fs, fscrypt: add an S_ENCRYPTED inode flag
Introduce a flag S_ENCRYPTED which can be set in ->i_flags to indicate
that the inode is encrypted using the fscrypt (fs/crypto/) mechanism.
Checking this flag will give the same information that
inode->i_sb->s_cop->is_encrypted(inode) currently does, but will be more
efficient. This will be useful for adding higher-level helper functions
for filesystems to use. For example we'll be able to replace this:
if (ext4_encrypted_inode(inode)) {
ret = fscrypt_get_encryption_info(inode);
if (ret)
return ret;
if (!fscrypt_has_encryption_key(inode))
return -ENOKEY;
}
with this:
ret = fscrypt_require_key(inode);
if (ret)
return ret;
... since we'll be able to retain the fast path for unencrypted files as
a single flag check, using an inline function. This wasn't possible
before because we'd have had to frequently call through the
->i_sb->s_cop->is_encrypted function pointer, even when the encryption
support was disabled or not being used.
Note: we don't define S_ENCRYPTED to 0 if CONFIG_FS_ENCRYPTION is
disabled because we want to continue to return an error if an encrypted
file is accessed without encryption support, rather than pretending that
it is unencrypted.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Acked-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b104096..dcfb195 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1181,7 +1181,8 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
ext4_clear_inode_state(inode,
EXT4_STATE_MAY_INLINE_DATA);
/*
- * Update inode->i_flags - e.g. S_DAX may get disabled
+ * Update inode->i_flags - S_ENCRYPTED will be enabled,
+ * S_DAX may be disabled
*/
ext4_set_inode_flags(inode);
}
@@ -1206,7 +1207,10 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
ctx, len, 0);
if (!res) {
ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
- /* Update inode->i_flags - e.g. S_DAX may get disabled */
+ /*
+ * Update inode->i_flags - S_ENCRYPTED will be enabled,
+ * S_DAX may be disabled
+ */
ext4_set_inode_flags(inode);
res = ext4_mark_inode_dirty(handle, inode);
if (res)