Re: [edk2-devel] [PATCH v3 1/2] Ext4Pkg: Improve Ext4IsBindingSupported() behavior

["Marvin Häuser" <mhaeuser@posteo.de>]

On 11/09/2021 00:11, Jeff Brasen via groups.io wrote:
> 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    | 54 +++++++++++++++++++++------
>   Features/Ext4Pkg/Ext4Dxe/Superblock.c | 35 +++++++++++++++++
>   3 files changed, 92 insertions(+), 11 deletions(-)
>
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> index 64eab455db..a9b932ed52 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.
> +
> +   @returns Whether the partition has a valid EXT4 superblock magic value.
> +**/
> +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..d9fbe9ea78 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 +642,65 @@ 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;
>     }
> -
> +  //
> +  // 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)) {
> +    if (!Ext4SuperblockCheckMagic (DiskIo, BlockIo)) {
> +      Status = EFI_UNSUPPORTED;
> +    }
> +  }
> +
> +  //
> +  // 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
> +          );
> +  }

GET_PROTOCOL protocols are not to be closed, I guess this was missed 
when there was still the question whether to use BY_DRIVER for BlockIo.

Best regards,
Marvin

>     return Status;
>   }
>   
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Superblock.c b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> index c321d8c3d8..0c965415c5 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 the superblock's magic value.
> +
> +   @param[in] DiskIo      Pointer to the DiskIo.
> +   @param[in] BlockIo     Pointer to the BlockIo.
> +
> +   @returns Whether the partition has a valid EXT4 superblock magic value.
> +**/
> +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.
>