fscrypt: remove 'ci' parameter from fscrypt_put_encryption_info()

fscrypt_put_encryption_info() is only called when evicting an inode, so
the 'struct fscrypt_info *ci' parameter is always NULL, and there cannot
be races with other threads.  This was cruft left over from the broken
key revocation code.  Remove the unused parameter and the cmpxchg().

Also remove the #ifdefs around the fscrypt_put_encryption_info() calls,
since fscrypt_notsupp.h defines a no-op stub for it.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

fs/crypto/keyinfo.c

@@ -355,19 +355,9 @@ int fscrypt_get_encryption_info(struct inode *inode)
 }
 EXPORT_SYMBOL(fscrypt_get_encryption_info);
 
-void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci)
+void fscrypt_put_encryption_info(struct inode *inode)
 {
-	struct fscrypt_info *prev;
-
-	if (ci == NULL)
-		ci = READ_ONCE(inode->i_crypt_info);
-	if (ci == NULL)
-		return;
-
-	prev = cmpxchg(&inode->i_crypt_info, ci, NULL);
-	if (prev != ci)
-		return;
-
-	put_crypt_info(ci);
+	put_crypt_info(inode->i_crypt_info);
+	inode->i_crypt_info = NULL;
 }
 EXPORT_SYMBOL(fscrypt_put_encryption_info);

fs/ext4/super.c

@@ -1069,9 +1069,7 @@ void ext4_clear_inode(struct inode *inode)
 		jbd2_free_inode(EXT4_I(inode)->jinode);
 		EXT4_I(inode)->jinode = NULL;
 	}
-#ifdef CONFIG_EXT4_FS_ENCRYPTION
-	fscrypt_put_encryption_info(inode, NULL);
-#endif
+	fscrypt_put_encryption_info(inode);
 }
 
 static struct inode *ext4_nfs_get_inode(struct super_block *sb,

fs/f2fs/inode.c

@@ -569,7 +569,7 @@ void f2fs_evict_inode(struct inode *inode)
 			!exist_written_data(sbi, inode->i_ino, ORPHAN_INO));
 	}
 out_clear:
-	fscrypt_put_encryption_info(inode, NULL);
+	fscrypt_put_encryption_info(inode);
 	clear_inode(inode);
 }
 

fs/ubifs/super.c

@@ -379,9 +379,7 @@ static void ubifs_evict_inode(struct inode *inode)
 	}
 done:
 	clear_inode(inode);
-#ifdef CONFIG_UBIFS_FS_ENCRYPTION
-	fscrypt_put_encryption_info(inode, NULL);
-#endif
+	fscrypt_put_encryption_info(inode);
 }
 
 static void ubifs_dirty_inode(struct inode *inode, int flags)

include/linux/fscrypt_notsupp.h

@@ -105,8 +105,7 @@ static inline int fscrypt_get_encryption_info(struct inode *inode)
 	return -EOPNOTSUPP;
 }
 
-static inline void fscrypt_put_encryption_info(struct inode *inode,
-					       struct fscrypt_info *ci)
+static inline void fscrypt_put_encryption_info(struct inode *inode)
 {
 	return;
 }

include/linux/fscrypt_supp.h

@@ -96,7 +96,7 @@ extern int fscrypt_inherit_context(struct inode *, struct inode *,
 					void *, bool);
 /* keyinfo.c */
 extern int fscrypt_get_encryption_info(struct inode *);
-extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
+extern void fscrypt_put_encryption_info(struct inode *);
 
 /* fname.c */
 extern int fscrypt_setup_filename(struct inode *, const struct qstr *,