[Virtio-fs] [PULL 05/12] virtiofsd: Don't assume header layout
Dr. David Alan Gilbert (git)
dgilbert at redhat.com
Thu May 6 18:56:34 UTC 2021
From: "Dr. David Alan Gilbert" <dgilbert at redhat.com>
virtiofsd incorrectly assumed a fixed set of header layout in the virt
queue; assuming that the fuse and write headers were conveniently
separated from the data; the spec doesn't allow us to take that
convenience, so fix it up to deal with it the hard way.
Signed-off-by: Dr. David Alan Gilbert <dgilbert at redhat.com>
Message-Id: <20210428110100.27757-3-dgilbert at redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert at redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha at redhat.com>
---
tools/virtiofsd/fuse_virtio.c | 94 +++++++++++++++++++++++++++--------
1 file changed, 73 insertions(+), 21 deletions(-)
diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 3e13997406..6dd73c9b72 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -129,18 +129,55 @@ static void fv_panic(VuDev *dev, const char *err)
* Copy from an iovec into a fuse_buf (memory only)
* Caller must ensure there is space
*/
-static void copy_from_iov(struct fuse_buf *buf, size_t out_num,
- const struct iovec *out_sg)
+static size_t copy_from_iov(struct fuse_buf *buf, size_t out_num,
+ const struct iovec *out_sg,
+ size_t max)
{
void *dest = buf->mem;
+ size_t copied = 0;
- while (out_num) {
+ while (out_num && max) {
size_t onelen = out_sg->iov_len;
+ onelen = MIN(onelen, max);
memcpy(dest, out_sg->iov_base, onelen);
dest += onelen;
+ copied += onelen;
out_sg++;
out_num--;
+ max -= onelen;
}
+
+ return copied;
+}
+
+/*
+ * Skip 'skip' bytes in the iov; 'sg_1stindex' is set as
+ * the index for the 1st iovec to read data from, and
+ * 'sg_1stskip' is the number of bytes to skip in that entry.
+ *
+ * Returns True if there are at least 'skip' bytes in the iovec
+ *
+ */
+static bool skip_iov(const struct iovec *sg, size_t sg_size,
+ size_t skip,
+ size_t *sg_1stindex, size_t *sg_1stskip)
+{
+ size_t vec;
+
+ for (vec = 0; vec < sg_size; vec++) {
+ if (sg[vec].iov_len > skip) {
+ *sg_1stskip = skip;
+ *sg_1stindex = vec;
+
+ return true;
+ }
+
+ skip -= sg[vec].iov_len;
+ }
+
+ *sg_1stindex = vec;
+ *sg_1stskip = 0;
+ return skip == 0;
}
/*
@@ -457,6 +494,7 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
bool allocated_bufv = false;
struct fuse_bufvec bufv;
struct fuse_bufvec *pbufv;
+ struct fuse_in_header inh;
assert(se->bufsize > sizeof(struct fuse_in_header));
@@ -505,14 +543,15 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
elem->index);
assert(0); /* TODO */
}
- /* Copy just the first element and look at it */
- copy_from_iov(&fbuf, 1, out_sg);
+ /* Copy just the fuse_in_header and look at it */
+ copy_from_iov(&fbuf, out_num, out_sg,
+ sizeof(struct fuse_in_header));
+ memcpy(&inh, fbuf.mem, sizeof(struct fuse_in_header));
pbufv = NULL; /* Compiler thinks an unitialised path */
- 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)) {
+ if (inh.opcode == FUSE_WRITE &&
+ out_len >= (sizeof(struct fuse_in_header) +
+ 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
@@ -521,15 +560,15 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
*/
fuse_log(FUSE_LOG_DEBUG, "%s: Write special case\n", __func__);
- /* copy the fuse_write_in header afte rthe 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;
+ fbuf.size = copy_from_iov(&fbuf, out_num, out_sg,
+ sizeof(struct fuse_in_header) +
+ sizeof(struct fuse_write_in));
+ /* That copy reread the in_header, make sure we use the original */
+ memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header));
/* Allocate the bufv, with space for the rest of the iov */
pbufv = malloc(sizeof(struct fuse_bufvec) +
- sizeof(struct fuse_buf) * (out_num - 2));
+ sizeof(struct fuse_buf) * out_num);
if (!pbufv) {
fuse_log(FUSE_LOG_ERR, "%s: pbufv malloc failed\n",
__func__);
@@ -540,24 +579,37 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
pbufv->count = 1;
pbufv->buf[0] = fbuf;
- size_t iovindex, pbufvindex;
- iovindex = 2; /* 2 headers, separate iovs */
+ size_t iovindex, pbufvindex, iov_bytes_skip;
pbufvindex = 1; /* 2 headers, 1 fusebuf */
+ if (!skip_iov(out_sg, out_num,
+ sizeof(struct fuse_in_header) +
+ sizeof(struct fuse_write_in),
+ &iovindex, &iov_bytes_skip)) {
+ fuse_log(FUSE_LOG_ERR, "%s: skip failed\n",
+ __func__);
+ goto out;
+ }
+
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;
+
+ if (iov_bytes_skip) {
+ pbufv->buf[pbufvindex].mem += iov_bytes_skip;
+ pbufv->buf[pbufvindex].size -= iov_bytes_skip;
+ iov_bytes_skip = 0;
+ }
}
} 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;
+ copy_from_iov(&fbuf, out_num, out_sg, se->bufsize);
+ /* That copy reread the in_header, make sure we use the original */
+ memcpy(fbuf.mem, &inh, sizeof(struct fuse_in_header));
fbuf.size = out_len;
/* TODO! Endianness of header */
--
2.31.1
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