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https://github.com/torvalds/linux
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43c780ba26
Rework f2fs's handling of filenames to use a new 'struct f2fs_filename'. Similar to 'struct ext4_filename', this stores the usr_fname, disk_name, dirhash, crypto_buf, and casefolded name. Some of these names can be NULL in some cases. 'struct f2fs_filename' differs from 'struct fscrypt_name' mainly in that the casefolded name is included. For user-initiated directory operations like lookup() and create(), initialize the f2fs_filename by translating the corresponding fscrypt_name, then computing the dirhash and casefolded name if needed. This makes the dirhash and casefolded name be cached for each syscall, so we don't have to recompute them repeatedly. (Previously, f2fs computed the dirhash once per directory level, and the casefolded name once per directory block.) This improves performance. This rework also makes it much easier to correctly handle all combinations of normal, encrypted, casefolded, and encrypted+casefolded directories. (The fourth isn't supported yet but is being worked on.) The only other cases where an f2fs_filename gets initialized are for two filesystem-internal operations: (1) when converting an inline directory to a regular one, we grab the needed disk_name and hash from an existing f2fs_dir_entry; and (2) when roll-forward recovering a new dentry, we grab the needed disk_name from f2fs_inode::i_name and compute the hash. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
129 lines
2.7 KiB
C
129 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/f2fs/hash.c
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* Portions of this code from linux/fs/ext3/hash.c
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*
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* Copyright (C) 2002 by Theodore Ts'o
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*/
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/f2fs_fs.h>
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#include <linux/cryptohash.h>
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#include <linux/pagemap.h>
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#include <linux/unicode.h>
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#include "f2fs.h"
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/*
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* Hashing code copied from ext3
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*/
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#define DELTA 0x9E3779B9
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static void TEA_transform(unsigned int buf[4], unsigned int const in[])
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{
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__u32 sum = 0;
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__u32 b0 = buf[0], b1 = buf[1];
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__u32 a = in[0], b = in[1], c = in[2], d = in[3];
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int n = 16;
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do {
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sum += DELTA;
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b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
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b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
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} while (--n);
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buf[0] += b0;
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buf[1] += b1;
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}
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static void str2hashbuf(const unsigned char *msg, size_t len,
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unsigned int *buf, int num)
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{
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unsigned pad, val;
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int i;
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pad = (__u32)len | ((__u32)len << 8);
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pad |= pad << 16;
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val = pad;
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if (len > num * 4)
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len = num * 4;
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for (i = 0; i < len; i++) {
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if ((i % 4) == 0)
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val = pad;
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val = msg[i] + (val << 8);
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if ((i % 4) == 3) {
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*buf++ = val;
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val = pad;
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num--;
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}
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}
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if (--num >= 0)
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*buf++ = val;
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while (--num >= 0)
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*buf++ = pad;
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}
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static u32 TEA_hash_name(const u8 *p, size_t len)
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{
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__u32 in[8], buf[4];
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/* Initialize the default seed for the hash checksum functions */
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buf[0] = 0x67452301;
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buf[1] = 0xefcdab89;
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buf[2] = 0x98badcfe;
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buf[3] = 0x10325476;
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while (1) {
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str2hashbuf(p, len, in, 4);
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TEA_transform(buf, in);
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p += 16;
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if (len <= 16)
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break;
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len -= 16;
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}
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return buf[0] & ~F2FS_HASH_COL_BIT;
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}
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/*
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* Compute @fname->hash. For all directories, @fname->disk_name must be set.
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* For casefolded directories, @fname->usr_fname must be set, and also
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* @fname->cf_name if the filename is valid Unicode.
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*/
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void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
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{
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const u8 *name = fname->disk_name.name;
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size_t len = fname->disk_name.len;
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WARN_ON_ONCE(!name);
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if (is_dot_dotdot(name, len)) {
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fname->hash = 0;
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return;
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}
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#ifdef CONFIG_UNICODE
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if (IS_CASEFOLDED(dir)) {
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/*
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* If the casefolded name is provided, hash it instead of the
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* on-disk name. If the casefolded name is *not* provided, that
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* should only be because the name wasn't valid Unicode, so fall
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* back to treating the name as an opaque byte sequence.
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*/
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WARN_ON_ONCE(!fname->usr_fname->name);
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if (fname->cf_name.name) {
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name = fname->cf_name.name;
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len = fname->cf_name.len;
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} else {
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name = fname->usr_fname->name;
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len = fname->usr_fname->len;
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}
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}
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#endif
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fname->hash = cpu_to_le32(TEA_hash_name(name, len));
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}
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