From: Eric Biggers <ebiggers@xxxxxxxxxx>
IV_INO_LBLK_64 encryption policies have special requirements from the
filesystem beyond those of the existing encryption policies:
- Inode numbers must never change, even if the filesystem is resized.
- Inode numbers must be <= 32 bits.
- File logical block numbers must be <= 32 bits.
ext4 has 32-bit inode and file logical block numbers. However,
resize2fs can re-number inodes when shrinking an ext4 filesystem.
However, typically the people who would want to use this format don't
care about filesystem shrinking. They'd be fine with a solution that
just prevents the filesystem from being shrunk.
Therefore, add a new feature flag EXT4_FEATURE_COMPAT_STABLE_INODES that
will do exactly that. Then wire up the fscrypt_operations to expose
this flag to fs/crypto/, so that it allows IV_INO_LBLK_64 policies when
this flag is set.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/super.c | 14 ++++++++++++++
2 files changed, 16 insertions(+)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 03db3e71676ce..b3a2cc7c0252f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1678,6 +1678,7 @@ static inline bool ext4_verity_in_progress(struct inode *inode)
#define EXT4_FEATURE_COMPAT_RESIZE_INODE 0x0010
#define EXT4_FEATURE_COMPAT_DIR_INDEX 0x0020
#define EXT4_FEATURE_COMPAT_SPARSE_SUPER2 0x0200
+#define EXT4_FEATURE_COMPAT_STABLE_INODES 0x0800
#define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
#define EXT4_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
@@ -1779,6 +1780,7 @@ EXT4_FEATURE_COMPAT_FUNCS(xattr, EXT_ATTR)
EXT4_FEATURE_COMPAT_FUNCS(resize_inode, RESIZE_INODE)
EXT4_FEATURE_COMPAT_FUNCS(dir_index, DIR_INDEX)
EXT4_FEATURE_COMPAT_FUNCS(sparse_super2, SPARSE_SUPER2)
+EXT4_FEATURE_COMPAT_FUNCS(stable_inodes, STABLE_INODES)
EXT4_FEATURE_RO_COMPAT_FUNCS(sparse_super, SPARSE_SUPER)
EXT4_FEATURE_RO_COMPAT_FUNCS(large_file, LARGE_FILE)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dd654e53ba3d9..b3cbf8622eab6 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1345,6 +1345,18 @@ static bool ext4_dummy_context(struct inode *inode)
return DUMMY_ENCRYPTION_ENABLED(EXT4_SB(inode->i_sb));
}
+static bool ext4_has_stable_inodes(struct super_block *sb)
+{
+ return ext4_has_feature_stable_inodes(sb);
+}
+
+static void ext4_get_ino_and_lblk_bits(struct super_block *sb,
+ int *ino_bits_ret, int *lblk_bits_ret)
+{
+ *ino_bits_ret = 8 * sizeof(EXT4_SB(sb)->s_es->s_inodes_count);
+ *lblk_bits_ret = 8 * sizeof(ext4_lblk_t);
+}
+
static const struct fscrypt_operations ext4_cryptops = {
.key_prefix = "ext4:",
.get_context = ext4_get_context,
@@ -1352,6 +1364,8 @@ static const struct fscrypt_operations ext4_cryptops = {
.dummy_context = ext4_dummy_context,
.empty_dir = ext4_empty_dir,
.max_namelen = EXT4_NAME_LEN,
+ .has_stable_inodes = ext4_has_stable_inodes,
+ .get_ino_and_lblk_bits = ext4_get_ino_and_lblk_bits,
};
#endif
--
2.24.0.rc0.303.g954a862665-goog
