Re: [PATCH 1/2] Ext4Pkg: Improve Binding support behavior

["Pedro Falcato" <pedro.falcato@gmail.com>]

Hi Jeff,

Comments below.

The patch itself looks good.

Nitpick on the commit message: I'd reword the commit message to
something like "Improve Ext4IsBindingSupported() behavior"
or "Improve IsBindingSupported behavior", since this patch doesn't
change Ext4Bind(), which does the actual bind.

On Thu, Sep 9, 2021 at 9:41 PM Jeff Brasen <jbrasen@nvidia.com> wrote:
>
> A couple improvements to improve performance.
> Add check to return ACCESS_DENIED if already connected
> Add check to verify superblock magic during supported to deduce start calls
>
> Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
> ---
>  Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h    | 14 +++++++
>  Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c    | 57 +++++++++++++++++++++------
>  Features/Ext4Pkg/Ext4Dxe/Superblock.c | 34 ++++++++++++++++
>  3 files changed, 92 insertions(+), 13 deletions(-)
>
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> index 64eab455db..9a3938e671 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> +++ b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.h
> @@ -1117,4 +1117,18 @@ Ext4GetVolumeName (
>    OUT UINTN          *VolNameLen
>    );
>
> +/**
> +   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
> +  );

I'd reword the first part of the comment into something like "Checks
the superblock's magic value.".
Aligning the two "Pointer to the ...Io" would be neat :)
Types and parameter names need to be separated by at least two
columns. So, something like:

 IN EFI_DISK_IO_PROTOCOL   *DiskIo,
 IN EFI_BLOCK_IO_PROTOCOL  *BlockIo

The feedback above also applies to the function's definition below, in
Superblock.c.

> +
>  #endif
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c b/Features/Ext4Pkg/Ext4Dxe/Ext4Dxe.c
> index ea2e048d77..cb1e6d532a 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 +642,64 @@ 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_STATUS            Status;
> +  EFI_DISK_IO_PROTOCOL  *DiskIo = NULL;
> +  EFI_BLOCK_IO_PROTOCOL *BlockIo = NULL;
>
Initialization of variables are always separate from the declaration. Example:
EFI_DISK_IO_PROTOCOL  *DiskIo;
...

DiskIo = 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..1f8cdd3705 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/Superblock.c
> @@ -34,6 +34,40 @@ 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
> +  )

Same as above.

> +{
> +  UINT16      Magic;
> +  EFI_STATUS Status;
> +
> +  Status = DiskIo->ReadDisk (DiskIo,
> +                             BlockIo->Media->MediaId,
> +                             EXT4_SUPERBLOCK_OFFSET + OFFSET_OF (EXT4_SUPERBLOCK, s_magic),
> +                             sizeof (Magic),
> +                             &Magic
> +                             );
Splitting a function call in multiple lines should be done like in
https://edk2-docs.gitbook.io/edk-ii-c-coding-standards-specification/5_source_files/52_spacing#5-2-2-4-subsequent-lines-of-multi-line-function-calls-should-line-up-two-spaces-from-the-beginning-of-the-function-name.

> +  if (EFI_ERROR (Status)) {
> +    return FALSE;
> +  }
> +
> +  if (Magic != EXT4_SIGNATURE) {
> +    return FALSE;
> +  }
> +
> +  return TRUE;
> +}
> +
>  /**
>     Does brief validation of the ext4 superblock.
>
> --
> 2.17.1
>


-- 
Pedro Falcato