ramfs: Rework NodeMTimeUpdater into NodeStatChangeNotifier.

This now does what notify_if_stat_changed used to, fixing a
race: if some thread was modifying a file, and some other thread
(or the same thread, in some other mtime-updating operation)
updated that file and this called MarkUnmodified() before the
first thread close()d it, then when the first thread called close(),
no node monitor notification would've been sent, as fModified
would've already been unset.

So, now every time we are to mark a file "unmodified", we also
send the node monitor notification at the same time.

Fixes the remainder of #19910.

src/add-ons/kernel/file_systems/ramfs/Node.cpp

@@ -135,6 +135,19 @@ Node::SetMTime(time_t mTime)
 }
 
 
+uint32
+Node::MarkUnmodified()
+{
+	uint32 modified = fModified;
+	if (modified) {
+		fCTime = time(NULL);
+		SetMTime(fCTime);
+		fModified = 0;
+	}
+	return modified;
+}
+
+
 status_t
 Node::CheckPermissions(int mode) const
 {
@@ -317,3 +330,20 @@ Node::GetAllocationInfo(AllocationInfo &info)
 	while (GetNextAttribute(&attribute) == B_OK)
 		attribute->GetAllocationInfo(info);
 }
+
+
+NodeStatChangeNotifier::~NodeStatChangeNotifier()
+{
+	if (fNode == NULL || !fNode->IsModified())
+		return;
+
+	uint32 statFields = fNode->MarkUnmodified();
+	for (Entry* entry = fNode->GetFirstReferrer(); entry != NULL;
+			entry = fNode->GetNextReferrer(entry)) {
+		ino_t parentID = -1;
+		if (entry->GetParent() != NULL)
+			parentID = ((Node*)entry->GetParent())->GetID();
+		notify_stat_changed(fNode->GetVolume()->GetID(), parentID,
+			fNode->GetID(), statFields);
+	}
+}

src/add-ons/kernel/file_systems/ramfs/Node.h

@@ -129,32 +129,15 @@ protected:
 	DoublyLinkedList<Entry, GetNodeReferrerLink>	fReferrers;
 };
 
-// MarkUnmodified
-inline
-uint32
-Node::MarkUnmodified()
-{
-	uint32 modified = fModified;
-	if (modified) {
-		fCTime = time(NULL);
-		SetMTime(fCTime);
-		fModified = 0;
-	}
-	return modified;
-}
 
-// NodeMTimeUpdater
+class NodeStatChangeNotifier {
-class NodeMTimeUpdater {
 public:
-	NodeMTimeUpdater(Node *node) : fNode(node) {}
+	NodeStatChangeNotifier(Node *node) : fNode(node) {}
-	~NodeMTimeUpdater()
+	~NodeStatChangeNotifier();
-	{
-		if (fNode && fNode->IsModified())
-			fNode->MarkUnmodified();
-	}
 
 private:
 	Node	*fNode;
 };
 
+
 #endif	// NODE_H

src/add-ons/kernel/file_systems/ramfs/kernel_interface.cpp

@@ -68,23 +68,6 @@ static const size_t kOptimalIOSize = 65536;
 static const bigtime_t kNotificationInterval = 1000000LL;
 
 
-static void
-notify_if_stat_changed(Volume *volume, Node *node)
-{
-	if (volume == NULL || node == NULL || !node->IsModified())
-		return;
-
-	uint32 statFields = node->MarkUnmodified();
-	for (Entry* entry = node->GetFirstReferrer(); entry != NULL;
-			entry = node->GetNextReferrer(entry)) {
-		ino_t parentID = -1;
-		if (entry->GetParent() != NULL)
-			parentID = entry->GetParent()->GetID();
-		notify_stat_changed(volume->GetID(), parentID, node->GetID(), statFields);
-	}
-}
-
-
 // #pragma mark - FS
 
 
@@ -418,7 +401,7 @@ ramfs_create_symlink(fs_volume* _volume, fs_vnode* _dir, const char *name,
 		RETURN_ERROR(B_ERROR);
 
 	status_t error = B_OK;
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	// directory deleted?
 	bool removed;
 	if (get_vnode_removed(volume->FSVolume(), dir->GetID(), &removed)
@@ -448,7 +431,7 @@ ramfs_create_symlink(fs_volume* _volume, fs_vnode* _dir, const char *name,
 			}
 		}
 	}
-	NodeMTimeUpdater mTimeUpdater2(node);
+	NodeStatChangeNotifier statNotifier2(node);
 	// notify listeners
 	if (error == B_OK) {
 		notify_entry_created(volume->GetID(), dir->GetID(), name,
@@ -476,7 +459,7 @@ ramfs_link(fs_volume* _volume, fs_vnode* _dir, const char *name,
 		RETURN_ERROR(B_ERROR);
 
 	status_t error = B_OK;
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	// directory deleted?
 	bool removed;
 	if (get_vnode_removed(volume->FSVolume(), dir->GetID(), &removed)
@@ -522,7 +505,7 @@ ramfs_unlink(fs_volume* _volume, fs_vnode* _dir, const char *name)
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	// check directory write permissions
 	error = dir->CheckPermissions(W_OK);
 	ino_t nodeID = -1;
@@ -568,8 +551,8 @@ ramfs_rename(fs_volume* _volume, fs_vnode* _oldDir, const char *oldName,
 
 	status_t error = B_OK;
 
-	NodeMTimeUpdater mTimeUpdater1(oldDir);
+	NodeStatChangeNotifier statNotifier1(oldDir);
-	NodeMTimeUpdater mTimeUpdater2(newDir);
+	NodeStatChangeNotifier statNotifier2(newDir);
 
 	// target directory deleted?
 	bool removed;
@@ -733,7 +716,7 @@ ramfs_write_stat(fs_volume* _volume, fs_vnode* _node, const struct stat *st,
 			mask, st) != B_OK)
 		RETURN_ERROR(B_NOT_ALLOWED);
 
-	NodeMTimeUpdater mTimeUpdater(node);
+	NodeStatChangeNotifier statNotifier(node);
 	status_t error = B_OK;
 
 	if ((mask & B_STAT_SIZE) != 0)
@@ -759,10 +742,6 @@ ramfs_write_stat(fs_volume* _volume, fs_vnode* _node, const struct stat *st,
 			node->SetCrTime(st->st_crtime);
 	}
 
-	// notify listeners
-	if (error == B_OK)
-		notify_if_stat_changed(volume, node);
-
 	RETURN_ERROR(error);
 }
 
@@ -814,7 +793,7 @@ ramfs_create(fs_volume* _volume, fs_vnode* _dir, const char *name, int openMode,
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	status_t error = B_OK;
 
 	// directory deleted?
@@ -879,7 +858,7 @@ ramfs_create(fs_volume* _volume, fs_vnode* _dir, const char *name, int openMode,
 		else if (cookie)
 			delete cookie;
 	}
-	NodeMTimeUpdater mTimeUpdater2(node);
+	NodeStatChangeNotifier statNotifier2(node);
 	// notify listeners
 	if (error == B_OK)
 		notify_entry_created(volume->GetID(), dir->GetID(), name, *vnid);
@@ -906,7 +885,7 @@ ramfs_create_special_node(fs_volume *_volume, fs_vnode *_dir, const char *name,
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	status_t error = B_OK;
 
 	// directory deleted?
@@ -944,7 +923,7 @@ ramfs_create_special_node(fs_volume *_volume, fs_vnode *_dir, const char *name,
 		RETURN_ERROR(error);
 	}
 
-	NodeMTimeUpdater mTimeUpdater2(node);
+	NodeStatChangeNotifier statNotifier2(node);
 
 	// notify listeners
 	notify_entry_created(volume->GetID(), dir->GetID(), name, *vnid);
@@ -989,7 +968,7 @@ ramfs_open(fs_volume* _volume, fs_vnode* _node, int openMode, void** _cookie)
 		VolumeWriteLocker writeLocker(volume);
 
 		error = node->SetSize(0);
-		NodeMTimeUpdater mTimeUpdater(node);
+		NodeStatChangeNotifier statNotifier(node);
 	}
 
 	// set result / cleanup on failure
@@ -1011,15 +990,12 @@ ramfs_close(fs_volume* _volume, fs_vnode* _node, void* /*cookie*/)
 
 	FUNCTION(("node: %lld\n", node->GetID()));
 
-	VolumeReadLocker locker(volume);
+	VolumeWriteLocker locker(volume);
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	status_t error = B_OK;
+	NodeStatChangeNotifier _(node);
-	// notify listeners
+	return B_OK;
-	notify_if_stat_changed(volume, node);
-
-	return error;
 }
 
 
@@ -1103,9 +1079,9 @@ ramfs_write(fs_volume* _volume, fs_vnode* _node, void* _cookie, off_t pos,
 		}
 	}
 	// notify listeners
-	if (error == B_OK && cookie->NotificationIntervalElapsed(true))
+	if (error == B_OK && cookie->NotificationIntervalElapsed(true)) {
-		notify_if_stat_changed(volume, node);
+		NodeStatChangeNotifier _(node);
-	NodeMTimeUpdater mTimeUpdater(node);
+	}
 	RETURN_ERROR(error);
 }
 
@@ -1210,7 +1186,7 @@ ramfs_create_dir(fs_volume* _volume, fs_vnode* _dir, const char *name, int mode)
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	// directory deleted?
 	bool removed;
 	status_t error = B_OK;
@@ -1241,7 +1217,7 @@ ramfs_create_dir(fs_volume* _volume, fs_vnode* _dir, const char *name, int mode)
 			}
 		}
 	}
-	NodeMTimeUpdater mTimeUpdater2(node);
+	NodeStatChangeNotifier statNotifier2(node);
 	// notify listeners
 	if (error == B_OK) {
 		notify_entry_created(volume->GetID(), dir->GetID(), name,
@@ -1268,7 +1244,7 @@ ramfs_remove_dir(fs_volume* _volume, fs_vnode* _dir, const char *name)
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(dir);
+	NodeStatChangeNotifier statNotifier(dir);
 	// check directory write permissions
 	status_t error = dir->CheckPermissions(W_OK);
 	ino_t nodeID = -1;
@@ -1638,7 +1614,7 @@ ramfs_create_attr(fs_volume* _volume, fs_vnode* _node, const char *name,
 		if (error != B_OK)
 			return error;
 	}
-	NodeMTimeUpdater mTimeUpdater(node);
+	NodeStatChangeNotifier statNotifier(node);
 
 	// success
 	cookieDeleter.Detach();
@@ -1689,7 +1665,7 @@ ramfs_open_attr(fs_volume* _volume, fs_vnode* _node, const char *name,
 	// truncate if requested
 	if (error == B_OK && (openMode & O_TRUNC))
 		error = attribute->SetSize(0);
-	NodeMTimeUpdater mTimeUpdater(node);
+	NodeStatChangeNotifier statNotifier(node);
 
 	// set result / cleanup on failure
 	if (error == B_OK)
@@ -1713,8 +1689,7 @@ ramfs_close_attr(fs_volume* _volume, fs_vnode* _node, void* _cookie)
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	// notify listeners
+	NodeStatChangeNotifier _(node);
-	notify_if_stat_changed(volume, node);
 	return B_OK;
 }
 
@@ -1788,7 +1763,7 @@ ramfs_write_attr(fs_volume* _volume, fs_vnode* _node, void* _cookie,
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(node);
+	NodeStatChangeNotifier statNotifier(node);
 
 	// find the attribute
 	Attribute *attribute = NULL;
@@ -1864,7 +1839,7 @@ ramfs_remove_attr(fs_volume* _volume, fs_vnode* _node, const char *name)
 	if (!locker.IsLocked())
 		RETURN_ERROR(B_ERROR);
 
-	NodeMTimeUpdater mTimeUpdater(node);
+	NodeStatChangeNotifier statNotifier(node);
 
 	// check permissions
 	error = node->CheckPermissions(W_OK);