" rebasing in this case (useful for renaming the backing file)\n"
" '-h' with or without a command shows this help and lists the supported formats\n"
" '-p' show progress of command (only certain commands)\n"
+ " '-S' indicates the consecutive number of bytes that must contain only zeros\n"
+ " for qemu-img to create a sparse image during conversion\n"
"\n"
"Parameters to snapshot subcommand:\n"
" 'snapshot' is the name of the snapshot to create, apply or delete\n"
/* Get image size, if specified */
if (optind < argc) {
int64_t sval;
- sval = strtosz_suffix(argv[optind++], NULL, STRTOSZ_DEFSUFFIX_B);
- if (sval < 0) {
+ char *end;
+ sval = strtosz_suffix(argv[optind++], &end, STRTOSZ_DEFSUFFIX_B);
+ if (sval < 0 || *end) {
error_report("Invalid image size specified! You may use k, M, G or "
"T suffixes for ");
error_report("kilobytes, megabytes, gigabytes and terabytes.");
return v;
}
+/*
+ * Like is_allocated_sectors, but if the buffer starts with a used sector,
+ * up to 'min' consecutive sectors containing zeros are ignored. This avoids
+ * breaking up write requests for only small sparse areas.
+ */
+static int is_allocated_sectors_min(const uint8_t *buf, int n, int *pnum,
+ int min)
+{
+ int ret;
+ int num_checked, num_used;
+
+ if (n < min) {
+ min = n;
+ }
+
+ ret = is_allocated_sectors(buf, n, pnum);
+ if (!ret) {
+ return ret;
+ }
+
+ num_used = *pnum;
+ buf += BDRV_SECTOR_SIZE * *pnum;
+ n -= *pnum;
+ num_checked = num_used;
+
+ while (n > 0) {
+ ret = is_allocated_sectors(buf, n, pnum);
+
+ buf += BDRV_SECTOR_SIZE * *pnum;
+ n -= *pnum;
+ num_checked += *pnum;
+ if (ret) {
+ num_used = num_checked;
+ } else if (*pnum >= min) {
+ break;
+ }
+ }
+
+ *pnum = num_used;
+ return 1;
+}
+
/*
* Compares two buffers sector by sector. Returns 0 if the first sector of both
* buffers matches, non-zero otherwise.
char *options = NULL;
const char *snapshot_name = NULL;
float local_progress;
+ int min_sparse = 8; /* Need at least 4k of zeros for sparse detection */
fmt = NULL;
out_fmt = "raw";
out_baseimg = NULL;
compress = 0;
for(;;) {
- c = getopt(argc, argv, "f:O:B:s:hce6o:pt:");
+ c = getopt(argc, argv, "f:O:B:s:hce6o:pS:t:");
if (c == -1) {
break;
}
case 's':
snapshot_name = optarg;
break;
+ case 'S':
+ {
+ int64_t sval;
+ char *end;
+ sval = strtosz_suffix(optarg, &end, STRTOSZ_DEFSUFFIX_B);
+ if (sval < 0 || *end) {
+ error_report("Invalid minimum zero buffer size for sparse output specified");
+ return 1;
+ }
+
+ min_sparse = sval / BDRV_SECTOR_SIZE;
+ break;
+ }
case 'p':
progress = 1;
break;
if (compress) {
QEMUOptionParameter *encryption =
get_option_parameter(param, BLOCK_OPT_ENCRYPT);
+ QEMUOptionParameter *preallocation =
+ get_option_parameter(param, BLOCK_OPT_PREALLOC);
if (!drv->bdrv_write_compressed) {
error_report("Compression not supported for this file format");
ret = -1;
goto out;
}
+
+ if (preallocation && preallocation->value.s
+ && strcmp(preallocation->value.s, "off"))
+ {
+ error_report("Compression and preallocation not supported at "
+ "the same time");
+ ret = -1;
+ goto out;
+ }
}
/* Create the new image */
ret = bdrv_read(bs[bs_i], bs_num, buf2, nlow);
if (ret < 0) {
- error_report("error while reading");
+ error_report("error while reading sector %" PRId64 ": %s",
+ bs_num, strerror(-ret));
goto out;
}
ret = bdrv_write_compressed(out_bs, sector_num, buf,
cluster_sectors);
if (ret != 0) {
- error_report("error while compressing sector %" PRId64,
- sector_num);
+ error_report("error while compressing sector %" PRId64
+ ": %s", sector_num, strerror(-ret));
goto out;
}
}
ret = bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n);
if (ret < 0) {
- error_report("error while reading");
+ error_report("error while reading sector %" PRId64 ": %s",
+ sector_num - bs_offset, strerror(-ret));
goto out;
}
/* NOTE: at the same time we convert, we do not write zero
sectors that are entirely 0, since whatever data was
already there is garbage, not 0s. */
if (!has_zero_init || out_baseimg ||
- is_allocated_sectors(buf1, n, &n1)) {
+ is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
ret = bdrv_write(out_bs, sector_num, buf1, n1);
if (ret < 0) {
- error_report("error while writing");
+ error_report("error while writing sector %" PRId64
+ ": %s", sector_num, strerror(-ret));
goto out;
}
}
*/
if (!unsafe) {
uint64_t num_sectors;
+ uint64_t old_backing_num_sectors;
+ uint64_t new_backing_num_sectors;
uint64_t sector;
int n;
uint8_t * buf_old;
buf_new = qemu_blockalign(bs, IO_BUF_SIZE);
bdrv_get_geometry(bs, &num_sectors);
+ bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
+ bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
local_progress = (float)100 /
(num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
continue;
}
- /* Read old and new backing file */
- ret = bdrv_read(bs_old_backing, sector, buf_old, n);
- if (ret < 0) {
- error_report("error while reading from old backing file");
- goto out;
+ /*
+ * Read old and new backing file and take into consideration that
+ * backing files may be smaller than the COW image.
+ */
+ if (sector >= old_backing_num_sectors) {
+ memset(buf_old, 0, n * BDRV_SECTOR_SIZE);
+ } else {
+ if (sector + n > old_backing_num_sectors) {
+ n = old_backing_num_sectors - sector;
+ }
+
+ ret = bdrv_read(bs_old_backing, sector, buf_old, n);
+ if (ret < 0) {
+ error_report("error while reading from old backing file");
+ goto out;
+ }
}
- ret = bdrv_read(bs_new_backing, sector, buf_new, n);
- if (ret < 0) {
- error_report("error while reading from new backing file");
- goto out;
+
+ if (sector >= new_backing_num_sectors) {
+ memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
+ } else {
+ if (sector + n > new_backing_num_sectors) {
+ n = new_backing_num_sectors - sector;
+ }
+
+ ret = bdrv_read(bs_new_backing, sector, buf_new, n);
+ if (ret < 0) {
+ error_report("error while reading from new backing file");
+ goto out;
+ }
}
/* If they differ, we need to write to the COW file */
projects / qemu.git / blobdiff