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/inode.c b/fs/ext4/inode.c
index b25f08f..76b23e4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4374,8 +4374,11 @@
new_fl |= S_DIRSYNC;
if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
new_fl |= S_DAX;
+ if (flags & EXT4_ENCRYPT_FL)
+ new_fl |= S_ENCRYPTED;
inode_set_flags(inode, new_fl,
- S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
+ S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
+ S_ENCRYPTED);
}
/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */