[merged mm-nonmm-stable] fscrypt-replace-local-base64url-helpers-with-lib-base64.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: fscrypt: replace local base64url helpers with lib/base64
has been removed from the -mm tree.  Its filename was
     fscrypt-replace-local-base64url-helpers-with-lib-base64.patch

This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Guan-Chun Wu <409411716@gms.tku.edu.tw>
Subject: fscrypt: replace local base64url helpers with lib/base64
Date: Fri, 14 Nov 2025 14:02:21 +0800

Replace the base64url encoding and decoding functions in fscrypt with the
generic base64_encode() and base64_decode() helpers from lib/base64.

This removes the custom implementation in fscrypt, reduces code
duplication, and relies on the shared Base64 implementation in lib.  The
helpers preserve RFC 4648-compliant URL-safe Base64 encoding without
padding, so there are no functional changes.

This change also improves performance: encoding is about 2.7x faster and
decoding achieves 43-52x speedups compared to the previous implementation.

Link: https://lkml.kernel.org/r/20251114060221.89734-1-409411716@gms.tku.edu.tw
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Cc: Xiubo Li <xiubli@redhat.com>
Cc: Yu-Sheng Huang <home7438072@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/crypto/fname.c |   89 ++------------------------------------------
 1 file changed, 6 insertions(+), 83 deletions(-)

--- a/fs/crypto/fname.c~fscrypt-replace-local-base64url-helpers-with-lib-base64
+++ a/fs/crypto/fname.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/namei.h>
 #include <linux/scatterlist.h>
+#include <linux/base64.h>
 
 #include "fscrypt_private.h"
 
@@ -71,7 +72,7 @@ struct fscrypt_nokey_name {
 
 /* Encoded size of max-size no-key name */
 #define FSCRYPT_NOKEY_NAME_MAX_ENCODED \
-		FSCRYPT_BASE64URL_CHARS(FSCRYPT_NOKEY_NAME_MAX)
+		BASE64_CHARS(FSCRYPT_NOKEY_NAME_MAX)
 
 static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
 {
@@ -162,84 +163,6 @@ static int fname_decrypt(const struct in
 	return 0;
 }
 
-static const char base64url_table[65] =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
-
-#define FSCRYPT_BASE64URL_CHARS(nbytes)	DIV_ROUND_UP((nbytes) * 4, 3)
-
-/**
- * fscrypt_base64url_encode() - base64url-encode some binary data
- * @src: the binary data to encode
- * @srclen: the length of @src in bytes
- * @dst: (output) the base64url-encoded string.  Not NUL-terminated.
- *
- * Encodes data using base64url encoding, i.e. the "Base 64 Encoding with URL
- * and Filename Safe Alphabet" specified by RFC 4648.  '='-padding isn't used,
- * as it's unneeded and not required by the RFC.  base64url is used instead of
- * base64 to avoid the '/' character, which isn't allowed in filenames.
- *
- * Return: the length of the resulting base64url-encoded string in bytes.
- *	   This will be equal to FSCRYPT_BASE64URL_CHARS(srclen).
- */
-static int fscrypt_base64url_encode(const u8 *src, int srclen, char *dst)
-{
-	u32 ac = 0;
-	int bits = 0;
-	int i;
-	char *cp = dst;
-
-	for (i = 0; i < srclen; i++) {
-		ac = (ac << 8) | src[i];
-		bits += 8;
-		do {
-			bits -= 6;
-			*cp++ = base64url_table[(ac >> bits) & 0x3f];
-		} while (bits >= 6);
-	}
-	if (bits)
-		*cp++ = base64url_table[(ac << (6 - bits)) & 0x3f];
-	return cp - dst;
-}
-
-/**
- * fscrypt_base64url_decode() - base64url-decode a string
- * @src: the string to decode.  Doesn't need to be NUL-terminated.
- * @srclen: the length of @src in bytes
- * @dst: (output) the decoded binary data
- *
- * Decodes a string using base64url encoding, i.e. the "Base 64 Encoding with
- * URL and Filename Safe Alphabet" specified by RFC 4648.  '='-padding isn't
- * accepted, nor are non-encoding characters such as whitespace.
- *
- * This implementation hasn't been optimized for performance.
- *
- * Return: the length of the resulting decoded binary data in bytes,
- *	   or -1 if the string isn't a valid base64url string.
- */
-static int fscrypt_base64url_decode(const char *src, int srclen, u8 *dst)
-{
-	u32 ac = 0;
-	int bits = 0;
-	int i;
-	u8 *bp = dst;
-
-	for (i = 0; i < srclen; i++) {
-		const char *p = strchr(base64url_table, src[i]);
-
-		if (p == NULL || src[i] == 0)
-			return -1;
-		ac = (ac << 6) | (p - base64url_table);
-		bits += 6;
-		if (bits >= 8) {
-			bits -= 8;
-			*bp++ = (u8)(ac >> bits);
-		}
-	}
-	if (ac & ((1 << bits) - 1))
-		return -1;
-	return bp - dst;
-}
-
 bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
 				    u32 orig_len, u32 max_len,
 				    u32 *encrypted_len_ret)
@@ -387,8 +310,8 @@ int fscrypt_fname_disk_to_usr(const stru
 		       nokey_name.sha256);
 		size = FSCRYPT_NOKEY_NAME_MAX;
 	}
-	oname->len = fscrypt_base64url_encode((const u8 *)&nokey_name, size,
-					      oname->name);
+	oname->len = base64_encode((const u8 *)&nokey_name, size,
+				   oname->name, false, BASE64_URLSAFE);
 	return 0;
 }
 EXPORT_SYMBOL(fscrypt_fname_disk_to_usr);
@@ -467,8 +390,8 @@ int fscrypt_setup_filename(struct inode
 	if (fname->crypto_buf.name == NULL)
 		return -ENOMEM;
 
-	ret = fscrypt_base64url_decode(iname->name, iname->len,
-				       fname->crypto_buf.name);
+	ret = base64_decode(iname->name, iname->len,
+			    fname->crypto_buf.name, false, BASE64_URLSAFE);
 	if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) ||
 	    (ret > offsetof(struct fscrypt_nokey_name, sha256) &&
 	     ret != FSCRYPT_NOKEY_NAME_MAX)) {
_

Patches currently in -mm which might be from 409411716@gms.tku.edu.tw are