From: Jason Dillaman <dillaman@redhat.com>
Date: Mon, 10 Aug 2015 13:34:42 +0000 (-0400)
Subject: common: bit_vector extent calculation incorrect for last page
X-Git-Tag: v0.94.4~78^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=fca78765366f3ac365cfa98224aca5fb79b2a7fe;p=ceph.git

common: bit_vector extent calculation incorrect for last page

It's highly probable that the last page in the bit vector will not
be a full page size.  As a result, the computed extents will extend
beyond the data portion of the bit vector, resulting in a end_of_buffer
exception.

Fixes: #12611
Backport: hammer
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit c6d98992691683524d3d96def83a90a6f5fe7f93)
---

diff --git a/src/common/bit_vector.hpp b/src/common/bit_vector.hpp
index 55403c5d35cd..f66294b54752 100644
--- a/src/common/bit_vector.hpp
+++ b/src/common/bit_vector.hpp
@@ -261,7 +261,10 @@ void BitVector<_b>::get_data_extents(uint64_t offset, uint64_t length,
   end_offset += (CEPH_PAGE_SIZE - (end_offset % CEPH_PAGE_SIZE));
   assert(*byte_offset <= end_offset);
 
-  *byte_length = MIN(end_offset - *byte_offset, m_data.length());
+  *byte_length = end_offset - *byte_offset;
+  if (*byte_offset + *byte_length > m_data.length()) {
+    *byte_length = m_data.length() - *byte_offset;
+  }
 }
 
 template <uint8_t _b>