[U-Boot] [PATCH v2 2/3] efi_loader: disk: install FILE_SYSTEM_PROTOCOL only if available

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Thu, Sep 12, 2019 at 10:57:20AM +0200, Heinrich Schuchardt wrote:
> On 9/12/19 6:51 AM, AKASHI Takahiro wrote:
> > In the current implementation, EFI_SIMPLEFILE_SYSTEM_PROTOCOL is always
> > installed to all the partitions even if some of them may house no file
> > system.
> >
> > With this patch, that protocol will be installed only if FAT file system
> > exists.
> >
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> >  lib/efi_loader/efi_disk.c | 16 +++++++++++++++-
> >  1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
> > index 7a6b06821a47..d72f455901f2 100644
> > --- a/lib/efi_loader/efi_disk.c
> > +++ b/lib/efi_loader/efi_disk.c
> > @@ -9,6 +9,7 @@
> >  #include <blk.h>
> >  #include <dm.h>
> >  #include <efi_loader.h>
> > +#include <fs.h>
> >  #include <part.h>
> >  #include <malloc.h>
> >
> > @@ -217,6 +218,19 @@ efi_fs_from_path(struct efi_device_path *full_path)
> >  	return handler->protocol_interface;
> >  }
> >
> > +static int efi_fs_exists(struct blk_desc *desc, int part)
> > +{
> > +	if (fs_set_blk_dev_with_part(desc, part))
> > +		return 0;
> > +
> > +	if (strcmp(fs_get_type_name(), "fat"))
> 
> Before your patch we could use any supported file system (e.g. EXT2). I
> see no need for a restriction to FAT. You could compare the string to
> "unsupported":

No. As far as you want to stick to compliance to UEFI specification,
"fat" is the only file system supported by UEFI.

> if (!strcmp(fs_get_type_name(), "unsupported"))
> 	return 0;
> 
> But wouldn't it be preferable to have a function to access fs_type (in
> fs/fs.c) directly instead of a string representation?

Agree, but there is no direct function in fs/fs.c.
I'm reluctant to invent a new function just for this purpose.

-Takahiro Akashi


> Otherwise we should convert the string "unsupported" of fstypes[] into a
> constant in fs.h so that we can be sure we are using the same value.
> 
> Best regards
> 
> Heinrich
> 
> > +		return 0;
> > +
> > +	fs_close();
> > +
> > +	return 1;
> > +}
> > +
> >  /*
> >   * Create a handle for a partition or disk
> >   *
> > @@ -270,7 +284,7 @@ static efi_status_t efi_disk_add_dev(
> >  			       diskobj->dp);
> >  	if (ret != EFI_SUCCESS)
> >  		return ret;
> > -	if (part >= 1) {
> > +	if (part >= 1 && efi_fs_exists(desc, part)) {
> >  		diskobj->volume = efi_simple_file_system(desc, part,
> >  							 diskobj->dp);
> >  		ret = efi_add_protocol(&diskobj->header,
> >
>