On 10/23/2017 06:59 AM, Marc-André Lureau wrote:
> Add a function to only create a memfd, without mmap. The function is
> used in the following memory backend.
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> include/qemu/memfd.h | 1 +
> util/memfd.c | 61
> +++++++++++++++++++++++++++++++---------------------
> 2 files changed, 37 insertions(+), 25 deletions(-)
>
> diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h
> index 745a8c501e..41c24d807c 100644
> --- a/include/qemu/memfd.h
> +++ b/include/qemu/memfd.h
> @@ -16,6 +16,7 @@
> #define F_SEAL_WRITE 0x0008 /* prevent writes */
> #endif
>
> +int qemu_memfd_create(const char *name, size_t size, unsigned int seals);
> void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals,
> int *fd);
> void qemu_memfd_free(void *ptr, size_t size, int fd);
> diff --git a/util/memfd.c b/util/memfd.c
> index 4571d1aba8..e9c1a0e700 100644
> --- a/util/memfd.c
> +++ b/util/memfd.c
> @@ -55,6 +55,38 @@ static int memfd_create(const char *name, unsigned int
> flags)
> #define MFD_ALLOW_SEALING 0x0002U
> #endif
>
> +int qemu_memfd_create(const char *name, size_t size, unsigned int seals)
> +{
> + int mfd = -1;
> +
> +#ifdef CONFIG_LINUX
> + unsigned int flags = MFD_CLOEXEC;
> +
> + if (seals) {
> + flags |= MFD_ALLOW_SEALING;
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
> + }
> +
> + mfd = memfd_create(name, flags);
> + if (mfd < 0) {
> + return -1;
> + }
> +
> + if (ftruncate(mfd, size) == -1) {
> + perror("ftruncate");
> + close(mfd);
> + return -1;
> + }
> +
> + if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
> + perror("fcntl");
> + close(mfd);
> + return -1;
> + }
> +#endif
> +
> + return mfd;
> +}
> +
> /*
> * This is a best-effort helper for shared memory allocation, with
> * optional sealing. The helper will do his best to allocate using
> @@ -65,35 +97,14 @@ void *qemu_memfd_alloc(const char *name, size_t size,
> unsigned int seals,
> int *fd)
> {
> void *ptr;
> - int mfd = -1;
> -
> - *fd = -1;
> -
> -#ifdef CONFIG_LINUX
> - if (seals) {
> - mfd = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
> - }
> + int mfd = qemu_memfd_create(name, size, seals);
>
> + /* some systems have memfd without sealing */
> if (mfd == -1) {
> - /* some systems have memfd without sealing */
> - mfd = memfd_create(name, MFD_CLOEXEC);
> - seals = 0;
> + mfd = qemu_memfd_create(name, size, 0);
> }
> -#endif
> -
> - if (mfd != -1) {
> - if (ftruncate(mfd, size) == -1) {
> - perror("ftruncate");
> - close(mfd);
> - return NULL;
> - }
>
> - if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
> - perror("fcntl");
> - close(mfd);
> - return NULL;
> - }
> - } else {
> + if (mfd == -1) {
> const char *tmpdir = g_get_tmp_dir();
> gchar *fname;
>
>
