GNU Linux-libre 4.9.308-gnu1
[releases.git] / fs / btrfs / zlib.c
1 /*
2  * Copyright (C) 2008 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  *
18  * Based on jffs2 zlib code:
19  * Copyright © 2001-2007 Red Hat, Inc.
20  * Created by David Woodhouse <dwmw2@infradead.org>
21  */
22
23 #include <linux/kernel.h>
24 #include <linux/slab.h>
25 #include <linux/zlib.h>
26 #include <linux/zutil.h>
27 #include <linux/vmalloc.h>
28 #include <linux/init.h>
29 #include <linux/err.h>
30 #include <linux/sched.h>
31 #include <linux/pagemap.h>
32 #include <linux/bio.h>
33 #include "compression.h"
34
35 struct workspace {
36         z_stream strm;
37         char *buf;
38         struct list_head list;
39 };
40
41 static void zlib_free_workspace(struct list_head *ws)
42 {
43         struct workspace *workspace = list_entry(ws, struct workspace, list);
44
45         vfree(workspace->strm.workspace);
46         kfree(workspace->buf);
47         kfree(workspace);
48 }
49
50 static struct list_head *zlib_alloc_workspace(void)
51 {
52         struct workspace *workspace;
53         int workspacesize;
54
55         workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
56         if (!workspace)
57                 return ERR_PTR(-ENOMEM);
58
59         workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
60                         zlib_inflate_workspacesize());
61         workspace->strm.workspace = vmalloc(workspacesize);
62         workspace->buf = kmalloc(PAGE_SIZE, GFP_NOFS);
63         if (!workspace->strm.workspace || !workspace->buf)
64                 goto fail;
65
66         INIT_LIST_HEAD(&workspace->list);
67
68         return &workspace->list;
69 fail:
70         zlib_free_workspace(&workspace->list);
71         return ERR_PTR(-ENOMEM);
72 }
73
74 static int zlib_compress_pages(struct list_head *ws,
75                                struct address_space *mapping,
76                                u64 start, unsigned long len,
77                                struct page **pages,
78                                unsigned long nr_dest_pages,
79                                unsigned long *out_pages,
80                                unsigned long *total_in,
81                                unsigned long *total_out,
82                                unsigned long max_out)
83 {
84         struct workspace *workspace = list_entry(ws, struct workspace, list);
85         int ret;
86         char *data_in;
87         char *cpage_out;
88         int nr_pages = 0;
89         struct page *in_page = NULL;
90         struct page *out_page = NULL;
91         unsigned long bytes_left;
92
93         *out_pages = 0;
94         *total_out = 0;
95         *total_in = 0;
96
97         if (Z_OK != zlib_deflateInit(&workspace->strm, 3)) {
98                 pr_warn("BTRFS: deflateInit failed\n");
99                 ret = -EIO;
100                 goto out;
101         }
102
103         workspace->strm.total_in = 0;
104         workspace->strm.total_out = 0;
105
106         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
107         data_in = kmap(in_page);
108
109         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
110         if (out_page == NULL) {
111                 ret = -ENOMEM;
112                 goto out;
113         }
114         cpage_out = kmap(out_page);
115         pages[0] = out_page;
116         nr_pages = 1;
117
118         workspace->strm.next_in = data_in;
119         workspace->strm.next_out = cpage_out;
120         workspace->strm.avail_out = PAGE_SIZE;
121         workspace->strm.avail_in = min(len, PAGE_SIZE);
122
123         while (workspace->strm.total_in < len) {
124                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
125                 if (ret != Z_OK) {
126                         pr_debug("BTRFS: deflate in loop returned %d\n",
127                                ret);
128                         zlib_deflateEnd(&workspace->strm);
129                         ret = -EIO;
130                         goto out;
131                 }
132
133                 /* we're making it bigger, give up */
134                 if (workspace->strm.total_in > 8192 &&
135                     workspace->strm.total_in <
136                     workspace->strm.total_out) {
137                         ret = -E2BIG;
138                         goto out;
139                 }
140                 /* we need another page for writing out.  Test this
141                  * before the total_in so we will pull in a new page for
142                  * the stream end if required
143                  */
144                 if (workspace->strm.avail_out == 0) {
145                         kunmap(out_page);
146                         if (nr_pages == nr_dest_pages) {
147                                 out_page = NULL;
148                                 ret = -E2BIG;
149                                 goto out;
150                         }
151                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
152                         if (out_page == NULL) {
153                                 ret = -ENOMEM;
154                                 goto out;
155                         }
156                         cpage_out = kmap(out_page);
157                         pages[nr_pages] = out_page;
158                         nr_pages++;
159                         workspace->strm.avail_out = PAGE_SIZE;
160                         workspace->strm.next_out = cpage_out;
161                 }
162                 /* we're all done */
163                 if (workspace->strm.total_in >= len)
164                         break;
165
166                 /* we've read in a full page, get a new one */
167                 if (workspace->strm.avail_in == 0) {
168                         if (workspace->strm.total_out > max_out)
169                                 break;
170
171                         bytes_left = len - workspace->strm.total_in;
172                         kunmap(in_page);
173                         put_page(in_page);
174
175                         start += PAGE_SIZE;
176                         in_page = find_get_page(mapping,
177                                                 start >> PAGE_SHIFT);
178                         data_in = kmap(in_page);
179                         workspace->strm.avail_in = min(bytes_left,
180                                                            PAGE_SIZE);
181                         workspace->strm.next_in = data_in;
182                 }
183         }
184         workspace->strm.avail_in = 0;
185         ret = zlib_deflate(&workspace->strm, Z_FINISH);
186         zlib_deflateEnd(&workspace->strm);
187
188         if (ret != Z_STREAM_END) {
189                 ret = -EIO;
190                 goto out;
191         }
192
193         if (workspace->strm.total_out >= workspace->strm.total_in) {
194                 ret = -E2BIG;
195                 goto out;
196         }
197
198         ret = 0;
199         *total_out = workspace->strm.total_out;
200         *total_in = workspace->strm.total_in;
201 out:
202         *out_pages = nr_pages;
203         if (out_page)
204                 kunmap(out_page);
205
206         if (in_page) {
207                 kunmap(in_page);
208                 put_page(in_page);
209         }
210         return ret;
211 }
212
213 static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
214                                   u64 disk_start,
215                                   struct bio_vec *bvec,
216                                   int vcnt,
217                                   size_t srclen)
218 {
219         struct workspace *workspace = list_entry(ws, struct workspace, list);
220         int ret = 0, ret2;
221         int wbits = MAX_WBITS;
222         char *data_in;
223         size_t total_out = 0;
224         unsigned long page_in_index = 0;
225         unsigned long page_out_index = 0;
226         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
227         unsigned long buf_start;
228         unsigned long pg_offset;
229
230         data_in = kmap(pages_in[page_in_index]);
231         workspace->strm.next_in = data_in;
232         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
233         workspace->strm.total_in = 0;
234
235         workspace->strm.total_out = 0;
236         workspace->strm.next_out = workspace->buf;
237         workspace->strm.avail_out = PAGE_SIZE;
238         pg_offset = 0;
239
240         /* If it's deflate, and it's got no preset dictionary, then
241            we can tell zlib to skip the adler32 check. */
242         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
243             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
244             !(((data_in[0]<<8) + data_in[1]) % 31)) {
245
246                 wbits = -((data_in[0] >> 4) + 8);
247                 workspace->strm.next_in += 2;
248                 workspace->strm.avail_in -= 2;
249         }
250
251         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
252                 pr_warn("BTRFS: inflateInit failed\n");
253                 return -EIO;
254         }
255         while (workspace->strm.total_in < srclen) {
256                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
257                 if (ret != Z_OK && ret != Z_STREAM_END)
258                         break;
259
260                 buf_start = total_out;
261                 total_out = workspace->strm.total_out;
262
263                 /* we didn't make progress in this inflate call, we're done */
264                 if (buf_start == total_out)
265                         break;
266
267                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
268                                                  total_out, disk_start,
269                                                  bvec, vcnt,
270                                                  &page_out_index, &pg_offset);
271                 if (ret2 == 0) {
272                         ret = 0;
273                         goto done;
274                 }
275
276                 workspace->strm.next_out = workspace->buf;
277                 workspace->strm.avail_out = PAGE_SIZE;
278
279                 if (workspace->strm.avail_in == 0) {
280                         unsigned long tmp;
281                         kunmap(pages_in[page_in_index]);
282                         page_in_index++;
283                         if (page_in_index >= total_pages_in) {
284                                 data_in = NULL;
285                                 break;
286                         }
287                         data_in = kmap(pages_in[page_in_index]);
288                         workspace->strm.next_in = data_in;
289                         tmp = srclen - workspace->strm.total_in;
290                         workspace->strm.avail_in = min(tmp,
291                                                            PAGE_SIZE);
292                 }
293         }
294         if (ret != Z_STREAM_END)
295                 ret = -EIO;
296         else
297                 ret = 0;
298 done:
299         zlib_inflateEnd(&workspace->strm);
300         if (data_in)
301                 kunmap(pages_in[page_in_index]);
302         if (!ret)
303                 btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
304         return ret;
305 }
306
307 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
308                            struct page *dest_page,
309                            unsigned long start_byte,
310                            size_t srclen, size_t destlen)
311 {
312         struct workspace *workspace = list_entry(ws, struct workspace, list);
313         int ret = 0;
314         int wbits = MAX_WBITS;
315         unsigned long bytes_left;
316         unsigned long total_out = 0;
317         unsigned long pg_offset = 0;
318         char *kaddr;
319
320         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
321         bytes_left = destlen;
322
323         workspace->strm.next_in = data_in;
324         workspace->strm.avail_in = srclen;
325         workspace->strm.total_in = 0;
326
327         workspace->strm.next_out = workspace->buf;
328         workspace->strm.avail_out = PAGE_SIZE;
329         workspace->strm.total_out = 0;
330         /* If it's deflate, and it's got no preset dictionary, then
331            we can tell zlib to skip the adler32 check. */
332         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
333             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
334             !(((data_in[0]<<8) + data_in[1]) % 31)) {
335
336                 wbits = -((data_in[0] >> 4) + 8);
337                 workspace->strm.next_in += 2;
338                 workspace->strm.avail_in -= 2;
339         }
340
341         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
342                 pr_warn("BTRFS: inflateInit failed\n");
343                 return -EIO;
344         }
345
346         while (bytes_left > 0) {
347                 unsigned long buf_start;
348                 unsigned long buf_offset;
349                 unsigned long bytes;
350
351                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
352                 if (ret != Z_OK && ret != Z_STREAM_END)
353                         break;
354
355                 buf_start = total_out;
356                 total_out = workspace->strm.total_out;
357
358                 if (total_out == buf_start) {
359                         ret = -EIO;
360                         break;
361                 }
362
363                 if (total_out <= start_byte)
364                         goto next;
365
366                 if (total_out > start_byte && buf_start < start_byte)
367                         buf_offset = start_byte - buf_start;
368                 else
369                         buf_offset = 0;
370
371                 bytes = min(PAGE_SIZE - pg_offset,
372                             PAGE_SIZE - buf_offset);
373                 bytes = min(bytes, bytes_left);
374
375                 kaddr = kmap_atomic(dest_page);
376                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
377                 kunmap_atomic(kaddr);
378
379                 pg_offset += bytes;
380                 bytes_left -= bytes;
381 next:
382                 workspace->strm.next_out = workspace->buf;
383                 workspace->strm.avail_out = PAGE_SIZE;
384         }
385
386         if (ret != Z_STREAM_END && bytes_left != 0)
387                 ret = -EIO;
388         else
389                 ret = 0;
390
391         zlib_inflateEnd(&workspace->strm);
392
393         /*
394          * this should only happen if zlib returned fewer bytes than we
395          * expected.  btrfs_get_block is responsible for zeroing from the
396          * end of the inline extent (destlen) to the end of the page
397          */
398         if (pg_offset < destlen) {
399                 kaddr = kmap_atomic(dest_page);
400                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
401                 kunmap_atomic(kaddr);
402         }
403         return ret;
404 }
405
406 const struct btrfs_compress_op btrfs_zlib_compress = {
407         .alloc_workspace        = zlib_alloc_workspace,
408         .free_workspace         = zlib_free_workspace,
409         .compress_pages         = zlib_compress_pages,
410         .decompress_biovec      = zlib_decompress_biovec,
411         .decompress             = zlib_decompress,
412 };