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Re: [PATCH 1/3] hostmem: Detect and cache fs type for file hostmem
From: |
Daniel P . Berrangé |
Subject: |
Re: [PATCH 1/3] hostmem: Detect and cache fs type for file hostmem |
Date: |
Wed, 19 Apr 2023 08:01:34 +0100 |
User-agent: |
Mutt/2.2.9 (2022-11-12) |
On Tue, Apr 18, 2023 at 06:57:47PM -0400, Peter Xu wrote:
> Detect the file system for a memory-backend-file object and cache it within
> the object if possible when CONFIG_LINUX (using statfs).
>
> Only support the two important types of memory (tmpfs, hugetlbfs) and keep
> the rest as "unknown" for now.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> backends/hostmem-file.c | 37 ++++++++++++++++++++++++++++++++++++-
> include/sysemu/hostmem.h | 1 +
> 2 files changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
> index 25141283c4..2484e45a11 100644
> --- a/backends/hostmem-file.c
> +++ b/backends/hostmem-file.c
> @@ -18,13 +18,17 @@
> #include "sysemu/hostmem.h"
> #include "qom/object_interfaces.h"
> #include "qom/object.h"
> +#ifdef CONFIG_LINUX
> +#include <sys/vfs.h>
> +#include <linux/magic.h>
> +#endif
>
> OBJECT_DECLARE_SIMPLE_TYPE(HostMemoryBackendFile, MEMORY_BACKEND_FILE)
>
>
> struct HostMemoryBackendFile {
> HostMemoryBackend parent_obj;
> -
> + __fsword_t fs_type;
> char *mem_path;
> uint64_t align;
> bool discard_data;
> @@ -52,6 +56,15 @@ file_backend_memory_alloc(HostMemoryBackend *backend,
> Error **errp)
> return;
> }
>
> +#ifdef CONFIG_LINUX
> + struct statfs fs;
> + if (!statfs(fb->mem_path, &fs)) {
> + fb->fs_type = fs.f_type;
> + } else {
> + fb->fs_type = 0;
> + }
> +#endif
> +
> name = host_memory_backend_get_name(backend);
> ram_flags = backend->share ? RAM_SHARED : 0;
> ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
> @@ -181,6 +194,28 @@ static void file_backend_unparent(Object *obj)
> }
> }
>
> +const char *file_memory_backend_get_fs_type(Object *obj)
> +{
> +#ifdef CONFIG_LINUX
> + HostMemoryBackendFile *fb = (HostMemoryBackendFile *)
> + object_dynamic_cast(obj, TYPE_MEMORY_BACKEND_FILE);
> +
> + if (!fb) {
> + goto out;
> + }
> +
> + switch (fb->fs_type) {
> + case TMPFS_MAGIC:
> + return "tmpfs";
> + case HUGETLBFS_MAGIC:
> + return "hugetlbfs";
> + }
> +
> +out:
> +#endif
> + return "unknown";
> +}
I rather feel this should be returning an enm, not strings, so
the caller just does a plain equality test rather than string
comparisons
With regards,
Daniel
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