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New qemu-img convert -B option, by Marc Bevand.

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git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4672 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
ths 2008-06-05 21:53:49 +00:00
parent ff7ab59f40
commit f58c7b3545
4 changed files with 76 additions and 8 deletions
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27
block.c
View File

@ -884,6 +884,33 @@ void bdrv_flush(BlockDriverState *bs)
bdrv_flush(bs->backing_hd);
}
/*
* Returns true iff the specified sector is present in the disk image. Drivers
* not implementing the functionality are assumed to not support backing files,
* hence all their sectors are reported as allocated.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the specified sector) that are known to be in the same
* allocated/unallocated state.
*
* 'nb_sectors' is the max value 'pnum' should be set to.
*/
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum)
{
int64_t n;
if (!bs->drv->bdrv_is_allocated) {
if (sector_num >= bs->total_sectors) {
*pnum = 0;
return 0;
}
n = bs->total_sectors - sector_num;
*pnum = (n < nb_sectors) ? (n) : (nb_sectors);
return 1;
}
return bs->drv->bdrv_is_allocated(bs, sector_num, nb_sectors, pnum);
}
#ifndef QEMU_IMG
void bdrv_info(void)
{

2
block.h
View File

@ -99,6 +99,8 @@ int qemu_key_check(BlockDriverState *bs, const char *name);
/* Ensure contents are flushed to disk. */
void bdrv_flush(BlockDriverState *bs);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum);
#define BDRV_TYPE_HD 0
#define BDRV_TYPE_CDROM 1

47
qemu-img.c
View File

@ -55,13 +55,17 @@ static void help(void)
"Command syntax:\n"
" create [-e] [-6] [-b base_image] [-f fmt] filename [size]\n"
" commit [-f fmt] filename\n"
" convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] filename [filename2 [...]] output_filename\n"
" convert [-c] [-e] [-6] [-f fmt] [-O output_fmt] [-B output_base_image] filename [filename2 [...]] output_filename\n"
" info [-f fmt] filename\n"
"\n"
"Command parameters:\n"
" 'filename' is a disk image filename\n"
" 'base_image' is the read-only disk image which is used as base for a copy on\n"
" write image; the copy on write image only stores the modified data\n"
" 'output_base_image' forces the output image to be created as a copy on write\n"
" image of the specified base image; 'output_base_image' should have the same\n"
" content as the input's base image, however the path, image format, etc may\n"
" differ\n"
" 'fmt' is the disk image format. It is guessed automatically in most cases\n"
" 'size' is the disk image size in kilobytes. Optional suffixes 'M' (megabyte)\n"
" and 'G' (gigabyte) are supported\n"
@ -350,6 +354,13 @@ static int is_not_zero(const uint8_t *sector, int len)
return 0;
}
/*
* Returns true iff the first sector pointed to by 'buf' contains at least
* a non-NUL byte.
*
* 'pnum' is set to the number of sectors (including and immediately following
* the first one) that are known to be in the same allocated/unallocated state.
*/
static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum)
{
int v, i;
@ -373,7 +384,7 @@ static int is_allocated_sectors(const uint8_t *buf, int n, int *pnum)
static int img_convert(int argc, char **argv)
{
int c, ret, n, n1, bs_n, bs_i, flags, cluster_size, cluster_sectors;
const char *fmt, *out_fmt, *out_filename;
const char *fmt, *out_fmt, *out_baseimg, *out_filename;
BlockDriver *drv;
BlockDriverState **bs, *out_bs;
int64_t total_sectors, nb_sectors, sector_num, bs_offset;
@ -384,9 +395,10 @@ static int img_convert(int argc, char **argv)
fmt = NULL;
out_fmt = "raw";
out_baseimg = NULL;
flags = 0;
for(;;) {
c = getopt(argc, argv, "f:O:hce6");
c = getopt(argc, argv, "f:O:B:hce6");
if (c == -1)
break;
switch(c) {
@ -399,6 +411,9 @@ static int img_convert(int argc, char **argv)
case 'O':
out_fmt = optarg;
break;
case 'B':
out_baseimg = optarg;
break;
case 'c':
flags |= BLOCK_FLAG_COMPRESS;
break;
@ -415,6 +430,9 @@ static int img_convert(int argc, char **argv)
if (bs_n < 1) help();
out_filename = argv[argc - 1];
if (bs_n > 1 && out_baseimg)
error("-B makes no sense when concatenating multiple input images");
bs = calloc(bs_n, sizeof(BlockDriverState *));
if (!bs)
@ -441,7 +459,7 @@ static int img_convert(int argc, char **argv)
if (flags & BLOCK_FLAG_ENCRYPT && flags & BLOCK_FLAG_COMPRESS)
error("Compression and encryption not supported at the same time");
ret = bdrv_create(drv, out_filename, total_sectors, NULL, flags);
ret = bdrv_create(drv, out_filename, total_sectors, out_baseimg, flags);
if (ret < 0) {
if (ret == -ENOTSUP) {
error("Formatting not supported for file format '%s'", fmt);
@ -520,7 +538,7 @@ static int img_convert(int argc, char **argv)
/* signal EOF to align */
bdrv_write_compressed(out_bs, 0, NULL, 0);
} else {
sector_num = 0;
sector_num = 0; // total number of sectors converted so far
for(;;) {
nb_sectors = total_sectors - sector_num;
if (nb_sectors <= 0)
@ -543,6 +561,20 @@ static int img_convert(int argc, char **argv)
if (n > bs_offset + bs_sectors - sector_num)
n = bs_offset + bs_sectors - sector_num;
/* If the output image is being created as a copy on write image,
assume that sectors which are unallocated in the input image
are present in both the output's and input's base images (no
need to copy them). */
if (out_baseimg) {
if (!bdrv_is_allocated(bs[bs_i], sector_num - bs_offset, n, &n1)) {
sector_num += n1;
continue;
}
/* The next 'n1' sectors are allocated in the input image. Copy
only those as they may be followed by unallocated sectors. */
n = n1;
}
if (bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n) < 0)
error("error while reading");
/* NOTE: at the same time we convert, we do not write zero
@ -550,7 +582,10 @@ static int img_convert(int argc, char **argv)
should add a specific call to have the info to go faster */
buf1 = buf;
while (n > 0) {
if (is_allocated_sectors(buf1, n, &n1)) {
/* If the output image is being created as a copy on write image,
copy all sectors even the ones containing only NUL bytes,
because they may differ from the sectors in the base image. */
if (out_baseimg || is_allocated_sectors(buf1, n, &n1)) {
if (bdrv_write(out_bs, sector_num, buf1, n1) < 0)
error("error while writing");
}

8
qemu-img.texi
View File

@ -10,7 +10,7 @@ The following commands are supported:
@table @option
@item create [-e] [-6] [-b @var{base_image}] [-f @var{fmt}] @var{filename} [@var{size}]
@item commit [-f @var{fmt}] @var{filename}
@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] @var{filename} [@var{filename2} [...]] @var{output_filename}
@item convert [-c] [-e] [-6] [-f @var{fmt}] [-O @var{output_fmt}] [-B @var{output_base_image}] @var{filename} [@var{filename2} [...]] @var{output_filename}
@item info [-f @var{fmt}] @var{filename}
@end table
@ -21,7 +21,11 @@ Command parameters:
@item base_image
is the read-only disk image which is used as base for a copy on
write image; the copy on write image only stores the modified data
@item output_base_image
forces the output image to be created as a copy on write
image of the specified base image; @code{output_base_image} should have the same
content as the input's base image, however the path, image format, etc may
differ
@item fmt
is the disk image format. It is guessed automatically in most cases. The following formats are supported: