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>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 766b7f7..3f248c9 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2063,8 +2063,7 @@
 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