This reorganization removes useless 'bytes' prior assignment and uses
'memdup_user' instead 'kmalloc' + 'copy_from_user'.
Signed-off-by: NGeyslan G. Bem <geyslan@gmail.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

Previously in 1fa7e695 efi_status_to_err() translated firmware status
EFI_NOT_FOUND to -EIO instead of -ENOENT for efivarfs operations to
avoid confusion. After refactoring in e14ab23d, it is also used in other
places where the translation may be unnecessary.

So move the translation to efivarfs specific code. Also return EOF
for reading zero-length files, which is what users would expect.

Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Lee, Chun-Yi <jlee@suse.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: NLingzhu Xiang <lxiang@redhat.com>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

Now that efivarfs uses the efivar API, move it out of efivars.c and
into fs/efivarfs where it belongs. This move will eventually allow us
to enable the efivarfs code without having to also enable
CONFIG_EFI_VARS built, and vice versa.

Furthermore, things like,

    mount -t efivarfs none /sys/firmware/efi/efivars

will now work if efivarfs is built as a module without requiring the
use of MODULE_ALIAS(), which would have been necessary when the
efivarfs code was part of efivars.c.

Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Jeremy Kerr <jk@ozlabs.org>
Reviewed-by: NTom Gundersen <teg@jklm.no>
Tested-by: NTom Gundersen <teg@jklm.no>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>