ramfs: Set the vnode's cache object when opening files.

Now it is possible to run applications, do Git checkouts, etc.
on a ramfs (and those seem to work just fine -- a git checkout
followed by a git fsck both succeeded.)

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

@@ -41,6 +41,15 @@ DataContainer::InitCheck() const
 	return (fVolume != NULL ? B_OK : B_ERROR);
 }
 
+// GetCache
+VMCache*
+DataContainer::GetCache()
+{
+	if (!_IsCacheMode())
+		_SwitchToCacheMode();
+	return fCache;
+}
+
 // Resize
 status_t
 DataContainer::Resize(off_t newSize)
@@ -63,7 +72,7 @@ DataContainer::Resize(off_t newSize)
 		// grow
 		if (_RequiresCacheMode(newSize)) {
 			if (!_IsCacheMode())
-				error = _SwitchToCacheMode(fSize);
+				error = _SwitchToCacheMode();
 			if (error != B_OK)
 				return error;
 
@@ -187,7 +196,7 @@ DataContainer::_CountBlocks() const
 
 // _SwitchToCacheMode
 status_t
-DataContainer::_SwitchToCacheMode(size_t newBlockSize)
+DataContainer::_SwitchToCacheMode()
 {
 	status_t error = VMCacheFactory::CreateAnonymousCache(fCache, false, 0,
 		0, false, VM_PRIORITY_SYSTEM);
@@ -195,9 +204,9 @@ DataContainer::_SwitchToCacheMode(size_t newBlockSize)
 		return error;
 
 	fCache->temporary = 1;
-	fCache->virtual_end = newBlockSize;
+	fCache->virtual_end = fSize;
 
-	error = fCache->Commit(newBlockSize, VM_PRIORITY_SYSTEM);
+	error = fCache->Commit(fSize, VM_PRIORITY_SYSTEM);
 	if (error != B_OK)
 		return error;
 

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

@@ -46,6 +46,8 @@ public:
 	status_t Resize(off_t newSize);
 	off_t GetSize() const { return fSize; }
 
+	VMCache* GetCache();
+
 	virtual status_t ReadAt(off_t offset, void *buffer, size_t size,
 							size_t *bytesRead);
 	virtual status_t WriteAt(off_t offset, const void *buffer, size_t size,
@@ -57,7 +59,7 @@ public:
 private:
 	inline bool _RequiresCacheMode(size_t size);
 	inline bool _IsCacheMode() const;
-	status_t _SwitchToCacheMode(size_t newBlockSize);
+	status_t _SwitchToCacheMode();
 	void _GetPages(off_t offset, off_t length, bool isWrite, vm_page** pages);
 	void _PutPages(off_t offset, off_t length, vm_page** pages, bool success);
 	status_t _DoCacheIO(const off_t offset, uint8* buffer, ssize_t length,

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

@@ -36,6 +36,7 @@
 #include <fs_interface.h>
 #include <fs_query.h>
 #include <fs_volume.h>
+#include <vfs.h>
 #include <KernelExport.h>
 #include <NodeMonitor.h>
 #include <TypeConstants.h>
@@ -227,9 +228,9 @@ SET_ERROR(error, error);
 }
 
 
-// ramfs_read_vnode
+// ramfs_get_vnode
 static status_t
-ramfs_read_vnode(fs_volume* _volume, ino_t vnid, fs_vnode* node, int* _type,
+ramfs_get_vnode(fs_volume* _volume, ino_t vnid, fs_vnode* node, int* _type,
 	uint32* _flags, bool reenter)
 {
 //	FUNCTION_START();
@@ -889,6 +890,13 @@ ramfs_open(fs_volume* _volume, fs_vnode* _node, int openMode, void** _cookie)
 		// truncate if requested
 		if (error == B_OK && (openMode & O_TRUNC))
 			error = node->SetSize(0);
+		// set cache in vnode
+		if (File *file = dynamic_cast<File*>(node)) {
+			struct vnode* vnode;
+			if (vfs_lookup_vnode(_volume->id, node->GetID(), &vnode) == B_OK) {
+				vfs_set_vnode_cache(vnode, file->GetCache());
+			}
+		}
 		NodeMTimeUpdater mTimeUpdater(node);
 		// set result / cleanup on failure
 		if (error == B_OK)
@@ -2146,7 +2154,7 @@ fs_volume_ops gRamFSVolumeOps = {
 	&ramfs_read_fs_info,
 	&ramfs_write_fs_info,
 	&ramfs_sync,
-	&ramfs_read_vnode,
+	&ramfs_get_vnode,
 
 	/* index directory & index operations */
 	&ramfs_open_index_dir,