fscrypt: support decrypting multiple filesystem blocks per page

Rename fscrypt_decrypt_page() to fscrypt_decrypt_pagecache_blocks() and
redefine its behavior to decrypt all filesystem blocks in the given
region of the given page, rather than assuming that the region consists
of just one filesystem block.  Also remove the 'inode' and 'lblk_num'
parameters, since they can be retrieved from the page as it's already
assumed to be a pagecache page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 315affc99b05..bd8f207a2fb6 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -112,8 +112,9 @@ extern int fscrypt_encrypt_block_inplace(const struct inode *inode,
                                          struct page *page, unsigned int len,
                                          unsigned int offs, u64 lblk_num,
                                          gfp_t gfp_flags);
-extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
-                                unsigned int, u64);
+
+extern int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
+                                            unsigned int offs);
 extern int fscrypt_decrypt_block_inplace(const struct inode *inode,
                                          struct page *page, unsigned int len,
                                          unsigned int offs, u64 lblk_num);
@@ -310,10 +311,9 @@ static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
         return -EOPNOTSUPP;
 }
 
-static inline int fscrypt_decrypt_page(const struct inode *inode,
-                                       struct page *page,
-                                       unsigned int len, unsigned int offs,
-                                       u64 lblk_num)
+static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
+                                                   unsigned int len,
+                                                   unsigned int offs)
 {
         return -EOPNOTSUPP;
 }