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linux/linux-5.4.31/fs/btrfs/lzo.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2008 Oracle. All rights reserved.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.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 <linux/refcount.h>
#include "compression.h"
#define LZO_LEN 4
/*
* Btrfs LZO compression format
*
* Regular and inlined LZO compressed data extents consist of:
*
* 1. Header
* Fixed size. LZO_LEN (4) bytes long, LE32.
* Records the total size (including the header) of compressed data.
*
* 2. Segment(s)
* Variable size. Each segment includes one segment header, followed by data
* payload.
* One regular LZO compressed extent can have one or more segments.
* For inlined LZO compressed extent, only one segment is allowed.
* One segment represents at most one page of uncompressed data.
*
* 2.1 Segment header
* Fixed size. LZO_LEN (4) bytes long, LE32.
* Records the total size of the segment (not including the header).
* Segment header never crosses page boundary, thus it's possible to
* have at most 3 padding zeros at the end of the page.
*
* 2.2 Data Payload
* Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
* which is 4419 for a 4KiB page.
*
* Example:
* Page 1:
* 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
* 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
* ...
* 0x0ff0 | SegHdr N | Data payload N ... |00|
* ^^ padding zeros
* Page 2:
* 0x1000 | SegHdr N+1| Data payload N+1 ... |
*/
struct workspace {
void *mem;
void *buf; /* where decompressed data goes */
void *cbuf; /* where compressed data goes */
struct list_head list;
};
static struct workspace_manager wsm;
static void lzo_init_workspace_manager(void)
{
btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
}
static void lzo_cleanup_workspace_manager(void)
{
btrfs_cleanup_workspace_manager(&wsm);
}
static struct list_head *lzo_get_workspace(unsigned int level)
{
return btrfs_get_workspace(&wsm, level);
}
static void lzo_put_workspace(struct list_head *ws)
{
btrfs_put_workspace(&wsm, ws);
}
static void lzo_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
kvfree(workspace->buf);
kvfree(workspace->cbuf);
kvfree(workspace->mem);
kfree(workspace);
}
static struct list_head *lzo_alloc_workspace(unsigned int level)
{
struct workspace *workspace;
workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
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: lzo 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) {
ret = -E2BIG;
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 compressed_bio *cb)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0, ret2;
char *data_in;
unsigned long page_in_index = 0;
size_t srclen = cb->compressed_len;
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;
const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
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;
struct page **pages_in = cb->compressed_pages;
u64 disk_start = cb->start;
struct bio *orig_bio = cb->orig_bio;
data_in = kmap(pages_in[0]);
tot_len = read_compress_length(data_in);
/*
* Compressed data header check.
*
* The real compressed size can't exceed the maximum extent length, and
* all pages should be used (whole unused page with just the segment
* header is not possible). If this happens it means the compressed
* extent is corrupted.
*/
if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
tot_len < srclen - PAGE_SIZE) {
ret = -EUCLEAN;
goto done;
}
tot_in = LZO_LEN;
in_offset = LZO_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;
/*
* Segment header check.
*
* The segment length must not exceed the maximum LZO
* compression size, nor the total compressed size.
*/
if (in_len > max_segment_len || tot_in + in_len > tot_len) {
ret = -EUCLEAN;
goto done;
}
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 = max_segment_len;
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 max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
int ret = 0;
char *kaddr;
unsigned long bytes;
if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
return -EUCLEAN;
in_len = read_compress_length(data_in);
if (in_len != srclen)
return -EUCLEAN;
data_in += LZO_LEN;
in_len = read_compress_length(data_in);
if (in_len != srclen - LZO_LEN * 2) {
ret = -EUCLEAN;
goto out;
}
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 = {
.init_workspace_manager = lzo_init_workspace_manager,
.cleanup_workspace_manager = lzo_cleanup_workspace_manager,
.get_workspace = lzo_get_workspace,
.put_workspace = lzo_put_workspace,
.alloc_workspace = lzo_alloc_workspace,
.free_workspace = lzo_free_workspace,
.compress_pages = lzo_compress_pages,
.decompress_bio = lzo_decompress_bio,
.decompress = lzo_decompress,
.max_level = 1,
.default_level = 1,
};
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