Re: [SPAM] [PATCH] 9pfs: disable msize warning for synth driver

[Greg Kurz <groug@kaod.org>]

On Sun, 6 Sep 2020 18:50:32 +0200
Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:

> Previous patch introduced a performance warning being logged on host
> side if client connected with an 'msize' <= 8192. Disable this
> performance warning for the synth driver to prevent that warning from
> being printed whenever the 9pfs (qtest) test cases are running.
> 
> Introduce a new export flag V9FS_NO_PERF_WARN for that purpose, which
> might also be used to disable such warnings from the CLI in future.
> 
> We could have also prevented the warning by simply raising P9_MAX_SIZE
> in virtio-9p-test.c to any value larger than 8192, however in the
> context of test cases it makes sense running for edge cases, which
> includes the lowest 'msize' value supported by the server which is
> 4096, hence we want to preserve an msize of 4096 for the test client.
> 
> Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
> ---

Heh, yes I guess it makes sense :)

I guess you could maybe queue this patch before the other one.

Reviewed-by: Greg Kurz <groug@kaod.org>

>  fsdev/file-op-9p.h | 4 ++++
>  hw/9pfs/9p-synth.c | 2 ++
>  hw/9pfs/9p.c       | 2 +-
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index f2f7772c86..d51cec2f3b 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -64,6 +64,10 @@ typedef struct ExtendedOps {
>   */
>  #define V9FS_REMAP_INODES           0x00000200
>  #define V9FS_FORBID_MULTIDEVS       0x00000400
> +/*
> + * Disables certain performance warnings from being logged on host side.
> + */
> +#define V9FS_NO_PERF_WARN           0x00000800
>  
>  #define V9FS_SEC_MASK               0x0000003C
>  
> diff --git a/hw/9pfs/9p-synth.c b/hw/9pfs/9p-synth.c
> index 7eb210ffa8..cec8c0eefc 100644
> --- a/hw/9pfs/9p-synth.c
> +++ b/hw/9pfs/9p-synth.c
> @@ -541,6 +541,8 @@ static int synth_init(FsContext *ctx, Error **errp)
>      QLIST_INIT(&synth_root.child);
>      qemu_mutex_init(&synth_mutex);
>  
> +    ctx->export_flags |= V9FS_NO_PERF_WARN;
> +
>      /* Add "." and ".." entries for root */
>      v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
>                        "..", synth_root.attr, synth_root.attr->inode);
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index 99b6f24fd6..741d222c3f 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -1354,7 +1354,7 @@ static void coroutine_fn v9fs_version(void *opaque)
>      }
>  
>      /* 8192 is the default msize of Linux clients */
> -    if (s->msize <= 8192) {
> +    if (s->msize <= 8192 && !(s->ctx.export_flags & V9FS_NO_PERF_WARN)) {
>          warn_report_once(
>              "9p: degraded performance: a reasonable high msize should be "
>              "chosen on client/guest side (chosen msize is <= 8192). See "