[Virtio-fs] [PATCH v4 1/2] virtiofsd: add definition of fuse_buf_writev()

[Dr. David Alan Gilbert]

* piaojun (piaojun at huawei.com) wrote:
> Define fuse_buf_writev() which use pwritev and writev to improve io
> bandwidth.
> 
> Signed-off-by: Jun Piao <piaojun at huawei.com>
> Suggested-by: Dr. David Alan Gilbert <dgilbert at redhat.com>
> Suggested-by: Stefan Hajnoczi <stefanha at redhat.com>

Yep, this part looks OK,


Reviewed-by: Dr. David Alan Gilbert <dgilbert at redhat.com>

> ---
>  contrib/virtiofsd/buffer.c  | 31 +++++++++++++++++++++++++++++++
>  contrib/virtiofsd/seccomp.c |  2 ++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/contrib/virtiofsd/buffer.c b/contrib/virtiofsd/buffer.c
> index 655be137..cec762f 100644
> --- a/contrib/virtiofsd/buffer.c
> +++ b/contrib/virtiofsd/buffer.c
> @@ -15,6 +15,7 @@
>  #include <unistd.h>
>  #include <errno.h>
>  #include <assert.h>
> +#include <stdlib.h>
> 
>  size_t fuse_buf_size(const struct fuse_bufvec *bufv)
>  {
> @@ -71,6 +72,36 @@ static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off,
>  	return copied;
>  }
> 
> +static ssize_t fuse_buf_writev(fuse_req_t req,
> +			     struct fuse_buf *out_buf,
> +			     struct fuse_bufvec *in_buf)
> +{
> +	ssize_t res, i;
> +	size_t iovcnt = in_buf->count;
> +	struct iovec * iov;
> +	int fd = out_buf->fd;
> +
> +	iov = calloc(iovcnt, sizeof(struct iovec));
> +	if (!iov)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < iovcnt; i++) {
> +		iov[i].iov_base = in_buf->buf[i].mem;
> +		iov[i].iov_len = in_buf->buf[i].size;
> +	}
> +
> +	if (out_buf->flags & FUSE_BUF_FD_SEEK)
> +		res = pwritev(fd, iov, iovcnt, out_buf->pos);
> +	else
> +		res = writev(fd, iov, iovcnt);
> +
> +	if (res == -1)
> +		res = -errno;
> +
> +	free(iov);
> +	return res;
> +}
> +
>  static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off,
>  			     const struct fuse_buf *src, size_t src_off,
>  			     size_t len)
> diff --git a/contrib/virtiofsd/seccomp.c b/contrib/virtiofsd/seccomp.c
> index 5f1c873..4bba30b 100644
> --- a/contrib/virtiofsd/seccomp.c
> +++ b/contrib/virtiofsd/seccomp.c
> @@ -60,6 +60,7 @@ static const int syscall_whitelist[] = {
>  	SCMP_SYS(ppoll),
>  	SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
>  	SCMP_SYS(preadv),
> +	SCMP_SYS(pwritev),
>  	SCMP_SYS(pwrite64),
>  	SCMP_SYS(read),
>  	SCMP_SYS(readlinkat),
> @@ -78,6 +79,7 @@ static const int syscall_whitelist[] = {
>  	SCMP_SYS(unlinkat),
>  	SCMP_SYS(utimensat),
>  	SCMP_SYS(write),
> +	SCMP_SYS(writev),
>  };
> 
>  /* Syscalls used when --syslog is enabled */
> -- 
--
Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK