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block: bdrv_has_zero_init

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This fixes the problem that qemu-img's use of no_zero_init only considered the
no_zero_init flag of the format driver, but not of the underlying protocols.

Between the raw/file split and this fix, converting to host devices is broken.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2010-04-14 17:30:35 +02:00
parent 66f82ceed6
commit f2feebbd93
3 changed files with 18 additions and 2 deletions
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13
block.c
View File

@ -1282,6 +1282,19 @@ void bdrv_flush_all(void)
}
}
int bdrv_has_zero_init(BlockDriverState *bs)
{
assert(bs->drv);
if (bs->drv->no_zero_init) {
return 0;
} else if (bs->file) {
return bdrv_has_zero_init(bs->file);
}
return 1;
}
/*
* Returns true iff the specified sector is present in the disk image. Drivers
* not implementing the functionality are assumed to not support backing files,

1
block.h
View File

@ -122,6 +122,7 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
void bdrv_flush(BlockDriverState *bs);
void bdrv_flush_all(void);
int bdrv_has_zero_init(BlockDriverState *bs);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum);

6
qemu-img.c
View File

@ -732,6 +732,8 @@ static int img_convert(int argc, char **argv)
/* signal EOF to align */
bdrv_write_compressed(out_bs, 0, NULL, 0);
} else {
int has_zero_init = bdrv_has_zero_init(out_bs);
sector_num = 0; // total number of sectors converted so far
for(;;) {
nb_sectors = total_sectors - sector_num;
@ -755,7 +757,7 @@ static int img_convert(int argc, char **argv)
if (n > bs_offset + bs_sectors - sector_num)
n = bs_offset + bs_sectors - sector_num;
if (!drv->no_zero_init) {
if (has_zero_init) {
/* 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
@ -788,7 +790,7 @@ static int img_convert(int argc, char **argv)
If the output is to a host device, we also write out
sectors that are entirely 0, since whatever data was
already there is garbage, not 0s. */
if (drv->no_zero_init || out_baseimg ||
if (!has_zero_init || out_baseimg ||
is_allocated_sectors(buf1, n, &n1)) {
if (bdrv_write(out_bs, sector_num, buf1, n1) < 0)
error("error while writing");