ext4 crypto: ext4_page_crypto() doesn't need a encryption context

Since ext4_page_crypto() doesn't need an encryption context (at least
not any more), this allows us to simplify a number function signature
and also allows us to avoid needing to allocate a context in
ext4_block_write_begin().  It also means we no longer need a separate
ext4_decrypt_one() function.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/crypto.c

@@ -253,8 +253,7 @@ typedef enum {
 	EXT4_ENCRYPT,
 } ext4_direction_t;
 
-static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
-			    struct inode *inode,
+static int ext4_page_crypto(struct inode *inode,
 			    ext4_direction_t rw,
 			    pgoff_t index,
 			    struct page *src_page,
@@ -353,7 +352,7 @@ struct page *ext4_encrypt(struct inode *inode,
 	if (IS_ERR(ciphertext_page))
 		goto errout;
 	ctx->w.control_page = plaintext_page;
-	err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, plaintext_page->index,
+	err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,
 			       plaintext_page, ciphertext_page);
 	if (err) {
 		ciphertext_page = ERR_PTR(err);
@@ -378,31 +377,14 @@ struct page *ext4_encrypt(struct inode *inode,
  *
  * Return: Zero on success, non-zero otherwise.
  */
-int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page)
+int ext4_decrypt(struct page *page)
 {
 	BUG_ON(!PageLocked(page));
 
-	return ext4_page_crypto(ctx, page->mapping->host,
+	return ext4_page_crypto(page->mapping->host,
 				EXT4_DECRYPT, page->index, page, page);
 }
 
-/*
- * Convenience function which takes care of allocating and
- * deallocating the encryption context
- */
-int ext4_decrypt_one(struct inode *inode, struct page *page)
-{
-	int ret;
-
-	struct ext4_crypto_ctx *ctx = ext4_get_crypto_ctx(inode);
-
-	if (IS_ERR(ctx))
-		return PTR_ERR(ctx);
-	ret = ext4_decrypt(ctx, page);
-	ext4_release_crypto_ctx(ctx);
-	return ret;
-}
-
 int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 {
 	struct ext4_crypto_ctx	*ctx;
@@ -426,7 +408,7 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 	}
 
 	while (len--) {
-		err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, lblk,
+		err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,
 				       ZERO_PAGE(0), ciphertext_page);
 		if (err)
 			goto errout;

fs/ext4/ext4.h

@@ -2063,8 +2063,7 @@ void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);
 void ext4_restore_control_page(struct page *data_page);
 struct page *ext4_encrypt(struct inode *inode,
 			  struct page *plaintext_page);
-int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page);
-int ext4_decrypt_one(struct inode *inode, struct page *page);
+int ext4_decrypt(struct page *page);
 int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex);
 
 #ifdef CONFIG_EXT4_FS_ENCRYPTION

fs/ext4/inode.c

@@ -965,7 +965,7 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 	if (unlikely(err))
 		page_zero_new_buffers(page, from, to);
 	else if (decrypt)
-		err = ext4_decrypt_one(inode, page);
+		err = ext4_decrypt(page);
 	return err;
 }
 #endif
@@ -3404,7 +3404,7 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 			/* We expect the key to be set. */
 			BUG_ON(!ext4_has_encryption_key(inode));
 			BUG_ON(blocksize != PAGE_CACHE_SIZE);
-			WARN_ON_ONCE(ext4_decrypt_one(inode, page));
+			WARN_ON_ONCE(ext4_decrypt(page));
 		}
 	}
 	if (ext4_should_journal_data(inode)) {

fs/ext4/readpage.c

@@ -62,7 +62,7 @@ static void completion_pages(struct work_struct *work)
 	bio_for_each_segment_all(bv, bio, i) {
 		struct page *page = bv->bv_page;
 
-		int ret = ext4_decrypt(ctx, page);
+		int ret = ext4_decrypt(page);
 		if (ret) {
 			WARN_ON_ONCE(1);
 			SetPageError(page);