Merge tag 'efi-next-for-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:
 "Although some more stuff is brewing, the EFI changes that are ready
  for mainline are few this cycle:

   - improve the PCI DMA paranoia logic in the EFI stub

   - some constification changes

   - add statfs support to efivarfs

   - allow user space to enumerate updatable firmware resources without
     CAP_SYS_ADMIN"

* tag 'efi-next-for-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi/libstub: Disable PCI DMA before grabbing the EFI memory map
  efi/esrt: Allow ESRT access without CAP_SYS_ADMIN
  efivarfs: expose used and total size
  efi: make kobj_type structure constant
  efi: x86: make kobj_type structure constant

1 files changed, 38 insertions, 1 deletions

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 482d612b716b..e028fafa04f3 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -13,6 +13,7 @@
 #include <linux/ucs2_string.h>
 #include <linux/slab.h>
 #include <linux/magic.h>
+#include <linux/statfs.h>
 
 #include "internal.h"
 
@@ -23,8 +24,44 @@ static void efivarfs_evict_inode(struct inode *inode)
 	clear_inode(inode);
 }
 
+static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	const u32 attr = EFI_VARIABLE_NON_VOLATILE |
+			 EFI_VARIABLE_BOOTSERVICE_ACCESS |
+			 EFI_VARIABLE_RUNTIME_ACCESS;
+	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);
+
+	/*
+	 * This is not a normal filesystem, so no point in pretending it has a block
+	 * size; we declare f_bsize to 1, so that we can then report the exact value
+	 * sent by EFI QueryVariableInfo in f_blocks and f_bfree
+	 */
+	buf->f_bsize	= 1;
+	buf->f_namelen	= NAME_MAX;
+	buf->f_blocks	= storage_space;
+	buf->f_bfree	= remaining_space;
+	buf->f_type	= dentry->d_sb->s_magic;
+
+	/*
+	 * In f_bavail we declare the free space that the kernel will allow writing
+	 * when the storage_paranoia x86 quirk is active. To use more, users
+	 * should boot the kernel with efi_no_storage_paranoia.
+	 */
+	if (remaining_space > efivar_reserved_space())
+		buf->f_bavail = remaining_space - efivar_reserved_space();
+	else
+		buf->f_bavail = 0;
+
+	return 0;
+}
 static const struct super_operations efivarfs_ops = {
-	.statfs = simple_statfs,
+	.statfs = efivarfs_statfs,
 	.drop_inode = generic_delete_inode,
 	.evict_inode = efivarfs_evict_inode,
 };