ext4 crypto: migrate into vfs's crypto engine

This patch removes the most parts of internal crypto codes.
And then, it modifies and adds some ext4-specific crypt codes to use the generic
facility.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 68323e3..67415e0 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -109,10 +109,10 @@
 	struct super_block *sb = inode->i_sb;
 	struct buffer_head *bh = NULL;
 	int dir_has_error = 0;
-	struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
+	struct fscrypt_str fstr = FSTR_INIT(NULL, 0);
 
 	if (ext4_encrypted_inode(inode)) {
-		err = ext4_get_encryption_info(inode);
+		err = fscrypt_get_encryption_info(inode);
 		if (err && err != -ENOKEY)
 			return err;
 	}
@@ -139,8 +139,7 @@
 	}
 
 	if (ext4_encrypted_inode(inode)) {
-		err = ext4_fname_crypto_alloc_buffer(inode, EXT4_NAME_LEN,
-						     &fname_crypto_str);
+		err = fscrypt_fname_alloc_buffer(inode, EXT4_NAME_LEN, &fstr);
 		if (err < 0)
 			return err;
 	}
@@ -253,16 +252,19 @@
 					    get_dtype(sb, de->file_type)))
 						goto done;
 				} else {
-					int save_len = fname_crypto_str.len;
+					int save_len = fstr.len;
+					struct fscrypt_str de_name =
+							FSTR_INIT(de->name,
+								de->name_len);
 
 					/* Directory is encrypted */
-					err = ext4_fname_disk_to_usr(inode,
-						NULL, de, &fname_crypto_str);
-					fname_crypto_str.len = save_len;
+					err = fscrypt_fname_disk_to_usr(inode,
+						0, 0, &de_name, &fstr);
+					fstr.len = save_len;
 					if (err < 0)
 						goto errout;
 					if (!dir_emit(ctx,
-					    fname_crypto_str.name, err,
+					    fstr.name, err,
 					    le32_to_cpu(de->inode),
 					    get_dtype(sb, de->file_type)))
 						goto done;
@@ -281,7 +283,7 @@
 	err = 0;
 errout:
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
-	ext4_fname_crypto_free_buffer(&fname_crypto_str);
+	fscrypt_fname_free_buffer(&fstr);
 #endif
 	brelse(bh);
 	return err;
@@ -432,7 +434,7 @@
 int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
 			     __u32 minor_hash,
 			    struct ext4_dir_entry_2 *dirent,
-			    struct ext4_str *ent_name)
+			    struct fscrypt_str *ent_name)
 {
 	struct rb_node **p, *parent = NULL;
 	struct fname *fname, *new_fn;
@@ -609,7 +611,7 @@
 static int ext4_dir_open(struct inode * inode, struct file * filp)
 {
 	if (ext4_encrypted_inode(inode))
-		return ext4_get_encryption_info(inode) ? -EACCES : 0;
+		return fscrypt_get_encryption_info(inode) ? -EACCES : 0;
 	return 0;
 }