blob: defb932eee9a9f45836ac2f62ee9dcf5f3838152 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright 2001 H. Peter Anvin - All Rights Reserved
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
8 * USA; either version 2 of the License, or (at your option) any later
9 * version; incorporated herein by reference.
10 *
11 * ----------------------------------------------------------------------- */
12
13/*
14 * linux/fs/isofs/compress.c
15 *
16 * Transparent decompression of files on an iso9660 filesystem
17 */
18
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/init.h>
Al Viro94f2f712005-04-25 18:32:12 -070021
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/vmalloc.h>
23#include <linux/zlib.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
Al Viro94f2f712005-04-25 18:32:12 -070025#include "isofs.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include "zisofs.h"
27
28/* This should probably be global. */
29static char zisofs_sink_page[PAGE_CACHE_SIZE];
30
31/*
32 * This contains the zlib memory allocation and the mutex for the
33 * allocation; this avoids failures at block-decompression time.
34 */
35static void *zisofs_zlib_workspace;
Dave Younga36a1512007-10-16 23:26:10 -070036static DEFINE_MUTEX(zisofs_zlib_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38/*
39 * When decompressing, we typically obtain more than one page
40 * per reference. We inject the additional pages into the page
41 * cache as a form of readahead.
42 */
43static int zisofs_readpage(struct file *file, struct page *page)
44{
Josef "Jeff" Sipek24858222006-12-08 02:36:40 -080045 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 struct address_space *mapping = inode->i_mapping;
47 unsigned int maxpage, xpage, fpage, blockindex;
48 unsigned long offset;
49 unsigned long blockptr, blockendptr, cstart, cend, csize;
50 struct buffer_head *bh, *ptrbh[2];
51 unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
52 unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
53 unsigned long bufmask = bufsize - 1;
54 int err = -EIO;
55 int i;
56 unsigned int header_size = ISOFS_I(inode)->i_format_parm[0];
57 unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
58 /* unsigned long zisofs_block_size = 1UL << zisofs_block_shift; */
59 unsigned int zisofs_block_page_shift = zisofs_block_shift-PAGE_CACHE_SHIFT;
60 unsigned long zisofs_block_pages = 1UL << zisofs_block_page_shift;
61 unsigned long zisofs_block_page_mask = zisofs_block_pages-1;
62 struct page *pages[zisofs_block_pages];
63 unsigned long index = page->index;
64 int indexblocks;
65
66 /* We have already been given one page, this is the one
67 we must do. */
68 xpage = index & zisofs_block_page_mask;
69 pages[xpage] = page;
70
71 /* The remaining pages need to be allocated and inserted */
72 offset = index & ~zisofs_block_page_mask;
73 blockindex = offset >> zisofs_block_page_shift;
74 maxpage = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Dave Young08ca0db2008-03-19 17:01:01 -070075
76 /*
77 * If this page is wholly outside i_size we just return zero;
78 * do_generic_file_read() will handle this for us
79 */
80 if (page->index >= maxpage) {
81 SetPageUptodate(page);
82 unlock_page(page);
83 return 0;
84 }
85
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 maxpage = min(zisofs_block_pages, maxpage-offset);
87
88 for ( i = 0 ; i < maxpage ; i++, offset++ ) {
89 if ( i != xpage ) {
90 pages[i] = grab_cache_page_nowait(mapping, offset);
91 }
92 page = pages[i];
93 if ( page ) {
94 ClearPageError(page);
95 kmap(page);
96 }
97 }
98
99 /* This is the last page filled, plus one; used in case of abort. */
100 fpage = 0;
101
102 /* Find the pointer to this specific chunk */
103 /* Note: we're not using isonum_731() here because the data is known aligned */
104 /* Note: header_size is in 32-bit words (4 bytes) */
105 blockptr = (header_size + blockindex) << 2;
106 blockendptr = blockptr + 4;
107
108 indexblocks = ((blockptr^blockendptr) >> bufshift) ? 2 : 1;
109 ptrbh[0] = ptrbh[1] = NULL;
110
111 if ( isofs_get_blocks(inode, blockptr >> bufshift, ptrbh, indexblocks) != indexblocks ) {
112 if ( ptrbh[0] ) brelse(ptrbh[0]);
113 printk(KERN_DEBUG "zisofs: Null buffer on reading block table, inode = %lu, block = %lu\n",
114 inode->i_ino, blockptr >> bufshift);
115 goto eio;
116 }
117 ll_rw_block(READ, indexblocks, ptrbh);
118
119 bh = ptrbh[0];
120 if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
121 printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
122 inode->i_ino, blockptr >> bufshift);
123 if ( ptrbh[1] )
124 brelse(ptrbh[1]);
125 goto eio;
126 }
127 cstart = le32_to_cpu(*(__le32 *)(bh->b_data + (blockptr & bufmask)));
128
129 if ( indexblocks == 2 ) {
130 /* We just crossed a block boundary. Switch to the next block */
131 brelse(bh);
132 bh = ptrbh[1];
133 if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
134 printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
135 inode->i_ino, blockendptr >> bufshift);
136 goto eio;
137 }
138 }
139 cend = le32_to_cpu(*(__le32 *)(bh->b_data + (blockendptr & bufmask)));
140 brelse(bh);
141
Linus Torvaldsfab5a602005-08-06 09:42:06 -0700142 if (cstart > cend)
143 goto eio;
144
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 csize = cend-cstart;
146
Linus Torvaldsfab5a602005-08-06 09:42:06 -0700147 if (csize > deflateBound(1UL << zisofs_block_shift))
148 goto eio;
149
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 /* Now page[] contains an array of pages, any of which can be NULL,
151 and the locks on which we hold. We should now read the data and
152 release the pages. If the pages are NULL the decompressed data
153 for that particular page should be discarded. */
154
155 if ( csize == 0 ) {
156 /* This data block is empty. */
157
158 for ( fpage = 0 ; fpage < maxpage ; fpage++ ) {
159 if ( (page = pages[fpage]) != NULL ) {
160 memset(page_address(page), 0, PAGE_CACHE_SIZE);
161
162 flush_dcache_page(page);
163 SetPageUptodate(page);
164 kunmap(page);
165 unlock_page(page);
166 if ( fpage == xpage )
167 err = 0; /* The critical page */
168 else
169 page_cache_release(page);
170 }
171 }
172 } else {
173 /* This data block is compressed. */
174 z_stream stream;
175 int bail = 0, left_out = -1;
176 int zerr;
177 int needblocks = (csize + (cstart & bufmask) + bufmask) >> bufshift;
178 int haveblocks;
179 struct buffer_head *bhs[needblocks+1];
180 struct buffer_head **bhptr;
181
182 /* Because zlib is not thread-safe, do all the I/O at the top. */
183
184 blockptr = cstart >> bufshift;
185 memset(bhs, 0, (needblocks+1)*sizeof(struct buffer_head *));
186 haveblocks = isofs_get_blocks(inode, blockptr, bhs, needblocks);
187 ll_rw_block(READ, haveblocks, bhs);
188
189 bhptr = &bhs[0];
190 bh = *bhptr++;
191
192 /* First block is special since it may be fractional.
193 We also wait for it before grabbing the zlib
Dave Younga36a1512007-10-16 23:26:10 -0700194 mutex; odds are that the subsequent blocks are
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 going to come in in short order so we don't hold
Dave Younga36a1512007-10-16 23:26:10 -0700196 the zlib mutex longer than necessary. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198 if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
199 printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
200 fpage, xpage, csize);
201 goto b_eio;
202 }
203 stream.next_in = bh->b_data + (cstart & bufmask);
204 stream.avail_in = min(bufsize-(cstart & bufmask), csize);
205 csize -= stream.avail_in;
206
207 stream.workspace = zisofs_zlib_workspace;
Dave Younga36a1512007-10-16 23:26:10 -0700208 mutex_lock(&zisofs_zlib_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
210 zerr = zlib_inflateInit(&stream);
211 if ( zerr != Z_OK ) {
212 if ( err && zerr == Z_MEM_ERROR )
213 err = -ENOMEM;
214 printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
215 zerr);
216 goto z_eio;
217 }
218
219 while ( !bail && fpage < maxpage ) {
220 page = pages[fpage];
221 if ( page )
222 stream.next_out = page_address(page);
223 else
224 stream.next_out = (void *)&zisofs_sink_page;
225 stream.avail_out = PAGE_CACHE_SIZE;
226
227 while ( stream.avail_out ) {
228 int ao, ai;
229 if ( stream.avail_in == 0 && left_out ) {
230 if ( !csize ) {
231 printk(KERN_WARNING "zisofs: ZF read beyond end of input\n");
232 bail = 1;
233 break;
234 } else {
235 bh = *bhptr++;
236 if ( !bh ||
237 (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
238 /* Reached an EIO */
239 printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
240 fpage, xpage, csize);
241
242 bail = 1;
243 break;
244 }
245 stream.next_in = bh->b_data;
246 stream.avail_in = min(csize,bufsize);
247 csize -= stream.avail_in;
248 }
249 }
250 ao = stream.avail_out; ai = stream.avail_in;
251 zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
252 left_out = stream.avail_out;
253 if ( zerr == Z_BUF_ERROR && stream.avail_in == 0 )
254 continue;
255 if ( zerr != Z_OK ) {
256 /* EOF, error, or trying to read beyond end of input */
257 if ( err && zerr == Z_MEM_ERROR )
258 err = -ENOMEM;
259 if ( zerr != Z_STREAM_END )
260 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",
261 zerr, inode->i_ino, index,
262 fpage, xpage,
263 stream.avail_in, stream.avail_out,
264 ai, ao);
265 bail = 1;
266 break;
267 }
268 }
269
270 if ( stream.avail_out && zerr == Z_STREAM_END ) {
271 /* Fractional page written before EOF. This may
272 be the last page in the file. */
273 memset(stream.next_out, 0, stream.avail_out);
274 stream.avail_out = 0;
275 }
276
277 if ( !stream.avail_out ) {
278 /* This page completed */
279 if ( page ) {
280 flush_dcache_page(page);
281 SetPageUptodate(page);
282 kunmap(page);
283 unlock_page(page);
284 if ( fpage == xpage )
285 err = 0; /* The critical page */
286 else
287 page_cache_release(page);
288 }
289 fpage++;
290 }
291 }
292 zlib_inflateEnd(&stream);
293
294 z_eio:
Dave Younga36a1512007-10-16 23:26:10 -0700295 mutex_unlock(&zisofs_zlib_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
297 b_eio:
298 for ( i = 0 ; i < haveblocks ; i++ ) {
299 if ( bhs[i] )
300 brelse(bhs[i]);
301 }
302 }
303
304eio:
305
306 /* Release any residual pages, do not SetPageUptodate */
307 while ( fpage < maxpage ) {
308 page = pages[fpage];
309 if ( page ) {
310 flush_dcache_page(page);
311 if ( fpage == xpage )
312 SetPageError(page);
313 kunmap(page);
314 unlock_page(page);
315 if ( fpage != xpage )
316 page_cache_release(page);
317 }
318 fpage++;
319 }
320
321 /* At this point, err contains 0 or -EIO depending on the "critical" page */
322 return err;
323}
324
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700325const struct address_space_operations zisofs_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 .readpage = zisofs_readpage,
327 /* No sync_page operation supported? */
328 /* No bmap operation supported */
329};
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331int __init zisofs_init(void)
332{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 zisofs_zlib_workspace = vmalloc(zlib_inflate_workspacesize());
334 if ( !zisofs_zlib_workspace )
335 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 return 0;
338}
339
340void zisofs_cleanup(void)
341{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 vfree(zisofs_zlib_workspace);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343}