From d467fbfd1714ef04faf41e604d6a78e33ef7fa10 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage.weil@dreamhost.com>
Date: Wed, 2 Mar 2011 16:13:54 -0800
Subject: [PATCH] mds: rip out rename linkmerge support

It turns out POSIX says rename(a,b) is a no-op when a and b link to the
same inode.  This is super weird but good news because it means we can
rip out a bunch of poorly tested code.

Signed-off-by: Sage Weil <sage.weil@dreamhost.com>
---
 src/mds/Server.cc | 225 ++++++++++++++++++----------------------------
 1 file changed, 87 insertions(+), 138 deletions(-)

diff --git a/src/mds/Server.cc b/src/mds/Server.cc
index 212b6ac861595..d006fba1ccba4 100644
--- a/src/mds/Server.cc
+++ b/src/mds/Server.cc
@@ -4544,14 +4544,14 @@ void Server::handle_client_rename(MDRequest *mdr)
     return;
   }
 
-  bool linkmerge = (srcdnl->get_inode() == destdnl->get_inode() &&
-		    (srcdnl->is_primary() || destdnl->is_primary()));
-  if (linkmerge)
-    dout(10) << " this is a link merge" << dendl;
+  if (srcdnl->get_inode() == destdnl->get_inode()) {
+    reply_request(mdr, 0);  // no-op.  POSIX makes no sense.
+    return;
+  }
 
   // -- create stray dentry? --
   CDentry *straydn = mdr->straydn;
-  if (destdnl->is_primary() && !linkmerge && !straydn) {
+  if (destdnl->is_primary() && !straydn) {
     straydn = mdcache->get_or_create_stray_dentry(destdnl->get_inode());
     mdr->pin(straydn);
     mdr->straydn = straydn;
@@ -4712,43 +4712,41 @@ void Server::handle_client_rename(MDRequest *mdr)
     assert(g_conf.mds_kill_rename_at != 3);    
   
   // -- prepare anchor updates -- 
-  if (!linkmerge || srcdnl->is_primary()) {
-    C_Gather *anchorgather = 0;
-
-    if (srcdnl->is_primary() &&
-	(srcdnl->get_inode()->is_anchored() || 
-	 (srcdnl->get_inode()->is_dir() && (srcdnl->get_inode()->inode.rstat.ranchors ||
-					    srcdnl->get_inode()->nested_anchors ||
-					    !mdcache->is_leaf_subtree(mdcache->get_subtree_root(srcdn->get_dir()))))) &&
-	!mdr->more()->src_reanchor_atid) {
-      dout(10) << "reanchoring src->dst " << *srcdnl->get_inode() << dendl;
-      vector<Anchor> trace;
-      destdn->make_anchor_trace(trace, srcdnl->get_inode());
-      
+  C_Gather *anchorgather = 0;
+
+  if (srcdnl->is_primary() &&
+      (srcdnl->get_inode()->is_anchored() || 
+       (srcdnl->get_inode()->is_dir() && (srcdnl->get_inode()->inode.rstat.ranchors ||
+					  srcdnl->get_inode()->nested_anchors ||
+					  !mdcache->is_leaf_subtree(mdcache->get_subtree_root(srcdn->get_dir()))))) &&
+      !mdr->more()->src_reanchor_atid) {
+    dout(10) << "reanchoring src->dst " << *srcdnl->get_inode() << dendl;
+    vector<Anchor> trace;
+    destdn->make_anchor_trace(trace, srcdnl->get_inode());
+    
+    anchorgather = new C_Gather(new C_MDS_RetryRequest(mdcache, mdr));
+    mds->anchorclient->prepare_update(srcdnl->get_inode()->ino(), trace, &mdr->more()->src_reanchor_atid, 
+				      anchorgather->new_sub());
+  }
+  if (destdnl->is_primary() &&
+      destdnl->get_inode()->is_anchored() &&
+      !mdr->more()->dst_reanchor_atid) {
+    dout(10) << "reanchoring dst->stray " << *destdnl->get_inode() << dendl;
+    
+    assert(straydn);
+    vector<Anchor> trace;
+    straydn->make_anchor_trace(trace, destdnl->get_inode());
+    
+    if (!anchorgather)
       anchorgather = new C_Gather(new C_MDS_RetryRequest(mdcache, mdr));
-      mds->anchorclient->prepare_update(srcdnl->get_inode()->ino(), trace, &mdr->more()->src_reanchor_atid, 
-					anchorgather->new_sub());
-    }
-    if (destdnl->is_primary() &&
-	destdnl->get_inode()->is_anchored() &&
-	!mdr->more()->dst_reanchor_atid) {
-      dout(10) << "reanchoring dst->stray " << *destdnl->get_inode() << dendl;
-
-      assert(straydn);
-      vector<Anchor> trace;
-      straydn->make_anchor_trace(trace, destdnl->get_inode());
-      
-      if (!anchorgather)
-	anchorgather = new C_Gather(new C_MDS_RetryRequest(mdcache, mdr));
-      mds->anchorclient->prepare_update(destdnl->get_inode()->ino(), trace, &mdr->more()->dst_reanchor_atid, 
-					anchorgather->new_sub());
-    }
-
-    if (anchorgather) 
-      return;  // waiting for anchor prepares
-
-    assert(g_conf.mds_kill_rename_at != 4);
+    mds->anchorclient->prepare_update(destdnl->get_inode()->ino(), trace, &mdr->more()->dst_reanchor_atid, 
+				      anchorgather->new_sub());
   }
+  
+  if (anchorgather) 
+    return;  // waiting for anchor prepares
+  
+  assert(g_conf.mds_kill_rename_at != 4);
 
   // -- prepare journal entry --
   mdr->ls = mdlog->get_current_segment();
@@ -4881,12 +4879,7 @@ void Server::_rename_prepare(MDRequest *mdr,
   CDentry::linkage_t *srcdnl = srcdn->get_projected_linkage();
   CDentry::linkage_t *destdnl = destdn->get_projected_linkage();
 
-  // primary+remote link merge?
-  bool linkmerge = (srcdnl->get_inode() == destdnl->get_inode() &&
-		    (srcdnl->is_primary() || destdnl->is_primary()));
   bool silent = srcdn->get_dir()->inode->is_stray();
-  if (linkmerge)
-    dout(10) << " merging remote and primary links to the same inode" << dendl;
   if (silent)
     dout(10) << " reintegrating stray; will avoid changing nlink or dir mtime" << dendl;
 
@@ -4895,41 +4888,31 @@ void Server::_rename_prepare(MDRequest *mdr,
   inode_t *tpi = 0, *tji = 0;  // target/overwritten inode
   
   // target inode
-  if (!linkmerge) {
-    if (destdnl->is_primary()) {
-      assert(straydn);  // moving to straydn.
-      // link--, and move.
-      if (destdn->is_auth()) {
-	tpi = destdnl->get_inode()->project_inode(); //project_snaprealm
-	tpi->version = straydn->pre_dirty(tpi->version);
-      }
-      straydn->push_projected_linkage(destdnl->get_inode());
-    } else if (destdnl->is_remote()) {
-      // nlink-- targeti
-      if (destdnl->get_inode()->is_auth()) {
-	tpi = destdnl->get_inode()->project_inode();
-	tpi->version = destdnl->get_inode()->pre_dirty();
-      }
+  if (destdnl->is_primary()) {
+    assert(straydn);  // moving to straydn.
+    // link--, and move.
+    if (destdn->is_auth()) {
+      tpi = destdnl->get_inode()->project_inode(); //project_snaprealm
+      tpi->version = straydn->pre_dirty(tpi->version);
+    }
+    straydn->push_projected_linkage(destdnl->get_inode());
+  } else if (destdnl->is_remote()) {
+    // nlink-- targeti
+    if (destdnl->get_inode()->is_auth()) {
+      tpi = destdnl->get_inode()->project_inode();
+      tpi->version = destdnl->get_inode()->pre_dirty();
     }
   }
 
   // dest
   if (srcdnl->is_remote()) {
-    if (!linkmerge) {
-      if (destdn->is_auth()) {
-	mdr->more()->pvmap[destdn] = destdn->pre_dirty();
-        destdn->push_projected_linkage(srcdnl->get_remote_ino(), srcdnl->get_remote_d_type());
-      }
-      if (srcdnl->get_inode()->is_auth()) {
-	pi = srcdnl->get_inode()->project_inode();
-	pi->version = srcdnl->get_inode()->pre_dirty();
-      }
-    } else {
-      dout(10) << " will merge remote onto primary link" << dendl;
-      if (destdn->is_auth()) {
-	pi = destdnl->get_inode()->project_inode();
-	pi->version = mdr->more()->pvmap[destdn] = destdn->pre_dirty(destdnl->get_inode()->inode.version);
-      }
+    if (destdn->is_auth()) {
+      mdr->more()->pvmap[destdn] = destdn->pre_dirty();
+      destdn->push_projected_linkage(srcdnl->get_remote_ino(), srcdnl->get_remote_d_type());
+    }
+    if (srcdnl->get_inode()->is_auth()) {
+      pi = srcdnl->get_inode()->project_inode();
+      pi->version = srcdnl->get_inode()->pre_dirty();
     }
   } else {
     if (destdn->is_auth()) {
@@ -4955,8 +4938,6 @@ void Server::_rename_prepare(MDRequest *mdr,
     if (pi) {
       pi->last_renamed_version = pi->version;
       pi->ctime = mdr->now;
-      if (linkmerge)
-	pi->nlink--;
     }
     if (tpi) {
       tpi->nlink--;
@@ -4990,38 +4971,28 @@ void Server::_rename_prepare(MDRequest *mdr,
 
   // add it all to the metablob
   // target inode
-  if (!linkmerge) {
-    if (destdnl->is_primary()) {
-      // project snaprealm, too
-      bufferlist snapbl;
-      if (destdn->is_auth())
-        destdnl->get_inode()->project_past_snaprealm_parent(straydn->get_dir()->inode->find_snaprealm(), snapbl);
-      straydn->first = MAX(destdnl->get_inode()->first, next_dest_snap);
-      tji = metablob->add_primary_dentry(straydn, true, destdnl->get_inode(), 0, &snapbl);
-    } else if (destdnl->is_remote()) {
-      metablob->add_dir_context(destdnl->get_inode()->get_parent_dir());
-      mdcache->journal_cow_dentry(mdr, metablob, destdnl->get_inode()->parent, CEPH_NOSNAP, 0, destdnl);
-      tji = metablob->add_primary_dentry(destdnl->get_inode()->parent, true, destdnl->get_inode());
-    }
+  if (destdnl->is_primary()) {
+    // project snaprealm, too
+    bufferlist snapbl;
+    if (destdn->is_auth())
+      destdnl->get_inode()->project_past_snaprealm_parent(straydn->get_dir()->inode->find_snaprealm(), snapbl);
+    straydn->first = MAX(destdnl->get_inode()->first, next_dest_snap);
+    tji = metablob->add_primary_dentry(straydn, true, destdnl->get_inode(), 0, &snapbl);
+  } else if (destdnl->is_remote()) {
+    metablob->add_dir_context(destdnl->get_inode()->get_parent_dir());
+    mdcache->journal_cow_dentry(mdr, metablob, destdnl->get_inode()->parent, CEPH_NOSNAP, 0, destdnl);
+    tji = metablob->add_primary_dentry(destdnl->get_inode()->parent, true, destdnl->get_inode());
   }
 
   // dest
   if (srcdnl->is_remote()) {
-    if (!linkmerge) {
-      if (!destdnl->is_null())
-	mdcache->journal_cow_dentry(mdr, metablob, destdn, CEPH_NOSNAP, 0, destdnl);
-      else
-	destdn->first = MAX(destdn->first, next_dest_snap);
-      metablob->add_remote_dentry(destdn, true, srcdnl->get_remote_ino(), srcdnl->get_remote_d_type());
-      mdcache->journal_cow_dentry(mdr, metablob, srcdnl->get_inode()->get_parent_dn(), CEPH_NOSNAP, 0, srcdnl);
-      ji = metablob->add_primary_dentry(srcdnl->get_inode()->get_parent_dn(), true, srcdnl->get_inode());
-    } else {
-      if (!destdnl->is_null())
-	mdcache->journal_cow_dentry(mdr, metablob, destdn, CEPH_NOSNAP, 0, destdnl);
-      else
-	destdn->first = MAX(destdn->first, next_dest_snap);
-      metablob->add_primary_dentry(destdn, true, destdnl->get_inode()); 
-    }
+    if (!destdnl->is_null())
+      mdcache->journal_cow_dentry(mdr, metablob, destdn, CEPH_NOSNAP, 0, destdnl);
+    else
+      destdn->first = MAX(destdn->first, next_dest_snap);
+    metablob->add_remote_dentry(destdn, true, srcdnl->get_remote_ino(), srcdnl->get_remote_d_type());
+    mdcache->journal_cow_dentry(mdr, metablob, srcdnl->get_inode()->get_parent_dn(), CEPH_NOSNAP, 0, srcdnl);
+    ji = metablob->add_primary_dentry(srcdnl->get_inode()->get_parent_dn(), true, srcdnl->get_inode());
   } else if (srcdnl->is_primary()) {
     // project snap parent update?
     bufferlist snapbl;
@@ -5047,8 +5018,6 @@ void Server::_rename_prepare(MDRequest *mdr,
   if (!silent) {
     if (ji && !pi) {
       ji->ctime = mdr->now;
-      if (linkmerge)
-	ji->nlink--;
     }
     if (tji && !tpi) {
       tji->nlink--;
@@ -5075,12 +5044,8 @@ void Server::_rename_apply(MDRequest *mdr, CDentry *srcdn, CDentry *destdn, CDen
 
   CInode *oldin = destdnl->get_inode();
   
-  // primary+remote link merge?
-  bool linkmerge = (srcdnl->get_inode() == destdnl->get_inode() &&
-		    (srcdnl->is_primary() || destdnl->is_primary()));
-
   // target inode
-  if (!linkmerge && oldin) {
+  if (oldin) {
     bool dest_primary = false;
     if (destdnl->is_primary()) {
       dest_primary = true;
@@ -5111,28 +5076,19 @@ void Server::_rename_apply(MDRequest *mdr, CDentry *srcdn, CDentry *destdn, CDen
   CInode *in = srcdnl->get_inode();
   assert(in);
   if (srcdnl->is_remote()) {
-    if (!linkmerge) {
-      srcdn->get_dir()->unlink_inode(srcdn);
-      if (destdn->is_auth())
-	destdnl = destdn->pop_projected_linkage();
-      else
-	destdn->get_dir()->link_remote_inode(destdn, in);
-      destdn->link_remote(destdnl, in);
-      if (destdn->is_auth())
-	destdn->mark_dirty(mdr->more()->pvmap[destdn], mdr->ls);
-    } else {
-      dout(10) << "merging remote onto primary link" << dendl;
-      srcdn->get_dir()->unlink_inode(srcdn);
-    }
+    srcdn->get_dir()->unlink_inode(srcdn);
+    if (destdn->is_auth())
+      destdnl = destdn->pop_projected_linkage();
+    else
+      destdn->get_dir()->link_remote_inode(destdn, in);
+    destdn->link_remote(destdnl, in);
+    if (destdn->is_auth())
+      destdn->mark_dirty(mdr->more()->pvmap[destdn], mdr->ls);
     if (destdnl->get_inode()->is_auth())
       destdnl->get_inode()->pop_and_dirty_projected_inode(mdr->ls);
     else
       destdnl->get_inode()->open_snaprealm();
   } else {
-    if (linkmerge) {
-      dout(10) << "merging primary onto remote link" << dendl;
-      destdn->get_dir()->unlink_inode(destdn);
-    }
     srcdn->get_dir()->unlink_inode(srcdn);
     if (destdn->is_auth())
       destdnl = destdn->pop_projected_linkage();
@@ -5250,10 +5206,8 @@ void Server::handle_slave_rename_prep(MDRequest *mdr)
   mdr->pin(srci);
 
   // stray?
-  bool linkmerge = (srcdnl->get_inode() == destdnl->get_inode() &&
-		    (srcdnl->is_primary() || destdnl->is_primary()));
   CDentry *straydn = 0;
-  if (destdnl->is_primary() && !linkmerge) {
+  if (destdnl->is_primary()) {
     assert(mdr->slave_request->stray.length() > 0);
     straydn = mdcache->add_replica_stray(mdr->slave_request->stray, mdr->slave_to_mds);
     assert(straydn);
@@ -5598,11 +5552,6 @@ void Server::do_rename_rollback(bufferlist &rbl, int master, MDRequest *mdr)
   if (straydn)
     straydir->unlink_inode(straydn);
 
-  bool linkmerge = ((rollback.orig_src.ino && 
-		     rollback.orig_src.ino == rollback.orig_dest.remote_ino) ||
-		    (rollback.orig_dest.ino && 
-		     rollback.orig_dest.ino == rollback.orig_src.remote_ino));
-  
   // repair src
   if (rollback.orig_src.ino)
     srcdir->link_primary_inode(srcdn, in);
@@ -5627,7 +5576,7 @@ void Server::do_rename_rollback(bufferlist &rbl, int master, MDRequest *mdr)
   if (rollback.orig_dest.ino) {
     target = mds->mdcache->get_inode(rollback.orig_dest.ino);
     destdir->link_primary_inode(destdn, target);
-    assert(linkmerge || straydn);
+    assert(straydn);
   } else if (rollback.orig_dest.remote_ino) {
     target = mds->mdcache->get_inode(rollback.orig_dest.remote_ino);
     destdir->link_remote_inode(destdn, rollback.orig_dest.remote_ino, 
-- 
2.39.5