btrfs: extend btrfs_dir_item type to store encryption status

For directories with encrypted files/filenames, we need to store a flag
indicating this fact. There's no room in other fields, so we'll need to
borrow a bit from dir_type. Since it's now a combination of type and
flags, we rename it to dir_flags to reflect its new usage.

The new flag, FT_ENCRYPTED, indicates a directory containing encrypted
data, which is orthogonal to file type; therefore, add the new
flag, and make conversion from directory type to file type strip the
flag.

As the file types almost never change we can afford to use the bits.
Actual usage will be guarded behind an incompat bit, this patch only
adds the support for later use by fscrypt.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 4809272f5063..29895ffa470d 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -376,6 +376,13 @@ enum btrfs_csum_type {
 #define BTRFS_FT_SYMLINK	7
 #define BTRFS_FT_XATTR		8
 #define BTRFS_FT_MAX		9
+/* Directory contains encrypted data */
+#define BTRFS_FT_ENCRYPTED	0x80
+
+static inline __u8 btrfs_dir_flags_to_ftype(__u8 flags)
+{
+	return flags & ~BTRFS_FT_ENCRYPTED;
+}
 
 /*
  * Inode flags