Added an identify_file_system() hook to the FS modules. The boot loader

does no longer give partitioning systems precedence over file systems.
The one with the greater identification priority wins. ATM, if a file
system wins, we still mount the first file system that recognized the
partition at all, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22446 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/boot/partitions.h

@@ -88,6 +88,7 @@ extern partition_module_info gIntelExtendedPartitionModule;
 struct file_system_module_info {
 	const char	*module_name;
 	const char	*pretty_name;
+	float		(*identify_file_system)(boot::Partition *device);
 	status_t	(*get_file_system)(boot::Partition *device, Directory **_root);
 };
 

src/system/boot/loader/file_systems/amiga_ffs/Volume.cpp

@@ -100,6 +100,15 @@ Volume::InitCheck()
 //	#pragma mark -
 
 
+float
+amiga_ffs_identify_file_system(boot::Partition *partition)
+{
+	Volume volume(partition);
+
+	return volume.InitCheck() < B_OK ? 0 : 0.8;
+}
+
+
 static status_t
 amiga_ffs_get_file_system(boot::Partition *partition, ::Directory **_root)
 {
@@ -120,6 +129,7 @@ amiga_ffs_get_file_system(boot::Partition *partition, ::Directory **_root)
 file_system_module_info gAmigaFFSFileSystemModule = {
 	"file_systems/amiga_ffs/v1",
 	kPartitionTypeAmigaFFS,
+	amiga_ffs_identify_file_system,
 	amiga_ffs_get_file_system
 };
 

src/system/boot/loader/file_systems/bfs/bfs.cpp

@@ -132,6 +132,15 @@ Volume::ToBlockRun(off_t block) const
 //	#pragma mark -
 
 
+float
+bfs_identify_file_system(boot::Partition *partition)
+{
+	Volume volume(partition);
+
+	return volume.InitCheck() < B_OK ? 0 : 0.8;
+}
+
+
 static status_t
 bfs_get_file_system(boot::Partition *partition, ::Directory **_root)
 {
@@ -152,6 +161,7 @@ bfs_get_file_system(boot::Partition *partition, ::Directory **_root)
 file_system_module_info gBFSFileSystemModule = {
 	"file_systems/bfs/v1",
 	kPartitionTypeBFS,
+	bfs_identify_file_system,
 	bfs_get_file_system
 };
 

src/system/boot/loader/file_systems/hfs_plus/hfs_plus.cpp

@@ -55,6 +55,7 @@ hfs_plus_get_file_system(boot::Partition *partition, ::Directory **_root)
 file_system_module_info gAmigaFFSFileSystemModule = {
 	"file_systems/hfs_plus/v1",
 	kPartitionTypeHFSPlus,
+	NULL,
 	hfs_plus_get_file_system
 };
 

src/system/boot/loader/file_systems/tarfs/tarfs.cpp

@@ -813,6 +813,7 @@ tarfs_get_file_system(boot::Partition *partition, ::Directory **_root)
 file_system_module_info gTarFileSystemModule = {
 	"file_systems/tarfs/v1",
 	kPartitionTypeTarFS,
+	NULL,	// identify_file_system
 	tarfs_get_file_system
 };
 

src/system/boot/loader/partitions.cpp

@@ -271,8 +271,26 @@ Partition::Scan(bool mountFileSystems, bool isBootDevice)
 		bestPriority = priority;
 	}
 
+
+	// find the best FS module
+	const file_system_module_info *bestFSModule = NULL;
+	float bestFSPriority = -1;
+	for (int32 i = 0; i < sNumFileSystemModules; i++) {
+		if (sFileSystemModules[i]->identify_file_system == NULL)
+			continue;
+
+		float priority = sFileSystemModules[i]->identify_file_system(this);
+		if (priority <= 0)
+			continue;
+
+		if (priority > bestFSPriority) {
+			bestFSModule = sFileSystemModules[i];
+			bestFSPriority = priority;
+		}
+	}
+
 	// now let the best matching disk system scan the partition
-	if (bestModule) {
+	if (bestModule && bestPriority >= bestFSPriority) {
 		NodeOpener opener(this, O_RDONLY);
 		status_t status = bestModule->scan_partition(opener.Descriptor(), this,
 			bestCookie);
@@ -323,8 +341,11 @@ Partition::Scan(bool mountFileSystems, bool isBootDevice)
 
 	// scan for file systems
 
-	if (mountFileSystems)
+	if (mountFileSystems) {
+		// TODO: Use the FS module we've got, if any. Requires to implement the
+		// identify_file_system() hook in every FS.
 		return Mount();
+	}
 
 	return B_ENTRY_NOT_FOUND; 
 }