From bd80259af568280944308025226dba5bad2e70f0 Mon Sep 17 00:00:00 2001
From: Michael Lotz <mmlr@mlotz.ch>
Date: Sat, 29 Aug 2009 16:24:33 +0000
Subject: [PATCH] If we create new nodes or modify existing ones, especially
 directories, we must ensure that these nodes are never put. As they keep all
 changes in memory, putting them and consequently freeing them destroys the
 modifications without a way to get them back from the underlaying filesystem.
 In case a created node was put but still had its entry in the parent
 directory this could also lead to the situation where an invalid node was
 requested from the underlaying filesystem, leading to #4347.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32815 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 .../layers/write_overlay/write_overlay.cpp    | 41 ++++++++++++++++++-
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/add-ons/kernel/file_systems/layers/write_overlay/write_overlay.cpp b/src/add-ons/kernel/file_systems/layers/write_overlay/write_overlay.cpp
index 2f7c9d2d2a..49bdb8e48d 100644
--- a/src/add-ons/kernel/file_systems/layers/write_overlay/write_overlay.cpp
+++ b/src/add-ons/kernel/file_systems/layers/write_overlay/write_overlay.cpp
@@ -103,12 +103,14 @@ public:
 		status_t			InitCheck();
 
 		bool				IsVirtual() { return fIsVirtual; }
+		bool				IsModified() { return fIsModified; }
 
 		fs_volume *			Volume() { return fVolume->Volume(); }
 		fs_volume *			SuperVolume() { return fVolume->SuperVolume(); }
 		fs_vnode *			SuperVnode() { return &fSuperVnode; }
 		ino_t				InodeNumber() { return fInodeNumber; }
 
+		void				SetModified();
 		void				CreateCache();
 
 		void				SetParentDir(OverlayInode *parentDir);
@@ -167,6 +169,7 @@ private:
 		bool				fHasStat;
 		bool				fHasDirents;
 		bool				fIsVirtual;
+		bool				fIsModified;
 		void *				fFileCache;
 };
 
@@ -202,6 +205,7 @@ OverlayInode::OverlayInode(OverlayVolume *volume, fs_vnode *superVnode,
 		fHasStat(false),
 		fHasDirents(false),
 		fIsVirtual(superVnode == NULL),
+		fIsModified(false),
 		fFileCache(NULL)
 {
 	TRACE("inode created %lld\n", fInodeNumber);
@@ -252,6 +256,19 @@ OverlayInode::InitCheck()
 }
 
 
+void
+OverlayInode::SetModified()
+{
+	// we must ensure that a modified node never get's put, as we cannot get it
+	// from the underlying filesystem, so we get an additional reference here
+	// and deliberately leak it
+	// TODO: what about non-force unmounting then?
+	void *unused = NULL;
+	get_vnode(Volume(), fInodeNumber, &unused);
+	fIsModified = true;
+}
+
+
 void
 OverlayInode::CreateCache()
 {
@@ -297,6 +314,8 @@ void
 OverlayInode::SetName(const char *name)
 {
 	fName = name;
+	if (!fIsModified)
+		SetModified();
 }
 
 
@@ -370,6 +389,9 @@ OverlayInode::WriteStat(const struct stat *stat, uint32 statMask)
 		statMask |= B_STAT_MODIFICATION_TIME;
 	}
 
+	if (!fIsModified)
+		SetModified();
+
 	notify_stat_changed(SuperVolume()->id, fInodeNumber, statMask);
 	return B_OK;
 }
@@ -422,8 +444,11 @@ OverlayInode::Open(int openMode, void **_cookie)
 		fOriginalNodeLength = stat.st_size;
 	}
 
-	if (openMode & O_TRUNC)
+	if (openMode & O_TRUNC) {
 		fStat.st_size = 0;
+		if (!fIsModified)
+			SetModified();
+	}
 
 	openMode &= ~(O_RDWR | O_WRONLY | O_TRUNC | O_CREAT);
 	status_t result = fSuperVnode.ops->open(SuperVolume(), &fSuperVnode,
@@ -557,6 +582,9 @@ OverlayInode::Write(void *_cookie, off_t position, const void *buffer,
 			position = fStat.st_size;
 	}
 
+	if (!fIsModified)
+		SetModified();
+
 	// find insertion point
 	write_buffer **link = &fWriteBuffers;
 	write_buffer *other = fWriteBuffers;
@@ -787,6 +815,10 @@ OverlayInode::AddEntry(overlay_dirent *entry)
 
 	fDirents = newDirents;
 	fDirents[fDirentCount++] = entry;
+
+	if (!fIsModified)
+		SetModified();
+
 	return B_OK;
 }
 
@@ -810,6 +842,9 @@ OverlayInode::RemoveEntry(const char *name, overlay_dirent **_entry)
 			else
 				entry->remove_and_dispose(Volume(), fInodeNumber);
 
+			if (!fIsModified)
+				SetModified();
+
 			return B_OK;
 		}
 	}
@@ -965,6 +1000,7 @@ OverlayInode::_CreateCommon(const char *name, int type, int perms,
 		return result;
 	}
 
+	node->SetModified();
 	node->CreateCache();
 
 	if (newInodeNumber != NULL)
@@ -998,7 +1034,8 @@ overlay_put_vnode(fs_volume *volume, fs_vnode *vnode, bool reenter)
 {
 	TRACE("put_vnode\n");
 	OverlayInode *node = (OverlayInode *)vnode->private_node;
-	if (node->IsVirtual()) {
+	if (node->IsVirtual() || node->IsModified()) {
+		panic("loosing virtual/modified node\n");
 		delete node;
 		return B_OK;
 	}