Commit f58c7b354595228e10f023e86b80a7bab527186a
1 parent
ff7ab59f
New qemu-img convert -B option, by Marc Bevand.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4672 c046a42c-6fe2-441c-8c8c-71466251a162
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4 changed files
with
76 additions
and
8 deletions
block.c
... | ... | @@ -884,6 +884,33 @@ void bdrv_flush(BlockDriverState *bs) |
884 | 884 | bdrv_flush(bs->backing_hd); |
885 | 885 | } |
886 | 886 | |
887 | +/* | |
888 | + * Returns true iff the specified sector is present in the disk image. Drivers | |
889 | + * not implementing the functionality are assumed to not support backing files, | |
890 | + * hence all their sectors are reported as allocated. | |
891 | + * | |
892 | + * 'pnum' is set to the number of sectors (including and immediately following | |
893 | + * the specified sector) that are known to be in the same | |
894 | + * allocated/unallocated state. | |
895 | + * | |
896 | + * 'nb_sectors' is the max value 'pnum' should be set to. | |
897 | + */ | |
898 | +int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, | |
899 | + int *pnum) | |
900 | +{ | |
901 | + int64_t n; | |
902 | + if (!bs->drv->bdrv_is_allocated) { | |
903 | + if (sector_num >= bs->total_sectors) { | |
904 | + *pnum = 0; | |
905 | + return 0; | |
906 | + } | |
907 | + n = bs->total_sectors - sector_num; | |
908 | + *pnum = (n < nb_sectors) ? (n) : (nb_sectors); | |
909 | + return 1; | |
910 | + } | |
911 | + return bs->drv->bdrv_is_allocated(bs, sector_num, nb_sectors, pnum); | |
912 | +} | |
913 | + | |
887 | 914 | #ifndef QEMU_IMG |
888 | 915 | void bdrv_info(void) |
889 | 916 | { | ... | ... |
block.h
... | ... | @@ -99,6 +99,8 @@ int qemu_key_check(BlockDriverState *bs, const char *name); |
99 | 99 | |
100 | 100 | /* Ensure contents are flushed to disk. */ |
101 | 101 | void bdrv_flush(BlockDriverState *bs); |
102 | +int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, | |
103 | + int *pnum); | |
102 | 104 | |
103 | 105 | #define BDRV_TYPE_HD 0 |
104 | 106 | #define BDRV_TYPE_CDROM 1 | ... | ... |
qemu-img.c
... | ... | @@ -55,13 +55,17 @@ static void help(void) |
55 | 55 | "Command syntax:\n" |
56 | 56 | " create [-e] [-6] [-b base_image] [-f fmt] filename [size]\n" |
57 | 57 | " commit [-f fmt] filename\n" |
58 | - " convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] filename [filename2 [...]] output_filename\n" | |
58 | + " convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] [-B output_base_image] filename [filename2 [...]] output_filename\n" | |
59 | 59 | " info [-f fmt] filename\n" |
60 | 60 | "\n" |
61 | 61 | "Command parameters:\n" |
62 | 62 | " 'filename' is a disk image filename\n" |
63 | 63 | " 'base_image' is the read-only disk image which is used as base for a copy on\n" |
64 | 64 | " write image; the copy on write image only stores the modified data\n" |
65 | + " 'output_base_image' forces the output image to be created as a copy on write\n" | |
66 | + " image of the specified base image; 'output_base_image' should have the same\n" | |
67 | + " content as the input's base image, however the path, image format, etc may\n" | |
68 | + " differ\n" | |
65 | 69 | " 'fmt' is the disk image format. It is guessed automatically in most cases\n" |
66 | 70 | " 'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte)\n" |
67 | 71 | " and 'G' (gigabyte) are supported\n" |
... | ... | @@ -350,6 +354,13 @@ static int is_not_zero(const uint8_t *sector, int len) |
350 | 354 | return 0; |
351 | 355 | } |
352 | 356 | |
357 | +/* | |
358 | + * Returns true iff the first sector pointed to by 'buf' contains at least | |
359 | + * a non-NUL byte. | |
360 | + * | |
361 | + * 'pnum' is set to the number of sectors (including and immediately following | |
362 | + * the first one) that are known to be in the same allocated/unallocated state. | |
363 | + */ | |
353 | 364 | static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum) |
354 | 365 | { |
355 | 366 | int v, i; |
... | ... | @@ -373,7 +384,7 @@ static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum) |
373 | 384 | static int img_convert(int argc, char **argv) |
374 | 385 | { |
375 | 386 | int c, ret, n, n1, bs_n, bs_i, flags, cluster_size, cluster_sectors; |
376 | - const char *fmt, *out_fmt, *out_filename; | |
387 | + const char *fmt, *out_fmt, *out_baseimg, *out_filename; | |
377 | 388 | BlockDriver *drv; |
378 | 389 | BlockDriverState **bs, *out_bs; |
379 | 390 | int64_t total_sectors, nb_sectors, sector_num, bs_offset; |
... | ... | @@ -384,9 +395,10 @@ static int img_convert(int argc, char **argv) |
384 | 395 | |
385 | 396 | fmt = NULL; |
386 | 397 | out_fmt = "raw"; |
398 | + out_baseimg = NULL; | |
387 | 399 | flags = 0; |
388 | 400 | for(;;) { |
389 | - c = getopt(argc, argv, "f:O:hce6"); | |
401 | + c = getopt(argc, argv, "f:O:B:hce6"); | |
390 | 402 | if (c == -1) |
391 | 403 | break; |
392 | 404 | switch(c) { |
... | ... | @@ -399,6 +411,9 @@ static int img_convert(int argc, char **argv) |
399 | 411 | case 'O': |
400 | 412 | out_fmt = optarg; |
401 | 413 | break; |
414 | + case 'B': | |
415 | + out_baseimg = optarg; | |
416 | + break; | |
402 | 417 | case 'c': |
403 | 418 | flags |= BLOCK_FLAG_COMPRESS; |
404 | 419 | break; |
... | ... | @@ -415,6 +430,9 @@ static int img_convert(int argc, char **argv) |
415 | 430 | if (bs_n < 1) help(); |
416 | 431 | |
417 | 432 | out_filename = argv[argc - 1]; |
433 | + | |
434 | + if (bs_n > 1 && out_baseimg) | |
435 | + error("-B makes no sense when concatenating multiple input images"); | |
418 | 436 | |
419 | 437 | bs = calloc(bs_n, sizeof(BlockDriverState *)); |
420 | 438 | if (!bs) |
... | ... | @@ -441,7 +459,7 @@ static int img_convert(int argc, char **argv) |
441 | 459 | if (flags & BLOCK_FLAG_ENCRYPT && flags & BLOCK_FLAG_COMPRESS) |
442 | 460 | error("Compression and encryption not supported at the same time"); |
443 | 461 | |
444 | - ret = bdrv_create(drv, out_filename, total_sectors, NULL, flags); | |
462 | + ret = bdrv_create(drv, out_filename, total_sectors, out_baseimg, flags); | |
445 | 463 | if (ret < 0) { |
446 | 464 | if (ret == -ENOTSUP) { |
447 | 465 | error("Formatting not supported for file format '%s'", fmt); |
... | ... | @@ -520,7 +538,7 @@ static int img_convert(int argc, char **argv) |
520 | 538 | /* signal EOF to align */ |
521 | 539 | bdrv_write_compressed(out_bs, 0, NULL, 0); |
522 | 540 | } else { |
523 | - sector_num = 0; | |
541 | + sector_num = 0; // total number of sectors converted so far | |
524 | 542 | for(;;) { |
525 | 543 | nb_sectors = total_sectors - sector_num; |
526 | 544 | if (nb_sectors <= 0) |
... | ... | @@ -543,6 +561,20 @@ static int img_convert(int argc, char **argv) |
543 | 561 | if (n > bs_offset + bs_sectors - sector_num) |
544 | 562 | n = bs_offset + bs_sectors - sector_num; |
545 | 563 | |
564 | + /* If the output image is being created as a copy on write image, | |
565 | + assume that sectors which are unallocated in the input image | |
566 | + are present in both the output's and input's base images (no | |
567 | + need to copy them). */ | |
568 | + if (out_baseimg) { | |
569 | + if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, n, &n1)) { | |
570 | + sector_num += n1; | |
571 | + continue; | |
572 | + } | |
573 | + /* The next 'n1' sectors are allocated in the input image. Copy | |
574 | + only those as they may be followed by unallocated sectors. */ | |
575 | + n = n1; | |
576 | + } | |
577 | + | |
546 | 578 | if (bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n) < 0) |
547 | 579 | error("error while reading"); |
548 | 580 | /* NOTE: at the same time we convert, we do not write zero |
... | ... | @@ -550,7 +582,10 @@ static int img_convert(int argc, char **argv) |
550 | 582 | should add a specific call to have the info to go faster */ |
551 | 583 | buf1 = buf; |
552 | 584 | while (n > 0) { |
553 | - if (is_allocated_sectors(buf1, n, &n1)) { | |
585 | + /* If the output image is being created as a copy on write image, | |
586 | + copy all sectors even the ones containing only NUL bytes, | |
587 | + because they may differ from the sectors in the base image. */ | |
588 | + if (out_baseimg || is_allocated_sectors(buf1, n, &n1)) { | |
554 | 589 | if (bdrv_write(out_bs, sector_num, buf1, n1) < 0) |
555 | 590 | error("error while writing"); |
556 | 591 | } | ... | ... |
qemu-img.texi
... | ... | @@ -10,7 +10,7 @@ The following commands are supported: |
10 | 10 | @table @option |
11 | 11 | @item create [-e] [-6] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}] |
12 | 12 | @item commit [-f @var{fmt}] @var{filename} |
13 | -@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] @var{filename} [@var{filename2} [...]] @var{output_filename} | |
13 | +@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] [-B @var{output_base_image}] @var{filename} [@var{filename2} [...]] @var{output_filename} | |
14 | 14 | @item info [-f @var{fmt}] @var{filename} |
15 | 15 | @end table |
16 | 16 | |
... | ... | @@ -21,7 +21,11 @@ Command parameters: |
21 | 21 | @item base_image |
22 | 22 | is the read-only disk image which is used as base for a copy on |
23 | 23 | write image; the copy on write image only stores the modified data |
24 | - | |
24 | +@item output_base_image | |
25 | +forces the output image to be created as a copy on write | |
26 | +image of the specified base image; @code{output_base_image} should have the same | |
27 | +content as the input's base image, however the path, image format, etc may | |
28 | +differ | |
25 | 29 | @item fmt |
26 | 30 | is the disk image format. It is guessed automatically in most cases. The following formats are supported: |
27 | 31 | ... | ... |