fscrypt: use EEXIST when file already uses different policy

As part of an effort to clean up fscrypt-related error codes, make
FS_IOC_SET_ENCRYPTION_POLICY fail with EEXIST when the file already uses
a different encryption policy.  This is more descriptive than EINVAL,
which was ambiguous with some of the other error cases.

I am not aware of any users who might be relying on the previous error
code of EINVAL, which was never documented anywhere.

This failure case will be exercised by an xfstest.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 40ecd7173e3479531752663db7473521d5013536..47f19800ceb7e935c5a7eac0daa5e35dd0a783dc 100644 (file)
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -129,7 +129,7 @@ int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg)
                printk(KERN_WARNING
                       "%s: Policy inconsistent with encryption context\n",
                       __func__);
-               ret = -EINVAL;
+               ret = -EEXIST;
        }
 
        inode_unlock(inode);