| 1 |
1275 |
phoenix |
/* -*- linux-c -*- ------------------------------------------------------- *
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*
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* Copyright 2001 H. Peter Anvin - All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
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* USA; either version 2 of the License, or (at your option) any later
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* version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* linux/fs/isofs/compress.c
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*
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* Transparent decompression of files on an iso9660 filesystem
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/stat.h>
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#include <linux/sched.h>
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#include <linux/iso_fs.h>
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#include <linux/kernel.h>
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#include <linux/major.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/locks.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include <linux/cdrom.h>
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#include <linux/init.h>
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#include <linux/nls.h>
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#include <linux/ctype.h>
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#include <linux/smp_lock.h>
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#include <linux/blkdev.h>
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#include <linux/vmalloc.h>
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#include <linux/zlib.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/semaphore.h>
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#include "zisofs.h"
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/* This should probably be global. */
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static char zisofs_sink_page[PAGE_CACHE_SIZE];
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/*
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* This contains the zlib memory allocation and the mutex for the
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* allocation; this avoids failures at block-decompression time.
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*/
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static void *zisofs_zlib_workspace;
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static struct semaphore zisofs_zlib_semaphore;
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/*
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* When decompressing, we typically obtain more than one page
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* per reference. We inject the additional pages into the page
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* cache as a form of readahead.
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*/
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static int zisofs_readpage(struct file *file, struct page *page)
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{
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struct inode *inode = file->f_dentry->d_inode;
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struct address_space *mapping = inode->i_mapping;
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unsigned int maxpage, xpage, fpage, blockindex;
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unsigned long offset;
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unsigned long blockptr, blockendptr, cstart, cend, csize;
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struct buffer_head *bh, *ptrbh[2];
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unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
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unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
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unsigned long bufmask = bufsize - 1;
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int err = -EIO;
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int i;
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unsigned int header_size = inode->u.isofs_i.i_format_parm[0];
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unsigned int zisofs_block_shift = inode->u.isofs_i.i_format_parm[1];
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/* unsigned long zisofs_block_size = 1UL << zisofs_block_shift; */
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unsigned int zisofs_block_page_shift = zisofs_block_shift-PAGE_CACHE_SHIFT;
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unsigned long zisofs_block_pages = 1UL << zisofs_block_page_shift;
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unsigned long zisofs_block_page_mask = zisofs_block_pages-1;
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struct page *pages[zisofs_block_pages];
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unsigned long index = page->index;
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int indexblocks;
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| 85 |
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/* We have already been given one page, this is the one
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| 86 |
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we must do. */
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xpage = index & zisofs_block_page_mask;
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pages[xpage] = page;
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| 90 |
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/* The remaining pages need to be allocated and inserted */
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offset = index & ~zisofs_block_page_mask;
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blockindex = offset >> zisofs_block_page_shift;
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maxpage = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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maxpage = min(zisofs_block_pages, maxpage-offset);
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| 96 |
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for ( i = 0 ; i < maxpage ; i++, offset++ ) {
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| 97 |
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if ( i != xpage ) {
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pages[i] = grab_cache_page_nowait(mapping, offset);
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}
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page = pages[i];
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| 101 |
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if ( page ) {
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ClearPageError(page);
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kmap(page);
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}
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}
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| 107 |
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/* This is the last page filled, plus one; used in case of abort. */
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fpage = 0;
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| 110 |
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/* Find the pointer to this specific chunk */
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/* Note: we're not using isonum_731() here because the data is known aligned */
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/* Note: header_size is in 32-bit words (4 bytes) */
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blockptr = (header_size + blockindex) << 2;
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blockendptr = blockptr + 4;
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| 115 |
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| 116 |
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indexblocks = ((blockptr^blockendptr) >> bufshift) ? 2 : 1;
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ptrbh[0] = ptrbh[1] = 0;
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| 119 |
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if ( isofs_get_blocks(inode, blockptr >> bufshift, ptrbh, indexblocks) != indexblocks ) {
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if ( ptrbh[0] ) brelse(ptrbh[0]);
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printk(KERN_DEBUG "zisofs: Null buffer on reading block table, inode = %lu, block = %lu\n",
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inode->i_ino, blockptr >> bufshift);
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goto eio;
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| 124 |
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}
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ll_rw_block(READ, indexblocks, ptrbh);
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bh = ptrbh[0];
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if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
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printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
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inode->i_ino, blockptr >> bufshift);
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if ( ptrbh[1] )
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brelse(ptrbh[1]);
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goto eio;
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}
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cstart = le32_to_cpu(*(u32 *)(bh->b_data + (blockptr & bufmask)));
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| 136 |
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if ( indexblocks == 2 ) {
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/* We just crossed a block boundary. Switch to the next block */
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brelse(bh);
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bh = ptrbh[1];
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if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
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printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
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inode->i_ino, blockendptr >> bufshift);
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goto eio;
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| 145 |
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}
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}
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cend = le32_to_cpu(*(u32 *)(bh->b_data + (blockendptr & bufmask)));
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brelse(bh);
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| 150 |
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csize = cend-cstart;
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/* Now page[] contains an array of pages, any of which can be NULL,
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and the locks on which we hold. We should now read the data and
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release the pages. If the pages are NULL the decompressed data
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for that particular page should be discarded. */
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| 156 |
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| 157 |
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if ( csize == 0 ) {
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/* This data block is empty. */
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| 159 |
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for ( fpage = 0 ; fpage < maxpage ; fpage++ ) {
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if ( (page = pages[fpage]) != NULL ) {
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memset(page_address(page), 0, PAGE_CACHE_SIZE);
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flush_dcache_page(page);
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SetPageUptodate(page);
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kunmap(page);
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| 167 |
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UnlockPage(page);
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| 168 |
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if ( fpage == xpage )
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| 169 |
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err = 0; /* The critical page */
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| 170 |
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else
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page_cache_release(page);
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| 172 |
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}
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| 173 |
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}
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| 174 |
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} else {
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| 175 |
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/* This data block is compressed. */
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| 176 |
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z_stream stream;
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| 177 |
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int bail = 0, left_out = -1;
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| 178 |
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int zerr;
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| 179 |
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int needblocks = (csize + (cstart & bufmask) + bufmask) >> bufshift;
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| 180 |
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int haveblocks;
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| 181 |
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struct buffer_head *bhs[needblocks+1];
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| 182 |
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struct buffer_head **bhptr;
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| 183 |
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| 184 |
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/* Because zlib is not thread-safe, do all the I/O at the top. */
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| 185 |
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| 186 |
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blockptr = cstart >> bufshift;
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| 187 |
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memset(bhs, 0, (needblocks+1)*sizeof(struct buffer_head *));
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| 188 |
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haveblocks = isofs_get_blocks(inode, blockptr, bhs, needblocks);
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| 189 |
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ll_rw_block(READ, haveblocks, bhs);
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| 190 |
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| 191 |
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bhptr = &bhs[0];
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| 192 |
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bh = *bhptr++;
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| 193 |
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| 194 |
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/* First block is special since it may be fractional.
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| 195 |
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We also wait for it before grabbing the zlib
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| 196 |
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semaphore; odds are that the subsequent blocks are
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| 197 |
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going to come in in short order so we don't hold
|
| 198 |
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the zlib semaphore longer than necessary. */
|
| 199 |
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|
| 200 |
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if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
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| 201 |
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printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
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| 202 |
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fpage, xpage, csize);
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| 203 |
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goto b_eio;
|
| 204 |
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}
|
| 205 |
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stream.next_in = bh->b_data + (cstart & bufmask);
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| 206 |
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stream.avail_in = min(bufsize-(cstart & bufmask), csize);
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| 207 |
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csize -= stream.avail_in;
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| 208 |
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| 209 |
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stream.workspace = zisofs_zlib_workspace;
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| 210 |
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down(&zisofs_zlib_semaphore);
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| 211 |
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|
| 212 |
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zerr = zlib_inflateInit(&stream);
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| 213 |
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if ( zerr != Z_OK ) {
|
| 214 |
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if ( err && zerr == Z_MEM_ERROR )
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| 215 |
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err = -ENOMEM;
|
| 216 |
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printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
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| 217 |
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zerr);
|
| 218 |
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goto z_eio;
|
| 219 |
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}
|
| 220 |
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|
| 221 |
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while ( !bail && fpage < maxpage ) {
|
| 222 |
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page = pages[fpage];
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| 223 |
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if ( page )
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| 224 |
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stream.next_out = page_address(page);
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| 225 |
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else
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| 226 |
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stream.next_out = (void *)&zisofs_sink_page;
|
| 227 |
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stream.avail_out = PAGE_CACHE_SIZE;
|
| 228 |
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|
| 229 |
|
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while ( stream.avail_out ) {
|
| 230 |
|
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int ao, ai;
|
| 231 |
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if ( stream.avail_in == 0 && left_out ) {
|
| 232 |
|
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if ( !csize ) {
|
| 233 |
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printk(KERN_WARNING "zisofs: ZF read beyond end of input\n");
|
| 234 |
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bail = 1;
|
| 235 |
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break;
|
| 236 |
|
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} else {
|
| 237 |
|
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bh = *bhptr++;
|
| 238 |
|
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if ( !bh ||
|
| 239 |
|
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(wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
|
| 240 |
|
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/* Reached an EIO */
|
| 241 |
|
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printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
|
| 242 |
|
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fpage, xpage, csize);
|
| 243 |
|
|
|
| 244 |
|
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bail = 1;
|
| 245 |
|
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break;
|
| 246 |
|
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}
|
| 247 |
|
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stream.next_in = bh->b_data;
|
| 248 |
|
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stream.avail_in = min(csize,bufsize);
|
| 249 |
|
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csize -= stream.avail_in;
|
| 250 |
|
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}
|
| 251 |
|
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}
|
| 252 |
|
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ao = stream.avail_out; ai = stream.avail_in;
|
| 253 |
|
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zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
|
| 254 |
|
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left_out = stream.avail_out;
|
| 255 |
|
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if ( zerr == Z_BUF_ERROR && stream.avail_in == 0 )
|
| 256 |
|
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continue;
|
| 257 |
|
|
if ( zerr != Z_OK ) {
|
| 258 |
|
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/* EOF, error, or trying to read beyond end of input */
|
| 259 |
|
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if ( err && zerr == Z_MEM_ERROR )
|
| 260 |
|
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err = -ENOMEM;
|
| 261 |
|
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if ( zerr != Z_STREAM_END )
|
| 262 |
|
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printk(KERN_DEBUG "zisofs: zisofs_inflate returned %d, inode = %lu, index = %lu, fpage = %d, xpage = %d, avail_in = %d, avail_out = %d, ai = %d, ao = %d\n",
|
| 263 |
|
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zerr, inode->i_ino, index,
|
| 264 |
|
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fpage, xpage,
|
| 265 |
|
|
stream.avail_in, stream.avail_out,
|
| 266 |
|
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ai, ao);
|
| 267 |
|
|
bail = 1;
|
| 268 |
|
|
break;
|
| 269 |
|
|
}
|
| 270 |
|
|
}
|
| 271 |
|
|
|
| 272 |
|
|
if ( stream.avail_out && zerr == Z_STREAM_END ) {
|
| 273 |
|
|
/* Fractional page written before EOF. This may
|
| 274 |
|
|
be the last page in the file. */
|
| 275 |
|
|
memset(stream.next_out, 0, stream.avail_out);
|
| 276 |
|
|
stream.avail_out = 0;
|
| 277 |
|
|
}
|
| 278 |
|
|
|
| 279 |
|
|
if ( !stream.avail_out ) {
|
| 280 |
|
|
/* This page completed */
|
| 281 |
|
|
if ( page ) {
|
| 282 |
|
|
flush_dcache_page(page);
|
| 283 |
|
|
SetPageUptodate(page);
|
| 284 |
|
|
kunmap(page);
|
| 285 |
|
|
UnlockPage(page);
|
| 286 |
|
|
if ( fpage == xpage )
|
| 287 |
|
|
err = 0; /* The critical page */
|
| 288 |
|
|
else
|
| 289 |
|
|
page_cache_release(page);
|
| 290 |
|
|
}
|
| 291 |
|
|
fpage++;
|
| 292 |
|
|
}
|
| 293 |
|
|
}
|
| 294 |
|
|
zlib_inflateEnd(&stream);
|
| 295 |
|
|
|
| 296 |
|
|
z_eio:
|
| 297 |
|
|
up(&zisofs_zlib_semaphore);
|
| 298 |
|
|
|
| 299 |
|
|
b_eio:
|
| 300 |
|
|
for ( i = 0 ; i < haveblocks ; i++ ) {
|
| 301 |
|
|
if ( bhs[i] )
|
| 302 |
|
|
brelse(bhs[i]);
|
| 303 |
|
|
}
|
| 304 |
|
|
}
|
| 305 |
|
|
|
| 306 |
|
|
eio:
|
| 307 |
|
|
|
| 308 |
|
|
/* Release any residual pages, do not SetPageUptodate */
|
| 309 |
|
|
while ( fpage < maxpage ) {
|
| 310 |
|
|
page = pages[fpage];
|
| 311 |
|
|
if ( page ) {
|
| 312 |
|
|
flush_dcache_page(page);
|
| 313 |
|
|
if ( fpage == xpage )
|
| 314 |
|
|
SetPageError(page);
|
| 315 |
|
|
kunmap(page);
|
| 316 |
|
|
UnlockPage(page);
|
| 317 |
|
|
if ( fpage != xpage )
|
| 318 |
|
|
page_cache_release(page);
|
| 319 |
|
|
}
|
| 320 |
|
|
fpage++;
|
| 321 |
|
|
}
|
| 322 |
|
|
|
| 323 |
|
|
/* At this point, err contains 0 or -EIO depending on the "critical" page */
|
| 324 |
|
|
return err;
|
| 325 |
|
|
}
|
| 326 |
|
|
|
| 327 |
|
|
struct address_space_operations zisofs_aops = {
|
| 328 |
|
|
readpage: zisofs_readpage,
|
| 329 |
|
|
/* No sync_page operation supported? */
|
| 330 |
|
|
/* No bmap operation supported */
|
| 331 |
|
|
};
|
| 332 |
|
|
|
| 333 |
|
|
static int initialized = 0;
|
| 334 |
|
|
|
| 335 |
|
|
int __init zisofs_init(void)
|
| 336 |
|
|
{
|
| 337 |
|
|
if ( initialized ) {
|
| 338 |
|
|
printk("zisofs_init: called more than once\n");
|
| 339 |
|
|
return 0;
|
| 340 |
|
|
}
|
| 341 |
|
|
|
| 342 |
|
|
zisofs_zlib_workspace = vmalloc(zlib_inflate_workspacesize());
|
| 343 |
|
|
if ( !zisofs_zlib_workspace )
|
| 344 |
|
|
return -ENOMEM;
|
| 345 |
|
|
init_MUTEX(&zisofs_zlib_semaphore);
|
| 346 |
|
|
|
| 347 |
|
|
initialized = 1;
|
| 348 |
|
|
return 0;
|
| 349 |
|
|
}
|
| 350 |
|
|
|
| 351 |
|
|
void __exit zisofs_cleanup(void)
|
| 352 |
|
|
{
|
| 353 |
|
|
if ( !initialized ) {
|
| 354 |
|
|
printk("zisofs_cleanup: called without initialization\n");
|
| 355 |
|
|
return;
|
| 356 |
|
|
}
|
| 357 |
|
|
|
| 358 |
|
|
vfree(zisofs_zlib_workspace);
|
| 359 |
|
|
initialized = 0;
|
| 360 |
|
|
}
|
