From d9a150b1f1f9ec3952555186722c9b13d7448e2d Mon Sep 17 00:00:00 2001
From: Marcus Watts <mwatts@redhat.com>
Date: Mon, 5 Mar 2018 16:10:29 -0500
Subject: [PATCH] rgw: fix memory fragmentation problem reading data from
 client.

mg_read returns 0 on EOF.  In some versions of civetweb, mg_read can
return "short" reads.  The logic in the rest of ceph depends on a read
always filling its buffer when possible.  So loop here and fill the
buffer.  Looping to fill the buffer means we must also track when
mg_read returns EOF, because after that further calls to mg_read will return -1.

Fixes: https://tracker.ceph.com/issues/23207

Signed-off-by: Marcus Watts <mwatts@redhat.com>
---
 src/rgw/rgw_civetweb.cc | 19 +++++++++++++++----
 src/rgw/rgw_civetweb.h  |  1 +
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/rgw/rgw_civetweb.cc b/src/rgw/rgw_civetweb.cc
index f4d17d721c18d..30f69406f18b8 100644
--- a/src/rgw/rgw_civetweb.cc
+++ b/src/rgw/rgw_civetweb.cc
@@ -33,6 +33,7 @@ RGWCivetWeb::RGWCivetWeb(mg_connection* const conn)
   : conn(conn),
     explicit_keepalive(false),
     explicit_conn_close(false),
+    got_eof_on_read(false),
     txbuf(*this)
 {
     sockaddr *lsa = mg_get_local_addr(conn);
@@ -50,11 +51,21 @@ RGWCivetWeb::RGWCivetWeb(mg_connection* const conn)
 
 size_t RGWCivetWeb::read_data(char *buf, size_t len)
 {
-  const int ret = mg_read(conn, buf, len);
-  if (ret < 0) {
-    throw rgw::io::Exception(EIO, std::system_category());
+  int c, ret;
+  if (got_eof_on_read) {
+    return 0;
+  }
+  for (c = 0; c < len; c += ret) {
+    ret = mg_read(conn, buf, len);
+    if (ret < 0) {
+      throw rgw::io::Exception(EIO, std::system_category());
+    }
+    if (!ret) {
+      got_eof_on_read = true;
+      break;
+    }
   }
-  return ret;
+  return c;
 }
 
 void RGWCivetWeb::flush()
diff --git a/src/rgw/rgw_civetweb.h b/src/rgw/rgw_civetweb.h
index 0160c03a42d98..b64eb1340bd07 100644
--- a/src/rgw/rgw_civetweb.h
+++ b/src/rgw/rgw_civetweb.h
@@ -19,6 +19,7 @@ class RGWCivetWeb : public rgw::io::RestfulClient,
 
   bool explicit_keepalive;
   bool explicit_conn_close;
+  bool got_eof_on_read;
 
   rgw::io::StaticOutputBufferer<> txbuf;
 
-- 
2.39.5