[PATCH] fscrypt: clean up comments in bio.c

Eric Biggers
2021-09-09T19:08:41Z

From: Eric Biggers <ebiggers@google.com>

The file comment in bio.c is almost completely irrelevant to the actual
contents of the file; it was originally copied from crypto.c. Fix it
up, and also add a kerneldoc comment for fscrypt_decrypt_bio().

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/crypto/bio.c | 32 +++++++++++++++++---------------
1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index 68a2de6b5a9b1..bfc2a5b74ed39 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -1,23 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
/*
- * This contains encryption functions for per-file encryption.
+ * Utility functions for file contents encryption/decryption on
+ * block device-based filesystems.
*
* Copyright (C) 2015, Google, Inc.
* Copyright (C) 2015, Motorola Mobility
- *
- * Written by Michael Halcrow, 2014.
- *
- * Filename encryption additions
- * Uday Savagaonkar, 2014
- * Encryption policy handling additions
- * Ildar Muslukhov, 2014
- * Add fscrypt_pullback_bio_page()
- * Jaegeuk Kim, 2015.
- *
- * This has not yet undergone a rigorous security audit.
- *
- * The usage of AES-XTS should conform to recommendations in NIST
- * Special Publication 800-38E and IEEE P1619/D16.
*/

#include <linux/pagemap.h>
@@ -26,6 +13,21 @@
#include <linux/namei.h>
#include "fscrypt_private.h"

+/**
+ * fscrypt_decrypt_bio() - decrypt the contents of a bio
+ * @bio: the bio to decrypt
+ *
+ * Decrypt the contents of a "read" bio following successful completion of the
+ * underlying disk read. The bio must be reading a whole number of blocks of an
+ * encrypted file directly into the page cache. If the bio is reading the
+ * ciphertext into bounce pages instead of the page cache (for example, because
+ * the file is also compressed, so decompression is required after decryption),
+ * then this function isn't applicable. This function may sleep, so it must be
+ * called from a workqueue rather than from the bio's bi_end_io callback.
+ *
+ * This function sets PG_error on any pages that contain any blocks that failed
+ * to be decrypted. The filesystem must not mark such pages uptodate.
+ */
void fscrypt_decrypt_bio(struct bio *bio)
{
struct bio_vec *bv;
--
2.33.0