Btrfs: cleanup scrub bio and worker wait code
[linux-3.10.git] / fs / btrfs / lzo.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
19 #include <linux/kernel.h>
20 #include <linux/slab.h>
21 #include <linux/vmalloc.h>
22 #include <linux/init.h>
23 #include <linux/err.h>
24 #include <linux/sched.h>
25 #include <linux/pagemap.h>
26 #include <linux/bio.h>
27 #include <linux/lzo.h>
28 #include "compression.h"
29
30 #define LZO_LEN 4
31
32 struct workspace {
33         void *mem;
34         void *buf;      /* where compressed data goes */
35         void *cbuf;     /* where decompressed data goes */
36         struct list_head list;
37 };
38
39 static void lzo_free_workspace(struct list_head *ws)
40 {
41         struct workspace *workspace = list_entry(ws, struct workspace, list);
42
43         vfree(workspace->buf);
44         vfree(workspace->cbuf);
45         vfree(workspace->mem);
46         kfree(workspace);
47 }
48
49 static struct list_head *lzo_alloc_workspace(void)
50 {
51         struct workspace *workspace;
52
53         workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
54         if (!workspace)
55                 return ERR_PTR(-ENOMEM);
56
57         workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
58         workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
59         workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
60         if (!workspace->mem || !workspace->buf || !workspace->cbuf)
61                 goto fail;
62
63         INIT_LIST_HEAD(&workspace->list);
64
65         return &workspace->list;
66 fail:
67         lzo_free_workspace(&workspace->list);
68         return ERR_PTR(-ENOMEM);
69 }
70
71 static inline void write_compress_length(char *buf, size_t len)
72 {
73         __le32 dlen;
74
75         dlen = cpu_to_le32(len);
76         memcpy(buf, &dlen, LZO_LEN);
77 }
78
79 static inline size_t read_compress_length(char *buf)
80 {
81         __le32 dlen;
82
83         memcpy(&dlen, buf, LZO_LEN);
84         return le32_to_cpu(dlen);
85 }
86
87 static int lzo_compress_pages(struct list_head *ws,
88                               struct address_space *mapping,
89                               u64 start, unsigned long len,
90                               struct page **pages,
91                               unsigned long nr_dest_pages,
92                               unsigned long *out_pages,
93                               unsigned long *total_in,
94                               unsigned long *total_out,
95                               unsigned long max_out)
96 {
97         struct workspace *workspace = list_entry(ws, struct workspace, list);
98         int ret = 0;
99         char *data_in;
100         char *cpage_out;
101         int nr_pages = 0;
102         struct page *in_page = NULL;
103         struct page *out_page = NULL;
104         unsigned long bytes_left;
105
106         size_t in_len;
107         size_t out_len;
108         char *buf;
109         unsigned long tot_in = 0;
110         unsigned long tot_out = 0;
111         unsigned long pg_bytes_left;
112         unsigned long out_offset;
113         unsigned long bytes;
114
115         *out_pages = 0;
116         *total_out = 0;
117         *total_in = 0;
118
119         in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
120         data_in = kmap(in_page);
121
122         /*
123          * store the size of all chunks of compressed data in
124          * the first 4 bytes
125          */
126         out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
127         if (out_page == NULL) {
128                 ret = -ENOMEM;
129                 goto out;
130         }
131         cpage_out = kmap(out_page);
132         out_offset = LZO_LEN;
133         tot_out = LZO_LEN;
134         pages[0] = out_page;
135         nr_pages = 1;
136         pg_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
137
138         /* compress at most one page of data each time */
139         in_len = min(len, PAGE_CACHE_SIZE);
140         while (tot_in < len) {
141                 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
142                                        &out_len, workspace->mem);
143                 if (ret != LZO_E_OK) {
144                         printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
145                                ret);
146                         ret = -1;
147                         goto out;
148                 }
149
150                 /* store the size of this chunk of compressed data */
151                 write_compress_length(cpage_out + out_offset, out_len);
152                 tot_out += LZO_LEN;
153                 out_offset += LZO_LEN;
154                 pg_bytes_left -= LZO_LEN;
155
156                 tot_in += in_len;
157                 tot_out += out_len;
158
159                 /* copy bytes from the working buffer into the pages */
160                 buf = workspace->cbuf;
161                 while (out_len) {
162                         bytes = min_t(unsigned long, pg_bytes_left, out_len);
163
164                         memcpy(cpage_out + out_offset, buf, bytes);
165
166                         out_len -= bytes;
167                         pg_bytes_left -= bytes;
168                         buf += bytes;
169                         out_offset += bytes;
170
171                         /*
172                          * we need another page for writing out.
173                          *
174                          * Note if there's less than 4 bytes left, we just
175                          * skip to a new page.
176                          */
177                         if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
178                             pg_bytes_left == 0) {
179                                 if (pg_bytes_left) {
180                                         memset(cpage_out + out_offset, 0,
181                                                pg_bytes_left);
182                                         tot_out += pg_bytes_left;
183                                 }
184
185                                 /* we're done, don't allocate new page */
186                                 if (out_len == 0 && tot_in >= len)
187                                         break;
188
189                                 kunmap(out_page);
190                                 if (nr_pages == nr_dest_pages) {
191                                         out_page = NULL;
192                                         ret = -1;
193                                         goto out;
194                                 }
195
196                                 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
197                                 if (out_page == NULL) {
198                                         ret = -ENOMEM;
199                                         goto out;
200                                 }
201                                 cpage_out = kmap(out_page);
202                                 pages[nr_pages++] = out_page;
203
204                                 pg_bytes_left = PAGE_CACHE_SIZE;
205                                 out_offset = 0;
206                         }
207                 }
208
209                 /* we're making it bigger, give up */
210                 if (tot_in > 8192 && tot_in < tot_out)
211                         goto out;
212
213                 /* we're all done */
214                 if (tot_in >= len)
215                         break;
216
217                 if (tot_out > max_out)
218                         break;
219
220                 bytes_left = len - tot_in;
221                 kunmap(in_page);
222                 page_cache_release(in_page);
223
224                 start += PAGE_CACHE_SIZE;
225                 in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
226                 data_in = kmap(in_page);
227                 in_len = min(bytes_left, PAGE_CACHE_SIZE);
228         }
229
230         if (tot_out > tot_in)
231                 goto out;
232
233         /* store the size of all chunks of compressed data */
234         cpage_out = kmap(pages[0]);
235         write_compress_length(cpage_out, tot_out);
236
237         kunmap(pages[0]);
238
239         ret = 0;
240         *total_out = tot_out;
241         *total_in = tot_in;
242 out:
243         *out_pages = nr_pages;
244         if (out_page)
245                 kunmap(out_page);
246
247         if (in_page) {
248                 kunmap(in_page);
249                 page_cache_release(in_page);
250         }
251
252         return ret;
253 }
254
255 static int lzo_decompress_biovec(struct list_head *ws,
256                                  struct page **pages_in,
257                                  u64 disk_start,
258                                  struct bio_vec *bvec,
259                                  int vcnt,
260                                  size_t srclen)
261 {
262         struct workspace *workspace = list_entry(ws, struct workspace, list);
263         int ret = 0, ret2;
264         char *data_in;
265         unsigned long page_in_index = 0;
266         unsigned long page_out_index = 0;
267         unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
268                                         PAGE_CACHE_SIZE;
269         unsigned long buf_start;
270         unsigned long buf_offset = 0;
271         unsigned long bytes;
272         unsigned long working_bytes;
273         unsigned long pg_offset;
274
275         size_t in_len;
276         size_t out_len;
277         unsigned long in_offset;
278         unsigned long in_page_bytes_left;
279         unsigned long tot_in;
280         unsigned long tot_out;
281         unsigned long tot_len;
282         char *buf;
283         bool may_late_unmap, need_unmap;
284
285         data_in = kmap(pages_in[0]);
286         tot_len = read_compress_length(data_in);
287
288         tot_in = LZO_LEN;
289         in_offset = LZO_LEN;
290         tot_len = min_t(size_t, srclen, tot_len);
291         in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
292
293         tot_out = 0;
294         pg_offset = 0;
295
296         while (tot_in < tot_len) {
297                 in_len = read_compress_length(data_in + in_offset);
298                 in_page_bytes_left -= LZO_LEN;
299                 in_offset += LZO_LEN;
300                 tot_in += LZO_LEN;
301
302                 tot_in += in_len;
303                 working_bytes = in_len;
304                 may_late_unmap = need_unmap = false;
305
306                 /* fast path: avoid using the working buffer */
307                 if (in_page_bytes_left >= in_len) {
308                         buf = data_in + in_offset;
309                         bytes = in_len;
310                         may_late_unmap = true;
311                         goto cont;
312                 }
313
314                 /* copy bytes from the pages into the working buffer */
315                 buf = workspace->cbuf;
316                 buf_offset = 0;
317                 while (working_bytes) {
318                         bytes = min(working_bytes, in_page_bytes_left);
319
320                         memcpy(buf + buf_offset, data_in + in_offset, bytes);
321                         buf_offset += bytes;
322 cont:
323                         working_bytes -= bytes;
324                         in_page_bytes_left -= bytes;
325                         in_offset += bytes;
326
327                         /* check if we need to pick another page */
328                         if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
329                             || in_page_bytes_left == 0) {
330                                 tot_in += in_page_bytes_left;
331
332                                 if (working_bytes == 0 && tot_in >= tot_len)
333                                         break;
334
335                                 if (page_in_index + 1 >= total_pages_in) {
336                                         ret = -1;
337                                         goto done;
338                                 }
339
340                                 if (may_late_unmap)
341                                         need_unmap = true;
342                                 else
343                                         kunmap(pages_in[page_in_index]);
344
345                                 data_in = kmap(pages_in[++page_in_index]);
346
347                                 in_page_bytes_left = PAGE_CACHE_SIZE;
348                                 in_offset = 0;
349                         }
350                 }
351
352                 out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
353                 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
354                                             &out_len);
355                 if (need_unmap)
356                         kunmap(pages_in[page_in_index - 1]);
357                 if (ret != LZO_E_OK) {
358                         printk(KERN_WARNING "btrfs decompress failed\n");
359                         ret = -1;
360                         break;
361                 }
362
363                 buf_start = tot_out;
364                 tot_out += out_len;
365
366                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
367                                                  tot_out, disk_start,
368                                                  bvec, vcnt,
369                                                  &page_out_index, &pg_offset);
370                 if (ret2 == 0)
371                         break;
372         }
373 done:
374         kunmap(pages_in[page_in_index]);
375         return ret;
376 }
377
378 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
379                           struct page *dest_page,
380                           unsigned long start_byte,
381                           size_t srclen, size_t destlen)
382 {
383         struct workspace *workspace = list_entry(ws, struct workspace, list);
384         size_t in_len;
385         size_t out_len;
386         size_t tot_len;
387         int ret = 0;
388         char *kaddr;
389         unsigned long bytes;
390
391         BUG_ON(srclen < LZO_LEN);
392
393         tot_len = read_compress_length(data_in);
394         data_in += LZO_LEN;
395
396         in_len = read_compress_length(data_in);
397         data_in += LZO_LEN;
398
399         out_len = PAGE_CACHE_SIZE;
400         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
401         if (ret != LZO_E_OK) {
402                 printk(KERN_WARNING "btrfs decompress failed!\n");
403                 ret = -1;
404                 goto out;
405         }
406
407         if (out_len < start_byte) {
408                 ret = -1;
409                 goto out;
410         }
411
412         bytes = min_t(unsigned long, destlen, out_len - start_byte);
413
414         kaddr = kmap_atomic(dest_page);
415         memcpy(kaddr, workspace->buf + start_byte, bytes);
416         kunmap_atomic(kaddr);
417 out:
418         return ret;
419 }
420
421 struct btrfs_compress_op btrfs_lzo_compress = {
422         .alloc_workspace        = lzo_alloc_workspace,
423         .free_workspace         = lzo_free_workspace,
424         .compress_pages         = lzo_compress_pages,
425         .decompress_biovec      = lzo_decompress_biovec,
426         .decompress             = lzo_decompress,
427 };