btrfs: add helpers for compression type and level
[sfrench/cifs-2.6.git] / fs / btrfs / zlib.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2008 Oracle.  All rights reserved.
4  *
5  * Based on jffs2 zlib code:
6  * Copyright © 2001-2007 Red Hat, Inc.
7  * Created by David Woodhouse <dwmw2@infradead.org>
8  */
9
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/zlib.h>
13 #include <linux/zutil.h>
14 #include <linux/mm.h>
15 #include <linux/init.h>
16 #include <linux/err.h>
17 #include <linux/sched.h>
18 #include <linux/pagemap.h>
19 #include <linux/bio.h>
20 #include <linux/refcount.h>
21 #include "compression.h"
22
23 struct workspace {
24         z_stream strm;
25         char *buf;
26         struct list_head list;
27         int level;
28 };
29
30 static void zlib_free_workspace(struct list_head *ws)
31 {
32         struct workspace *workspace = list_entry(ws, struct workspace, list);
33
34         kvfree(workspace->strm.workspace);
35         kfree(workspace->buf);
36         kfree(workspace);
37 }
38
39 static struct list_head *zlib_alloc_workspace(void)
40 {
41         struct workspace *workspace;
42         int workspacesize;
43
44         workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
45         if (!workspace)
46                 return ERR_PTR(-ENOMEM);
47
48         workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
49                         zlib_inflate_workspacesize());
50         workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
51         workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
52         if (!workspace->strm.workspace || !workspace->buf)
53                 goto fail;
54
55         INIT_LIST_HEAD(&workspace->list);
56
57         return &workspace->list;
58 fail:
59         zlib_free_workspace(&workspace->list);
60         return ERR_PTR(-ENOMEM);
61 }
62
63 static int zlib_compress_pages(struct list_head *ws,
64                                struct address_space *mapping,
65                                u64 start,
66                                struct page **pages,
67                                unsigned long *out_pages,
68                                unsigned long *total_in,
69                                unsigned long *total_out)
70 {
71         struct workspace *workspace = list_entry(ws, struct workspace, list);
72         int ret;
73         char *data_in;
74         char *cpage_out;
75         int nr_pages = 0;
76         struct page *in_page = NULL;
77         struct page *out_page = NULL;
78         unsigned long bytes_left;
79         unsigned long len = *total_out;
80         unsigned long nr_dest_pages = *out_pages;
81         const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
82
83         *out_pages = 0;
84         *total_out = 0;
85         *total_in = 0;
86
87         if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
88                 pr_warn("BTRFS: deflateInit failed\n");
89                 ret = -EIO;
90                 goto out;
91         }
92
93         workspace->strm.total_in = 0;
94         workspace->strm.total_out = 0;
95
96         in_page = find_get_page(mapping, start >> PAGE_SHIFT);
97         data_in = kmap(in_page);
98
99         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
100         if (out_page == NULL) {
101                 ret = -ENOMEM;
102                 goto out;
103         }
104         cpage_out = kmap(out_page);
105         pages[0] = out_page;
106         nr_pages = 1;
107
108         workspace->strm.next_in = data_in;
109         workspace->strm.next_out = cpage_out;
110         workspace->strm.avail_out = PAGE_SIZE;
111         workspace->strm.avail_in = min(len, PAGE_SIZE);
112
113         while (workspace->strm.total_in < len) {
114                 ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
115                 if (ret != Z_OK) {
116                         pr_debug("BTRFS: deflate in loop returned %d\n",
117                                ret);
118                         zlib_deflateEnd(&workspace->strm);
119                         ret = -EIO;
120                         goto out;
121                 }
122
123                 /* we're making it bigger, give up */
124                 if (workspace->strm.total_in > 8192 &&
125                     workspace->strm.total_in <
126                     workspace->strm.total_out) {
127                         ret = -E2BIG;
128                         goto out;
129                 }
130                 /* we need another page for writing out.  Test this
131                  * before the total_in so we will pull in a new page for
132                  * the stream end if required
133                  */
134                 if (workspace->strm.avail_out == 0) {
135                         kunmap(out_page);
136                         if (nr_pages == nr_dest_pages) {
137                                 out_page = NULL;
138                                 ret = -E2BIG;
139                                 goto out;
140                         }
141                         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
142                         if (out_page == NULL) {
143                                 ret = -ENOMEM;
144                                 goto out;
145                         }
146                         cpage_out = kmap(out_page);
147                         pages[nr_pages] = out_page;
148                         nr_pages++;
149                         workspace->strm.avail_out = PAGE_SIZE;
150                         workspace->strm.next_out = cpage_out;
151                 }
152                 /* we're all done */
153                 if (workspace->strm.total_in >= len)
154                         break;
155
156                 /* we've read in a full page, get a new one */
157                 if (workspace->strm.avail_in == 0) {
158                         if (workspace->strm.total_out > max_out)
159                                 break;
160
161                         bytes_left = len - workspace->strm.total_in;
162                         kunmap(in_page);
163                         put_page(in_page);
164
165                         start += PAGE_SIZE;
166                         in_page = find_get_page(mapping,
167                                                 start >> PAGE_SHIFT);
168                         data_in = kmap(in_page);
169                         workspace->strm.avail_in = min(bytes_left,
170                                                            PAGE_SIZE);
171                         workspace->strm.next_in = data_in;
172                 }
173         }
174         workspace->strm.avail_in = 0;
175         ret = zlib_deflate(&workspace->strm, Z_FINISH);
176         zlib_deflateEnd(&workspace->strm);
177
178         if (ret != Z_STREAM_END) {
179                 ret = -EIO;
180                 goto out;
181         }
182
183         if (workspace->strm.total_out >= workspace->strm.total_in) {
184                 ret = -E2BIG;
185                 goto out;
186         }
187
188         ret = 0;
189         *total_out = workspace->strm.total_out;
190         *total_in = workspace->strm.total_in;
191 out:
192         *out_pages = nr_pages;
193         if (out_page)
194                 kunmap(out_page);
195
196         if (in_page) {
197                 kunmap(in_page);
198                 put_page(in_page);
199         }
200         return ret;
201 }
202
203 static int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
204 {
205         struct workspace *workspace = list_entry(ws, struct workspace, list);
206         int ret = 0, ret2;
207         int wbits = MAX_WBITS;
208         char *data_in;
209         size_t total_out = 0;
210         unsigned long page_in_index = 0;
211         size_t srclen = cb->compressed_len;
212         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
213         unsigned long buf_start;
214         struct page **pages_in = cb->compressed_pages;
215         u64 disk_start = cb->start;
216         struct bio *orig_bio = cb->orig_bio;
217
218         data_in = kmap(pages_in[page_in_index]);
219         workspace->strm.next_in = data_in;
220         workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
221         workspace->strm.total_in = 0;
222
223         workspace->strm.total_out = 0;
224         workspace->strm.next_out = workspace->buf;
225         workspace->strm.avail_out = PAGE_SIZE;
226
227         /* If it's deflate, and it's got no preset dictionary, then
228            we can tell zlib to skip the adler32 check. */
229         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
230             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
231             !(((data_in[0]<<8) + data_in[1]) % 31)) {
232
233                 wbits = -((data_in[0] >> 4) + 8);
234                 workspace->strm.next_in += 2;
235                 workspace->strm.avail_in -= 2;
236         }
237
238         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
239                 pr_warn("BTRFS: inflateInit failed\n");
240                 kunmap(pages_in[page_in_index]);
241                 return -EIO;
242         }
243         while (workspace->strm.total_in < srclen) {
244                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
245                 if (ret != Z_OK && ret != Z_STREAM_END)
246                         break;
247
248                 buf_start = total_out;
249                 total_out = workspace->strm.total_out;
250
251                 /* we didn't make progress in this inflate call, we're done */
252                 if (buf_start == total_out)
253                         break;
254
255                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
256                                                  total_out, disk_start,
257                                                  orig_bio);
258                 if (ret2 == 0) {
259                         ret = 0;
260                         goto done;
261                 }
262
263                 workspace->strm.next_out = workspace->buf;
264                 workspace->strm.avail_out = PAGE_SIZE;
265
266                 if (workspace->strm.avail_in == 0) {
267                         unsigned long tmp;
268                         kunmap(pages_in[page_in_index]);
269                         page_in_index++;
270                         if (page_in_index >= total_pages_in) {
271                                 data_in = NULL;
272                                 break;
273                         }
274                         data_in = kmap(pages_in[page_in_index]);
275                         workspace->strm.next_in = data_in;
276                         tmp = srclen - workspace->strm.total_in;
277                         workspace->strm.avail_in = min(tmp,
278                                                            PAGE_SIZE);
279                 }
280         }
281         if (ret != Z_STREAM_END)
282                 ret = -EIO;
283         else
284                 ret = 0;
285 done:
286         zlib_inflateEnd(&workspace->strm);
287         if (data_in)
288                 kunmap(pages_in[page_in_index]);
289         if (!ret)
290                 zero_fill_bio(orig_bio);
291         return ret;
292 }
293
294 static int zlib_decompress(struct list_head *ws, unsigned char *data_in,
295                            struct page *dest_page,
296                            unsigned long start_byte,
297                            size_t srclen, size_t destlen)
298 {
299         struct workspace *workspace = list_entry(ws, struct workspace, list);
300         int ret = 0;
301         int wbits = MAX_WBITS;
302         unsigned long bytes_left;
303         unsigned long total_out = 0;
304         unsigned long pg_offset = 0;
305         char *kaddr;
306
307         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
308         bytes_left = destlen;
309
310         workspace->strm.next_in = data_in;
311         workspace->strm.avail_in = srclen;
312         workspace->strm.total_in = 0;
313
314         workspace->strm.next_out = workspace->buf;
315         workspace->strm.avail_out = PAGE_SIZE;
316         workspace->strm.total_out = 0;
317         /* If it's deflate, and it's got no preset dictionary, then
318            we can tell zlib to skip the adler32 check. */
319         if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
320             ((data_in[0] & 0x0f) == Z_DEFLATED) &&
321             !(((data_in[0]<<8) + data_in[1]) % 31)) {
322
323                 wbits = -((data_in[0] >> 4) + 8);
324                 workspace->strm.next_in += 2;
325                 workspace->strm.avail_in -= 2;
326         }
327
328         if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
329                 pr_warn("BTRFS: inflateInit failed\n");
330                 return -EIO;
331         }
332
333         while (bytes_left > 0) {
334                 unsigned long buf_start;
335                 unsigned long buf_offset;
336                 unsigned long bytes;
337
338                 ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
339                 if (ret != Z_OK && ret != Z_STREAM_END)
340                         break;
341
342                 buf_start = total_out;
343                 total_out = workspace->strm.total_out;
344
345                 if (total_out == buf_start) {
346                         ret = -EIO;
347                         break;
348                 }
349
350                 if (total_out <= start_byte)
351                         goto next;
352
353                 if (total_out > start_byte && buf_start < start_byte)
354                         buf_offset = start_byte - buf_start;
355                 else
356                         buf_offset = 0;
357
358                 bytes = min(PAGE_SIZE - pg_offset,
359                             PAGE_SIZE - buf_offset);
360                 bytes = min(bytes, bytes_left);
361
362                 kaddr = kmap_atomic(dest_page);
363                 memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
364                 kunmap_atomic(kaddr);
365
366                 pg_offset += bytes;
367                 bytes_left -= bytes;
368 next:
369                 workspace->strm.next_out = workspace->buf;
370                 workspace->strm.avail_out = PAGE_SIZE;
371         }
372
373         if (ret != Z_STREAM_END && bytes_left != 0)
374                 ret = -EIO;
375         else
376                 ret = 0;
377
378         zlib_inflateEnd(&workspace->strm);
379
380         /*
381          * this should only happen if zlib returned fewer bytes than we
382          * expected.  btrfs_get_block is responsible for zeroing from the
383          * end of the inline extent (destlen) to the end of the page
384          */
385         if (pg_offset < destlen) {
386                 kaddr = kmap_atomic(dest_page);
387                 memset(kaddr + pg_offset, 0, destlen - pg_offset);
388                 kunmap_atomic(kaddr);
389         }
390         return ret;
391 }
392
393 static void zlib_set_level(struct list_head *ws, unsigned int type)
394 {
395         struct workspace *workspace = list_entry(ws, struct workspace, list);
396         unsigned int level = btrfs_compress_level(type);
397
398         if (level > 9)
399                 level = 9;
400
401         workspace->level = level > 0 ? level : 3;
402 }
403
404 const struct btrfs_compress_op btrfs_zlib_compress = {
405         .alloc_workspace        = zlib_alloc_workspace,
406         .free_workspace         = zlib_free_workspace,
407         .compress_pages         = zlib_compress_pages,
408         .decompress_bio         = zlib_decompress_bio,
409         .decompress             = zlib_decompress,
410         .set_level              = zlib_set_level,
411 };