tests: virtio-9p: rename PCI configuration test
[qemu.git] / block / vhdx-log.c
1 /*
2 * Block driver for Hyper-V VHDX Images
3 *
4 * Copyright (c) 2013 Red Hat, Inc.,
5 *
6 * Authors:
7 * Jeff Cody <jcody@redhat.com>
8 *
9 * This is based on the "VHDX Format Specification v1.00", published 8/25/2012
10 * by Microsoft:
11 * https://www.microsoft.com/en-us/download/details.aspx?id=34750
12 *
13 * This file covers the functionality of the metadata log writing, parsing, and
14 * replay.
15 *
16 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
17 * See the COPYING.LIB file in the top-level directory.
18 *
19 */
20 #include "qemu/osdep.h"
21 #include "qapi/error.h"
22 #include "qemu-common.h"
23 #include "block/block_int.h"
24 #include "qemu/error-report.h"
25 #include "qemu/module.h"
26 #include "qemu/bswap.h"
27 #include "block/vhdx.h"
28
29
30 typedef struct VHDXLogSequence {
31 bool valid;
32 uint32_t count;
33 VHDXLogEntries log;
34 VHDXLogEntryHeader hdr;
35 } VHDXLogSequence;
36
37 typedef struct VHDXLogDescEntries {
38 VHDXLogEntryHeader hdr;
39 VHDXLogDescriptor desc[];
40 } VHDXLogDescEntries;
41
42 static const MSGUID zero_guid = { 0 };
43
44 /* The log located on the disk is circular buffer containing
45 * sectors of 4096 bytes each.
46 *
47 * It is assumed for the read/write functions below that the
48 * circular buffer scheme uses a 'one sector open' to indicate
49 * the buffer is full. Given the validation methods used for each
50 * sector, this method should be compatible with other methods that
51 * do not waste a sector.
52 */
53
54
55 /* Allow peeking at the hdr entry at the beginning of the current
56 * read index, without advancing the read index */
57 static int vhdx_log_peek_hdr(BlockDriverState *bs, VHDXLogEntries *log,
58 VHDXLogEntryHeader *hdr)
59 {
60 int ret = 0;
61 uint64_t offset;
62 uint32_t read;
63
64 assert(hdr != NULL);
65
66 /* peek is only supported on sector boundaries */
67 if (log->read % VHDX_LOG_SECTOR_SIZE) {
68 ret = -EFAULT;
69 goto exit;
70 }
71
72 read = log->read;
73 /* we are guaranteed that a) log sectors are 4096 bytes,
74 * and b) the log length is a multiple of 1MB. So, there
75 * is always a round number of sectors in the buffer */
76 if ((read + sizeof(VHDXLogEntryHeader)) > log->length) {
77 read = 0;
78 }
79
80 if (read == log->write) {
81 ret = -EINVAL;
82 goto exit;
83 }
84
85 offset = log->offset + read;
86
87 ret = bdrv_pread(bs->file, offset, hdr, sizeof(VHDXLogEntryHeader));
88 if (ret < 0) {
89 goto exit;
90 }
91 vhdx_log_entry_hdr_le_import(hdr);
92
93 exit:
94 return ret;
95 }
96
97 /* Index increment for log, based on sector boundaries */
98 static int vhdx_log_inc_idx(uint32_t idx, uint64_t length)
99 {
100 idx += VHDX_LOG_SECTOR_SIZE;
101 /* we are guaranteed that a) log sectors are 4096 bytes,
102 * and b) the log length is a multiple of 1MB. So, there
103 * is always a round number of sectors in the buffer */
104 return idx >= length ? 0 : idx;
105 }
106
107
108 /* Reset the log to empty */
109 static void vhdx_log_reset(BlockDriverState *bs, BDRVVHDXState *s)
110 {
111 MSGUID guid = { 0 };
112 s->log.read = s->log.write = 0;
113 /* a log guid of 0 indicates an empty log to any parser of v0
114 * VHDX logs */
115 vhdx_update_headers(bs, s, false, &guid);
116 }
117
118 /* Reads num_sectors from the log (all log sectors are 4096 bytes),
119 * into buffer 'buffer'. Upon return, *sectors_read will contain
120 * the number of sectors successfully read.
121 *
122 * It is assumed that 'buffer' is already allocated, and of sufficient
123 * size (i.e. >= 4096*num_sectors).
124 *
125 * If 'peek' is true, then the tail (read) pointer for the circular buffer is
126 * not modified.
127 *
128 * 0 is returned on success, -errno otherwise. */
129 static int vhdx_log_read_sectors(BlockDriverState *bs, VHDXLogEntries *log,
130 uint32_t *sectors_read, void *buffer,
131 uint32_t num_sectors, bool peek)
132 {
133 int ret = 0;
134 uint64_t offset;
135 uint32_t read;
136
137 read = log->read;
138
139 *sectors_read = 0;
140 while (num_sectors) {
141 if (read == log->write) {
142 /* empty */
143 break;
144 }
145 offset = log->offset + read;
146
147 ret = bdrv_pread(bs->file, offset, buffer, VHDX_LOG_SECTOR_SIZE);
148 if (ret < 0) {
149 goto exit;
150 }
151 read = vhdx_log_inc_idx(read, log->length);
152
153 *sectors_read = *sectors_read + 1;
154 num_sectors--;
155 }
156
157 exit:
158 if (!peek) {
159 log->read = read;
160 }
161 return ret;
162 }
163
164 /* Writes num_sectors to the log (all log sectors are 4096 bytes),
165 * from buffer 'buffer'. Upon return, *sectors_written will contain
166 * the number of sectors successfully written.
167 *
168 * It is assumed that 'buffer' is at least 4096*num_sectors large.
169 *
170 * 0 is returned on success, -errno otherwise */
171 static int vhdx_log_write_sectors(BlockDriverState *bs, VHDXLogEntries *log,
172 uint32_t *sectors_written, void *buffer,
173 uint32_t num_sectors)
174 {
175 int ret = 0;
176 uint64_t offset;
177 uint32_t write;
178 void *buffer_tmp;
179 BDRVVHDXState *s = bs->opaque;
180
181 ret = vhdx_user_visible_write(bs, s);
182 if (ret < 0) {
183 goto exit;
184 }
185
186 write = log->write;
187
188 buffer_tmp = buffer;
189 while (num_sectors) {
190
191 offset = log->offset + write;
192 write = vhdx_log_inc_idx(write, log->length);
193 if (write == log->read) {
194 /* full */
195 break;
196 }
197 ret = bdrv_pwrite(bs->file, offset, buffer_tmp,
198 VHDX_LOG_SECTOR_SIZE);
199 if (ret < 0) {
200 goto exit;
201 }
202 buffer_tmp += VHDX_LOG_SECTOR_SIZE;
203
204 log->write = write;
205 *sectors_written = *sectors_written + 1;
206 num_sectors--;
207 }
208
209 exit:
210 return ret;
211 }
212
213
214 /* Validates a log entry header */
215 static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr,
216 BDRVVHDXState *s)
217 {
218 int valid = false;
219
220 if (hdr->signature != VHDX_LOG_SIGNATURE) {
221 goto exit;
222 }
223
224 /* if the individual entry length is larger than the whole log
225 * buffer, that is obviously invalid */
226 if (log->length < hdr->entry_length) {
227 goto exit;
228 }
229
230 /* length of entire entry must be in units of 4KB (log sector size) */
231 if (hdr->entry_length % (VHDX_LOG_SECTOR_SIZE)) {
232 goto exit;
233 }
234
235 /* per spec, sequence # must be > 0 */
236 if (hdr->sequence_number == 0) {
237 goto exit;
238 }
239
240 /* log entries are only valid if they match the file-wide log guid
241 * found in the active header */
242 if (!guid_eq(hdr->log_guid, s->headers[s->curr_header]->log_guid)) {
243 goto exit;
244 }
245
246 if (hdr->descriptor_count * sizeof(VHDXLogDescriptor) > hdr->entry_length) {
247 goto exit;
248 }
249
250 valid = true;
251
252 exit:
253 return valid;
254 }
255
256 /*
257 * Given a log header, this will validate that the descriptors and the
258 * corresponding data sectors (if applicable)
259 *
260 * Validation consists of:
261 * 1. Making sure the sequence numbers matches the entry header
262 * 2. Verifying a valid signature ('zero' or 'desc' for descriptors)
263 * 3. File offset field is a multiple of 4KB
264 * 4. If a data descriptor, the corresponding data sector
265 * has its signature ('data') and matching sequence number
266 *
267 * @desc: the data buffer containing the descriptor
268 * @hdr: the log entry header
269 *
270 * Returns true if valid
271 */
272 static bool vhdx_log_desc_is_valid(VHDXLogDescriptor *desc,
273 VHDXLogEntryHeader *hdr)
274 {
275 bool ret = false;
276
277 if (desc->sequence_number != hdr->sequence_number) {
278 goto exit;
279 }
280 if (desc->file_offset % VHDX_LOG_SECTOR_SIZE) {
281 goto exit;
282 }
283
284 if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
285 if (desc->zero_length % VHDX_LOG_SECTOR_SIZE == 0) {
286 /* valid */
287 ret = true;
288 }
289 } else if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
290 /* valid */
291 ret = true;
292 }
293
294 exit:
295 return ret;
296 }
297
298
299 /* Prior to sector data for a log entry, there is the header
300 * and the descriptors referenced in the header:
301 *
302 * [] = 4KB sector
303 *
304 * [ hdr, desc ][ desc ][ ... ][ data ][ ... ]
305 *
306 * The first sector in a log entry has a 64 byte header, and
307 * up to 126 32-byte descriptors. If more descriptors than
308 * 126 are required, then subsequent sectors can have up to 128
309 * descriptors. Each sector is 4KB. Data follows the descriptor
310 * sectors.
311 *
312 * This will return the number of sectors needed to encompass
313 * the passed number of descriptors in desc_cnt.
314 *
315 * This will never return 0, even if desc_cnt is 0.
316 */
317 static int vhdx_compute_desc_sectors(uint32_t desc_cnt)
318 {
319 uint32_t desc_sectors;
320
321 desc_cnt += 2; /* account for header in first sector */
322 desc_sectors = desc_cnt / 128;
323 if (desc_cnt % 128) {
324 desc_sectors++;
325 }
326
327 return desc_sectors;
328 }
329
330
331 /* Reads the log header, and subsequent descriptors (if any). This
332 * will allocate all the space for buffer, which must be NULL when
333 * passed into this function. Each descriptor will also be validated,
334 * and error returned if any are invalid. */
335 static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
336 VHDXLogEntries *log, VHDXLogDescEntries **buffer,
337 bool convert_endian)
338 {
339 int ret = 0;
340 uint32_t desc_sectors;
341 uint32_t sectors_read;
342 VHDXLogEntryHeader hdr;
343 VHDXLogDescEntries *desc_entries = NULL;
344 VHDXLogDescriptor desc;
345 int i;
346
347 assert(*buffer == NULL);
348
349 ret = vhdx_log_peek_hdr(bs, log, &hdr);
350 if (ret < 0) {
351 goto exit;
352 }
353
354 if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
355 ret = -EINVAL;
356 goto exit;
357 }
358
359 desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count);
360 desc_entries = qemu_try_blockalign(bs->file->bs,
361 desc_sectors * VHDX_LOG_SECTOR_SIZE);
362 if (desc_entries == NULL) {
363 ret = -ENOMEM;
364 goto exit;
365 }
366
367 ret = vhdx_log_read_sectors(bs, log, &sectors_read, desc_entries,
368 desc_sectors, false);
369 if (ret < 0) {
370 goto free_and_exit;
371 }
372 if (sectors_read != desc_sectors) {
373 ret = -EINVAL;
374 goto free_and_exit;
375 }
376
377 /* put in proper endianness, and validate each desc */
378 for (i = 0; i < hdr.descriptor_count; i++) {
379 desc = desc_entries->desc[i];
380 vhdx_log_desc_le_import(&desc);
381 if (convert_endian) {
382 desc_entries->desc[i] = desc;
383 }
384 if (vhdx_log_desc_is_valid(&desc, &hdr) == false) {
385 ret = -EINVAL;
386 goto free_and_exit;
387 }
388 }
389 if (convert_endian) {
390 desc_entries->hdr = hdr;
391 }
392
393 *buffer = desc_entries;
394 goto exit;
395
396 free_and_exit:
397 qemu_vfree(desc_entries);
398 exit:
399 return ret;
400 }
401
402
403 /* Flushes the descriptor described by desc to the VHDX image file.
404 * If the descriptor is a data descriptor, than 'data' must be non-NULL,
405 * and >= 4096 bytes (VHDX_LOG_SECTOR_SIZE), containing the data to be
406 * written.
407 *
408 * Verification is performed to make sure the sequence numbers of a data
409 * descriptor match the sequence number in the desc.
410 *
411 * For a zero descriptor, it may describe multiple sectors to fill with zeroes.
412 * In this case, it should be noted that zeroes are written to disk, and the
413 * image file is not extended as a sparse file. */
414 static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc,
415 VHDXLogDataSector *data)
416 {
417 int ret = 0;
418 uint64_t seq, file_offset;
419 uint32_t offset = 0;
420 void *buffer = NULL;
421 uint64_t count = 1;
422 int i;
423
424 buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
425
426 if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
427 /* data sector */
428 if (data == NULL) {
429 ret = -EFAULT;
430 goto exit;
431 }
432
433 /* The sequence number of the data sector must match that
434 * in the descriptor */
435 seq = data->sequence_high;
436 seq <<= 32;
437 seq |= data->sequence_low & 0xffffffff;
438
439 if (seq != desc->sequence_number) {
440 ret = -EINVAL;
441 goto exit;
442 }
443
444 /* Each data sector is in total 4096 bytes, however the first
445 * 8 bytes, and last 4 bytes, are located in the descriptor */
446 memcpy(buffer, &desc->leading_bytes, 8);
447 offset += 8;
448
449 memcpy(buffer+offset, data->data, 4084);
450 offset += 4084;
451
452 memcpy(buffer+offset, &desc->trailing_bytes, 4);
453
454 } else if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
455 /* write 'count' sectors of sector */
456 memset(buffer, 0, VHDX_LOG_SECTOR_SIZE);
457 count = desc->zero_length / VHDX_LOG_SECTOR_SIZE;
458 } else {
459 error_report("Invalid VHDX log descriptor entry signature 0x%" PRIx32,
460 desc->signature);
461 ret = -EINVAL;
462 goto exit;
463 }
464
465 file_offset = desc->file_offset;
466
467 /* count is only > 1 if we are writing zeroes */
468 for (i = 0; i < count; i++) {
469 ret = bdrv_pwrite_sync(bs->file, file_offset, buffer,
470 VHDX_LOG_SECTOR_SIZE);
471 if (ret < 0) {
472 goto exit;
473 }
474 file_offset += VHDX_LOG_SECTOR_SIZE;
475 }
476
477 exit:
478 qemu_vfree(buffer);
479 return ret;
480 }
481
482 /* Flush the entire log (as described by 'logs') to the VHDX image
483 * file, and then set the log to 'empty' status once complete.
484 *
485 * The log entries should be validate prior to flushing */
486 static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
487 VHDXLogSequence *logs)
488 {
489 int ret = 0;
490 int i;
491 uint32_t cnt, sectors_read;
492 uint64_t new_file_size;
493 void *data = NULL;
494 VHDXLogDescEntries *desc_entries = NULL;
495 VHDXLogEntryHeader hdr_tmp = { 0 };
496
497 cnt = logs->count;
498
499 data = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
500
501 ret = vhdx_user_visible_write(bs, s);
502 if (ret < 0) {
503 goto exit;
504 }
505
506 /* each iteration represents one log sequence, which may span multiple
507 * sectors */
508 while (cnt--) {
509 ret = vhdx_log_peek_hdr(bs, &logs->log, &hdr_tmp);
510 if (ret < 0) {
511 goto exit;
512 }
513 /* if the log shows a FlushedFileOffset larger than our current file
514 * size, then that means the file has been truncated / corrupted, and
515 * we must refused to open it / use it */
516 if (hdr_tmp.flushed_file_offset > bdrv_getlength(bs->file->bs)) {
517 ret = -EINVAL;
518 goto exit;
519 }
520
521 ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries, true);
522 if (ret < 0) {
523 goto exit;
524 }
525
526 for (i = 0; i < desc_entries->hdr.descriptor_count; i++) {
527 if (desc_entries->desc[i].signature == VHDX_LOG_DESC_SIGNATURE) {
528 /* data sector, so read a sector to flush */
529 ret = vhdx_log_read_sectors(bs, &logs->log, &sectors_read,
530 data, 1, false);
531 if (ret < 0) {
532 goto exit;
533 }
534 if (sectors_read != 1) {
535 ret = -EINVAL;
536 goto exit;
537 }
538 vhdx_log_data_le_import(data);
539 }
540
541 ret = vhdx_log_flush_desc(bs, &desc_entries->desc[i], data);
542 if (ret < 0) {
543 goto exit;
544 }
545 }
546 if (bdrv_getlength(bs->file->bs) < desc_entries->hdr.last_file_offset) {
547 new_file_size = desc_entries->hdr.last_file_offset;
548 if (new_file_size % (1024*1024)) {
549 /* round up to nearest 1MB boundary */
550 new_file_size = ((new_file_size >> 20) + 1) << 20;
551 bdrv_truncate(bs->file->bs, new_file_size);
552 }
553 }
554 qemu_vfree(desc_entries);
555 desc_entries = NULL;
556 }
557
558 bdrv_flush(bs);
559 /* once the log is fully flushed, indicate that we have an empty log
560 * now. This also sets the log guid to 0, to indicate an empty log */
561 vhdx_log_reset(bs, s);
562
563 exit:
564 qemu_vfree(data);
565 qemu_vfree(desc_entries);
566 return ret;
567 }
568
569 static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
570 VHDXLogEntries *log, uint64_t seq,
571 bool *valid, VHDXLogEntryHeader *entry)
572 {
573 int ret = 0;
574 VHDXLogEntryHeader hdr;
575 void *buffer = NULL;
576 uint32_t i, desc_sectors, total_sectors, crc;
577 uint32_t sectors_read = 0;
578 VHDXLogDescEntries *desc_buffer = NULL;
579
580 *valid = false;
581
582 ret = vhdx_log_peek_hdr(bs, log, &hdr);
583 if (ret < 0) {
584 goto inc_and_exit;
585 }
586
587 if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
588 goto inc_and_exit;
589 }
590
591 if (seq > 0) {
592 if (hdr.sequence_number != seq + 1) {
593 goto inc_and_exit;
594 }
595 }
596
597 desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count);
598
599 /* Read all log sectors, and calculate log checksum */
600
601 total_sectors = hdr.entry_length / VHDX_LOG_SECTOR_SIZE;
602
603
604 /* read_desc() will increment the read idx */
605 ret = vhdx_log_read_desc(bs, s, log, &desc_buffer, false);
606 if (ret < 0) {
607 goto free_and_exit;
608 }
609
610 crc = vhdx_checksum_calc(0xffffffff, (void *)desc_buffer,
611 desc_sectors * VHDX_LOG_SECTOR_SIZE, 4);
612 crc ^= 0xffffffff;
613
614 buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
615 if (total_sectors > desc_sectors) {
616 for (i = 0; i < total_sectors - desc_sectors; i++) {
617 sectors_read = 0;
618 ret = vhdx_log_read_sectors(bs, log, &sectors_read, buffer,
619 1, false);
620 if (ret < 0 || sectors_read != 1) {
621 goto free_and_exit;
622 }
623 crc = vhdx_checksum_calc(crc, buffer, VHDX_LOG_SECTOR_SIZE, -1);
624 crc ^= 0xffffffff;
625 }
626 }
627 crc ^= 0xffffffff;
628 if (crc != hdr.checksum) {
629 goto free_and_exit;
630 }
631
632 *valid = true;
633 *entry = hdr;
634 goto free_and_exit;
635
636 inc_and_exit:
637 log->read = vhdx_log_inc_idx(log->read, log->length);
638
639 free_and_exit:
640 qemu_vfree(buffer);
641 qemu_vfree(desc_buffer);
642 return ret;
643 }
644
645 /* Search through the log circular buffer, and find the valid, active
646 * log sequence, if any exists
647 * */
648 static int vhdx_log_search(BlockDriverState *bs, BDRVVHDXState *s,
649 VHDXLogSequence *logs)
650 {
651 int ret = 0;
652 uint32_t tail;
653 bool seq_valid = false;
654 VHDXLogSequence candidate = { 0 };
655 VHDXLogEntryHeader hdr = { 0 };
656 VHDXLogEntries curr_log;
657
658 memcpy(&curr_log, &s->log, sizeof(VHDXLogEntries));
659 curr_log.write = curr_log.length; /* assume log is full */
660 curr_log.read = 0;
661
662
663 /* now we will go through the whole log sector by sector, until
664 * we find a valid, active log sequence, or reach the end of the
665 * log buffer */
666 for (;;) {
667 uint64_t curr_seq = 0;
668 VHDXLogSequence current = { 0 };
669
670 tail = curr_log.read;
671
672 ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq,
673 &seq_valid, &hdr);
674 if (ret < 0) {
675 goto exit;
676 }
677
678 if (seq_valid) {
679 current.valid = true;
680 current.log = curr_log;
681 current.log.read = tail;
682 current.log.write = curr_log.read;
683 current.count = 1;
684 current.hdr = hdr;
685
686
687 for (;;) {
688 ret = vhdx_validate_log_entry(bs, s, &curr_log, curr_seq,
689 &seq_valid, &hdr);
690 if (ret < 0) {
691 goto exit;
692 }
693 if (seq_valid == false) {
694 break;
695 }
696 current.log.write = curr_log.read;
697 current.count++;
698
699 curr_seq = hdr.sequence_number;
700 }
701 }
702
703 if (current.valid) {
704 if (candidate.valid == false ||
705 current.hdr.sequence_number > candidate.hdr.sequence_number) {
706 candidate = current;
707 }
708 }
709
710 if (curr_log.read < tail) {
711 break;
712 }
713 }
714
715 *logs = candidate;
716
717 if (candidate.valid) {
718 /* this is the next sequence number, for writes */
719 s->log.sequence = candidate.hdr.sequence_number + 1;
720 }
721
722
723 exit:
724 return ret;
725 }
726
727 /* Parse the replay log. Per the VHDX spec, if the log is present
728 * it must be replayed prior to opening the file, even read-only.
729 *
730 * If read-only, we must replay the log in RAM (or refuse to open
731 * a dirty VHDX file read-only) */
732 int vhdx_parse_log(BlockDriverState *bs, BDRVVHDXState *s, bool *flushed,
733 Error **errp)
734 {
735 int ret = 0;
736 VHDXHeader *hdr;
737 VHDXLogSequence logs = { 0 };
738
739 hdr = s->headers[s->curr_header];
740
741 *flushed = false;
742
743 /* s->log.hdr is freed in vhdx_close() */
744 if (s->log.hdr == NULL) {
745 s->log.hdr = qemu_blockalign(bs, sizeof(VHDXLogEntryHeader));
746 }
747
748 s->log.offset = hdr->log_offset;
749 s->log.length = hdr->log_length;
750
751 if (s->log.offset < VHDX_LOG_MIN_SIZE ||
752 s->log.offset % VHDX_LOG_MIN_SIZE) {
753 ret = -EINVAL;
754 goto exit;
755 }
756
757 /* per spec, only log version of 0 is supported */
758 if (hdr->log_version != 0) {
759 ret = -EINVAL;
760 goto exit;
761 }
762
763 /* If either the log guid, or log length is zero,
764 * then a replay log is not present */
765 if (guid_eq(hdr->log_guid, zero_guid)) {
766 goto exit;
767 }
768
769 if (hdr->log_length == 0) {
770 goto exit;
771 }
772
773 if (hdr->log_length % VHDX_LOG_MIN_SIZE) {
774 ret = -EINVAL;
775 goto exit;
776 }
777
778
779 /* The log is present, we need to find if and where there is an active
780 * sequence of valid entries present in the log. */
781
782 ret = vhdx_log_search(bs, s, &logs);
783 if (ret < 0) {
784 goto exit;
785 }
786
787 if (logs.valid) {
788 if (bs->read_only) {
789 ret = -EPERM;
790 error_setg(errp,
791 "VHDX image file '%s' opened read-only, but "
792 "contains a log that needs to be replayed",
793 bs->filename);
794 error_append_hint(errp, "To replay the log, run:\n"
795 "qemu-img check -r all '%s'\n",
796 bs->filename);
797 goto exit;
798 }
799 /* now flush the log */
800 ret = vhdx_log_flush(bs, s, &logs);
801 if (ret < 0) {
802 goto exit;
803 }
804 *flushed = true;
805 }
806
807
808 exit:
809 return ret;
810 }
811
812
813
814 static void vhdx_log_raw_to_le_sector(VHDXLogDescriptor *desc,
815 VHDXLogDataSector *sector, void *data,
816 uint64_t seq)
817 {
818 /* 8 + 4084 + 4 = 4096, 1 log sector */
819 memcpy(&desc->leading_bytes, data, 8);
820 data += 8;
821 cpu_to_le64s(&desc->leading_bytes);
822 memcpy(sector->data, data, 4084);
823 data += 4084;
824 memcpy(&desc->trailing_bytes, data, 4);
825 cpu_to_le32s(&desc->trailing_bytes);
826 data += 4;
827
828 sector->sequence_high = (uint32_t) (seq >> 32);
829 sector->sequence_low = (uint32_t) (seq & 0xffffffff);
830 sector->data_signature = VHDX_LOG_DATA_SIGNATURE;
831
832 vhdx_log_desc_le_export(desc);
833 vhdx_log_data_le_export(sector);
834 }
835
836
837 static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s,
838 void *data, uint32_t length, uint64_t offset)
839 {
840 int ret = 0;
841 void *buffer = NULL;
842 void *merged_sector = NULL;
843 void *data_tmp, *sector_write;
844 unsigned int i;
845 int sector_offset;
846 uint32_t desc_sectors, sectors, total_length;
847 uint32_t sectors_written = 0;
848 uint32_t aligned_length;
849 uint32_t leading_length = 0;
850 uint32_t trailing_length = 0;
851 uint32_t partial_sectors = 0;
852 uint32_t bytes_written = 0;
853 uint64_t file_offset;
854 VHDXHeader *header;
855 VHDXLogEntryHeader new_hdr;
856 VHDXLogDescriptor *new_desc = NULL;
857 VHDXLogDataSector *data_sector = NULL;
858 MSGUID new_guid = { 0 };
859
860 header = s->headers[s->curr_header];
861
862 /* need to have offset read data, and be on 4096 byte boundary */
863
864 if (length > header->log_length) {
865 /* no log present. we could create a log here instead of failing */
866 ret = -EINVAL;
867 goto exit;
868 }
869
870 if (guid_eq(header->log_guid, zero_guid)) {
871 vhdx_guid_generate(&new_guid);
872 vhdx_update_headers(bs, s, false, &new_guid);
873 } else {
874 /* currently, we require that the log be flushed after
875 * every write. */
876 ret = -ENOTSUP;
877 goto exit;
878 }
879
880 /* 0 is an invalid sequence number, but may also represent the first
881 * log write (or a wrapped seq) */
882 if (s->log.sequence == 0) {
883 s->log.sequence = 1;
884 }
885
886 sector_offset = offset % VHDX_LOG_SECTOR_SIZE;
887 file_offset = (offset / VHDX_LOG_SECTOR_SIZE) * VHDX_LOG_SECTOR_SIZE;
888
889 aligned_length = length;
890
891 /* add in the unaligned head and tail bytes */
892 if (sector_offset) {
893 leading_length = (VHDX_LOG_SECTOR_SIZE - sector_offset);
894 leading_length = leading_length > length ? length : leading_length;
895 aligned_length -= leading_length;
896 partial_sectors++;
897 }
898
899 sectors = aligned_length / VHDX_LOG_SECTOR_SIZE;
900 trailing_length = aligned_length - (sectors * VHDX_LOG_SECTOR_SIZE);
901 if (trailing_length) {
902 partial_sectors++;
903 }
904
905 sectors += partial_sectors;
906
907 /* sectors is now how many sectors the data itself takes, not
908 * including the header and descriptor metadata */
909
910 new_hdr = (VHDXLogEntryHeader) {
911 .signature = VHDX_LOG_SIGNATURE,
912 .tail = s->log.tail,
913 .sequence_number = s->log.sequence,
914 .descriptor_count = sectors,
915 .reserved = 0,
916 .flushed_file_offset = bdrv_getlength(bs->file->bs),
917 .last_file_offset = bdrv_getlength(bs->file->bs),
918 };
919
920 new_hdr.log_guid = header->log_guid;
921
922 desc_sectors = vhdx_compute_desc_sectors(new_hdr.descriptor_count);
923
924 total_length = (desc_sectors + sectors) * VHDX_LOG_SECTOR_SIZE;
925 new_hdr.entry_length = total_length;
926
927 vhdx_log_entry_hdr_le_export(&new_hdr);
928
929 buffer = qemu_blockalign(bs, total_length);
930 memcpy(buffer, &new_hdr, sizeof(new_hdr));
931
932 new_desc = buffer + sizeof(new_hdr);
933 data_sector = buffer + (desc_sectors * VHDX_LOG_SECTOR_SIZE);
934 data_tmp = data;
935
936 /* All log sectors are 4KB, so for any partial sectors we must
937 * merge the data with preexisting data from the final file
938 * destination */
939 merged_sector = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
940
941 for (i = 0; i < sectors; i++) {
942 new_desc->signature = VHDX_LOG_DESC_SIGNATURE;
943 new_desc->sequence_number = s->log.sequence;
944 new_desc->file_offset = file_offset;
945
946 if (i == 0 && leading_length) {
947 /* partial sector at the front of the buffer */
948 ret = bdrv_pread(bs->file, file_offset, merged_sector,
949 VHDX_LOG_SECTOR_SIZE);
950 if (ret < 0) {
951 goto exit;
952 }
953 memcpy(merged_sector + sector_offset, data_tmp, leading_length);
954 bytes_written = leading_length;
955 sector_write = merged_sector;
956 } else if (i == sectors - 1 && trailing_length) {
957 /* partial sector at the end of the buffer */
958 ret = bdrv_pread(bs->file,
959 file_offset,
960 merged_sector + trailing_length,
961 VHDX_LOG_SECTOR_SIZE - trailing_length);
962 if (ret < 0) {
963 goto exit;
964 }
965 memcpy(merged_sector, data_tmp, trailing_length);
966 bytes_written = trailing_length;
967 sector_write = merged_sector;
968 } else {
969 bytes_written = VHDX_LOG_SECTOR_SIZE;
970 sector_write = data_tmp;
971 }
972
973 /* populate the raw sector data into the proper structures,
974 * as well as update the descriptor, and convert to proper
975 * endianness */
976 vhdx_log_raw_to_le_sector(new_desc, data_sector, sector_write,
977 s->log.sequence);
978
979 data_tmp += bytes_written;
980 data_sector++;
981 new_desc++;
982 file_offset += VHDX_LOG_SECTOR_SIZE;
983 }
984
985 /* checksum covers entire entry, from the log header through the
986 * last data sector */
987 vhdx_update_checksum(buffer, total_length,
988 offsetof(VHDXLogEntryHeader, checksum));
989
990 /* now write to the log */
991 ret = vhdx_log_write_sectors(bs, &s->log, &sectors_written, buffer,
992 desc_sectors + sectors);
993 if (ret < 0) {
994 goto exit;
995 }
996
997 if (sectors_written != desc_sectors + sectors) {
998 /* instead of failing, we could flush the log here */
999 ret = -EINVAL;
1000 goto exit;
1001 }
1002
1003 s->log.sequence++;
1004 /* write new tail */
1005 s->log.tail = s->log.write;
1006
1007 exit:
1008 qemu_vfree(buffer);
1009 qemu_vfree(merged_sector);
1010 return ret;
1011 }
1012
1013 /* Perform a log write, and then immediately flush the entire log */
1014 int vhdx_log_write_and_flush(BlockDriverState *bs, BDRVVHDXState *s,
1015 void *data, uint32_t length, uint64_t offset)
1016 {
1017 int ret = 0;
1018 VHDXLogSequence logs = { .valid = true,
1019 .count = 1,
1020 .hdr = { 0 } };
1021
1022
1023 /* Make sure data written (new and/or changed blocks) is stable
1024 * on disk, before creating log entry */
1025 bdrv_flush(bs);
1026 ret = vhdx_log_write(bs, s, data, length, offset);
1027 if (ret < 0) {
1028 goto exit;
1029 }
1030 logs.log = s->log;
1031
1032 /* Make sure log is stable on disk */
1033 bdrv_flush(bs);
1034 ret = vhdx_log_flush(bs, s, &logs);
1035 if (ret < 0) {
1036 goto exit;
1037 }
1038
1039 s->log = logs.log;
1040
1041 exit:
1042 return ret;
1043 }
1044