mds: mark and pin dentries while purging, so they don't get trimmed out from under us

Aslo avoid purging more than once.

Previously it was possible to drop the dentry from the cache while
it was being purged.

diff --git a/src/mds/CDentry.h b/src/mds/CDentry.h
index 9bda79ddc7aeaac386cb08cbd29b9f4e588f6263..274651f028bfd80dedf90cde957cfe3742d5d82f 100644 (file)
--- a/src/mds/CDentry.h
+++ b/src/mds/CDentry.h
@@ -51,14 +51,17 @@ class CDentry : public MDSCacheObject, public LRUObject {
   // -- state --
   static const int STATE_NEW = 1;
   static const int STATE_FRAGMENTING = 2;
+  static const int STATE_PURGING = 3;
 
   // -- pins --
   static const int PIN_INODEPIN =     1;  // linked inode is pinned
   static const int PIN_FRAGMENTING = -2;  // containing dir is refragmenting
+  static const int PIN_PURGING =      3;
   const char *pin_name(int p) {
     switch (p) {
     case PIN_INODEPIN: return "inodepin";
     case PIN_FRAGMENTING: return "fragmenting";
+    case PIN_PURGING: return "purging";
     default: return generic_pin_name(p);
     }
   };

diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index 3326b5e4808e165a28ee0cc346e99eccbce7273e..d267290a3c73c64a389abd20226cb79695f29923 100644 (file)
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -6334,6 +6334,7 @@ void MDCache::eval_stray(CDentry *dn)
     }
     if (dn->is_replicated() || in->is_any_caps()) return;  // wait
     if (!in->dirfrags.empty()) return;  // wait for dirs to close/trim
+    if (dn->state_test(CDentry::STATE_PURGING)) return;  // already purging
     _purge_stray(dn);
   }
   else if (in->inode.nlink == 1) {
@@ -6394,9 +6395,9 @@ void MDCache::_purge_stray(CDentry *dn)
   le->metablob.add_null_dentry(dn, true);
   le->metablob.add_inode_truncate(dn->inode->ino(), 0, dn->inode->inode.size);
 
+  dn->state_set(CDentry::STATE_PURGING);
+  dn->get(CDentry::PIN_PURGING);
   mds->mdlog->submit_entry(le, new C_MDC_PurgeStray(this, dn, pdv, mds->mdlog->get_current_segment()));
-
-
 }
 
 void MDCache::_purge_stray_logged(CDentry *dn, version_t pdv, LogSegment *ls)
@@ -6405,6 +6406,8 @@ void MDCache::_purge_stray_logged(CDentry *dn, version_t pdv, LogSegment *ls)
   CInode *in = dn->inode;
   
   // dirty+unlink dentry
+  dn->state_clear(CDentry::STATE_PURGING);
+  dn->put(CDentry::PIN_PURGING);
   dn->dir->mark_dirty(pdv, ls);
   dn->dir->unlink_inode(dn);
   dn->dir->remove_dentry(dn);