[PATCH v2 1/2] Ext4Pkg: Improve Ext4IsBindingSupported() behavior

["Jeff Brasen" <jbrasen@nvidia.com>]

A couple of improvements to improve performance.
Add check to return ACCESS_DENIED if already connected
Add check to verify superblock magic during supported to reduce start calls

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
---
 Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h    | 14 +++++++
 Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c    | 58 +++++++++++++++++++++------
 Features/Ext4Pkg/Ext4Dxe/Superblock.c | 35 ++++++++++++++++
 3 files changed, 95 insertions(+), 12 deletions(-)

diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
index 64eab455db..5c60860894 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
@@ -1117,4 +1117,18 @@ Ext4GetVolumeName (
   OUT UINTN          *VolNameLen
   );
 
+/**
+   Checks the superblock's magic value.
+
+   @param[in] DiskIo     Pointer to the DiskIo.
+   @param[in] BlockIo     Pointer to the BlockIo.
+
+   @return TRUE if a valid ext4 superblock, else FALSE.
+**/
+BOOLEAN
+Ext4SuperblockCheckMagic (
+  IN EFI_DISK_IO_PROTOCOL   *DiskIo,
+  IN EFI_BLOCK_IO_PROTOCOL  *BlockIo
+  );
+
 #endif
diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c
index ea2e048d77..5ae93d0484 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c
@@ -631,7 +631,6 @@ Ext4Unload (
   @retval EFI_ACCESS_DENIED        The device specified by ControllerHandle and
                                    RemainingDevicePath is already being managed by a different
                                    driver or an application that requires exclusive access.
-                                   Currently not implemented.
   @retval EFI_UNSUPPORTED          The device specified by ControllerHandle and
                                    RemainingDevicePath is not supported by the driver specified by This.
 **/
@@ -643,32 +642,67 @@ Ext4IsBindingSupported (
   IN EFI_DEVICE_PATH *RemainingDevicePath  OPTIONAL
   )
 {
-  // Note to self: EFI_OPEN_PROTOCOL_TEST_PROTOCOL lets us not close the
-  // protocol and ignore the output argument entirely
+  EFI_STATUS            Status;
+  EFI_DISK_IO_PROTOCOL  *DiskIo;
+  EFI_BLOCK_IO_PROTOCOL *BlockIo;
 
-  EFI_STATUS  Status;
+  DiskIo = NULL;
+  BlockIo = NULL;
 
+  //
+  // Open the IO Abstraction(s) needed to perform the supported test
+  //
   Status = gBS->OpenProtocol (
                   ControllerHandle,
                   &gEfiDiskIoProtocolGuid,
-                  NULL,
-                  BindingProtocol->ImageHandle,
+                  (VOID **) &DiskIo,
+                  BindingProtocol->DriverBindingHandle,
                   ControllerHandle,
-                  EFI_OPEN_PROTOCOL_TEST_PROTOCOL
+                  EFI_OPEN_PROTOCOL_BY_DRIVER
                   );
 
   if (EFI_ERROR (Status)) {
-    return Status;
+    goto Exit;
   }
-
+  //
+  // Open the IO Abstraction(s) needed to perform the supported test
+  //
   Status = gBS->OpenProtocol (
                   ControllerHandle,
                   &gEfiBlockIoProtocolGuid,
-                  NULL,
-                  BindingProtocol->ImageHandle,
+                  (VOID **) &BlockIo,
+                  BindingProtocol->DriverBindingHandle,
                   ControllerHandle,
-                  EFI_OPEN_PROTOCOL_TEST_PROTOCOL
+                  EFI_OPEN_PROTOCOL_GET_PROTOCOL
                   );
+  if (EFI_ERROR (Status)) {
+    goto Exit;
+  }
+
+  if (!Ext4SuperblockCheckMagic (DiskIo, BlockIo)) {
+    Status = EFI_UNSUPPORTED;
+  }
+
+Exit:
+  //
+  // Close the I/O Abstraction(s) used to perform the supported test
+  //
+  if (DiskIo != NULL) {
+    gBS->CloseProtocol (
+          ControllerHandle,
+          &gEfiDiskIoProtocolGuid,
+          BindingProtocol->DriverBindingHandle,
+          ControllerHandle
+          );
+  }
+  if (BlockIo != NULL) {
+    gBS->CloseProtocol (
+          ControllerHandle,
+          &gEfiBlockIoProtocolGuid,
+          BindingProtocol->DriverBindingHandle,
+          ControllerHandle
+          );
+  }
   return Status;
 }
 
diff --git a/Features/Ext4Pkg/Ext4Dxe/Superblock.c b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
index c321d8c3d8..1ceb0d5cbb 100644
--- a/Features/Ext4Pkg/Ext4Dxe/Superblock.c
+++ b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
@@ -34,6 +34,41 @@ STATIC CONST UINT32  gSupportedIncompatFeat =
 // this is desired, it's fairly trivial to look for EFI_VOLUME_CORRUPTED
 // references and add some Ext4SignalCorruption function + function call.
 
+/**
+   Checks only superblock magic value.
+
+   @param[in] DiskIo     Pointer to the DiskIo.
+   @param[in] BlockIo     Pointer to the BlockIo.
+
+   @return TRUE if a valid ext4 superblock, else FALSE.
+**/
+BOOLEAN
+Ext4SuperblockCheckMagic (
+  IN EFI_DISK_IO_PROTOCOL   *DiskIo,
+  IN EFI_BLOCK_IO_PROTOCOL  *BlockIo
+  )
+{
+  UINT16      Magic;
+  EFI_STATUS  Status;
+
+  Status = DiskIo->ReadDisk (
+                     DiskIo,
+                     BlockIo->Media->MediaId,
+                     EXT4_SUPERBLOCK_OFFSET + OFFSET_OF (EXT4_SUPERBLOCK, s_magic),
+                     sizeof (Magic),
+                     &Magic
+                     );
+  if (EFI_ERROR (Status)) {
+    return FALSE;
+  }
+
+  if (Magic != EXT4_SIGNATURE) {
+    return FALSE;
+  }
+
+  return TRUE;
+}
+
 /**
    Does brief validation of the ext4 superblock.
 
-- 
2.17.1