Revision a22f123c qemu-img.c
| b/qemu-img.c | ||
|---|---|---|
| 82 | 82 |
" rebasing in this case (useful for renaming the backing file)\n" |
| 83 | 83 |
" '-h' with or without a command shows this help and lists the supported formats\n" |
| 84 | 84 |
" '-p' show progress of command (only certain commands)\n" |
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" '-S' indicates the consecutive number of bytes that must contain only zeros\n" |
|
| 86 |
" for qemu-img to create a sparse image during conversion\n" |
|
| 85 | 87 |
"\n" |
| 86 | 88 |
"Parameters to snapshot subcommand:\n" |
| 87 | 89 |
" 'snapshot' is the name of the snapshot to create, apply or delete\n" |
| ... | ... | |
| 571 | 573 |
} |
| 572 | 574 |
|
| 573 | 575 |
/* |
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* Like is_allocated_sectors, but if the buffer starts with a used sector, |
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* up to 'min' consecutive sectors containing zeros are ignored. This avoids |
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* breaking up write requests for only small sparse areas. |
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*/ |
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static int is_allocated_sectors_min(const uint8_t *buf, int n, int *pnum, |
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int min) |
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{
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int ret; |
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int num_checked, num_used; |
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|
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if (n < min) {
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min = n; |
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} |
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ret = is_allocated_sectors(buf, n, pnum); |
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if (!ret) {
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return ret; |
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} |
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|
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num_used = *pnum; |
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buf += BDRV_SECTOR_SIZE * *pnum; |
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n -= *pnum; |
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num_checked = num_used; |
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|
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while (n > 0) {
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ret = is_allocated_sectors(buf, n, pnum); |
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|
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buf += BDRV_SECTOR_SIZE * *pnum; |
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n -= *pnum; |
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num_checked += *pnum; |
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if (ret) {
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num_used = num_checked; |
|
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} else if (*pnum >= min) {
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break; |
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} |
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} |
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|
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*pnum = num_used; |
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return 1; |
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} |
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|
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/* |
|
| 574 | 618 |
* Compares two buffers sector by sector. Returns 0 if the first sector of both |
| 575 | 619 |
* buffers matches, non-zero otherwise. |
| 576 | 620 |
* |
| ... | ... | |
| 620 | 664 |
char *options = NULL; |
| 621 | 665 |
const char *snapshot_name = NULL; |
| 622 | 666 |
float local_progress; |
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int min_sparse = 8; /* Need at least 4k of zeros for sparse detection */ |
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| 623 | 668 |
|
| 624 | 669 |
fmt = NULL; |
| 625 | 670 |
out_fmt = "raw"; |
| ... | ... | |
| 627 | 672 |
out_baseimg = NULL; |
| 628 | 673 |
compress = 0; |
| 629 | 674 |
for(;;) {
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c = getopt(argc, argv, "f:O:B:s:hce6o:pt:"); |
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c = getopt(argc, argv, "f:O:B:s:hce6o:pS:t:");
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| 631 | 676 |
if (c == -1) {
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| 632 | 677 |
break; |
| 633 | 678 |
} |
| ... | ... | |
| 662 | 707 |
case 's': |
| 663 | 708 |
snapshot_name = optarg; |
| 664 | 709 |
break; |
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case 'S': |
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{
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int64_t sval; |
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sval = strtosz_suffix(optarg, NULL, STRTOSZ_DEFSUFFIX_B); |
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if (sval < 0) {
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error_report("Invalid minimum zero buffer size for sparse output specified");
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return 1; |
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} |
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|
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min_sparse = sval / BDRV_SECTOR_SIZE; |
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break; |
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} |
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| 665 | 722 |
case 'p': |
| 666 | 723 |
progress = 1; |
| 667 | 724 |
break; |
| ... | ... | |
| 970 | 1027 |
sectors that are entirely 0, since whatever data was |
| 971 | 1028 |
already there is garbage, not 0s. */ |
| 972 | 1029 |
if (!has_zero_init || out_baseimg || |
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is_allocated_sectors(buf1, n, &n1)) {
|
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is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
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| 974 | 1031 |
ret = bdrv_write(out_bs, sector_num, buf1, n1); |
| 975 | 1032 |
if (ret < 0) {
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| 976 | 1033 |
error_report("error while writing sector %" PRId64
|
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