Il 29/02/2012 15:37, Stefan Hajnoczi ha scritto:
>> Makefile.objs | 2 +-
>> block/blkmirror.c | 153
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> docs/blkmirror.txt | 16 ++++++
>> 3 files changed, 170 insertions(+), 1 deletions(-)
>> create mode 100644 block/blkmirror.c
>> create mode 100644 docs/blkmirror.txt
>
> Mostly happy here, I just recommend tweaking the name of this block
> driver and documenting clearly that this is not a general-purpose
> mirroring driver, given that it points image B's backing file at image
> A's backing file. I see this driver as internal functionality and
> it's fairly easy for users to misuse it and be surprised by the
> results.
I was thinking of adding something like no_user later.
And of course docs/blkmirror.txt is totally obsolete, I'll merge it into
block/blkmirror.c.
>> +static int blkmirror_co_writev(BlockDriverState *bs,
>> + int64_t sector_num, int nb_sectors,
>> + QEMUIOVector *qiov)
>> +{
>> + int ret;
>> +
>> + /* bs->backing_hd is set after initialization. */
>> + bs->file->backing_hd = bs->backing_hd;
>> +
>> + ret = bdrv_co_writev(bs->backing_hd, sector_num, nb_sectors, qiov);
>> + if (ret >= 0) {
>> + ret = bdrv_co_writev(bs->file, sector_num, nb_sectors, qiov);
>> + }
>> +
>> + return ret;
>> +}
>
> Have you done performance tests? It seems suboptimal to use
> .bdrv_co_writev() and perform writes sequentially, even with
> cache=unsafe.
No, not yet. I can add back AIO here.
Paolo
