Re: [Qemu-devel] [PATCH V9 3/4] raw-posix: Add full image preallocation option

[Hu Tao]

On Wed, May 28, 2014 at 07:36:26AM +0200, Markus Armbruster wrote:
> Peter Lieven <address@hidden> writes:
> 
> > Am 27.05.2014 um 21:24 schrieb Eric Blake <address@hidden>:
> >
> >> On 05/27/2014 02:22 AM, Chen Fan wrote:
> >>> From: Hu Tao <address@hidden>
> >>> 
> >>> This patch adds a new option preallocation for raw format, and implements
> >>> full preallocation by writing zeros to disk.
> >>> 
> >>> The metadata option is changed to use posix_fallocate() to ensure
> >>> subsquent writes to image file won't fail because of lack of disk space.
> >>> 
> >>> The purpose is to ensure disk space for image file. In cases
> >>> posix_fallocate() is supported, metadata option can be used, otherwise
> >>> (posix_fallocate() is not supported by filesystem, or in case of thin
> >>> provisioning), full option has to be used. User has to choose the proper
> >>> way to use.
> >>> 
> >>> Signed-off-by: Hu Tao <address@hidden>
> >>> ---
> >>> block/raw-posix.c | 61
> >>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
> >>> 1 file changed, 54 insertions(+), 7 deletions(-)
> >>> 
> >> 
> >>> @@ -1254,6 +1255,18 @@ static int raw_create(const char *filename, 
> >>> QEMUOptionParameter *options,
> >>>         if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> >>>             total_size = (options->value.n + BDRV_SECTOR_SIZE) &
> >>>                 BDRV_SECTOR_MASK;
> >>> +        } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
> >>> +            if (!options->value.s || !strcmp(options->value.s, "off")) {
> >>> +                prealloc = PREALLOC_MODE_OFF;
> >>> +            } else if (!strcmp(options->value.s, "metadata")) {
> >>> +                prealloc = PREALLOC_MODE_METADATA;
> >>> +            } else if (!strcmp(options->value.s, "full")) {
> >>> +                prealloc = PREALLOC_MODE_FULL;
> >>> +            } else {
> >> 
> >> Instead of open-coding this conversion from string to enum, can you
> >> reuse Peter's pending patch?  (Hmm, that means Peter needs to export it
> >> to somewhere public, not just blockdev.c)
> >> 
> >> https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg03772.html
> >
> > I don't mind if this function is made public. You can send a patch for it.
> > Please don't forget to remove the static declaration. You might
> > also want to remove the inline. This was just to avoid an unused
> > function error. I don't know if blockdev.c is still the right
> > place for this function then.
> 
> Probably not.  I'd rename to qapi_enum_parse(), and move it to qapi/.
> If no existing file fits, create a new one, say qapi/qapi-util.c.


Thanks. I'll use the function in next version.