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![Dave Young](/assets/img/avatar_default.png)
A read request outside i_size will be handled in do_generic_file_read(). So we just return 0 to avoid getting -EIO as normal reading, let do_generic_file_read do the rest. At the same time we need unlock the page to avoid system stuck. Fixes http://bugzilla.kernel.org/show_bug.cgi?id=10227 Signed-off-by: Dave Young <hidave.darkstar@gmail.com> Acked-by: Jan Kara <jack@suse.cz> Report-by: Christian Perle <chris@linuxinfotag.de> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
343 lines
9.8 KiB
C
343 lines
9.8 KiB
C
/* -*- 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/module.h>
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#include <linux/init.h>
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#include <linux/vmalloc.h>
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#include <linux/zlib.h>
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#include "isofs.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 DEFINE_MUTEX(zisofs_zlib_lock);
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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_path.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 = ISOFS_I(inode)->i_format_parm[0];
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unsigned int zisofs_block_shift = ISOFS_I(inode)->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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/* We have already been given one page, this is the one
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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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/* 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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/*
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* If this page is wholly outside i_size we just return zero;
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* do_generic_file_read() will handle this for us
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*/
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if (page->index >= maxpage) {
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SetPageUptodate(page);
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unlock_page(page);
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return 0;
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}
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maxpage = min(zisofs_block_pages, maxpage-offset);
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for ( i = 0 ; i < maxpage ; i++, offset++ ) {
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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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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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/* This is the last page filled, plus one; used in case of abort. */
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fpage = 0;
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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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indexblocks = ((blockptr^blockendptr) >> bufshift) ? 2 : 1;
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ptrbh[0] = ptrbh[1] = NULL;
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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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}
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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(*(__le32 *)(bh->b_data + (blockptr & bufmask)));
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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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}
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}
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cend = le32_to_cpu(*(__le32 *)(bh->b_data + (blockendptr & bufmask)));
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brelse(bh);
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if (cstart > cend)
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goto eio;
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csize = cend-cstart;
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if (csize > deflateBound(1UL << zisofs_block_shift))
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goto eio;
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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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if ( csize == 0 ) {
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/* This data block is empty. */
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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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unlock_page(page);
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if ( fpage == xpage )
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err = 0; /* The critical page */
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else
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page_cache_release(page);
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}
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}
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} else {
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/* This data block is compressed. */
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z_stream stream;
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int bail = 0, left_out = -1;
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int zerr;
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int needblocks = (csize + (cstart & bufmask) + bufmask) >> bufshift;
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int haveblocks;
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struct buffer_head *bhs[needblocks+1];
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struct buffer_head **bhptr;
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/* Because zlib is not thread-safe, do all the I/O at the top. */
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blockptr = cstart >> bufshift;
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memset(bhs, 0, (needblocks+1)*sizeof(struct buffer_head *));
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haveblocks = isofs_get_blocks(inode, blockptr, bhs, needblocks);
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ll_rw_block(READ, haveblocks, bhs);
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bhptr = &bhs[0];
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bh = *bhptr++;
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/* First block is special since it may be fractional.
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We also wait for it before grabbing the zlib
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mutex; odds are that the subsequent blocks are
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going to come in in short order so we don't hold
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the zlib mutex longer than necessary. */
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if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
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printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
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fpage, xpage, csize);
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goto b_eio;
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}
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stream.next_in = bh->b_data + (cstart & bufmask);
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stream.avail_in = min(bufsize-(cstart & bufmask), csize);
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csize -= stream.avail_in;
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stream.workspace = zisofs_zlib_workspace;
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mutex_lock(&zisofs_zlib_lock);
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zerr = zlib_inflateInit(&stream);
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if ( zerr != Z_OK ) {
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if ( err && zerr == Z_MEM_ERROR )
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err = -ENOMEM;
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printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
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zerr);
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goto z_eio;
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}
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while ( !bail && fpage < maxpage ) {
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page = pages[fpage];
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if ( page )
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stream.next_out = page_address(page);
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else
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stream.next_out = (void *)&zisofs_sink_page;
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stream.avail_out = PAGE_CACHE_SIZE;
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while ( stream.avail_out ) {
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int ao, ai;
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if ( stream.avail_in == 0 && left_out ) {
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if ( !csize ) {
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printk(KERN_WARNING "zisofs: ZF read beyond end of input\n");
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bail = 1;
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break;
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} else {
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bh = *bhptr++;
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if ( !bh ||
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(wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
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/* Reached an EIO */
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printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
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fpage, xpage, csize);
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bail = 1;
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break;
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}
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stream.next_in = bh->b_data;
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stream.avail_in = min(csize,bufsize);
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csize -= stream.avail_in;
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}
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}
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ao = stream.avail_out; ai = stream.avail_in;
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zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
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left_out = stream.avail_out;
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if ( zerr == Z_BUF_ERROR && stream.avail_in == 0 )
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continue;
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if ( zerr != Z_OK ) {
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/* EOF, error, or trying to read beyond end of input */
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if ( err && zerr == Z_MEM_ERROR )
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err = -ENOMEM;
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if ( zerr != Z_STREAM_END )
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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",
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zerr, inode->i_ino, index,
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fpage, xpage,
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stream.avail_in, stream.avail_out,
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ai, ao);
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bail = 1;
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break;
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}
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}
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if ( stream.avail_out && zerr == Z_STREAM_END ) {
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/* Fractional page written before EOF. This may
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be the last page in the file. */
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memset(stream.next_out, 0, stream.avail_out);
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stream.avail_out = 0;
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}
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if ( !stream.avail_out ) {
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/* This page completed */
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if ( page ) {
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flush_dcache_page(page);
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SetPageUptodate(page);
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kunmap(page);
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unlock_page(page);
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if ( fpage == xpage )
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err = 0; /* The critical page */
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else
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page_cache_release(page);
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}
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fpage++;
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}
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}
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zlib_inflateEnd(&stream);
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z_eio:
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mutex_unlock(&zisofs_zlib_lock);
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b_eio:
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for ( i = 0 ; i < haveblocks ; i++ ) {
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if ( bhs[i] )
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brelse(bhs[i]);
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}
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}
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eio:
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/* Release any residual pages, do not SetPageUptodate */
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while ( fpage < maxpage ) {
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page = pages[fpage];
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if ( page ) {
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flush_dcache_page(page);
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if ( fpage == xpage )
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SetPageError(page);
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kunmap(page);
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unlock_page(page);
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if ( fpage != xpage )
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page_cache_release(page);
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}
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fpage++;
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}
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/* At this point, err contains 0 or -EIO depending on the "critical" page */
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return err;
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}
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const struct address_space_operations zisofs_aops = {
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.readpage = zisofs_readpage,
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/* No sync_page operation supported? */
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/* No bmap operation supported */
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};
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int __init zisofs_init(void)
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{
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zisofs_zlib_workspace = vmalloc(zlib_inflate_workspacesize());
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if ( !zisofs_zlib_workspace )
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return -ENOMEM;
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return 0;
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}
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void zisofs_cleanup(void)
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{
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vfree(zisofs_zlib_workspace);
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}
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