/*
* 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.
*
* Based on jffs2 zlib code:
* Copyright © 2001-2007 Red Hat, Inc.
* Created by David Woodhouse <dwmw2@infradead.org>
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/zlib.h>
#include <linux/zutil.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>
/* Plan: call deflate() with avail_in == *sourcelen,
avail_out = *dstlen - 12 and flush == Z_FINISH.
If it doesn't manage to finish, call it again with
avail_in == 0 and avail_out set to the remaining 12
bytes for it to clean up.
Q: Is 12 bytes sufficient?
*/
#define STREAM_END_SPACE 12
struct workspace {
z_stream inf_strm;
z_stream def_strm;
char *buf;
struct list_head list;
};
static LIST_HEAD(idle_workspace);
static DEFINE_SPINLOCK(workspace_lock);
static unsigned long num_workspace;
static atomic_t alloc_workspace = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(workspace_wait);
/*
* this finds an available zlib workspace or allocates a new one
* NULL or an ERR_PTR is returned if things go bad.
*/
static struct workspace *find_zlib_workspace(void)
{
struct workspace *workspace;
int ret;
int cpus = num_online_cpus();
again:
spin_lock(&workspace_lock);
if (!list_empty(&idle_workspace)) {
workspace = list_entry(idle_workspace.next, struct workspace,
list);
list_del(&workspace->list);
num_workspace--;
spin_unlock(&workspace_lock);
return workspace;
}
spin_unlock(&workspace_lock);
if (atomic_read(&alloc_workspace) > cpus) {
DEFINE_WAIT(wait);
prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
if (atomic_read(&alloc_workspace) > cpus)
schedule();
finish_wait(&workspace_wait, &wait);
goto again;
}
atomic_inc(&alloc_workspace);
workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
if (!workspace) {
ret = -ENOMEM;
goto fail;
}
workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize());
if (!workspace->def_strm.workspace) {
ret = -ENOMEM;
goto fail;
}
workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
if (!workspace->inf_strm.workspace) {
ret = -ENOMEM;
goto fail_inflate;
}
workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
if (!workspace->buf) {
ret = -ENOMEM;
goto fail_kmalloc;
}
return workspace;
fail_kmalloc:
vfree(workspace->inf_strm.workspace);
fail_inflate:
vfree(workspace->def_strm.workspace);
fail:
kfree(workspace);
atomic_dec(&alloc_workspace);
wake_up(&workspace_wait);
return ERR_PTR(ret);
}
/*
* put a workspace struct back on the list or free it if we have enough
* idle ones sitting around
*/
static int free_workspace(struct workspace *workspace)
{
spin_lock(&workspace_lock);
if (num_workspace < num_online_cpus()) {
list_add_tail(&workspace->list, &idle_workspace);
num_workspace++;
spin_unlock(&workspace_lock);
if (waitqueue_active(&workspace_wait))
wake_up(&workspace_wait);
return 0;
}
spin_unlock(&workspace_lock);
vfree(workspace->def_strm.workspace);
vfree(workspace->inf_strm.workspace);
kfree(workspace->buf);
kfree(workspace);
atomic_dec(&alloc_workspace);
if (waitqueue_active(&workspace_wait))
wake_up(&workspace_wait);
return 0;
}
/*
* cleanup function for module exit
*/
static void free_workspaces(void)
{
struct workspace *workspace;
while(!list_empty(&idle_workspace)) {
workspace = list_entry(idle_workspace.next, struct workspace,
list);
list_del(&workspace->list);
vfree(workspace->def_strm.workspace);
vfree(workspace->inf_strm.workspace);
kfree(workspace->buf);
kfree(workspace);
atomic_dec(&alloc_workspace);
}
}
/*
* given an address space and start/len, compress the bytes.
*
* pages are allocated to hold the compressed result and stored
* in 'pages'
*
* out_pages is used to return the number of pages allocated. There
* may be pages allocated even if we return an error
*
* total_in is used to return the number of bytes actually read. It
* may be smaller then len if we had to exit early because we
* ran out of room in the pages array or because we cross the
* max_out threshold.
*
* total_out is used to return the total number of compressed bytes
*
* max_out tells us the max number of bytes that we're allowed to
* stuff into pages
*/
int btrfs_zlib_compress_pages(struct address_space *mapping,
u64 start, unsigned long len,
struct page **pages,
unsigned long nr_dest_pages,
unsigned long *out_pages,
unsigned long *total_in,
unsigned long *total_out,
unsigned long max_out)
{
int ret;
struct workspace *workspace;
char *data_in;
char *cpage_out;
int nr_pages = 0;
struct page *in_page = NULL;
struct page *out_page = NULL;
int out_written = 0;
int in_read = 0;
unsigned long bytes_left;
*out_pages = 0;
*total_out = 0;
*total_in = 0;
workspace = find_zlib_workspace();
if (!workspace)
return -1;
if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
printk(KERN_WARNING "deflateInit failed\n");
ret = -1;
goto out;
}
workspace->def_strm.total_in = 0;
workspace->def_strm.total_out = 0;
in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
cpage_out = kmap(out_page);
pages[0] = out_page;
nr_pages = 1;
workspace->def_strm.next_in = data_in;
workspace->def_strm.next_out = cpage_out;
workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
out_written = 0;
in_read = 0;
while (workspace->def_strm.total_in < len) {
ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
if (ret != Z_OK) {
printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
ret);
zlib_deflateEnd(&workspace->def_strm);
ret = -1;
goto out;
}
/* we're making it bigger, give up */
if (workspace->def_strm.total_in > 8192 &&
workspace->def_strm.total_in <
workspace->def_strm.total_out) {
ret = -1;
goto out;
}
/* we need another page for writing out. Test this
* before the total_in so we will pull in a new page for
* the stream end if required
*/
if (workspace->def_strm.avail_out == 0) {
kunmap(out_page);
if (nr_pages == nr_dest_pages) {
out_page = NULL;
ret = -1;
goto out;
}
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
cpage_out = kmap(out_page);
pages[nr_pages] = out_page;
nr_pages++;
workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
workspace->def_strm.next_out = cpage_out;
}
/* we're all done */
if (workspace->def_strm.total_in >= len)
break;
/* we've read in a full page, get a new one */
if (workspace->def_strm.avail_in == 0) {
if (workspace->def_strm.total_out > max_out)
break;
bytes_left = len - workspace->def_strm.total_in;
kunmap(in_page);
page_cache_release(in_page);
start += PAGE_CACHE_SIZE;
in_page = find_get_page(mapping,
start >> PAGE_CACHE_SHIFT);
data_in = kmap(in_page);
workspace->def_strm.avail_in = min(bytes_left,
PAGE_CACHE_SIZE);
workspace->def_strm.next_in = data_in;
}
}
workspace->def_strm.avail_in = 0;
ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
zlib_deflateEnd(&workspace->def_strm);
if (ret != Z_STREAM_END) {
ret = -1;
goto out;
}
if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
ret = -1;
goto out;
}
ret = 0;
*total_out = workspace->def_strm.total_out;
*total_in = workspace->def_strm.total_in;
out:
*out_pages = nr_pages;
if (out_page)
kunmap(out_page);
if (in_page) {
kunmap(in_page);
page_cache_release(in_page);
}
free_workspace(workspace);
return ret;
}
/*
* pages_in is an array of pages with compressed data.
*
* disk_start is the starting logical offset of this array in the file
*
* bvec is a bio_vec of pages from the file that we want to decompress into
*
* vcnt is the count of pages in the biovec
*
* srclen is the number of bytes in pages_in
*
* The basic idea is that we have a bio that was created by readpages.
* The pages in the bio are for the uncompressed data, and they may not
* be contiguous. They all correspond to the range of bytes covered by
* the compressed extent.
*/
int btrfs_zlib_decompress_biovec(struct page **pages_in,
u64 disk_start,
struct bio_vec *bvec,
int vcnt,
size_t srclen)
{
int ret = 0;
int wbits = MAX_WBITS;
struct workspace *workspace;
char *data_in;
size_t total_out = 0;
unsigned long page_bytes_left;
unsigned long page_in_index = 0;
unsigned long page_out_index = 0;
struct page *page_out;
unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
PAGE_CACHE_SIZE;
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
unsigned long working_bytes;
unsigned long pg_offset;
unsigned long start_byte;
unsigned long current_buf_start;
char *kaddr;
workspace = find_zlib_workspace();
if (!workspace)
return -ENOMEM;
data_in = kmap(pages_in[page_in_index]);
workspace->inf_strm.next_in = data_in;
workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
workspace->inf_strm.total_in = 0;
workspace->inf_strm.total_out = 0;
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
page_out = bvec[page_out_index].bv_page;
page_bytes_left = PAGE_CACHE_SIZE;
pg_offset = 0;
/* If it's deflate, and it's got no preset dictionary, then
we can tell zlib to skip the adler32 check. */
if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
((data_in[0] & 0x0f) == Z_DEFLATED) &&
!(((data_in[0]<<8) + data_in[1]) % 31)) {
wbits = -((data_in[0] >> 4) + 8);
workspace->inf_strm.next_in += 2;
workspace->inf_strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
printk(KERN_WARNING "inflateInit failed\n");
ret = -1;
goto out;
}
while(workspace->inf_strm.total_in < srclen) {
ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END) {
break;
}
/*
* buf start is the byte offset we're of the start of
* our workspace buffer
*/
buf_start = total_out;
/* total_out is the last byte of the workspace buffer */
total_out = workspace->inf_strm.total_out;
working_bytes = total_out - buf_start;
/*
* start byte is the first byte of the page we're currently
* copying into relative to the start of the compressed data.
*/
start_byte = page_offset(page_out) - disk_start;
if (working_bytes == 0) {
/* we didn't make progress in this inflate
* call, we're done
*/
if (ret != Z_STREAM_END) {
ret = -1;
}
break;
}
/* we haven't yet hit data corresponding to this page */
if (total_out <= start_byte) {
goto next;
}
/*
* the start of the data we care about is offset into
* the middle of our working buffer
*/
if (total_out > start_byte && buf_start < start_byte) {
buf_offset = start_byte - buf_start;
working_bytes -= buf_offset;
} else {
buf_offset = 0;
}
current_buf_start = buf_start;
/* copy bytes from the working buffer into the pages */
while(working_bytes > 0) {
bytes = min(PAGE_CACHE_SIZE - pg_offset,
PAGE_CACHE_SIZE - buf_offset);
bytes = min(bytes, working_bytes);
kaddr = kmap_atomic(page_out, KM_USER0);
memcpy(kaddr + pg_offset, workspace->buf + buf_offset,
bytes);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page_out);
pg_offset += bytes;
page_bytes_left -= bytes;
buf_offset += bytes;
working_bytes -= bytes;
current_buf_start += bytes;
/* check if we need to pick another page */
if (page_bytes_left == 0) {
page_out_index++;
if (page_out_index >= vcnt) {
ret = 0;
goto done;
}
page_out = bvec[page_out_index].bv_page;
pg_offset = 0;
page_bytes_left = PAGE_CACHE_SIZE;
start_byte = page_offset(page_out) - disk_start;
/*
* make sure our new page is covered by this
* working buffer
*/
if (total_out <= start_byte) {
goto next;
}
/* the next page in the biovec might not
* be adjacent to the last page, but it
* might still be found inside this working
* buffer. bump our offset pointer
*/
if (total_out > start_byte &&
current_buf_start < start_byte) {
buf_offset = start_byte - buf_start;
working_bytes = total_out - start_byte;
current_buf_start = buf_start +
buf_offset;
}
}
}
next:
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
if (workspace->inf_strm.avail_in == 0) {
unsigned long tmp;
kunmap(pages_in[page_in_index]);
page_in_index++;
if (page_in_index >= total_pages_in) {
data_in = NULL;
break;
}
data_in = kmap(pages_in[page_in_index]);
workspace->inf_strm.next_in = data_in;
tmp = srclen - workspace->inf_strm.total_in;
workspace->inf_strm.avail_in = min(tmp,
PAGE_CACHE_SIZE);
}
}
if (ret != Z_STREAM_END) {
ret = -1;
} else {
ret = 0;
}
done:
zlib_inflateEnd(&workspace->inf_strm);
if (data_in)
kunmap(pages_in[page_in_index]);
out:
free_workspace(workspace);
return ret;
}
/*
* a less complex decompression routine. Our compressed data fits in a
* single page, and we want to read a single page out of it.
* start_byte tells us the offset into the compressed data we're interested in
*/
int btrfs_zlib_decompress(unsigned char *data_in,
struct page *dest_page,
unsigned long start_byte,
size_t srclen, size_t destlen)
{
int ret = 0;
int wbits = MAX_WBITS;
struct workspace *workspace;
unsigned long bytes_left = destlen;
unsigned long total_out = 0;
char *kaddr;
if (destlen > PAGE_CACHE_SIZE)
return -ENOMEM;
workspace = find_zlib_workspace();
if (!workspace)
return -ENOMEM;
workspace->inf_strm.next_in = data_in;
workspace->inf_strm.avail_in = srclen;
workspace->inf_strm.total_in = 0;
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
workspace->inf_strm.total_out = 0;
/* If it's deflate, and it's got no preset dictionary, then
we can tell zlib to skip the adler32 check. */
if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
((data_in[0] & 0x0f) == Z_DEFLATED) &&
!(((data_in[0]<<8) + data_in[1]) % 31)) {
wbits = -((data_in[0] >> 4) + 8);
workspace->inf_strm.next_in += 2;
workspace->inf_strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
printk(KERN_WARNING "inflateInit failed\n");
ret = -1;
goto out;
}
while(bytes_left > 0) {
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
unsigned long pg_offset = 0;
ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END) {
break;
}
buf_start = total_out;
total_out = workspace->inf_strm.total_out;
if (total_out == buf_start) {
ret = -1;
break;
}
if (total_out <= start_byte) {
goto next;
}
if (total_out > start_byte && buf_start < start_byte) {
buf_offset = start_byte - buf_start;
} else {
buf_offset = 0;
}
bytes = min(PAGE_CACHE_SIZE - pg_offset,
PAGE_CACHE_SIZE - buf_offset);
bytes = min(bytes, bytes_left);
kaddr = kmap_atomic(dest_page, KM_USER0);
memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
kunmap_atomic(kaddr, KM_USER0);
pg_offset += bytes;
bytes_left -= bytes;
next:
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
}
if (ret != Z_STREAM_END && bytes_left != 0) {
ret = -1;
} else {
ret = 0;
}
zlib_inflateEnd(&workspace->inf_strm);
out:
free_workspace(workspace);
return ret;
}
void btrfs_zlib_exit(void)
{
free_workspaces();
}
