Re: [Qemu-devel] [PATCH 01/11] block: Use writeback in .bdrv_create() implementations

[Paolo Bonzini]

On 08/03/2016 17:34, Kevin Wolf wrote:
> There's no reason to use a writethrough cache mode while creating an
> image.

There's no reason to do flushes in fact, so you could use
BDRV_O_NO_FLUSH too. :)

Paolo

> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block/parallels.c | 3 ++-
>  block/qcow.c      | 3 ++-
>  block/qcow2.c     | 3 ++-
>  block/sheepdog.c  | 6 ++++--
>  block/vdi.c       | 3 ++-
>  block/vhdx.c      | 3 ++-
>  block/vmdk.c      | 9 ++++++---
>  block/vpc.c       | 3 ++-
>  8 files changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/block/parallels.c b/block/parallels.c
> index 645521d..3f9fd48 100644
> --- a/block/parallels.c
> +++ b/block/parallels.c
> @@ -479,7 +479,8 @@ static int parallels_create(const char *filename, 
> QemuOpts *opts, Error **errp)
>  
>      file = NULL;
>      ret = bdrv_open(&file, filename, NULL, NULL,
> -                    BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
> +                    &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
>          return ret;
> diff --git a/block/qcow.c b/block/qcow.c
> index 251910c..c46810c 100644
> --- a/block/qcow.c
> +++ b/block/qcow.c
> @@ -798,7 +798,8 @@ static int qcow_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>  
>      qcow_bs = NULL;
>      ret = bdrv_open(&qcow_bs, filename, NULL, NULL,
> -                    BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
> +                    &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
>          goto cleanup;
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 8babecd..5a79177 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -2173,7 +2173,8 @@ static int qcow2_create2(const char *filename, int64_t 
> total_size,
>      }
>  
>      bs = NULL;
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index 8739acc..5f31ab3 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -1646,7 +1646,8 @@ static int sd_prealloc(const char *filename, Error 
> **errp)
>      void *buf = NULL;
>      int ret;
>  
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      errp);
>      if (ret < 0) {
>          goto out_with_err_set;
> @@ -1839,7 +1840,8 @@ static int sd_create(const char *filename, QemuOpts 
> *opts,
>          }
>  
>          bs = NULL;
> -        ret = bdrv_open(&bs, backing_file, NULL, NULL, BDRV_O_PROTOCOL, 
> errp);
> +        ret = bdrv_open(&bs, backing_file, NULL, NULL,
> +                        BDRV_O_PROTOCOL | BDRV_O_CACHE_WB, errp);
>          if (ret < 0) {
>              goto out;
>          }
> diff --git a/block/vdi.c b/block/vdi.c
> index b403243..12407c4 100644
> --- a/block/vdi.c
> +++ b/block/vdi.c
> @@ -766,7 +766,8 @@ static int vdi_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>          error_propagate(errp, local_err);
>          goto exit;
>      }
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
> diff --git a/block/vhdx.c b/block/vhdx.c
> index 9a51428..ea030ad 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -1838,7 +1838,8 @@ static int vhdx_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>      }
>  
>      bs = NULL;
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 03be7f0..dd80936 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1664,7 +1664,8 @@ static int vmdk_create_extent(const char *filename, 
> int64_t filesize,
>      }
>  
>      assert(bs == NULL);
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
> @@ -1944,7 +1945,8 @@ static int vmdk_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>              ret = -ENOENT;
>              goto exit;
>          }
> -        ret = bdrv_open(&bs, full_backing, NULL, NULL, BDRV_O_NO_BACKING, 
> errp);
> +        ret = bdrv_open(&bs, full_backing, NULL, NULL,
> +                        BDRV_O_NO_BACKING | BDRV_O_CACHE_WB, errp);
>          g_free(full_backing);
>          if (ret != 0) {
>              goto exit;
> @@ -2015,7 +2017,8 @@ static int vmdk_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>      }
>      assert(new_bs == NULL);
>      ret = bdrv_open(&new_bs, filename, NULL, NULL,
> -                    BDRV_O_RDWR | BDRV_O_PROTOCOL, &local_err);
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
> +                    &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
>          goto exit;
> diff --git a/block/vpc.c b/block/vpc.c
> index 318e6d6..1db47d6 100644
> --- a/block/vpc.c
> +++ b/block/vpc.c
> @@ -886,7 +886,8 @@ static int vpc_create(const char *filename, QemuOpts 
> *opts, Error **errp)
>          error_propagate(errp, local_err);
>          goto out;
>      }
> -    ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
> +    ret = bdrv_open(&bs, filename, NULL, NULL,
> +                    BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_PROTOCOL,
>                      &local_err);
>      if (ret < 0) {
>          error_propagate(errp, local_err);
>