[PATCH v11 08/13] copy-on-read: add support for BDRV_REQ_PREFETCH to COR-filter
mreitz at redhat.com
Wed Oct 14 12:40:20 UTC 2020
On 12.10.20 19:43, Andrey Shinkevich wrote:
> Add support for the BDRV_REQ_PREFETCH flag to the supported_write_flags
> of the COR-filter.
> Signed-off-by: Andrey Shinkevich <andrey.shinkevich at virtuozzo.com>
> block/copy-on-read.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/block/copy-on-read.c b/block/copy-on-read.c
> index dfbd6ad..b136895 100644
> --- a/block/copy-on-read.c
> +++ b/block/copy-on-read.c
> @@ -50,6 +50,7 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
> return -EINVAL;
> + bs->supported_read_flags = BDRV_REQ_PREFETCH;
> bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
> (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
Then we mustn’t let cor_co_preadv_part() pass the flag on to
bdrv_co_preadv_part() unless BDRV_REQ_COPY_ON_READ is set, too. I
suspect the following patch is going to do that, but in the meantime the
code is wrong.
Perhaps just swap both patches?
And by the way, I’m also missing a patch that makes the block layer
evaluate supported_read_flags and e.g. strip BDRV_REQ_PREFETCH if it
isn’t supported, before it gets passed to such a block driver.
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