On 2019/12/13 0:38, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert"<dgilbert@redhat.com>
>
> Pass the write iov pointing to guest RAM all the way through rather
> than copying the data.
>
> Signed-off-by: Dr. David Alan Gilbert<dgilbert@redhat.com>
> ---
> tools/virtiofsd/fuse_virtio.c | 79 ++++++++++++++++++++++++++++++++---
> 1 file changed, 73 insertions(+), 6 deletions(-)
>
> diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
> index 99c877ea2e..3c778b6296 100644
> --- a/tools/virtiofsd/fuse_virtio.c
> +++ b/tools/virtiofsd/fuse_virtio.c
> @@ -452,6 +452,10 @@ static void *fv_queue_thread(void *opaque)
> __func__, qi->qidx, (size_t)evalue, in_bytes, out_bytes);
>
> while (1) {
> + bool allocated_bufv = false;
> + struct fuse_bufvec bufv;
> + struct fuse_bufvec *pbufv;
> +
> /*
> * An element contains one request and the space to send our
> * response They're spread over multiple descriptors in a
> @@ -493,14 +497,76 @@ static void *fv_queue_thread(void *opaque)
> __func__, elem->index);
> assert(0); /* TODO */
> }
> - copy_from_iov(&fbuf, out_num, out_sg);
> - fbuf.size = out_len;
> + /* Copy just the first element and look at it */
> + copy_from_iov(&fbuf, 1, out_sg);
> +
> + if (out_num> 2&&
> + out_sg[0].iov_len == sizeof(struct fuse_in_header)&&
> + ((struct fuse_in_header *)fbuf.mem)->opcode == FUSE_WRITE&&
> + out_sg[1].iov_len == sizeof(struct fuse_write_in)) {
> + /*
> + * For a write we don't actually need to copy the
> + * data, we can just do it straight out of guest memory
> + * but we must still copy the headers in case the guest
> + * was nasty and changed them while we were using them.
> + */
> + fuse_log(FUSE_LOG_DEBUG, "%s: Write special case\n", __func__);
> +
> + /* copy the fuse_write_in header after the fuse_in_header */
> + fbuf.mem += out_sg->iov_len;
> + copy_from_iov(&fbuf, 1, out_sg + 1);
> + fbuf.mem -= out_sg->iov_len;
> + fbuf.size = out_sg[0].iov_len + out_sg[1].iov_len;
> +
> + /* Allocate the bufv, with space for the rest of the iov */
> + allocated_bufv = true;
> + pbufv = malloc(sizeof(struct fuse_bufvec) +
> + sizeof(struct fuse_buf) * (out_num - 2));
> + if (!pbufv) {
> + vu_queue_unpop(dev, q, elem, 0);
> + free(elem);
> + fuse_log(FUSE_LOG_ERR, "%s: pbufv malloc failed\n",
> + __func__);
> + goto out;
> + }
> +
> + pbufv->count = 1;
> + pbufv->buf[0] = fbuf;
> +
> + size_t iovindex, pbufvindex;
> + iovindex = 2; /* 2 headers, separate iovs */
> + pbufvindex = 1; /* 2 headers, 1 fusebuf */
> +
> + for (; iovindex< out_num; iovindex++, pbufvindex++) {
> + pbufv->count++;
> + pbufv->buf[pbufvindex].pos = ~0; /* Dummy */
> + pbufv->buf[pbufvindex].flags = 0;
> + pbufv->buf[pbufvindex].mem = out_sg[iovindex].iov_base;
> + pbufv->buf[pbufvindex].size = out_sg[iovindex].iov_len;
> + }
> + } else {
> + /* Normal (non fast write) path */
> +
> + /* Copy the rest of the buffer */
> + fbuf.mem += out_sg->iov_len;
> + copy_from_iov(&fbuf, out_num - 1, out_sg + 1);
> + fbuf.mem -= out_sg->iov_len;
> + fbuf.size = out_len;
>
> - /* TODO! Endianness of header */
> + /* TODO! Endianness of header */
>
> - /* TODO: Add checks for fuse_session_exited */
> - struct fuse_bufvec bufv = { .buf[0] = fbuf, .count = 1 };
> - fuse_session_process_buf_int(se,&bufv,&ch);
> + /* TODO: Add checks for fuse_session_exited */
> + bufv.buf[0] = fbuf;
> + bufv.count = 1;
> + pbufv =&bufv;
> + }
> + pbufv->idx = 0;
> + pbufv->off = 0;
> + fuse_session_process_buf_int(se, pbufv,&ch);
> +
> + if (allocated_bufv) {
> + free(pbufv);
> + }
>
> if (!qi->reply_sent) {
> fuse_log(FUSE_LOG_DEBUG, "%s: elem %d no reply sent\n",
> @@ -514,6 +580,7 @@ static void *fv_queue_thread(void *opaque)
> elem = NULL;
> }
> }
> +out:
> pthread_mutex_destroy(&ch.lock);
> free(fbuf.mem);
>
Hi,
Tested the patch and got the correct data written by guest, so it looks
fine to me.
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Best Regards,
Xiao Yang