efivarfs: fix statfs() on efivarfs

Some firmware (notably U-Boot) provides GetVariable() and
GetNextVariableName() but not QueryVariableInfo().

With commit d86ff3333cb1 ("efivarfs: expose used and total size") the
statfs syscall was broken for such firmware.

If QueryVariableInfo() does not exist or returns EFI_UNSUPPORTED, just
report the file system size as 0 as statfs_simple() previously did.

Fixes: d86ff3333cb1 ("efivarfs: expose used and total size")
Link: https://lore.kernel.org/all/20230910045445.41632-1-heinrich.schuchardt@canonical.com/
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
[ardb: log warning on QueryVariableInfo() failure]
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index e028fafa04f38c51739bb56c796bb5d854c7c4ba..996271473609a0dbde8cd3db3eadb73e35d2510d 100644 (file)
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -32,10 +32,16 @@ static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
        u64 storage_space, remaining_space, max_variable_size;
        efi_status_t status;
 
-       status = efivar_query_variable_info(attr, &storage_space, &remaining_space,
-                                           &max_variable_size);
-       if (status != EFI_SUCCESS)
-               return efi_status_to_err(status);
+       /* Some UEFI firmware does not implement QueryVariableInfo() */
+       storage_space = remaining_space = 0;
+       if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) {
+               status = efivar_query_variable_info(attr, &storage_space,
+                                                   &remaining_space,
+                                                   &max_variable_size);
+               if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED)
+                       pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n",
+                                           status);
+       }
 
        /*
         * This is not a normal filesystem, so no point in pretending it has a block