On 04/09/2014 01:12 AM, Hu Tao wrote: > and avoid converting it back later. > > Signed-off-by: Hu Tao <hu...@cn.fujitsu.com> > --- > block/qcow2.c | 8 ++++---- > block/raw-posix.c | 4 ++-- > block/raw-win32.c | 4 ++-- > 3 files changed, 8 insertions(+), 8 deletions(-) >
> @@ -1777,7 +1777,7 @@ static int qcow2_create(const char *filename,
> QEMUOptionParameter *options,
> /* Read out options */
> while (options && options->name) {
> if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> - sectors = options->value.n / 512;
> + size = options->value.n & BDRV_SECTOR_MASK;
The old code rounds down, which in my opinion is a bug. The qcow2 file
format has a size parameter that is recorded in bytes, not sectors, so I
see no technical reason why we can't support a file where the last
sector is partial. If I request a size 1025 bytes, I should get a file
with 3 sectors (where the last sector is partial), and not a file with 2
sectors (where the last byte that I requested cannot be accessed). Your
patch preserves the pre-existing behavior, but I think this series
should consider fixing the bug and allowing for the creation of a qcow2
file whose size exposed to the guest is NOT a multiple of sector size,
or at least, at a bare minimum, round my request UP to the nearest
sector size rather than giving me something smaller than what I asked for.
> +++ b/block/raw-posix.c
> @@ -1246,7 +1246,7 @@ static int raw_create(const char *filename,
> QEMUOptionParameter *options,
> /* Read out options */
> while (options && options->name) {
> if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> - total_size = options->value.n / BDRV_SECTOR_SIZE;
> + total_size = options->value.n & BDRV_SECTOR_MASK;
Another case of incorrectly rounding down.
> +++ b/block/raw-win32.c
> @@ -486,7 +486,7 @@ static int raw_create(const char *filename,
> QEMUOptionParameter *options,
> /* Read out options */
> while (options && options->name) {
> if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> - total_size = options->value.n / 512;
> + total_size = options->value.n & BDRV_SECTOR_MASK;
and another
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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