From b98ed828162ce00f334e6afc9e9a0801c0ab23d7 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Wed, 6 Jan 2016 12:57:12 -0500
Subject: [PATCH] os/bluestore/BlockDevice: make pread() safe

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/os/bluestore/BlockDevice.cc | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/os/bluestore/BlockDevice.cc b/src/os/bluestore/BlockDevice.cc
index 13607ad2b84c4..33370bf495052 100644
--- a/src/os/bluestore/BlockDevice.cc
+++ b/src/os/bluestore/BlockDevice.cc
@@ -496,14 +496,21 @@ int BlockDevice::read_buffered(uint64_t off, uint64_t len, char *buf)
   assert(off < size);
   assert(off + len <= size);
 
-  int r = ::pread(fd_buffered, buf, len, off);
-  if (r < 0) {
-    r = -errno;
-    goto out;
+  int r = 0;
+  char *t = buf;
+  uint64_t left = len;
+  while (left > 0) {
+    r = ::pread(fd_buffered, t, left, off);
+    if (r < 0) {
+      r = -errno;
+      goto out;
+    }
+    off += r;
+    t += r;
+    left -= r;
   }
-  assert(r == len);
 
-  dout(40) << "data: ";
+  dout(40) << __func__ << " data: ";
   bufferlist bl;
   bl.append(buf, len);
   bl.hexdump(*_dout);
-- 
2.39.5