--- /dev/null
+/* -*- 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/module.h>
+#include <linux/init.h>
+
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+
+#include "isofs.h"
+#include "zisofs.h"
+
+/* 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 DEFINE_MUTEX(zisofs_zlib_lock);
+
+/*
+ * Read data of @inode from @block_start to @block_end and uncompress
+ * to one zisofs block. Store the data in the @pages array with @pcount
+ * entries. Start storing at offset @poffset of the first page.
+ */
+static loff_t zisofs_uncompress_block(struct inode *inode, loff_t block_start,
+ loff_t block_end, int pcount,
+ struct page **pages, unsigned poffset,
+ int *errp)
+{
+ unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
+ unsigned int bufsize = ISOFS_BUFFER_SIZE(inode);
+ unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
+ unsigned int bufmask = bufsize - 1;
+ int i, block_size = block_end - block_start;
+ z_stream stream = { .total_out = 0,
+ .avail_in = 0,
+ .avail_out = 0, };
+ int zerr;
+ int needblocks = (block_size + (block_start & bufmask) + bufmask)
+ >> bufshift;
+ int haveblocks;
+ blkcnt_t blocknum;
+ struct buffer_head *bhs[needblocks + 1];
+ int curbh, curpage;
+
+ if (block_size > deflateBound(1UL << zisofs_block_shift)) {
+ *errp = -EIO;
+ return 0;
+ }
+ /* Empty block? */
+ if (block_size == 0) {
+ for ( i = 0 ; i < pcount ; i++ ) {
+ if (!pages[i])
+ continue;
+ memset(page_address(pages[i]), 0, PAGE_CACHE_SIZE);
+ flush_dcache_page(pages[i]);
+ SetPageUptodate(pages[i]);
+ }
+ return ((loff_t)pcount) << PAGE_CACHE_SHIFT;
+ }
+
+ /* Because zlib is not thread-safe, do all the I/O at the top. */
+ blocknum = block_start >> bufshift;
+ memset(bhs, 0, (needblocks + 1) * sizeof(struct buffer_head *));
+ haveblocks = isofs_get_blocks(inode, blocknum, bhs, needblocks);
+ ll_rw_block(READ, haveblocks, bhs);
+
+ curbh = 0;
+ curpage = 0;
+ /*
+ * First block is special since it may be fractional. We also wait for
+ * it before grabbing the zlib mutex; odds are that the subsequent
+ * blocks are going to come in in short order so we don't hold the zlib
+ * mutex longer than necessary.
+ */
+
+ if (!bhs[0])
+ goto b_eio;
+
+ wait_on_buffer(bhs[0]);
+ if (!buffer_uptodate(bhs[0])) {
+ *errp = -EIO;
+ goto b_eio;
+ }
+
+ stream.workspace = zisofs_zlib_workspace;
+ mutex_lock(&zisofs_zlib_lock);
+
+ zerr = zlib_inflateInit(&stream);
+ if (zerr != Z_OK) {
+ if (zerr == Z_MEM_ERROR)
+ *errp = -ENOMEM;
+ else
+ *errp = -EIO;
+ printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
+ zerr);
+ goto z_eio;
+ }
+
+ while (curpage < pcount && curbh < haveblocks &&
+ zerr != Z_STREAM_END) {
+ if (!stream.avail_out) {
+ if (pages[curpage]) {
+ stream.next_out = page_address(pages[curpage])
+ + poffset;
+ stream.avail_out = PAGE_CACHE_SIZE - poffset;
+ poffset = 0;
+ } else {
+ stream.next_out = (void *)&zisofs_sink_page;
+ stream.avail_out = PAGE_CACHE_SIZE;
+ }
+ }
+ if (!stream.avail_in) {
+ wait_on_buffer(bhs[curbh]);
+ if (!buffer_uptodate(bhs[curbh])) {
+ *errp = -EIO;
+ break;
+ }
+ stream.next_in = bhs[curbh]->b_data +
+ (block_start & bufmask);
+ stream.avail_in = min_t(unsigned, bufsize -
+ (block_start & bufmask),
+ block_size);
+ block_size -= stream.avail_in;
+ block_start = 0;
+ }
+
+ while (stream.avail_out && stream.avail_in) {
+ zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
+ if (zerr == Z_BUF_ERROR && stream.avail_in == 0)
+ break;
+ if (zerr == Z_STREAM_END)
+ break;
+ if (zerr != Z_OK) {
+ /* EOF, error, or trying to read beyond end of input */
+ if (zerr == Z_MEM_ERROR)
+ *errp = -ENOMEM;
+ else {
+ printk(KERN_DEBUG
+ "zisofs: zisofs_inflate returned"
+ " %d, inode = %lu,"
+ " page idx = %d, bh idx = %d,"
+ " avail_in = %ld,"
+ " avail_out = %ld\n",
+ zerr, inode->i_ino, curpage,
+ curbh, stream.avail_in,
+ stream.avail_out);
+ *errp = -EIO;
+ }
+ goto inflate_out;
+ }
+ }
+
+ if (!stream.avail_out) {
+ /* This page completed */
+ if (pages[curpage]) {
+ flush_dcache_page(pages[curpage]);
+ SetPageUptodate(pages[curpage]);
+ }
+ curpage++;
+ }
+ if (!stream.avail_in)
+ curbh++;
+ }
+inflate_out:
+ zlib_inflateEnd(&stream);
+
+z_eio:
+ mutex_unlock(&zisofs_zlib_lock);
+
+b_eio:
+ for (i = 0; i < haveblocks; i++)
+ brelse(bhs[i]);
+ return stream.total_out;
+}
+
+/*
+ * Uncompress data so that pages[full_page] is fully uptodate and possibly
+ * fills in other pages if we have data for them.
+ */
+static int zisofs_fill_pages(struct inode *inode, int full_page, int pcount,
+ struct page **pages)
+{
+ loff_t start_off, end_off;
+ loff_t block_start, block_end;
+ unsigned int header_size = ISOFS_I(inode)->i_format_parm[0];
+ unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
+ unsigned int blockptr;
+ loff_t poffset = 0;
+ blkcnt_t cstart_block, cend_block;
+ struct buffer_head *bh;
+ unsigned int blkbits = ISOFS_BUFFER_BITS(inode);
+ unsigned int blksize = 1 << blkbits;
+ int err;
+ loff_t ret;
+
+ BUG_ON(!pages[full_page]);
+
+ /*
+ * We want to read at least 'full_page' page. Because we have to
+ * uncompress the whole compression block anyway, fill the surrounding
+ * pages with the data we have anyway...
+ */
+ start_off = page_offset(pages[full_page]);
+ end_off = min_t(loff_t, start_off + PAGE_CACHE_SIZE, inode->i_size);
+
+ cstart_block = start_off >> zisofs_block_shift;
+ cend_block = (end_off + (1 << zisofs_block_shift) - 1)
+ >> zisofs_block_shift;
+
+ WARN_ON(start_off - (full_page << PAGE_CACHE_SHIFT) !=
+ ((cstart_block << zisofs_block_shift) & PAGE_CACHE_MASK));
+
+ /* 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 + cstart_block) << 2;
+ bh = isofs_bread(inode, blockptr >> blkbits);
+ if (!bh)
+ return -EIO;
+ block_start = le32_to_cpu(*(__le32 *)
+ (bh->b_data + (blockptr & (blksize - 1))));
+
+ while (cstart_block < cend_block && pcount > 0) {
+ /* Load end of the compressed block in the file */
+ blockptr += 4;
+ /* Traversed to next block? */
+ if (!(blockptr & (blksize - 1))) {
+ brelse(bh);
+
+ bh = isofs_bread(inode, blockptr >> blkbits);
+ if (!bh)
+ return -EIO;
+ }
+ block_end = le32_to_cpu(*(__le32 *)
+ (bh->b_data + (blockptr & (blksize - 1))));
+ if (block_start > block_end) {
+ brelse(bh);
+ return -EIO;
+ }
+ err = 0;
+ ret = zisofs_uncompress_block(inode, block_start, block_end,
+ pcount, pages, poffset, &err);
+ poffset += ret;
+ pages += poffset >> PAGE_CACHE_SHIFT;
+ pcount -= poffset >> PAGE_CACHE_SHIFT;
+ full_page -= poffset >> PAGE_CACHE_SHIFT;
+ poffset &= ~PAGE_CACHE_MASK;
+
+ if (err) {
+ brelse(bh);
+ /*
+ * Did we finish reading the page we really wanted
+ * to read?
+ */
+ if (full_page < 0)
+ return 0;
+ return err;
+ }
+
+ block_start = block_end;
+ cstart_block++;
+ }
+
+ if (poffset && *pages) {
+ memset(page_address(*pages) + poffset, 0,
+ PAGE_CACHE_SIZE - poffset);
+ flush_dcache_page(*pages);
+ SetPageUptodate(*pages);
+ }
+ return 0;
+}
+
+/*
+ * 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_inode(file);
+ struct address_space *mapping = inode->i_mapping;
+ int err;
+ int i, pcount, full_page;
+ unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
+ unsigned int zisofs_pages_per_cblock =
+ PAGE_CACHE_SHIFT <= zisofs_block_shift ?
+ (1 << (zisofs_block_shift - PAGE_CACHE_SHIFT)) : 0;
+ struct page *pages[max_t(unsigned, zisofs_pages_per_cblock, 1)];
+ pgoff_t index = page->index, end_index;
+
+ end_index = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ /*
+ * If this page is wholly outside i_size we just return zero;
+ * do_generic_file_read() will handle this for us
+ */
+ if (index >= end_index) {
+ SetPageUptodate(page);
+ unlock_page(page);
+ return 0;
+ }
+
+ if (PAGE_CACHE_SHIFT <= zisofs_block_shift) {
+ /* We have already been given one page, this is the one
+ we must do. */
+ full_page = index & (zisofs_pages_per_cblock - 1);
+ pcount = min_t(int, zisofs_pages_per_cblock,
+ end_index - (index & ~(zisofs_pages_per_cblock - 1)));
+ index -= full_page;
+ } else {
+ full_page = 0;
+ pcount = 1;
+ }
+ pages[full_page] = page;
+
+ for (i = 0; i < pcount; i++, index++) {
+ if (i != full_page)
+ pages[i] = grab_cache_page_nowait(mapping, index);
+ if (pages[i]) {
+ ClearPageError(pages[i]);
+ kmap(pages[i]);
+ }
+ }
+
+ err = zisofs_fill_pages(inode, full_page, pcount, pages);
+
+ /* Release any residual pages, do not SetPageUptodate */
+ for (i = 0; i < pcount; i++) {
+ if (pages[i]) {
+ flush_dcache_page(pages[i]);
+ if (i == full_page && err)
+ SetPageError(pages[i]);
+ kunmap(pages[i]);
+ unlock_page(pages[i]);
+ if (i != full_page)
+ page_cache_release(pages[i]);
+ }
+ }
+
+ /* At this point, err contains 0 or -EIO depending on the "critical" page */
+ return err;
+}
+
+const struct address_space_operations zisofs_aops = {
+ .readpage = zisofs_readpage,
+ /* No sync_page operation supported? */
+ /* No bmap operation supported */
+};
+
+int __init zisofs_init(void)
+{
+ zisofs_zlib_workspace = vmalloc(zlib_inflate_workspacesize());
+ if ( !zisofs_zlib_workspace )
+ return -ENOMEM;
+
+ return 0;
+}
+
+void zisofs_cleanup(void)
+{
+ vfree(zisofs_zlib_workspace);
+}
Code Review / kvmfornfv.git / blobdiff