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![David Sterba](/assets/img/avatar_default.png)
There are some op tables that can be easily made const, similarly the sysfs feature and raid tables. This is motivated by PaX CONSTIFY plugin. Signed-off-by: David Sterba <dsterba@suse.cz>
443 lines
10 KiB
C
443 lines
10 KiB
C
/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/pagemap.h>
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#include <linux/bio.h>
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#include <linux/lzo.h>
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#include "compression.h"
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#define LZO_LEN 4
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struct workspace {
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void *mem;
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void *buf; /* where decompressed data goes */
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void *cbuf; /* where compressed data goes */
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struct list_head list;
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};
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static void lzo_free_workspace(struct list_head *ws)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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vfree(workspace->buf);
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vfree(workspace->cbuf);
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vfree(workspace->mem);
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kfree(workspace);
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}
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static struct list_head *lzo_alloc_workspace(void)
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{
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struct workspace *workspace;
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workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
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if (!workspace)
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return ERR_PTR(-ENOMEM);
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workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
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workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
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workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
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if (!workspace->mem || !workspace->buf || !workspace->cbuf)
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goto fail;
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INIT_LIST_HEAD(&workspace->list);
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return &workspace->list;
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fail:
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lzo_free_workspace(&workspace->list);
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return ERR_PTR(-ENOMEM);
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}
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static inline void write_compress_length(char *buf, size_t len)
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{
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__le32 dlen;
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dlen = cpu_to_le32(len);
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memcpy(buf, &dlen, LZO_LEN);
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}
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static inline size_t read_compress_length(char *buf)
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{
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__le32 dlen;
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memcpy(&dlen, buf, LZO_LEN);
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return le32_to_cpu(dlen);
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}
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static int lzo_compress_pages(struct list_head *ws,
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struct address_space *mapping,
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u64 start, unsigned long len,
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struct page **pages,
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unsigned long nr_dest_pages,
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unsigned long *out_pages,
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unsigned long *total_in,
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unsigned long *total_out,
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unsigned long max_out)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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int ret = 0;
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char *data_in;
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char *cpage_out;
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int nr_pages = 0;
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struct page *in_page = NULL;
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struct page *out_page = NULL;
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unsigned long bytes_left;
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size_t in_len;
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size_t out_len;
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char *buf;
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unsigned long tot_in = 0;
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unsigned long tot_out = 0;
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unsigned long pg_bytes_left;
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unsigned long out_offset;
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unsigned long bytes;
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*out_pages = 0;
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*total_out = 0;
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*total_in = 0;
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in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
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data_in = kmap(in_page);
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/*
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* store the size of all chunks of compressed data in
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* the first 4 bytes
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*/
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out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
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if (out_page == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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cpage_out = kmap(out_page);
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out_offset = LZO_LEN;
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tot_out = LZO_LEN;
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pages[0] = out_page;
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nr_pages = 1;
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pg_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
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/* compress at most one page of data each time */
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in_len = min(len, PAGE_CACHE_SIZE);
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while (tot_in < len) {
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ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
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&out_len, workspace->mem);
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if (ret != LZO_E_OK) {
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printk(KERN_DEBUG "BTRFS: deflate in loop returned %d\n",
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ret);
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ret = -EIO;
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goto out;
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}
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/* store the size of this chunk of compressed data */
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write_compress_length(cpage_out + out_offset, out_len);
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tot_out += LZO_LEN;
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out_offset += LZO_LEN;
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pg_bytes_left -= LZO_LEN;
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tot_in += in_len;
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tot_out += out_len;
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/* copy bytes from the working buffer into the pages */
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buf = workspace->cbuf;
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while (out_len) {
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bytes = min_t(unsigned long, pg_bytes_left, out_len);
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memcpy(cpage_out + out_offset, buf, bytes);
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out_len -= bytes;
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pg_bytes_left -= bytes;
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buf += bytes;
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out_offset += bytes;
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/*
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* we need another page for writing out.
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*
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* Note if there's less than 4 bytes left, we just
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* skip to a new page.
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*/
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if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
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pg_bytes_left == 0) {
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if (pg_bytes_left) {
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memset(cpage_out + out_offset, 0,
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pg_bytes_left);
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tot_out += pg_bytes_left;
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}
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/* we're done, don't allocate new page */
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if (out_len == 0 && tot_in >= len)
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break;
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kunmap(out_page);
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if (nr_pages == nr_dest_pages) {
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out_page = NULL;
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ret = -E2BIG;
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goto out;
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}
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out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
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if (out_page == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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cpage_out = kmap(out_page);
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pages[nr_pages++] = out_page;
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pg_bytes_left = PAGE_CACHE_SIZE;
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out_offset = 0;
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}
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}
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/* we're making it bigger, give up */
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if (tot_in > 8192 && tot_in < tot_out) {
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ret = -E2BIG;
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goto out;
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}
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/* we're all done */
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if (tot_in >= len)
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break;
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if (tot_out > max_out)
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break;
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bytes_left = len - tot_in;
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kunmap(in_page);
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page_cache_release(in_page);
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start += PAGE_CACHE_SIZE;
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in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
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data_in = kmap(in_page);
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in_len = min(bytes_left, PAGE_CACHE_SIZE);
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}
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if (tot_out > tot_in)
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goto out;
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/* store the size of all chunks of compressed data */
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cpage_out = kmap(pages[0]);
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write_compress_length(cpage_out, tot_out);
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kunmap(pages[0]);
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ret = 0;
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*total_out = tot_out;
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*total_in = tot_in;
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out:
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*out_pages = nr_pages;
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if (out_page)
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kunmap(out_page);
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if (in_page) {
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kunmap(in_page);
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page_cache_release(in_page);
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}
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return ret;
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}
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static int lzo_decompress_biovec(struct list_head *ws,
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struct page **pages_in,
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u64 disk_start,
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struct bio_vec *bvec,
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int vcnt,
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size_t srclen)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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int ret = 0, ret2;
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char *data_in;
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unsigned long page_in_index = 0;
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unsigned long page_out_index = 0;
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unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE);
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unsigned long buf_start;
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unsigned long buf_offset = 0;
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unsigned long bytes;
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unsigned long working_bytes;
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unsigned long pg_offset;
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size_t in_len;
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size_t out_len;
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unsigned long in_offset;
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unsigned long in_page_bytes_left;
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unsigned long tot_in;
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unsigned long tot_out;
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unsigned long tot_len;
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char *buf;
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bool may_late_unmap, need_unmap;
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data_in = kmap(pages_in[0]);
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tot_len = read_compress_length(data_in);
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tot_in = LZO_LEN;
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in_offset = LZO_LEN;
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tot_len = min_t(size_t, srclen, tot_len);
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in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
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tot_out = 0;
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pg_offset = 0;
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while (tot_in < tot_len) {
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in_len = read_compress_length(data_in + in_offset);
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in_page_bytes_left -= LZO_LEN;
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in_offset += LZO_LEN;
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tot_in += LZO_LEN;
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tot_in += in_len;
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working_bytes = in_len;
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may_late_unmap = need_unmap = false;
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/* fast path: avoid using the working buffer */
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if (in_page_bytes_left >= in_len) {
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buf = data_in + in_offset;
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bytes = in_len;
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may_late_unmap = true;
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goto cont;
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}
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/* copy bytes from the pages into the working buffer */
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buf = workspace->cbuf;
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buf_offset = 0;
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while (working_bytes) {
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bytes = min(working_bytes, in_page_bytes_left);
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memcpy(buf + buf_offset, data_in + in_offset, bytes);
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buf_offset += bytes;
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cont:
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working_bytes -= bytes;
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in_page_bytes_left -= bytes;
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in_offset += bytes;
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/* check if we need to pick another page */
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if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
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|| in_page_bytes_left == 0) {
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tot_in += in_page_bytes_left;
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if (working_bytes == 0 && tot_in >= tot_len)
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break;
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if (page_in_index + 1 >= total_pages_in) {
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ret = -EIO;
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goto done;
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}
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if (may_late_unmap)
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need_unmap = true;
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else
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kunmap(pages_in[page_in_index]);
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data_in = kmap(pages_in[++page_in_index]);
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in_page_bytes_left = PAGE_CACHE_SIZE;
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in_offset = 0;
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}
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}
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out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
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ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
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&out_len);
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if (need_unmap)
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kunmap(pages_in[page_in_index - 1]);
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if (ret != LZO_E_OK) {
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printk(KERN_WARNING "BTRFS: decompress failed\n");
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ret = -EIO;
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break;
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}
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buf_start = tot_out;
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tot_out += out_len;
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ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
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tot_out, disk_start,
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bvec, vcnt,
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&page_out_index, &pg_offset);
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if (ret2 == 0)
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break;
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}
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done:
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kunmap(pages_in[page_in_index]);
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if (!ret)
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btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
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return ret;
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}
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static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
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struct page *dest_page,
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unsigned long start_byte,
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size_t srclen, size_t destlen)
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{
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struct workspace *workspace = list_entry(ws, struct workspace, list);
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size_t in_len;
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size_t out_len;
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size_t tot_len;
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int ret = 0;
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char *kaddr;
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unsigned long bytes;
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BUG_ON(srclen < LZO_LEN);
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tot_len = read_compress_length(data_in);
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data_in += LZO_LEN;
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in_len = read_compress_length(data_in);
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data_in += LZO_LEN;
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out_len = PAGE_CACHE_SIZE;
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ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
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if (ret != LZO_E_OK) {
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printk(KERN_WARNING "BTRFS: decompress failed!\n");
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ret = -EIO;
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goto out;
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}
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if (out_len < start_byte) {
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ret = -EIO;
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goto out;
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}
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/*
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* the caller is already checking against PAGE_SIZE, but lets
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* move this check closer to the memcpy/memset
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*/
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destlen = min_t(unsigned long, destlen, PAGE_SIZE);
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bytes = min_t(unsigned long, destlen, out_len - start_byte);
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kaddr = kmap_atomic(dest_page);
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memcpy(kaddr, workspace->buf + start_byte, bytes);
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/*
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* btrfs_getblock is doing a zero on the tail of the page too,
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* but this will cover anything missing from the decompressed
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* data.
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*/
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if (bytes < destlen)
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memset(kaddr+bytes, 0, destlen-bytes);
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kunmap_atomic(kaddr);
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out:
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return ret;
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}
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const struct btrfs_compress_op btrfs_lzo_compress = {
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.alloc_workspace = lzo_alloc_workspace,
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.free_workspace = lzo_free_workspace,
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.compress_pages = lzo_compress_pages,
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.decompress_biovec = lzo_decompress_biovec,
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.decompress = lzo_decompress,
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};
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