From: "Dr. David Alan Gilbert" <dgilb...@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 <dgilb...@redhat.com>
Reviewed-by: Xiao Yang <yangx...@cn.fujitsu.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 fd588a4829..872968f2c8 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -454,6 +454,10 @@ 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
@@ -495,14 +499,76 @@ 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",
@@ -516,6 +582,7 @@ static void *fv_queue_thread(void *opaque)
elem = NULL;
}
}
+out:
pthread_mutex_destroy(&ch.lock);
free(fbuf.mem);
--
2.24.1
