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c8b97818 CM |
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 | ||
34 | /* Plan: call deflate() with avail_in == *sourcelen, | |
35 | avail_out = *dstlen - 12 and flush == Z_FINISH. | |
36 | If it doesn't manage to finish, call it again with | |
37 | avail_in == 0 and avail_out set to the remaining 12 | |
38 | bytes for it to clean up. | |
39 | Q: Is 12 bytes sufficient? | |
40 | */ | |
41 | #define STREAM_END_SPACE 12 | |
42 | ||
43 | struct workspace { | |
44 | z_stream inf_strm; | |
45 | z_stream def_strm; | |
46 | char *buf; | |
47 | struct list_head list; | |
48 | }; | |
49 | ||
50 | static LIST_HEAD(idle_workspace); | |
51 | static DEFINE_SPINLOCK(workspace_lock); | |
52 | static unsigned long num_workspace; | |
53 | static atomic_t alloc_workspace = ATOMIC_INIT(0); | |
54 | static DECLARE_WAIT_QUEUE_HEAD(workspace_wait); | |
55 | ||
56 | /* | |
57 | * this finds an available zlib workspace or allocates a new one | |
58 | * NULL or an ERR_PTR is returned if things go bad. | |
59 | */ | |
60 | static struct workspace *find_zlib_workspace(void) | |
61 | { | |
62 | struct workspace *workspace; | |
63 | int ret; | |
64 | int cpus = num_online_cpus(); | |
65 | ||
66 | again: | |
67 | spin_lock(&workspace_lock); | |
68 | if (!list_empty(&idle_workspace)) { | |
69 | workspace = list_entry(idle_workspace.next, struct workspace, | |
70 | list); | |
71 | list_del(&workspace->list); | |
72 | num_workspace--; | |
73 | spin_unlock(&workspace_lock); | |
74 | return workspace; | |
75 | ||
76 | } | |
77 | spin_unlock(&workspace_lock); | |
78 | if (atomic_read(&alloc_workspace) > cpus) { | |
79 | DEFINE_WAIT(wait); | |
80 | prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE); | |
81 | if (atomic_read(&alloc_workspace) > cpus) | |
82 | schedule(); | |
83 | finish_wait(&workspace_wait, &wait); | |
84 | goto again; | |
85 | } | |
86 | atomic_inc(&alloc_workspace); | |
87 | workspace = kzalloc(sizeof(*workspace), GFP_NOFS); | |
88 | if (!workspace) { | |
89 | ret = -ENOMEM; | |
90 | goto fail; | |
91 | } | |
92 | ||
93 | workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize()); | |
94 | if (!workspace->def_strm.workspace) { | |
95 | ret = -ENOMEM; | |
96 | goto fail; | |
97 | } | |
98 | workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize()); | |
99 | if (!workspace->inf_strm.workspace) { | |
100 | ret = -ENOMEM; | |
101 | goto fail_inflate; | |
102 | } | |
103 | workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS); | |
104 | if (!workspace->buf) { | |
105 | ret = -ENOMEM; | |
106 | goto fail_kmalloc; | |
107 | } | |
108 | return workspace; | |
109 | ||
110 | fail_kmalloc: | |
111 | vfree(workspace->inf_strm.workspace); | |
112 | fail_inflate: | |
113 | vfree(workspace->def_strm.workspace); | |
114 | fail: | |
115 | kfree(workspace); | |
116 | atomic_dec(&alloc_workspace); | |
117 | wake_up(&workspace_wait); | |
118 | return ERR_PTR(ret); | |
119 | } | |
120 | ||
121 | /* | |
122 | * put a workspace struct back on the list or free it if we have enough | |
123 | * idle ones sitting around | |
124 | */ | |
125 | static int free_workspace(struct workspace *workspace) | |
126 | { | |
127 | spin_lock(&workspace_lock); | |
128 | if (num_workspace < num_online_cpus()) { | |
129 | list_add_tail(&workspace->list, &idle_workspace); | |
130 | num_workspace++; | |
131 | spin_unlock(&workspace_lock); | |
132 | if (waitqueue_active(&workspace_wait)) | |
133 | wake_up(&workspace_wait); | |
134 | return 0; | |
135 | } | |
136 | spin_unlock(&workspace_lock); | |
137 | vfree(workspace->def_strm.workspace); | |
138 | vfree(workspace->inf_strm.workspace); | |
139 | kfree(workspace->buf); | |
140 | kfree(workspace); | |
141 | ||
142 | atomic_dec(&alloc_workspace); | |
143 | if (waitqueue_active(&workspace_wait)) | |
144 | wake_up(&workspace_wait); | |
145 | return 0; | |
146 | } | |
147 | ||
148 | /* | |
149 | * cleanup function for module exit | |
150 | */ | |
151 | static void free_workspaces(void) | |
152 | { | |
153 | struct workspace *workspace; | |
154 | while(!list_empty(&idle_workspace)) { | |
155 | workspace = list_entry(idle_workspace.next, struct workspace, | |
156 | list); | |
157 | list_del(&workspace->list); | |
158 | vfree(workspace->def_strm.workspace); | |
159 | vfree(workspace->inf_strm.workspace); | |
160 | kfree(workspace->buf); | |
161 | kfree(workspace); | |
162 | atomic_dec(&alloc_workspace); | |
163 | } | |
164 | } | |
165 | ||
166 | /* | |
167 | * given an address space and start/len, compress the bytes. | |
168 | * | |
169 | * pages are allocated to hold the compressed result and stored | |
170 | * in 'pages' | |
171 | * | |
172 | * out_pages is used to return the number of pages allocated. There | |
173 | * may be pages allocated even if we return an error | |
174 | * | |
175 | * total_in is used to return the number of bytes actually read. It | |
176 | * may be smaller then len if we had to exit early because we | |
177 | * ran out of room in the pages array or because we cross the | |
178 | * max_out threshold. | |
179 | * | |
180 | * total_out is used to return the total number of compressed bytes | |
181 | * | |
182 | * max_out tells us the max number of bytes that we're allowed to | |
183 | * stuff into pages | |
184 | */ | |
185 | int btrfs_zlib_compress_pages(struct address_space *mapping, | |
186 | u64 start, unsigned long len, | |
187 | struct page **pages, | |
188 | unsigned long nr_dest_pages, | |
189 | unsigned long *out_pages, | |
190 | unsigned long *total_in, | |
191 | unsigned long *total_out, | |
192 | unsigned long max_out) | |
193 | { | |
194 | int ret; | |
195 | struct workspace *workspace; | |
196 | char *data_in; | |
197 | char *cpage_out; | |
198 | int nr_pages = 0; | |
199 | struct page *in_page = NULL; | |
200 | struct page *out_page = NULL; | |
201 | int out_written = 0; | |
202 | int in_read = 0; | |
203 | unsigned long bytes_left; | |
204 | ||
205 | *out_pages = 0; | |
206 | *total_out = 0; | |
207 | *total_in = 0; | |
208 | ||
209 | workspace = find_zlib_workspace(); | |
210 | if (!workspace) | |
211 | return -1; | |
212 | ||
213 | if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) { | |
214 | printk(KERN_WARNING "deflateInit failed\n"); | |
215 | ret = -1; | |
216 | goto out; | |
217 | } | |
218 | ||
219 | workspace->def_strm.total_in = 0; | |
220 | workspace->def_strm.total_out = 0; | |
221 | ||
222 | in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT); | |
223 | data_in = kmap(in_page); | |
224 | ||
225 | out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); | |
226 | cpage_out = kmap(out_page); | |
227 | pages[0] = out_page; | |
228 | nr_pages = 1; | |
229 | ||
230 | workspace->def_strm.next_in = data_in; | |
231 | workspace->def_strm.next_out = cpage_out; | |
232 | workspace->def_strm.avail_out = PAGE_CACHE_SIZE; | |
233 | workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE); | |
234 | ||
235 | out_written = 0; | |
236 | in_read = 0; | |
237 | ||
238 | while (workspace->def_strm.total_in < len) { | |
239 | ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH); | |
240 | if (ret != Z_OK) { | |
241 | printk(KERN_DEBUG "btrfs deflate in loop returned %d\n", | |
242 | ret); | |
243 | zlib_deflateEnd(&workspace->def_strm); | |
244 | ret = -1; | |
245 | goto out; | |
246 | } | |
247 | ||
248 | /* we're making it bigger, give up */ | |
249 | if (workspace->def_strm.total_in > 8192 && | |
250 | workspace->def_strm.total_in < | |
251 | workspace->def_strm.total_out) { | |
252 | ret = -1; | |
253 | goto out; | |
254 | } | |
255 | /* we need another page for writing out. Test this | |
256 | * before the total_in so we will pull in a new page for | |
257 | * the stream end if required | |
258 | */ | |
259 | if (workspace->def_strm.avail_out == 0) { | |
260 | kunmap(out_page); | |
261 | if (nr_pages == nr_dest_pages) { | |
262 | out_page = NULL; | |
263 | ret = -1; | |
264 | goto out; | |
265 | } | |
266 | out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); | |
267 | cpage_out = kmap(out_page); | |
268 | pages[nr_pages] = out_page; | |
269 | nr_pages++; | |
270 | workspace->def_strm.avail_out = PAGE_CACHE_SIZE; | |
271 | workspace->def_strm.next_out = cpage_out; | |
272 | } | |
273 | /* we're all done */ | |
274 | if (workspace->def_strm.total_in >= len) | |
275 | break; | |
276 | ||
277 | /* we've read in a full page, get a new one */ | |
278 | if (workspace->def_strm.avail_in == 0) { | |
279 | if (workspace->def_strm.total_out > max_out) | |
280 | break; | |
281 | ||
282 | bytes_left = len - workspace->def_strm.total_in; | |
283 | kunmap(in_page); | |
284 | page_cache_release(in_page); | |
285 | ||
286 | start += PAGE_CACHE_SIZE; | |
287 | in_page = find_get_page(mapping, | |
288 | start >> PAGE_CACHE_SHIFT); | |
289 | data_in = kmap(in_page); | |
290 | workspace->def_strm.avail_in = min(bytes_left, | |
291 | PAGE_CACHE_SIZE); | |
292 | workspace->def_strm.next_in = data_in; | |
293 | } | |
294 | } | |
295 | workspace->def_strm.avail_in = 0; | |
296 | ret = zlib_deflate(&workspace->def_strm, Z_FINISH); | |
297 | zlib_deflateEnd(&workspace->def_strm); | |
298 | ||
299 | if (ret != Z_STREAM_END) { | |
300 | ret = -1; | |
301 | goto out; | |
302 | } | |
303 | ||
304 | if (workspace->def_strm.total_out >= workspace->def_strm.total_in) { | |
305 | ret = -1; | |
306 | goto out; | |
307 | } | |
308 | ||
309 | ret = 0; | |
310 | *total_out = workspace->def_strm.total_out; | |
311 | *total_in = workspace->def_strm.total_in; | |
312 | out: | |
313 | *out_pages = nr_pages; | |
314 | if (out_page) | |
315 | kunmap(out_page); | |
316 | ||
317 | if (in_page) { | |
318 | kunmap(in_page); | |
319 | page_cache_release(in_page); | |
320 | } | |
321 | free_workspace(workspace); | |
322 | return ret; | |
323 | } | |
324 | ||
325 | /* | |
326 | * pages_in is an array of pages with compressed data. | |
327 | * | |
328 | * disk_start is the starting logical offset of this array in the file | |
329 | * | |
330 | * bvec is a bio_vec of pages from the file that we want to decompress into | |
331 | * | |
332 | * vcnt is the count of pages in the biovec | |
333 | * | |
334 | * srclen is the number of bytes in pages_in | |
335 | * | |
336 | * The basic idea is that we have a bio that was created by readpages. | |
337 | * The pages in the bio are for the uncompressed data, and they may not | |
338 | * be contiguous. They all correspond to the range of bytes covered by | |
339 | * the compressed extent. | |
340 | */ | |
341 | int btrfs_zlib_decompress_biovec(struct page **pages_in, | |
342 | u64 disk_start, | |
343 | struct bio_vec *bvec, | |
344 | int vcnt, | |
345 | size_t srclen) | |
346 | { | |
347 | int ret = 0; | |
348 | int wbits = MAX_WBITS; | |
349 | struct workspace *workspace; | |
350 | char *data_in; | |
351 | size_t total_out = 0; | |
352 | unsigned long page_bytes_left; | |
353 | unsigned long page_in_index = 0; | |
354 | unsigned long page_out_index = 0; | |
355 | struct page *page_out; | |
356 | unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) / | |
357 | PAGE_CACHE_SIZE; | |
358 | unsigned long buf_start; | |
359 | unsigned long buf_offset; | |
360 | unsigned long bytes; | |
361 | unsigned long working_bytes; | |
362 | unsigned long pg_offset; | |
363 | unsigned long start_byte; | |
364 | unsigned long current_buf_start; | |
365 | char *kaddr; | |
366 | ||
367 | workspace = find_zlib_workspace(); | |
368 | if (!workspace) | |
369 | return -ENOMEM; | |
370 | ||
371 | data_in = kmap(pages_in[page_in_index]); | |
372 | workspace->inf_strm.next_in = data_in; | |
373 | workspace->inf_strm.avail_in = min(srclen, PAGE_CACHE_SIZE); | |
374 | workspace->inf_strm.total_in = 0; | |
375 | ||
376 | workspace->inf_strm.total_out = 0; | |
377 | workspace->inf_strm.next_out = workspace->buf; | |
378 | workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; | |
379 | page_out = bvec[page_out_index].bv_page; | |
380 | page_bytes_left = PAGE_CACHE_SIZE; | |
381 | pg_offset = 0; | |
382 | ||
383 | /* If it's deflate, and it's got no preset dictionary, then | |
384 | we can tell zlib to skip the adler32 check. */ | |
385 | if (srclen > 2 && !(data_in[1] & PRESET_DICT) && | |
386 | ((data_in[0] & 0x0f) == Z_DEFLATED) && | |
387 | !(((data_in[0]<<8) + data_in[1]) % 31)) { | |
388 | ||
389 | wbits = -((data_in[0] >> 4) + 8); | |
390 | workspace->inf_strm.next_in += 2; | |
391 | workspace->inf_strm.avail_in -= 2; | |
392 | } | |
393 | ||
394 | if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) { | |
395 | printk(KERN_WARNING "inflateInit failed\n"); | |
396 | ret = -1; | |
397 | goto out; | |
398 | } | |
399 | while(workspace->inf_strm.total_in < srclen) { | |
400 | ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH); | |
401 | if (ret != Z_OK && ret != Z_STREAM_END) { | |
402 | break; | |
403 | } | |
404 | ||
405 | /* | |
406 | * buf start is the byte offset we're of the start of | |
407 | * our workspace buffer | |
408 | */ | |
409 | buf_start = total_out; | |
410 | ||
411 | /* total_out is the last byte of the workspace buffer */ | |
412 | total_out = workspace->inf_strm.total_out; | |
413 | ||
414 | working_bytes = total_out - buf_start; | |
415 | ||
416 | /* | |
417 | * start byte is the first byte of the page we're currently | |
418 | * copying into relative to the start of the compressed data. | |
419 | */ | |
420 | start_byte = page_offset(page_out) - disk_start; | |
421 | ||
422 | if (working_bytes == 0) { | |
423 | /* we didn't make progress in this inflate | |
424 | * call, we're done | |
425 | */ | |
426 | if (ret != Z_STREAM_END) | |
427 | ret = -1; | |
428 | break; | |
429 | } | |
430 | ||
431 | /* we haven't yet hit data corresponding to this page */ | |
432 | if (total_out <= start_byte) { | |
433 | goto next; | |
434 | } | |
435 | ||
436 | /* | |
437 | * the start of the data we care about is offset into | |
438 | * the middle of our working buffer | |
439 | */ | |
440 | if (total_out > start_byte && buf_start < start_byte) { | |
441 | buf_offset = start_byte - buf_start; | |
442 | working_bytes -= buf_offset; | |
443 | } else { | |
444 | buf_offset = 0; | |
445 | } | |
446 | current_buf_start = buf_start; | |
447 | ||
448 | /* copy bytes from the working buffer into the pages */ | |
449 | while(working_bytes > 0) { | |
450 | bytes = min(PAGE_CACHE_SIZE - pg_offset, | |
451 | PAGE_CACHE_SIZE - buf_offset); | |
452 | bytes = min(bytes, working_bytes); | |
453 | kaddr = kmap_atomic(page_out, KM_USER0); | |
454 | memcpy(kaddr + pg_offset, workspace->buf + buf_offset, | |
455 | bytes); | |
456 | kunmap_atomic(kaddr, KM_USER0); | |
457 | flush_dcache_page(page_out); | |
458 | ||
459 | pg_offset += bytes; | |
460 | page_bytes_left -= bytes; | |
461 | buf_offset += bytes; | |
462 | working_bytes -= bytes; | |
463 | current_buf_start += bytes; | |
464 | ||
465 | /* check if we need to pick another page */ | |
466 | if (page_bytes_left == 0) { | |
467 | page_out_index++; | |
468 | if (page_out_index >= vcnt) { | |
469 | ret = 0; | |
470 | goto done; | |
471 | } | |
472 | page_out = bvec[page_out_index].bv_page; | |
473 | pg_offset = 0; | |
474 | page_bytes_left = PAGE_CACHE_SIZE; | |
475 | start_byte = page_offset(page_out) - disk_start; | |
476 | ||
477 | /* | |
478 | * make sure our new page is covered by this | |
479 | * working buffer | |
480 | */ | |
481 | if (total_out <= start_byte) { | |
482 | goto next; | |
483 | } | |
484 | ||
485 | /* the next page in the biovec might not | |
486 | * be adjacent to the last page, but it | |
487 | * might still be found inside this working | |
488 | * buffer. bump our offset pointer | |
489 | */ | |
490 | if (total_out > start_byte && | |
491 | current_buf_start < start_byte) { | |
492 | buf_offset = start_byte - buf_start; | |
493 | working_bytes = total_out - start_byte; | |
494 | current_buf_start = buf_start + | |
495 | buf_offset; | |
496 | } | |
497 | } | |
498 | } | |
499 | next: | |
500 | workspace->inf_strm.next_out = workspace->buf; | |
501 | workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; | |
502 | ||
503 | if (workspace->inf_strm.avail_in == 0) { | |
504 | unsigned long tmp; | |
505 | kunmap(pages_in[page_in_index]); | |
506 | page_in_index++; | |
507 | if (page_in_index >= total_pages_in) { | |
508 | data_in = NULL; | |
509 | break; | |
510 | } | |
511 | data_in = kmap(pages_in[page_in_index]); | |
512 | workspace->inf_strm.next_in = data_in; | |
513 | tmp = srclen - workspace->inf_strm.total_in; | |
514 | workspace->inf_strm.avail_in = min(tmp, | |
515 | PAGE_CACHE_SIZE); | |
516 | } | |
517 | } | |
518 | if (ret != Z_STREAM_END) { | |
519 | ret = -1; | |
520 | } else { | |
521 | ret = 0; | |
522 | } | |
523 | done: | |
524 | zlib_inflateEnd(&workspace->inf_strm); | |
525 | if (data_in) | |
526 | kunmap(pages_in[page_in_index]); | |
527 | out: | |
528 | free_workspace(workspace); | |
529 | return ret; | |
530 | } | |
531 | ||
532 | /* | |
533 | * a less complex decompression routine. Our compressed data fits in a | |
534 | * single page, and we want to read a single page out of it. | |
535 | * start_byte tells us the offset into the compressed data we're interested in | |
536 | */ | |
537 | int btrfs_zlib_decompress(unsigned char *data_in, | |
538 | struct page *dest_page, | |
539 | unsigned long start_byte, | |
540 | size_t srclen, size_t destlen) | |
541 | { | |
542 | int ret = 0; | |
543 | int wbits = MAX_WBITS; | |
544 | struct workspace *workspace; | |
545 | unsigned long bytes_left = destlen; | |
546 | unsigned long total_out = 0; | |
547 | char *kaddr; | |
548 | ||
549 | if (destlen > PAGE_CACHE_SIZE) | |
550 | return -ENOMEM; | |
551 | ||
552 | workspace = find_zlib_workspace(); | |
553 | if (!workspace) | |
554 | return -ENOMEM; | |
555 | ||
556 | workspace->inf_strm.next_in = data_in; | |
557 | workspace->inf_strm.avail_in = srclen; | |
558 | workspace->inf_strm.total_in = 0; | |
559 | ||
560 | workspace->inf_strm.next_out = workspace->buf; | |
561 | workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; | |
562 | workspace->inf_strm.total_out = 0; | |
563 | /* If it's deflate, and it's got no preset dictionary, then | |
564 | we can tell zlib to skip the adler32 check. */ | |
565 | if (srclen > 2 && !(data_in[1] & PRESET_DICT) && | |
566 | ((data_in[0] & 0x0f) == Z_DEFLATED) && | |
567 | !(((data_in[0]<<8) + data_in[1]) % 31)) { | |
568 | ||
569 | wbits = -((data_in[0] >> 4) + 8); | |
570 | workspace->inf_strm.next_in += 2; | |
571 | workspace->inf_strm.avail_in -= 2; | |
572 | } | |
573 | ||
574 | if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) { | |
575 | printk(KERN_WARNING "inflateInit failed\n"); | |
576 | ret = -1; | |
577 | goto out; | |
578 | } | |
579 | ||
580 | while(bytes_left > 0) { | |
581 | unsigned long buf_start; | |
582 | unsigned long buf_offset; | |
583 | unsigned long bytes; | |
584 | unsigned long pg_offset = 0; | |
585 | ||
586 | ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH); | |
587 | if (ret != Z_OK && ret != Z_STREAM_END) { | |
588 | break; | |
589 | } | |
590 | ||
591 | buf_start = total_out; | |
592 | total_out = workspace->inf_strm.total_out; | |
593 | ||
594 | if (total_out == buf_start) { | |
595 | ret = -1; | |
596 | break; | |
597 | } | |
598 | ||
599 | if (total_out <= start_byte) { | |
600 | goto next; | |
601 | } | |
602 | ||
603 | if (total_out > start_byte && buf_start < start_byte) { | |
604 | buf_offset = start_byte - buf_start; | |
605 | } else { | |
606 | buf_offset = 0; | |
607 | } | |
608 | ||
609 | bytes = min(PAGE_CACHE_SIZE - pg_offset, | |
610 | PAGE_CACHE_SIZE - buf_offset); | |
611 | bytes = min(bytes, bytes_left); | |
612 | ||
613 | kaddr = kmap_atomic(dest_page, KM_USER0); | |
614 | memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes); | |
615 | kunmap_atomic(kaddr, KM_USER0); | |
616 | ||
617 | pg_offset += bytes; | |
618 | bytes_left -= bytes; | |
619 | next: | |
620 | workspace->inf_strm.next_out = workspace->buf; | |
621 | workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; | |
622 | } | |
623 | if (ret != Z_STREAM_END && bytes_left != 0) { | |
624 | ret = -1; | |
625 | } else { | |
626 | ret = 0; | |
627 | } | |
628 | zlib_inflateEnd(&workspace->inf_strm); | |
629 | out: | |
630 | free_workspace(workspace); | |
631 | return ret; | |
632 | } | |
633 | ||
634 | void btrfs_zlib_exit(void) | |
635 | { | |
636 | free_workspaces(); | |
637 | } |