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linux/fs/btrfs/zstd.c
David Sterba 431e98226c btrfs: move some zstd work data from stack to workspace 
* ZSTD_inBuffer in_buf
* ZSTD_outBuffer out_buf

are used in all functions to pass the compression parameters and the
local variables consume some space. We can move them to the workspace
and reduce the stack consumption:

zstd.c:zstd_decompress                        -24 (136 -> 112)
zstd.c:zstd_decompress_bio                    -24 (144 -> 120)
zstd.c:zstd_compress_pages                    -24 (264 -> 240)

Signed-off-by: David Sterba <dsterba@suse.com>
Reviewed-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2018-01-22 16:08:14 +01:00

440 lines
11 KiB
C
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/*
* Copyright (c) 2016-present, Facebook, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/bio.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/refcount.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/zstd.h>
#include "compression.h"
#define ZSTD_BTRFS_MAX_WINDOWLOG 17
#define ZSTD_BTRFS_MAX_INPUT (1 << ZSTD_BTRFS_MAX_WINDOWLOG)
#define ZSTD_BTRFS_DEFAULT_LEVEL 3
static ZSTD_parameters zstd_get_btrfs_parameters(size_t src_len)
{
ZSTD_parameters params = ZSTD_getParams(ZSTD_BTRFS_DEFAULT_LEVEL,
src_len, 0);
if (params.cParams.windowLog > ZSTD_BTRFS_MAX_WINDOWLOG)
params.cParams.windowLog = ZSTD_BTRFS_MAX_WINDOWLOG;
WARN_ON(src_len > ZSTD_BTRFS_MAX_INPUT);
return params;
}
struct workspace {
void *mem;
size_t size;
char *buf;
struct list_head list;
ZSTD_inBuffer in_buf;
ZSTD_outBuffer out_buf;
};
static void zstd_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
kvfree(workspace->mem);
kfree(workspace->buf);
kfree(workspace);
}
static struct list_head *zstd_alloc_workspace(void)
{
ZSTD_parameters params =
zstd_get_btrfs_parameters(ZSTD_BTRFS_MAX_INPUT);
struct workspace *workspace;
workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspace->size = max_t(size_t,
ZSTD_CStreamWorkspaceBound(params.cParams),
ZSTD_DStreamWorkspaceBound(ZSTD_BTRFS_MAX_INPUT));
workspace->mem = kvmalloc(workspace->size, GFP_KERNEL);
workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!workspace->mem || !workspace->buf)
goto fail;
INIT_LIST_HEAD(&workspace->list);
return &workspace->list;
fail:
zstd_free_workspace(&workspace->list);
return ERR_PTR(-ENOMEM);
}
static int zstd_compress_pages(struct list_head *ws,
struct address_space *mapping,
u64 start,
struct page **pages,
unsigned long *out_pages,
unsigned long *total_in,
unsigned long *total_out)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
ZSTD_CStream *stream;
int ret = 0;
int nr_pages = 0;
struct page *in_page = NULL; /* The current page to read */
struct page *out_page = NULL; /* The current page to write to */
unsigned long tot_in = 0;
unsigned long tot_out = 0;
unsigned long len = *total_out;
const unsigned long nr_dest_pages = *out_pages;
unsigned long max_out = nr_dest_pages * PAGE_SIZE;
ZSTD_parameters params = zstd_get_btrfs_parameters(len);
*out_pages = 0;
*total_out = 0;
*total_in = 0;
/* Initialize the stream */
stream = ZSTD_initCStream(params, len, workspace->mem,
workspace->size);
if (!stream) {
pr_warn("BTRFS: ZSTD_initCStream failed\n");
ret = -EIO;
goto out;
}
/* map in the first page of input data */
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
workspace->in_buf.src = kmap(in_page);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
/* Allocate and map in the output buffer */
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
while (1) {
size_t ret2;
ret2 = ZSTD_compressStream(stream, &workspace->out_buf,
&workspace->in_buf);
if (ZSTD_isError(ret2)) {
pr_debug("BTRFS: ZSTD_compressStream returned %d\n",
ZSTD_getErrorCode(ret2));
ret = -EIO;
goto out;
}
/* Check to see if we are making it bigger */
if (tot_in + workspace->in_buf.pos > 8192 &&
tot_in + workspace->in_buf.pos <
tot_out + workspace->out_buf.pos) {
ret = -E2BIG;
goto out;
}
/* We've reached the end of our output range */
if (workspace->out_buf.pos >= max_out) {
tot_out += workspace->out_buf.pos;
ret = -E2BIG;
goto out;
}
/* Check if we need more output space */
if (workspace->out_buf.pos == workspace->out_buf.size) {
tot_out += PAGE_SIZE;
max_out -= PAGE_SIZE;
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out,
PAGE_SIZE);
}
/* We've reached the end of the input */
if (workspace->in_buf.pos >= len) {
tot_in += workspace->in_buf.pos;
break;
}
/* Check if we need more input */
if (workspace->in_buf.pos == workspace->in_buf.size) {
tot_in += PAGE_SIZE;
kunmap(in_page);
put_page(in_page);
start += PAGE_SIZE;
len -= PAGE_SIZE;
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
workspace->in_buf.src = kmap(in_page);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, len, PAGE_SIZE);
}
}
while (1) {
size_t ret2;
ret2 = ZSTD_endStream(stream, &workspace->out_buf);
if (ZSTD_isError(ret2)) {
pr_debug("BTRFS: ZSTD_endStream returned %d\n",
ZSTD_getErrorCode(ret2));
ret = -EIO;
goto out;
}
if (ret2 == 0) {
tot_out += workspace->out_buf.pos;
break;
}
if (workspace->out_buf.pos >= max_out) {
tot_out += workspace->out_buf.pos;
ret = -E2BIG;
goto out;
}
tot_out += PAGE_SIZE;
max_out -= PAGE_SIZE;
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -E2BIG;
goto out;
}
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
goto out;
}
pages[nr_pages++] = out_page;
workspace->out_buf.dst = kmap(out_page);
workspace->out_buf.pos = 0;
workspace->out_buf.size = min_t(size_t, max_out, PAGE_SIZE);
}
if (tot_out >= tot_in) {
ret = -E2BIG;
goto out;
}
ret = 0;
*total_in = tot_in;
*total_out = tot_out;
out:
*out_pages = nr_pages;
/* Cleanup */
if (in_page) {
kunmap(in_page);
put_page(in_page);
}
if (out_page)
kunmap(out_page);
return ret;
}
static int zstd_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
struct page **pages_in = cb->compressed_pages;
u64 disk_start = cb->start;
struct bio *orig_bio = cb->orig_bio;
size_t srclen = cb->compressed_len;
ZSTD_DStream *stream;
int ret = 0;
unsigned long page_in_index = 0;
unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
unsigned long buf_start;
unsigned long total_out = 0;
stream = ZSTD_initDStream(
ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
if (!stream) {
pr_debug("BTRFS: ZSTD_initDStream failed\n");
ret = -EIO;
goto done;
}
workspace->in_buf.src = kmap(pages_in[page_in_index]);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
workspace->out_buf.dst = workspace->buf;
workspace->out_buf.pos = 0;
workspace->out_buf.size = PAGE_SIZE;
while (1) {
size_t ret2;
ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
&workspace->in_buf);
if (ZSTD_isError(ret2)) {
pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
ZSTD_getErrorCode(ret2));
ret = -EIO;
goto done;
}
buf_start = total_out;
total_out += workspace->out_buf.pos;
workspace->out_buf.pos = 0;
ret = btrfs_decompress_buf2page(workspace->out_buf.dst,
buf_start, total_out, disk_start, orig_bio);
if (ret == 0)
break;
if (workspace->in_buf.pos >= srclen)
break;
/* Check if we've hit the end of a frame */
if (ret2 == 0)
break;
if (workspace->in_buf.pos == workspace->in_buf.size) {
kunmap(pages_in[page_in_index++]);
if (page_in_index >= total_pages_in) {
workspace->in_buf.src = NULL;
ret = -EIO;
goto done;
}
srclen -= PAGE_SIZE;
workspace->in_buf.src = kmap(pages_in[page_in_index]);
workspace->in_buf.pos = 0;
workspace->in_buf.size = min_t(size_t, srclen, PAGE_SIZE);
}
}
ret = 0;
zero_fill_bio(orig_bio);
done:
if (workspace->in_buf.src)
kunmap(pages_in[page_in_index]);
return ret;
}
static int zstd_decompress(struct list_head *ws, unsigned char *data_in,
struct page *dest_page,
unsigned long start_byte,
size_t srclen, size_t destlen)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
ZSTD_DStream *stream;
int ret = 0;
size_t ret2;
unsigned long total_out = 0;
unsigned long pg_offset = 0;
char *kaddr;
stream = ZSTD_initDStream(
ZSTD_BTRFS_MAX_INPUT, workspace->mem, workspace->size);
if (!stream) {
pr_warn("BTRFS: ZSTD_initDStream failed\n");
ret = -EIO;
goto finish;
}
destlen = min_t(size_t, destlen, PAGE_SIZE);
workspace->in_buf.src = data_in;
workspace->in_buf.pos = 0;
workspace->in_buf.size = srclen;
workspace->out_buf.dst = workspace->buf;
workspace->out_buf.pos = 0;
workspace->out_buf.size = PAGE_SIZE;
ret2 = 1;
while (pg_offset < destlen
&& workspace->in_buf.pos < workspace->in_buf.size) {
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
/* Check if the frame is over and we still need more input */
if (ret2 == 0) {
pr_debug("BTRFS: ZSTD_decompressStream ended early\n");
ret = -EIO;
goto finish;
}
ret2 = ZSTD_decompressStream(stream, &workspace->out_buf,
&workspace->in_buf);
if (ZSTD_isError(ret2)) {
pr_debug("BTRFS: ZSTD_decompressStream returned %d\n",
ZSTD_getErrorCode(ret2));
ret = -EIO;
goto finish;
}
buf_start = total_out;
total_out += workspace->out_buf.pos;
workspace->out_buf.pos = 0;
if (total_out <= start_byte)
continue;
if (total_out > start_byte && buf_start < start_byte)
buf_offset = start_byte - buf_start;
else
buf_offset = 0;
bytes = min_t(unsigned long, destlen - pg_offset,
workspace->out_buf.size - buf_offset);
kaddr = kmap_atomic(dest_page);
memcpy(kaddr + pg_offset, workspace->out_buf.dst + buf_offset,
bytes);
kunmap_atomic(kaddr);
pg_offset += bytes;
}
ret = 0;
finish:
if (pg_offset < destlen) {
kaddr = kmap_atomic(dest_page);
memset(kaddr + pg_offset, 0, destlen - pg_offset);
kunmap_atomic(kaddr);
}
return ret;
}
static void zstd_set_level(struct list_head *ws, unsigned int type)
{
}
const struct btrfs_compress_op btrfs_zstd_compress = {
.alloc_workspace = zstd_alloc_workspace,
.free_workspace = zstd_free_workspace,
.compress_pages = zstd_compress_pages,
.decompress_bio = zstd_decompress_bio,
.decompress = zstd_decompress,
.set_level = zstd_set_level,
};
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