[PULL 07/15] virtiofsd: Check EOF before short read

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

From: Vivek Goyal <vgoyal@redhat.com>

In virtio_send_data_iov() we are checking first for short read and then
EOF condition. Change the order. Basically check for error and EOF first
and last remaining piece is short ready which will lead to retry
automatically at the end of while loop.

Just that it is little simpler to read to the code. There is no need
to call "continue" and also one less call of "len-=ret".

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: <20210518213538.693422-7-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 tools/virtiofsd/fuse_virtio.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index 49c7dd788a..99f91c9d87 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -410,25 +410,24 @@ int virtio_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,
                      __func__, len);
             goto err;
         }
-        fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
-                 ret, len);
-        if (ret < len && ret) {
-            fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__);
-            /* Skip over this much next time around */
-            iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret);
-            buf->buf[0].pos += ret;
-            len -= ret;
 
-            /* Lets do another read */
-            continue;
-        }
         if (!ret) {
             /* EOF case? */
             fuse_log(FUSE_LOG_DEBUG, "%s: !ret len remaining=%zd\n", __func__,
                      len);
             break;
         }
+        fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
+                 ret, len);
+
         len -= ret;
+        /* Short read. Retry reading remaining bytes */
+        if (len) {
+            fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__);
+            /* Skip over this much next time around */
+            iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret);
+            buf->buf[0].pos += ret;
+        }
     } while (len);
 
     /* Need to fix out->len on EOF */
-- 
2.31.1