Revision ae1e206b806ccc490dadff59af8a7a2477b32884 authored by Josef Bacik on 07 August 2012, 20:00:32 UTC, committed by Chris Mason on 28 August 2012, 20:53:38 UTC
Daniel Blueman reported a bug with fio+balance on a ramdisk setup. Basically what happens is the balance relocates a tree block which will drop the implicit refs for all of its children and adds a full backref. Once the block is relocated we have to add the implicit refs back, so when we cow the block again we add the implicit refs for its children back. The problem comes when the original drop ref doesn't get run before we add the implicit refs back. The delayed ref stuff will specifically prefer ADD operations over DROP to keep us from freeing up an extent that will have references to it, so we try to add the implicit ref before it is actually removed and we panic. This worked fine before because the add would have just canceled the drop out and we would have been fine. But the backref walking work needs to be able to freeze the delayed ref stuff in time so we have this ever increasing sequence number that gets attached to all new delayed ref updates which makes us not merge refs and we run into this issue. So to fix this we need to merge delayed refs. So everytime we run a clustered ref we need to try and merge all of its delayed refs. The backref walking stuff locks the delayed ref head before processing, so if we have it locked we are safe to merge any refs inside of the sequence number. If there is no sequence number we can merge all refs. Doing this not only fixes our bug but keeps the delayed ref code from adding and removing useless refs and batching together multiple refs into one search instead of one search per delayed ref, which will really help our commit times. I ran this with Daniels test and 276 and I haven't seen any problems. Thanks, Reported-by: Daniel J Blueman <daniel@quora.org> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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salsa20_generic.c
/*
* Salsa20: Salsa20 stream cipher algorithm
*
* Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
*
* Derived from:
* - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
*
* Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
* Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
* More information about eSTREAM and Salsa20 can be found here:
* http://www.ecrypt.eu.org/stream/
* http://cr.yp.to/snuffle.html
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/crypto.h>
#include <linux/types.h>
#include <linux/bitops.h>
#include <crypto/algapi.h>
#include <asm/byteorder.h>
#define SALSA20_IV_SIZE 8U
#define SALSA20_MIN_KEY_SIZE 16U
#define SALSA20_MAX_KEY_SIZE 32U
/*
* Start of code taken from D. J. Bernstein's reference implementation.
* With some modifications and optimizations made to suit our needs.
*/
/*
salsa20-ref.c version 20051118
D. J. Bernstein
Public domain.
*/
#define U32TO8_LITTLE(p, v) \
{ (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \
(p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
#define U8TO32_LITTLE(p) \
(((u32)((p)[0]) ) | ((u32)((p)[1]) << 8) | \
((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24) )
struct salsa20_ctx
{
u32 input[16];
};
static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
{
u32 x[16];
int i;
memcpy(x, input, sizeof(x));
for (i = 20; i > 0; i -= 2) {
x[ 4] ^= rol32((x[ 0] + x[12]), 7);
x[ 8] ^= rol32((x[ 4] + x[ 0]), 9);
x[12] ^= rol32((x[ 8] + x[ 4]), 13);
x[ 0] ^= rol32((x[12] + x[ 8]), 18);
x[ 9] ^= rol32((x[ 5] + x[ 1]), 7);
x[13] ^= rol32((x[ 9] + x[ 5]), 9);
x[ 1] ^= rol32((x[13] + x[ 9]), 13);
x[ 5] ^= rol32((x[ 1] + x[13]), 18);
x[14] ^= rol32((x[10] + x[ 6]), 7);
x[ 2] ^= rol32((x[14] + x[10]), 9);
x[ 6] ^= rol32((x[ 2] + x[14]), 13);
x[10] ^= rol32((x[ 6] + x[ 2]), 18);
x[ 3] ^= rol32((x[15] + x[11]), 7);
x[ 7] ^= rol32((x[ 3] + x[15]), 9);
x[11] ^= rol32((x[ 7] + x[ 3]), 13);
x[15] ^= rol32((x[11] + x[ 7]), 18);
x[ 1] ^= rol32((x[ 0] + x[ 3]), 7);
x[ 2] ^= rol32((x[ 1] + x[ 0]), 9);
x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
x[ 6] ^= rol32((x[ 5] + x[ 4]), 7);
x[ 7] ^= rol32((x[ 6] + x[ 5]), 9);
x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
x[11] ^= rol32((x[10] + x[ 9]), 7);
x[ 8] ^= rol32((x[11] + x[10]), 9);
x[ 9] ^= rol32((x[ 8] + x[11]), 13);
x[10] ^= rol32((x[ 9] + x[ 8]), 18);
x[12] ^= rol32((x[15] + x[14]), 7);
x[13] ^= rol32((x[12] + x[15]), 9);
x[14] ^= rol32((x[13] + x[12]), 13);
x[15] ^= rol32((x[14] + x[13]), 18);
}
for (i = 0; i < 16; ++i)
x[i] += input[i];
for (i = 0; i < 16; ++i)
U32TO8_LITTLE(output + 4 * i,x[i]);
}
static const char sigma[16] = "expand 32-byte k";
static const char tau[16] = "expand 16-byte k";
static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
{
const char *constants;
ctx->input[1] = U8TO32_LITTLE(k + 0);
ctx->input[2] = U8TO32_LITTLE(k + 4);
ctx->input[3] = U8TO32_LITTLE(k + 8);
ctx->input[4] = U8TO32_LITTLE(k + 12);
if (kbytes == 32) { /* recommended */
k += 16;
constants = sigma;
} else { /* kbytes == 16 */
constants = tau;
}
ctx->input[11] = U8TO32_LITTLE(k + 0);
ctx->input[12] = U8TO32_LITTLE(k + 4);
ctx->input[13] = U8TO32_LITTLE(k + 8);
ctx->input[14] = U8TO32_LITTLE(k + 12);
ctx->input[0] = U8TO32_LITTLE(constants + 0);
ctx->input[5] = U8TO32_LITTLE(constants + 4);
ctx->input[10] = U8TO32_LITTLE(constants + 8);
ctx->input[15] = U8TO32_LITTLE(constants + 12);
}
static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv)
{
ctx->input[6] = U8TO32_LITTLE(iv + 0);
ctx->input[7] = U8TO32_LITTLE(iv + 4);
ctx->input[8] = 0;
ctx->input[9] = 0;
}
static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst,
const u8 *src, unsigned int bytes)
{
u8 buf[64];
if (dst != src)
memcpy(dst, src, bytes);
while (bytes) {
salsa20_wordtobyte(buf, ctx->input);
ctx->input[8]++;
if (!ctx->input[8])
ctx->input[9]++;
if (bytes <= 64) {
crypto_xor(dst, buf, bytes);
return;
}
crypto_xor(dst, buf, 64);
bytes -= 64;
dst += 64;
}
}
/*
* End of code taken from D. J. Bernstein's reference implementation.
*/
static int setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keysize)
{
struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
salsa20_keysetup(ctx, key, keysize);
return 0;
}
static int encrypt(struct blkcipher_desc *desc,
struct scatterlist *dst, struct scatterlist *src,
unsigned int nbytes)
{
struct blkcipher_walk walk;
struct crypto_blkcipher *tfm = desc->tfm;
struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
int err;
blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt_block(desc, &walk, 64);
salsa20_ivsetup(ctx, walk.iv);
if (likely(walk.nbytes == nbytes))
{
salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
walk.src.virt.addr, nbytes);
return blkcipher_walk_done(desc, &walk, 0);
}
while (walk.nbytes >= 64) {
salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
walk.src.virt.addr,
walk.nbytes - (walk.nbytes % 64));
err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
}
if (walk.nbytes) {
salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
walk.src.virt.addr, walk.nbytes);
err = blkcipher_walk_done(desc, &walk, 0);
}
return err;
}
static struct crypto_alg alg = {
.cra_name = "salsa20",
.cra_driver_name = "salsa20-generic",
.cra_priority = 100,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_type = &crypto_blkcipher_type,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct salsa20_ctx),
.cra_alignmask = 3,
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(alg.cra_list),
.cra_u = {
.blkcipher = {
.setkey = setkey,
.encrypt = encrypt,
.decrypt = encrypt,
.min_keysize = SALSA20_MIN_KEY_SIZE,
.max_keysize = SALSA20_MAX_KEY_SIZE,
.ivsize = SALSA20_IV_SIZE,
}
}
};
static int __init salsa20_generic_mod_init(void)
{
return crypto_register_alg(&alg);
}
static void __exit salsa20_generic_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(salsa20_generic_mod_init);
module_exit(salsa20_generic_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
MODULE_ALIAS("salsa20");
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