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virtiofsd: Pass write iov's all the way through 

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>
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2019-01-04 16:47:39 +00:00
parent 469f9d2fc4
commit e17f7a580e
1 changed files with 73 additions and 6 deletions
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79
tools/virtiofsd/fuse_virtio.c
View File

@ -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);
/* TODO! Endianness of header */
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__);
/* TODO: Add checks for fuse_session_exited */
struct fuse_bufvec bufv = { .buf[0] = fbuf, .count = 1 };
fuse_session_process_buf_int(se, &bufv, &ch);
/* 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: 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);