mds: don't crash MDS when snapshot data not found

When remote dentry and inode are in different snapshot realms.
The inode may not contain snapshot data for snapshot of the remote
dentry.

This issue are difficult to fix. This patch MDS print an error
instead of triggering assersion.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

diff --git a/src/mds/CInode.cc b/src/mds/CInode.cc
index 46eefad1353199af25595928d796c7cb9e73b89e..8309c88e078bc23f5c91539763d2d91eb1d2b6ed 100644 (file)
--- a/src/mds/CInode.cc
+++ b/src/mds/CInode.cc
@@ -2981,26 +2981,36 @@ int CInode::encode_inodestat(bufferlist& bl, Session *session,
 
   map<string, bufferptr> *pxattrs = 0;
 
-  if (snapid != CEPH_NOSNAP && is_multiversion()) {
+  if (snapid != CEPH_NOSNAP) {
 
     // for now at least, old_inodes is only defined/valid on the auth
     if (!is_auth())
       valid = false;
 
-    compact_map<snapid_t,old_inode_t>::iterator p = old_inodes.lower_bound(snapid);
-    if (p != old_inodes.end()) {
-      if (p->second.first > snapid) {
-        if  (p != old_inodes.begin())
-          --p;
-        else dout(0) << "old_inode lower_bound starts after snapid!" << dendl;
+    if (is_multiversion()) {
+      compact_map<snapid_t,old_inode_t>::iterator p = old_inodes.lower_bound(snapid);
+      if (p != old_inodes.end()) {
+       if (p->second.first > snapid) {
+         if  (p != old_inodes.begin())
+           --p;
+       }
+       if (p->second.first <= snapid && snapid <= p->first) {
+         dout(15) << "encode_inodestat snapid " << snapid
+                  << " to old_inode [" << p->second.first << "," << p->first << "]"
+                  << " " << p->second.inode.rstat
+                  << dendl;
+         pi = oi = &p->second.inode;
+         pxattrs = &p->second.xattrs;
+       } else {
+         // snapshoted remote dentry can result this
+         dout(0) << "encode_inodestat old_inode for snapid " << snapid
+                 << " not found" << dendl;
+       }
       }
-      dout(15) << "encode_inodestat snapid " << snapid
-              << " to old_inode [" << p->second.first << "," << p->first << "]" 
-              << " " << p->second.inode.rstat
-              << dendl;
-      assert(p->second.first <= snapid && snapid <= p->first);
-      pi = oi = &p->second.inode;
-      pxattrs = &p->second.xattrs;
+    } else if (snapid < first || snapid > last) {
+      // snapshoted remote dentry can result this
+      dout(0) << "encode_inodestat [" << first << "," << last << "]"
+             << " not match snapid " << snapid << dendl;
     }
   }