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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deflate.c
/*
* Cryptographic API.
*
* Deflate algorithm (RFC 1951), implemented here primarily for use
* by IPCOMP (RFC 3173 & RFC 2394).
*
* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
*
* 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.
*
* FIXME: deflate transforms will require up to a total of about 436k of kernel
* memory on i386 (390k for compression, the rest for decompression), as the
* current zlib kernel code uses a worst case pre-allocation system by default.
* This needs to be fixed so that the amount of memory required is properly
* related to the winbits and memlevel parameters.
*
* The default winbits of 11 should suit most packets, and it may be something
* to configure on a per-tfm basis in the future.
*
* Currently, compression history is not maintained between tfm calls, as
* it is not needed for IPCOMP and keeps the code simpler. It can be
* implemented if someone wants it.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/zlib.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/net.h>
#define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
#define DEFLATE_DEF_WINBITS 11
#define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
struct deflate_ctx {
struct z_stream_s comp_stream;
struct z_stream_s decomp_stream;
};
static int deflate_comp_init(struct deflate_ctx *ctx)
{
int ret = 0;
struct z_stream_s *stream = &ctx->comp_stream;
stream->workspace = vzalloc(zlib_deflate_workspacesize(
-DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL));
if (!stream->workspace) {
ret = -ENOMEM;
goto out;
}
ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED,
-DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
Z_DEFAULT_STRATEGY);
if (ret != Z_OK) {
ret = -EINVAL;
goto out_free;
}
out:
return ret;
out_free:
vfree(stream->workspace);
goto out;
}
static int deflate_decomp_init(struct deflate_ctx *ctx)
{
int ret = 0;
struct z_stream_s *stream = &ctx->decomp_stream;
stream->workspace = vzalloc(zlib_inflate_workspacesize());
if (!stream->workspace) {
ret = -ENOMEM;
goto out;
}
ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
if (ret != Z_OK) {
ret = -EINVAL;
goto out_free;
}
out:
return ret;
out_free:
vfree(stream->workspace);
goto out;
}
static void deflate_comp_exit(struct deflate_ctx *ctx)
{
zlib_deflateEnd(&ctx->comp_stream);
vfree(ctx->comp_stream.workspace);
}
static void deflate_decomp_exit(struct deflate_ctx *ctx)
{
zlib_inflateEnd(&ctx->decomp_stream);
vfree(ctx->decomp_stream.workspace);
}
static int deflate_init(struct crypto_tfm *tfm)
{
struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
int ret;
ret = deflate_comp_init(ctx);
if (ret)
goto out;
ret = deflate_decomp_init(ctx);
if (ret)
deflate_comp_exit(ctx);
out:
return ret;
}
static void deflate_exit(struct crypto_tfm *tfm)
{
struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
deflate_comp_exit(ctx);
deflate_decomp_exit(ctx);
}
static int deflate_compress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
int ret = 0;
struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
struct z_stream_s *stream = &dctx->comp_stream;
ret = zlib_deflateReset(stream);
if (ret != Z_OK) {
ret = -EINVAL;
goto out;
}
stream->next_in = (u8 *)src;
stream->avail_in = slen;
stream->next_out = (u8 *)dst;
stream->avail_out = *dlen;
ret = zlib_deflate(stream, Z_FINISH);
if (ret != Z_STREAM_END) {
ret = -EINVAL;
goto out;
}
ret = 0;
*dlen = stream->total_out;
out:
return ret;
}
static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
int ret = 0;
struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
struct z_stream_s *stream = &dctx->decomp_stream;
ret = zlib_inflateReset(stream);
if (ret != Z_OK) {
ret = -EINVAL;
goto out;
}
stream->next_in = (u8 *)src;
stream->avail_in = slen;
stream->next_out = (u8 *)dst;
stream->avail_out = *dlen;
ret = zlib_inflate(stream, Z_SYNC_FLUSH);
/*
* Work around a bug in zlib, which sometimes wants to taste an extra
* byte when being used in the (undocumented) raw deflate mode.
* (From USAGI).
*/
if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
u8 zerostuff = 0;
stream->next_in = &zerostuff;
stream->avail_in = 1;
ret = zlib_inflate(stream, Z_FINISH);
}
if (ret != Z_STREAM_END) {
ret = -EINVAL;
goto out;
}
ret = 0;
*dlen = stream->total_out;
out:
return ret;
}
static struct crypto_alg alg = {
.cra_name = "deflate",
.cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
.cra_ctxsize = sizeof(struct deflate_ctx),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(alg.cra_list),
.cra_init = deflate_init,
.cra_exit = deflate_exit,
.cra_u = { .compress = {
.coa_compress = deflate_compress,
.coa_decompress = deflate_decompress } }
};
static int __init deflate_mod_init(void)
{
return crypto_register_alg(&alg);
}
static void __exit deflate_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(deflate_mod_init);
module_exit(deflate_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
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