[PULL 04/15] virtiofsd: Use iov_discard_front() to skip bytes

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Vivek Goyal <vgoyal@redhat.com>

There are places where we need to skip few bytes from front of the iovec
array. We have our own custom code for that. Looks like iov_discard_front()
can do same thing. So use that helper instead.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210518213538.693422-4-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 tools/virtiofsd/fuse_virtio.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 28e2974d1a..09674f2e90 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -389,23 +389,15 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
     memcpy(in_sg_cpy, in_sg, sizeof(struct iovec) * in_num);
     /* These get updated as we skip */
     struct iovec *in_sg_ptr = in_sg_cpy;
-    int in_sg_cpy_count = in_num;
+    unsigned int in_sg_cpy_count = in_num;
 
     /* skip over parts of in_sg that contained the header iov */
     size_t skip_size = iov_len;
 
     size_t in_sg_left = 0;
     do {
-        while (skip_size != 0 && in_sg_cpy_count) {
-            if (skip_size >= in_sg_ptr[0].iov_len) {
-                skip_size -= in_sg_ptr[0].iov_len;
-                in_sg_ptr++;
-                in_sg_cpy_count--;
-            } else {
-                in_sg_ptr[0].iov_len -= skip_size;
-                in_sg_ptr[0].iov_base += skip_size;
-                break;
-            }
+        if (skip_size != 0) {
+            iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, skip_size);
         }
 
         int i;
-- 
2.31.1