags, bool is_zero_write)
389 {
390     QEMUIOVector log_qiov;
391     size_t niov = qiov ? qiov->niov : 0;
392     BDRVBlkLogWritesState *s = bs->opaque;
393     BlkLogWritesFileReq fr = {
394         .bs         = bs,
395         .offset     = offset,
396         .bytes      = bytes,
397         .file_flags = flags,
398         .qiov       = qiov,
399         .func       = file_func,
400     };
401     BlkLogWritesLogReq lr = {
402         .bs             = bs,
403         .qiov           = &log_qiov,
404         .entry = {
405             .sector     = cpu_to_le64(offset >> s->sectorbits),
406             .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
407             .flags      = cpu_to_le64(entry_flags),
408             .data_len   = 0,
409         },
410         .zero_size = is_zero_write ? bytes : 0,
411     };
412     void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
413 
414     assert((1 << s->sectorbits) == s->sectorsize);
415     assert(bs->bl.request_alignment == s->sectorsize);
416     assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
417     assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
418 
419     qemu_iovec_init(&log_qiov, niov + 2);
420     qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
421     qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
422     if (qiov) {
423         qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
424     }
425 
426     blk_log_writes_co_do_file(&fr);
427     blk_log_writes_co_do_log(&lr);
428 
429     qemu_iovec_destroy(&log_qiov);
430     g_free(zeroes);
431 
432     if (lr.log_ret < 0) {
433         return lr.log_ret;
434     }
435 
436     return fr.file_ret;
437 }
438 
439 static int coroutine_fn
440 blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
441 {
442     return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
443                            fr->qiov, fr->file_flags);
444 }
445 
446 static int coroutine_fn
447 blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
448 {
449     return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
450                                  fr->file_flags);
451 }
452 
453 static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
454 {
455     return bdrv_co_flush(fr->bs->file->bs);
456 }
457 
458 static int coroutine_fn
459 blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
460 {
461     return bdrv_co_pdiscard(fr->bs->file, fr->offset, fr->bytes);
462 }
463 
464 static int coroutine_fn
465 blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
466                           QEMUIOVector *qiov, int flags)
467 {
468     return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
469                                  blk_log_writes_co_do_file_pwritev, 0, false);
470 }
471 
472 static int coroutine_fn
473 blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
474                                 BdrvRequestFlags flags)
475 {
476     return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
477                                  blk_log_writes_co_do_file_pwrite_zeroes, 0,
478                                  true);
479 }
480 
481 static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
482 {
483     return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
484                                  blk_log_writes_co_do_file_flush,
485                                  LOG_FLUSH_FLAG, false);
486 }
487 
488 static int coroutine_fn
489 blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
490 {
491     return blk_log_writes_co_log(bs, offset, count, NULL, 0,
492                                  blk_log_writes_co_do_file_pdiscard,
493                                  LOG_DISCARD_FLAG, false);
494 }
495 
496 static const char *const blk_log_writes_strong_runtime_opts[] = {
497     "log-append",
498     "log-sector-size",
499 
500     NULL
501 };
502 
503 static BlockDriver bdrv_blk_log_writes = {
504     .format_name            = "blklogwrites",
505     .instance_size          = sizeof(BDRVBlkLogWritesState),
506 
507     .bdrv_open              = blk_log_writes_open,
508     .bdrv_close             = blk_log_writes_close,
509     .bdrv_getlength         = blk_log_writes_getlength,
510     .bdrv_child_perm        = blk_log_writes_child_perm,
511     .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
512 
513     .bdrv_co_preadv         = blk_log_writes_co_preadv,
514     .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
515     .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
516     .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
517     .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
518 
519     .is_filter              = true,
520     .strong_runtime_opts    = blk_log_writes_strong_runtime_opts,
521 };
522 
523 static void bdrv_blk_log_writes_init(void)
524 {
525     bdrv_register(&bdrv_blk_log_writes);
526 }
527 
528 block_init(bdrv_blk_log_writes_init);
529