Re: [Qemu-devel] [PATCH v6 07/33] util: introduce qemu_file_get_page_size()

[Eduardo Habkost]

On Fri, Oct 30, 2015 at 01:56:01PM +0800, Xiao Guangrong wrote:
> There are three places use the some logic to get the page size on
> the file path or file fd
> 
> This patch introduces qemu_file_get_page_size() to unify the code
> 
> Signed-off-by: Xiao Guangrong <address@hidden>
[...]
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 914cef5..ad94c5a 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -360,6 +360,22 @@ static size_t fd_getpagesize(int fd)
>      return getpagesize();
>  }
>  
> +size_t qemu_file_get_page_size(const char *path)
> +{
> +    size_t size = 0;
> +    int fd = qemu_open(path, O_RDONLY);
> +
> +    if (fd < 0) {
> +        fprintf(stderr, "Could not open %s.\n", path);
> +        goto exit;

Have you considered using a Error** argument here?

> +    }
> +
> +    size = fd_getpagesize(fd);
> +    qemu_close(fd);
> +exit:
> +    return size;
> +}
> +
> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
> index ac70f08..c661f1c 100644
> --- a/target-ppc/kvm.c
> +++ b/target-ppc/kvm.c
> @@ -308,28 +308,13 @@ static void kvm_get_smmu_info(PowerPCCPU *cpu, struct 
> kvm_ppc_smmu_info *info)
>  
>  static long gethugepagesize(const char *mem_path)
>  {
> -    struct statfs fs;
> -    int ret;
> -
> -    do {
> -        ret = statfs(mem_path, &fs);
> -    } while (ret != 0 && errno == EINTR);
> +    long size = qemu_file_get_page_size(mem_path);
>  
> -    if (ret != 0) {
> -        fprintf(stderr, "Couldn't statfs() memory path: %s\n",
> -                strerror(errno));
> +    if (!size) {
>          exit(1);
>      }
>  
> -#define HUGETLBFS_MAGIC       0x958458f6
> -
> -    if (fs.f_type != HUGETLBFS_MAGIC) {
> -        /* Explicit mempath, but it's ordinary pages */
> -        return getpagesize();
> -    }
> -
> -    /* It's hugepage, return the huge page size */
> -    return fs.f_bsize;
> +    return size;
>  }

Why are you changing target-ppc/kvm.c:gethugepagesize() to use the new
funtion, but not the copy at exec.c? To make it simpler, we could
eliminate both gethugepagesize() functions completely and replace them
with qemu_file_get_page_size() calls (maybe as part of this patch, maybe
in a separate patch, I'm not sure).

-- 
Eduardo