efi_pstore: Check remaining space with QueryVariableInfo() before writing data

[Issue]

As discussed in a thread below, Running out of space in EFI isn't a well-tested scenario.
And we wouldn't expect all firmware to handle it gracefully.
http://marc.info/?l=linux-kernel&m=134305325801789&w=2

On the other hand, current efi_pstore doesn't check a remaining space of storage at writing time.
Therefore, efi_pstore may not work if it tries to write a large amount of data.

[Patch Description]

To avoid handling the situation above, this patch checks if there is a space enough to log with
QueryVariableInfo() before writing data.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Acked-by: Mike Waychison <mikew@google.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8670eb1eb8cd..c47ec36f3f39 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -643,6 +643,7 @@ struct efivar_operations {
         efi_get_variable_t *get_variable;
         efi_get_next_variable_t *get_next_variable;
         efi_set_variable_t *set_variable;
+        efi_query_variable_info_t *query_variable_info;
 };
 
 struct efivars {