linux/fs/btrfs/lzo.c
David Sterba e5d7490236 btrfs: derive maximum output size in the compression implementation
The value of max_out can be calculated from the parameters passed to the
compressors, which is number of pages and the page size, and we don't
have to needlessly pass it around.

Signed-off-by: David Sterba <dsterba@suse.com>
2017-02-28 14:26:36 +01:00

437 lines
10 KiB
C

/*
* Copyright (C) 2008 Oracle. 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.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/bio.h>
#include <linux/lzo.h>
#include "compression.h"
#define LZO_LEN 4
struct workspace {
void *mem;
void *buf; /* where decompressed data goes */
void *cbuf; /* where compressed data goes */
struct list_head list;
};
static void lzo_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
vfree(workspace->buf);
vfree(workspace->cbuf);
vfree(workspace->mem);
kfree(workspace);
}
static struct list_head *lzo_alloc_workspace(void)
{
struct workspace *workspace;
workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
if (!workspace->mem || !workspace->buf || !workspace->cbuf)
goto fail;
INIT_LIST_HEAD(&workspace->list);
return &workspace->list;
fail:
lzo_free_workspace(&workspace->list);
return ERR_PTR(-ENOMEM);
}
static inline void write_compress_length(char *buf, size_t len)
{
__le32 dlen;
dlen = cpu_to_le32(len);
memcpy(buf, &dlen, LZO_LEN);
}
static inline size_t read_compress_length(const char *buf)
{
__le32 dlen;
memcpy(&dlen, buf, LZO_LEN);
return le32_to_cpu(dlen);
}
static int lzo_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);
int ret = 0;
char *data_in;
char *cpage_out;
int nr_pages = 0;
struct page *in_page = NULL;
struct page *out_page = NULL;
unsigned long bytes_left;
unsigned long len = *total_out;
unsigned long nr_dest_pages = *out_pages;
const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
size_t in_len;
size_t out_len;
char *buf;
unsigned long tot_in = 0;
unsigned long tot_out = 0;
unsigned long pg_bytes_left;
unsigned long out_offset;
unsigned long bytes;
*out_pages = 0;
*total_out = 0;
*total_in = 0;
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
data_in = kmap(in_page);
/*
* store the size of all chunks of compressed data in
* the first 4 bytes
*/
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
goto out;
}
cpage_out = kmap(out_page);
out_offset = LZO_LEN;
tot_out = LZO_LEN;
pages[0] = out_page;
nr_pages = 1;
pg_bytes_left = PAGE_SIZE - LZO_LEN;
/* compress at most one page of data each time */
in_len = min(len, PAGE_SIZE);
while (tot_in < len) {
ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
&out_len, workspace->mem);
if (ret != LZO_E_OK) {
pr_debug("BTRFS: deflate in loop returned %d\n",
ret);
ret = -EIO;
goto out;
}
/* store the size of this chunk of compressed data */
write_compress_length(cpage_out + out_offset, out_len);
tot_out += LZO_LEN;
out_offset += LZO_LEN;
pg_bytes_left -= LZO_LEN;
tot_in += in_len;
tot_out += out_len;
/* copy bytes from the working buffer into the pages */
buf = workspace->cbuf;
while (out_len) {
bytes = min_t(unsigned long, pg_bytes_left, out_len);
memcpy(cpage_out + out_offset, buf, bytes);
out_len -= bytes;
pg_bytes_left -= bytes;
buf += bytes;
out_offset += bytes;
/*
* we need another page for writing out.
*
* Note if there's less than 4 bytes left, we just
* skip to a new page.
*/
if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
pg_bytes_left == 0) {
if (pg_bytes_left) {
memset(cpage_out + out_offset, 0,
pg_bytes_left);
tot_out += pg_bytes_left;
}
/* we're done, don't allocate new page */
if (out_len == 0 && tot_in >= len)
break;
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;
}
cpage_out = kmap(out_page);
pages[nr_pages++] = out_page;
pg_bytes_left = PAGE_SIZE;
out_offset = 0;
}
}
/* we're making it bigger, give up */
if (tot_in > 8192 && tot_in < tot_out) {
ret = -E2BIG;
goto out;
}
/* we're all done */
if (tot_in >= len)
break;
if (tot_out > max_out)
break;
bytes_left = len - tot_in;
kunmap(in_page);
put_page(in_page);
start += PAGE_SIZE;
in_page = find_get_page(mapping, start >> PAGE_SHIFT);
data_in = kmap(in_page);
in_len = min(bytes_left, PAGE_SIZE);
}
if (tot_out > tot_in)
goto out;
/* store the size of all chunks of compressed data */
cpage_out = kmap(pages[0]);
write_compress_length(cpage_out, tot_out);
kunmap(pages[0]);
ret = 0;
*total_out = tot_out;
*total_in = tot_in;
out:
*out_pages = nr_pages;
if (out_page)
kunmap(out_page);
if (in_page) {
kunmap(in_page);
put_page(in_page);
}
return ret;
}
static int lzo_decompress_bio(struct list_head *ws,
struct page **pages_in,
u64 disk_start,
struct bio *orig_bio,
size_t srclen)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0, ret2;
char *data_in;
unsigned long page_in_index = 0;
unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
unsigned long buf_start;
unsigned long buf_offset = 0;
unsigned long bytes;
unsigned long working_bytes;
size_t in_len;
size_t out_len;
unsigned long in_offset;
unsigned long in_page_bytes_left;
unsigned long tot_in;
unsigned long tot_out;
unsigned long tot_len;
char *buf;
bool may_late_unmap, need_unmap;
data_in = kmap(pages_in[0]);
tot_len = read_compress_length(data_in);
tot_in = LZO_LEN;
in_offset = LZO_LEN;
tot_len = min_t(size_t, srclen, tot_len);
in_page_bytes_left = PAGE_SIZE - LZO_LEN;
tot_out = 0;
while (tot_in < tot_len) {
in_len = read_compress_length(data_in + in_offset);
in_page_bytes_left -= LZO_LEN;
in_offset += LZO_LEN;
tot_in += LZO_LEN;
tot_in += in_len;
working_bytes = in_len;
may_late_unmap = need_unmap = false;
/* fast path: avoid using the working buffer */
if (in_page_bytes_left >= in_len) {
buf = data_in + in_offset;
bytes = in_len;
may_late_unmap = true;
goto cont;
}
/* copy bytes from the pages into the working buffer */
buf = workspace->cbuf;
buf_offset = 0;
while (working_bytes) {
bytes = min(working_bytes, in_page_bytes_left);
memcpy(buf + buf_offset, data_in + in_offset, bytes);
buf_offset += bytes;
cont:
working_bytes -= bytes;
in_page_bytes_left -= bytes;
in_offset += bytes;
/* check if we need to pick another page */
if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
|| in_page_bytes_left == 0) {
tot_in += in_page_bytes_left;
if (working_bytes == 0 && tot_in >= tot_len)
break;
if (page_in_index + 1 >= total_pages_in) {
ret = -EIO;
goto done;
}
if (may_late_unmap)
need_unmap = true;
else
kunmap(pages_in[page_in_index]);
data_in = kmap(pages_in[++page_in_index]);
in_page_bytes_left = PAGE_SIZE;
in_offset = 0;
}
}
out_len = lzo1x_worst_compress(PAGE_SIZE);
ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
&out_len);
if (need_unmap)
kunmap(pages_in[page_in_index - 1]);
if (ret != LZO_E_OK) {
pr_warn("BTRFS: decompress failed\n");
ret = -EIO;
break;
}
buf_start = tot_out;
tot_out += out_len;
ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
tot_out, disk_start, orig_bio);
if (ret2 == 0)
break;
}
done:
kunmap(pages_in[page_in_index]);
if (!ret)
zero_fill_bio(orig_bio);
return ret;
}
static int lzo_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);
size_t in_len;
size_t out_len;
size_t tot_len;
int ret = 0;
char *kaddr;
unsigned long bytes;
BUG_ON(srclen < LZO_LEN);
tot_len = read_compress_length(data_in);
data_in += LZO_LEN;
in_len = read_compress_length(data_in);
data_in += LZO_LEN;
out_len = PAGE_SIZE;
ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
if (ret != LZO_E_OK) {
pr_warn("BTRFS: decompress failed!\n");
ret = -EIO;
goto out;
}
if (out_len < start_byte) {
ret = -EIO;
goto out;
}
/*
* the caller is already checking against PAGE_SIZE, but lets
* move this check closer to the memcpy/memset
*/
destlen = min_t(unsigned long, destlen, PAGE_SIZE);
bytes = min_t(unsigned long, destlen, out_len - start_byte);
kaddr = kmap_atomic(dest_page);
memcpy(kaddr, workspace->buf + start_byte, bytes);
/*
* btrfs_getblock is doing a zero on the tail of the page too,
* but this will cover anything missing from the decompressed
* data.
*/
if (bytes < destlen)
memset(kaddr+bytes, 0, destlen-bytes);
kunmap_atomic(kaddr);
out:
return ret;
}
const struct btrfs_compress_op btrfs_lzo_compress = {
.alloc_workspace = lzo_alloc_workspace,
.free_workspace = lzo_free_workspace,
.compress_pages = lzo_compress_pages,
.decompress_bio = lzo_decompress_bio,
.decompress = lzo_decompress,
};