From: Sage Weil <sage@redhat.com>
Date: Thu, 28 Jan 2016 02:45:27 +0000 (-0500)
Subject: os/bluestore/BlueStore: fix wal tail block padding
X-Git-Tag: v10.0.4~35^2~10
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=f1bf983e43c0d24151fe9b75b091b7144d15f9f5;p=ceph.git

os/bluestore/BlueStore: fix wal tail block padding

If the wal write starts partway into the tail block, we need to allocate
less than a full block.

Signed-off-by: Sage Weil <sage@redhat.com>
---

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index e28e46a04cd9..6574d4e67340 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -4911,9 +4911,17 @@ void BlueStore::_pad_zeros_tail(
   uint64_t end = offset + *length;
   unsigned back_copy = end % block_size;
   assert(back_copy);  // or we wouldn't have been called
-  uint64_t back_pad = block_size - back_copy;
-  assert(back_copy <= *length);
-  bufferptr tail(block_size);
+  uint64_t tail_len;
+  if (back_copy <= *length) {
+    // we start at or before the block boundary
+    tail_len = block_size;
+  } else {
+    // we start partway into the tail block
+    back_copy = *length;
+    tail_len = block_size - (offset % block_size);
+  }
+  uint64_t back_pad = tail_len - back_copy;
+  bufferptr tail(tail_len);
   memcpy(tail.c_str(), bl->get_contiguous(*length - back_copy, back_copy),
 	 back_copy);
   memset(tail.c_str() + back_copy, 0, back_pad);