From b5c399cc4119e55b705f55c58b051e9e40070fdb Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Fri, 14 Nov 2008 14:31:24 -0800
Subject: [PATCH] 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.
---
 src/mds/CDentry.h  | 3 +++
 src/mds/MDCache.cc | 7 +++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/mds/CDentry.h b/src/mds/CDentry.h
index 9bda79ddc7aea..274651f028bfd 100644
--- 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 3326b5e4808e1..d267290a3c73c 100644
--- 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);
-- 
2.39.5