patch-2.4.14 linux/fs/isofs/compress.c

• Lines: 364
• Date: Thu Oct 25 13:53:53 2001
• Orig file: v2.4.13/linux/fs/isofs/compress.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.13/linux/fs/isofs/compress.c linux/fs/isofs/compress.c
@@ -0,0 +1,363 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *   
+ *   Copyright 2001 H. Peter Anvin - 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 as published by
+ *   the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
+ *   USA; either version 2 of the License, or (at your option) any later
+ *   version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * linux/fs/isofs/compress.c
+ *
+ * Transparent decompression of files on an iso9660 filesystem
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+
+#include <linux/stat.h>
+#include <linux/sched.h>
+#include <linux/iso_fs.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/locks.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/cdrom.h>
+#include <linux/init.h>
+#include <linux/nls.h>
+#include <linux/ctype.h>
+#include <linux/smp_lock.h>
+#include <linux/blkdev.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib_fs.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include "zisofs.h"
+
+#define min(a,b)	((a)<(b)?(a):(b))
+#define max(a,b)	((a)>(b)?(a):(b))
+
+/* This should probably be global. */
+static char zisofs_sink_page[PAGE_CACHE_SIZE];
+
+/*
+ * This contains the zlib memory allocation and the mutex for the
+ * allocation; this avoids failures at block-decompression time.
+ */
+static void *zisofs_zlib_workspace;
+static struct semaphore zisofs_zlib_semaphore;
+
+/*
+ * When decompressing, we typically obtain more than one page
+ * per reference.  We inject the additional pages into the page
+ * cache as a form of readahead.
+ */
+static int zisofs_readpage(struct file *file, struct page *page)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct address_space *mapping = inode->i_mapping;
+	unsigned int maxpage, xpage, fpage, blockindex;
+	unsigned long offset;
+	unsigned long blockptr, blockendptr, cstart, cend, csize;
+	struct buffer_head *bh, *ptrbh[2];
+	unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
+	unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
+	unsigned long bufmask  = bufsize - 1;
+	int err = -EIO;
+	int i;
+	unsigned int header_size = inode->u.isofs_i.i_format_parm[0];
+	unsigned int zisofs_block_shift = inode->u.isofs_i.i_format_parm[1];
+	/* unsigned long zisofs_block_size = 1UL << zisofs_block_shift; */
+	unsigned int zisofs_block_page_shift = zisofs_block_shift-PAGE_CACHE_SHIFT;
+	unsigned long zisofs_block_pages = 1UL << zisofs_block_page_shift;
+	unsigned long zisofs_block_page_mask = zisofs_block_pages-1;
+	struct page *pages[zisofs_block_pages];
+	unsigned long index = page->index;
+	int indexblocks;
+
+	/* We have already been given one page, this is the one
+	   we must do. */
+	xpage = index & zisofs_block_page_mask;
+	pages[xpage] = page;
+ 
+	/* The remaining pages need to be allocated and inserted */
+	offset = index & ~zisofs_block_page_mask;
+	blockindex = offset >> zisofs_block_page_shift;
+	maxpage = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+	maxpage = min(zisofs_block_pages, maxpage-offset);
+
+	for ( i = 0 ; i < maxpage ; i++, offset++ ) {
+		if ( i != xpage ) {
+			pages[i] = grab_cache_page_nowait(mapping, offset);
+		}
+		page = pages[i];
+		if ( page ) {
+			ClearPageError(page);
+			kmap(page);
+		}
+	}
+
+	/* This is the last page filled, plus one; used in case of abort. */
+	fpage = 0;
+
+	/* Find the pointer to this specific chunk */
+	/* Note: we're not using isonum_731() here because the data is known aligned */
+	/* Note: header_size is in 32-bit words (4 bytes) */
+	blockptr = (header_size + blockindex) << 2;
+	blockendptr = blockptr + 4;
+
+	indexblocks = ((blockptr^blockendptr) >> bufshift) ? 2 : 1;
+	ptrbh[0] = ptrbh[1] = 0;
+
+	if ( isofs_get_blocks(inode, blockptr >> bufshift, ptrbh, indexblocks) != indexblocks ) {
+		if ( ptrbh[0] ) brelse(ptrbh[0]);
+		printk(KERN_DEBUG "zisofs: Null buffer on reading block table, inode = %lu, block = %lu\n",
+		       inode->i_ino, blockptr >> bufshift);
+		goto eio;
+	}
+	ll_rw_block(READ, indexblocks, ptrbh);
+
+	bh = ptrbh[0];
+	if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
+		printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
+		       inode->i_ino, blockptr >> bufshift);
+		if ( ptrbh[1] )
+			brelse(ptrbh[1]);
+		goto eio;
+	}
+	cstart = le32_to_cpu(*(u32 *)(bh->b_data + (blockptr & bufmask)));
+
+	if ( indexblocks == 2 ) {
+		/* We just crossed a block boundary.  Switch to the next block */
+		brelse(bh);
+		bh = ptrbh[1];
+		if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
+			printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
+			       inode->i_ino, blockendptr >> bufshift);
+			goto eio;
+		}
+	}
+	cend = le32_to_cpu(*(u32 *)(bh->b_data + (blockendptr & bufmask)));
+	brelse(bh);
+
+	csize = cend-cstart;
+
+	/* Now page[] contains an array of pages, any of which can be NULL,
+	   and the locks on which we hold.  We should now read the data and
+	   release the pages.  If the pages are NULL the decompressed data
+	   for that particular page should be discarded. */
+	
+	if ( csize == 0 ) {
+		/* This data block is empty. */
+
+		for ( fpage = 0 ; fpage < maxpage ; fpage++ ) {
+			if ( (page = pages[fpage]) != NULL ) {
+				memset(page_address(page), 0, PAGE_CACHE_SIZE);
+				
+				flush_dcache_page(page);
+				SetPageUptodate(page);
+				kunmap(page);
+				UnlockPage(page);
+				if ( fpage == xpage )
+					err = 0; /* The critical page */
+				else
+					page_cache_release(page);
+			}
+		}
+	} else {
+		/* This data block is compressed. */
+		z_stream stream;
+		int bail = 0, left_out = -1;
+		int zerr;
+		int needblocks = (csize + (cstart & bufmask) + bufmask) >> bufshift;
+		int haveblocks;
+		struct buffer_head *bhs[needblocks+1];
+		struct buffer_head **bhptr;
+
+		/* Because zlib is not thread-safe, do all the I/O at the top. */
+
+		blockptr = cstart >> bufshift;
+		memset(bhs, 0, (needblocks+1)*sizeof(struct buffer_head *));
+		haveblocks = isofs_get_blocks(inode, blockptr, bhs, needblocks);
+		ll_rw_block(READ, haveblocks, bhs);
+
+		bhptr = &bhs[0];
+		bh = *bhptr++;
+
+		/* First block is special since it may be fractional.
+		   We also wait for it before grabbing the zlib
+		   semaphore; odds are that the subsequent blocks are
+		   going to come in in short order so we don't hold
+		   the zlib semaphore longer than necessary. */
+
+		if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
+			printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
+			       fpage, xpage, csize);
+			goto b_eio;
+		}
+		stream.next_in  = bh->b_data + (cstart & bufmask);
+		stream.avail_in = min(bufsize-(cstart & bufmask), csize);
+		csize -= stream.avail_in;
+
+		stream.workspace = zisofs_zlib_workspace;
+		down(&zisofs_zlib_semaphore);
+		
+		zerr = zlib_fs_inflateInit(&stream);
+		if ( zerr != Z_OK ) {
+			if ( err && zerr == Z_MEM_ERROR )
+				err = -ENOMEM;
+			printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
+			       zerr);
+			goto z_eio;
+		}
+
+		while ( !bail && fpage < maxpage ) {
+			page = pages[fpage];
+			if ( page )
+				stream.next_out = page_address(page);
+			else
+				stream.next_out = (void *)&zisofs_sink_page;
+			stream.avail_out = PAGE_CACHE_SIZE;
+
+			while ( stream.avail_out ) {
+				int ao, ai;
+				if ( stream.avail_in == 0 && left_out ) {
+					if ( !csize ) {
+						printk(KERN_WARNING "zisofs: ZF read beyond end of input\n");
+						bail = 1;
+						break;
+					} else {
+						bh = *bhptr++;
+						if ( !bh ||
+						     (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
+							/* Reached an EIO */
+ 							printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
+							       fpage, xpage, csize);
+							       
+							bail = 1;
+							break;
+						}
+						stream.next_in = bh->b_data;
+						stream.avail_in = min(csize,bufsize);
+						csize -= stream.avail_in;
+					}
+				}
+				ao = stream.avail_out;  ai = stream.avail_in;
+				zerr = zlib_fs_inflate(&stream, Z_SYNC_FLUSH);
+				left_out = stream.avail_out;
+				if ( zerr == Z_BUF_ERROR && stream.avail_in == 0 )
+					continue;
+				if ( zerr != Z_OK ) {
+					/* EOF, error, or trying to read beyond end of input */
+					if ( err && zerr == Z_MEM_ERROR )
+						err = -ENOMEM;
+					if ( zerr != Z_STREAM_END )
+						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",
+						       zerr, inode->i_ino, index,
+						       fpage, xpage,
+						       stream.avail_in, stream.avail_out,
+						       ai, ao);
+					bail = 1;
+					break;
+				}
+			}
+
+			if ( stream.avail_out && zerr == Z_STREAM_END ) {
+				/* Fractional page written before EOF.  This may
+				   be the last page in the file. */
+				memset(stream.next_out, 0, stream.avail_out);
+				stream.avail_out = 0;
+			}
+
+			if ( !stream.avail_out ) {
+				/* This page completed */
+				if ( page ) {
+					flush_dcache_page(page);
+					SetPageUptodate(page);
+					kunmap(page);
+					UnlockPage(page);
+					if ( fpage == xpage )
+						err = 0; /* The critical page */
+					else
+						page_cache_release(page);
+				}
+				fpage++;
+			}
+		}
+		zlib_fs_inflateEnd(&stream);
+
+	z_eio:
+		up(&zisofs_zlib_semaphore);
+
+	b_eio:
+		for ( i = 0 ; i < haveblocks ; i++ ) {
+			if ( bhs[i] )
+				brelse(bhs[i]);
+		}
+	}
+
+eio:
+
+	/* Release any residual pages, do not SetPageUptodate */
+	while ( fpage < maxpage ) {
+		page = pages[fpage];
+		if ( page ) {
+			flush_dcache_page(page);
+			if ( fpage == xpage )
+				SetPageError(page);
+			kunmap(page);
+			UnlockPage(page);
+			if ( fpage != xpage )
+				page_cache_release(page);
+		}
+		fpage++;
+	}			
+
+	/* At this point, err contains 0 or -EIO depending on the "critical" page */
+	return err;
+}
+
+struct address_space_operations zisofs_aops = {
+	readpage: zisofs_readpage,
+	/* No sync_page operation supported? */
+	/* No bmap operation supported */
+};
+
+static int initialized = 0;
+
+int __init zisofs_init(void)
+{
+	if ( initialized ) {
+		printk("zisofs_init: called more than once\n");
+		return 0;
+	}
+
+	zisofs_zlib_workspace = vmalloc(zlib_fs_inflate_workspacesize());
+	if ( !zisofs_zlib_workspace )
+		return -ENOMEM;
+	init_MUTEX(&zisofs_zlib_semaphore);
+
+	initialized = 1;
+	return 0;
+}
+
+void __exit zisofs_cleanup(void)
+{
+	if ( !initialized ) {
+		printk("zisofs_cleanup: called without initialization\n");
+		return;
+	}
+
+	vfree(zisofs_zlib_workspace);
+	initialized = 0;
+}