From: Xiubo Li <xiubli@redhat.com>
Date: Tue, 28 Apr 2020 04:55:29 +0000 (-0400)
Subject: ceph-fuse: switch to fuse_reply_iov to reduce the memory copy
X-Git-Tag: v16.1.0~1746^2~3
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=969c575622c364395ecbc97d7b072bcbe6d50ded;p=ceph.git

ceph-fuse: switch to fuse_reply_iov to reduce the memory copy

Fixes: https://tracker.ceph.com/issues/45267
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---

diff --git a/src/client/fuse_ll.cc b/src/client/fuse_ll.cc
index 3b2118bdcdd..16f4d12abd0 100644
--- a/src/client/fuse_ll.cc
+++ b/src/client/fuse_ll.cc
@@ -612,9 +612,12 @@ static void fuse_ll_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t off,
   Fh *fh = reinterpret_cast<Fh*>(fi->fh);
   bufferlist bl;
   int r = cfuse->client->ll_read(fh, off, size, &bl);
-  if (r >= 0)
-    fuse_reply_buf(req, bl.c_str(), bl.length());
-  else
+  if (r >= 0) {
+    vector<iovec> iov;
+    bl.prepare_iov(&iov);
+    iov.insert(iov.begin(), {0}); // the first one is reserved for fuse_out_header
+    fuse_reply_iov(req, &iov[0], iov.size());
+  } else
     fuse_reply_err(req, -r);
 }