From: Omar Sandoval <osandov@osandov.com>

As encrypted files will be incompatible with older filesystem versions,
new filesystems should be created with an incompat flag for fscrypt,
which will gate access to the encryption ioctls.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
---

v5: https://lore.kernel.org/linux-btrfs/ccbea52046c1dadbbef926bfc878cc23af952729.1706116485.git.josef@toxicpanda.com/
 * No changes since.
---
 fs/btrfs/fs.h              | 3 ++-
 fs/btrfs/super.c           | 5 +++++
 fs/btrfs/sysfs.c           | 6 ++++++
 include/uapi/linux/btrfs.h | 1 +
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
index d3762fbe7267..5077b7eed4b8 100644
--- a/fs/btrfs/fs.h
+++ b/fs/btrfs/fs.h
@@ -315,7 +315,8 @@ enum {
 	(BTRFS_FEATURE_INCOMPAT_SUPP_STABLE |	\
 	 BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
 	 BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2 | \
-	 BTRFS_FEATURE_INCOMPAT_REMAP_TREE)
+	 BTRFS_FEATURE_INCOMPAT_REMAP_TREE |	\
+	 BTRFS_FEATURE_INCOMPAT_ENCRYPT)
 
 #else
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7eb367b1f6f6..3914abec5b12 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2567,6 +2567,11 @@ static int __init btrfs_print_mod_info(void)
 			", fsverity=yes"
 #else
 			", fsverity=no"
+#endif
+#ifdef CONFIG_FS_ENCRYPTION
+			", fscrypt=yes"
+#else
+			", fscrypt=no"
 #endif
 			;
 
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 27bfb7b55ec4..98d6b1594d43 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -305,6 +305,9 @@ BTRFS_FEAT_ATTR_INCOMPAT(remap_tree, REMAP_TREE);
 #ifdef CONFIG_FS_VERITY
 BTRFS_FEAT_ATTR_COMPAT_RO(verity, VERITY);
 #endif
+#ifdef CONFIG_FS_ENCRYPTION
+BTRFS_FEAT_ATTR_INCOMPAT(encryption, ENCRYPT);
+#endif /* CONFIG_FS_ENCRYPTION */
 
 /*
  * Features which depend on feature bits and may differ between each fs.
@@ -338,6 +341,9 @@ static struct attribute *btrfs_supported_feature_attrs[] = {
 #ifdef CONFIG_FS_VERITY
 	BTRFS_FEAT_ATTR_PTR(verity),
 #endif
+#ifdef CONFIG_FS_ENCRYPTION
+	BTRFS_FEAT_ATTR_PTR(encryption),
+#endif /* CONFIG_FS_ENCRYPTION */
 	NULL
 };
 
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 9165154a274d..2f6a46e5f4ce 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -335,6 +335,7 @@ struct btrfs_ioctl_fs_info_args {
 #define BTRFS_FEATURE_INCOMPAT_ZONED		(1ULL << 12)
 #define BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2	(1ULL << 13)
 #define BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE	(1ULL << 14)
+#define BTRFS_FEATURE_INCOMPAT_ENCRYPT		(1ULL << 15)
 #define BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA	(1ULL << 16)
 #define BTRFS_FEATURE_INCOMPAT_REMAP_TREE	(1ULL << 17)
 
-- 
2.51.0