Re: [RFC PATCH V2 02/11] hw/block/nvme: open code for volatile write cache

[Klaus Jensen]

On Jan 17 23:53, Minwoo Im wrote:
> Volatile Write Cache(VWC) feature is set in nvme_ns_setup() in the
> initial time.  This feature is related to block device backed,  but this
> feature is controlled in controller level via Set/Get Features command.
> 
> This patch removed dependency between nvme and nvme-ns to manage the VWC
> flag value.  Also, it open coded the Get Features for VWC to check all
> namespaces attached to the controller, and if false detected, return
> directly false.
> 
> Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
> ---
>  hw/block/nvme-ns.c |  4 ----
>  hw/block/nvme.c    | 15 ++++++++++++---
>  hw/block/nvme.h    |  1 -
>  3 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/block/nvme-ns.c b/hw/block/nvme-ns.c
> index 32662230130b..c403cd36b6bd 100644
> --- a/hw/block/nvme-ns.c
> +++ b/hw/block/nvme-ns.c
> @@ -89,10 +89,6 @@ static int nvme_ns_init_blk(NvmeCtrl *n, NvmeNamespace 
> *ns, Error **errp)
>          return -1;
>      }
>  
> -    if (blk_enable_write_cache(ns->blkconf.blk)) {
> -        n->features.vwc = 0x1;
> -    }
> -
>      return 0;
>  }
>  
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index cf0fe28fe6eb..b2a9c48a9d81 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -3033,6 +3033,7 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, 
> NvmeRequest *req)
>      NvmeGetFeatureSelect sel = NVME_GETFEAT_SELECT(dw10);
>      uint16_t iv;
>      NvmeNamespace *ns;
> +    int i;
>  
>      static const uint32_t nvme_feature_default[NVME_FID_MAX] = {
>          [NVME_ARBITRATION] = NVME_ARB_AB_NOLIMIT,
> @@ -3108,7 +3109,17 @@ static uint16_t nvme_get_feature(NvmeCtrl *n, 
> NvmeRequest *req)
>          result = ns->features.err_rec;
>          goto out;
>      case NVME_VOLATILE_WRITE_CACHE:
> -        result = n->features.vwc;
> +        for (i = 1; i <= n->num_namespaces; i++) {
> +            ns = nvme_ns(n, i);
> +            if (!ns) {
> +                continue;
> +            }
> +
> +            result = blk_enable_write_cache(ns->blkconf.blk);
> +            if (!result) {
> +                break;
> +            }
> +        }

I did a small tweak here and changed `if (!result)` to `if (result)`. We
want to report that a volatile write cache is present if ANY of the
namespace backing devices have a write cache.

signature.asc
Description: PGP signature