From: Kefu Chai <kchai@redhat.com>
Date: Wed, 23 Nov 2016 06:48:11 +0000 (+0800)
Subject: FileStore::_do_fiemap: do not reference fiemap after it is freed
X-Git-Tag: v0.94.10~9^2
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=7106f426c96978a0a41e9d1482239a4da505157e;p=ceph.git

FileStore::_do_fiemap: do not reference fiemap after it is freed

`last` points to fiemap::fm_extends[n], and if fiemap gets freed, we can
not reference any of its fieldis. so we could remember the check result before
freeing it.

Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit c3748fa7737b6c43de2dae5d957fcff01322515c)

Conflicts:
	src/os/FileStore.cc
	put the parameter is_last in the right place
---

diff --git a/src/os/FileStore.cc b/src/os/FileStore.cc
index 53663241ec545..61bad358ff162 100644
--- a/src/os/FileStore.cc
+++ b/src/os/FileStore.cc
@@ -2957,9 +2957,10 @@ more:
       i++;
       extent++;
     }
+    const bool is_last = last->fe_flags & FIEMAP_EXTENT_LAST;
     free(fiemap);
 
-    if (!(last->fe_flags & FIEMAP_EXTENT_LAST)) {
+    if (!is_last) {
       uint64_t xoffset = last->fe_logical + last->fe_length - offset;
       offset = last->fe_logical + last->fe_length;
       len -= xoffset;