On Fri, 2025-11-14 at 14:02 +0800, Guan-Chun Wu wrote:
> Remove the ceph_base64_encode() and ceph_base64_decode() functions and
> replace their usage with the generic base64_encode() and base64_decode()
> helpers from lib/base64.
> 
> This eliminates the custom implementation in Ceph, reduces code
> duplication, and relies on the shared Base64 code in lib.
> The helpers preserve RFC 3501-compliant 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 local
> implementation.
> 
> Reviewed-by: Kuan-Wei Chiu <[email protected]>
> Signed-off-by: Guan-Chun Wu <[email protected]>
> ---
>  fs/ceph/crypto.c | 60 ++++--------------------------------------------
>  fs/ceph/crypto.h |  6 +----
>  fs/ceph/dir.c    |  5 ++--
>  fs/ceph/inode.c  |  2 +-
>  4 files changed, 9 insertions(+), 64 deletions(-)
> 
> diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
> index 7026e794813c..b6016dcffbb6 100644
> --- a/fs/ceph/crypto.c
> +++ b/fs/ceph/crypto.c
> @@ -15,59 +15,6 @@
>  #include "mds_client.h"
>  #include "crypto.h"
>  
> -/*
> - * The base64url encoding used by fscrypt includes the '_' character, which 
> may
> - * cause problems in snapshot names (which can not start with '_').  Thus, we
> - * used the base64 encoding defined for IMAP mailbox names (RFC 3501) 
> instead,
> - * which replaces '-' and '_' by '+' and ','.
> - */
> -static const char base64_table[65] =
> -     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
> -
> -int ceph_base64_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++ = base64_table[(ac >> bits) & 0x3f];
> -             } while (bits >= 6);
> -     }
> -     if (bits)
> -             *cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
> -     return cp - dst;
> -}
> -
> -int ceph_base64_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(base64_table, src[i]);
> -
> -             if (p == NULL || src[i] == 0)
> -                     return -1;
> -             ac = (ac << 6) | (p - base64_table);
> -             bits += 6;
> -             if (bits >= 8) {
> -                     bits -= 8;
> -                     *bp++ = (u8)(ac >> bits);
> -             }
> -     }
> -     if (ac & ((1 << bits) - 1))
> -             return -1;
> -     return bp - dst;
> -}
> -
>  static int ceph_crypt_get_context(struct inode *inode, void *ctx, size_t len)
>  {
>       struct ceph_inode_info *ci = ceph_inode(inode);
> @@ -318,7 +265,7 @@ int ceph_encode_encrypted_dname(struct inode *parent, 
> char *buf, int elen)
>       }
>  
>       /* base64 encode the encrypted name */
> -     elen = ceph_base64_encode(cryptbuf, len, p);
> +     elen = base64_encode(cryptbuf, len, p, false, BASE64_IMAP);
>       doutc(cl, "base64-encoded ciphertext name = %.*s\n", elen, p);
>  
>       /* To understand the 240 limit, see CEPH_NOHASH_NAME_MAX comments */
> @@ -412,7 +359,8 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, 
> struct fscrypt_str *tname,
>                       tname = &_tname;
>               }
>  
> -             declen = ceph_base64_decode(name, name_len, tname->name);
> +             declen = base64_decode(name, name_len,
> +                                    tname->name, false, BASE64_IMAP);
>               if (declen <= 0) {
>                       ret = -EIO;
>                       goto out;
> @@ -426,7 +374,7 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, 
> struct fscrypt_str *tname,
>  
>       ret = fscrypt_fname_disk_to_usr(dir, 0, 0, &iname, oname);
>       if (!ret && (dir != fname->dir)) {
> -             char tmp_buf[CEPH_BASE64_CHARS(NAME_MAX)];
> +             char tmp_buf[BASE64_CHARS(NAME_MAX)];
>  
>               name_len = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
>                                   oname->len, oname->name, dir->i_ino);
> diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
> index 23612b2e9837..b748e2060bc9 100644
> --- a/fs/ceph/crypto.h
> +++ b/fs/ceph/crypto.h
> @@ -8,6 +8,7 @@
>  
>  #include <crypto/sha2.h>
>  #include <linux/fscrypt.h>
> +#include <linux/base64.h>
>  
>  #define CEPH_FSCRYPT_BLOCK_SHIFT   12
>  #define CEPH_FSCRYPT_BLOCK_SIZE    (_AC(1, UL) << CEPH_FSCRYPT_BLOCK_SHIFT)
> @@ -89,11 +90,6 @@ static inline u32 ceph_fscrypt_auth_len(struct 
> ceph_fscrypt_auth *fa)
>   */
>  #define CEPH_NOHASH_NAME_MAX (180 - SHA256_DIGEST_SIZE)
>  
> -#define CEPH_BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)
> -
> -int ceph_base64_encode(const u8 *src, int srclen, char *dst);
> -int ceph_base64_decode(const char *src, int srclen, u8 *dst);
> -
>  void ceph_fscrypt_set_ops(struct super_block *sb);
>  
>  void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc);
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index d18c0eaef9b7..0fa7c7777242 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -998,13 +998,14 @@ static int prep_encrypted_symlink_target(struct 
> ceph_mds_request *req,
>       if (err)
>               goto out;
>  
> -     req->r_path2 = kmalloc(CEPH_BASE64_CHARS(osd_link.len) + 1, GFP_KERNEL);
> +     req->r_path2 = kmalloc(BASE64_CHARS(osd_link.len) + 1, GFP_KERNEL);
>       if (!req->r_path2) {
>               err = -ENOMEM;
>               goto out;
>       }
>  
> -     len = ceph_base64_encode(osd_link.name, osd_link.len, req->r_path2);
> +     len = base64_encode(osd_link.name, osd_link.len,
> +                         req->r_path2, false, BASE64_IMAP);
>       req->r_path2[len] = '\0';
>  out:
>       fscrypt_fname_free_buffer(&osd_link);
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index a6e260d9e420..b691343cb7f1 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -958,7 +958,7 @@ static int decode_encrypted_symlink(struct 
> ceph_mds_client *mdsc,
>       if (!sym)
>               return -ENOMEM;
>  
> -     declen = ceph_base64_decode(encsym, enclen, sym);
> +     declen = base64_decode(encsym, enclen, sym, false, BASE64_IMAP);
>       if (declen < 0) {
>               pr_err_client(cl,
>                       "can't decode symlink (%d). Content: %.*s\n",

Looks good!

Reviewed-by: Viacheslav Dubeyko <[email protected]>

Have you run xfstests for this patchset?

Thanks,
Slava.

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