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Linux/fs/btrfs/lzo.c

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  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 decompressed data goes */
 35         void *cbuf;     /* where compressed 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 = -EIO;
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 = -E2BIG;
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                         ret = -E2BIG;
212                         goto out;
213                 }
214 
215                 /* we're all done */
216                 if (tot_in >= len)
217                         break;
218 
219                 if (tot_out > max_out)
220                         break;
221 
222                 bytes_left = len - tot_in;
223                 kunmap(in_page);
224                 page_cache_release(in_page);
225 
226                 start += PAGE_CACHE_SIZE;
227                 in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
228                 data_in = kmap(in_page);
229                 in_len = min(bytes_left, PAGE_CACHE_SIZE);
230         }
231 
232         if (tot_out > tot_in)
233                 goto out;
234 
235         /* store the size of all chunks of compressed data */
236         cpage_out = kmap(pages[0]);
237         write_compress_length(cpage_out, tot_out);
238 
239         kunmap(pages[0]);
240 
241         ret = 0;
242         *total_out = tot_out;
243         *total_in = tot_in;
244 out:
245         *out_pages = nr_pages;
246         if (out_page)
247                 kunmap(out_page);
248 
249         if (in_page) {
250                 kunmap(in_page);
251                 page_cache_release(in_page);
252         }
253 
254         return ret;
255 }
256 
257 static int lzo_decompress_biovec(struct list_head *ws,
258                                  struct page **pages_in,
259                                  u64 disk_start,
260                                  struct bio_vec *bvec,
261                                  int vcnt,
262                                  size_t srclen)
263 {
264         struct workspace *workspace = list_entry(ws, struct workspace, list);
265         int ret = 0, ret2;
266         char *data_in;
267         unsigned long page_in_index = 0;
268         unsigned long page_out_index = 0;
269         unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE);
270         unsigned long buf_start;
271         unsigned long buf_offset = 0;
272         unsigned long bytes;
273         unsigned long working_bytes;
274         unsigned long pg_offset;
275 
276         size_t in_len;
277         size_t out_len;
278         unsigned long in_offset;
279         unsigned long in_page_bytes_left;
280         unsigned long tot_in;
281         unsigned long tot_out;
282         unsigned long tot_len;
283         char *buf;
284         bool may_late_unmap, need_unmap;
285 
286         data_in = kmap(pages_in[0]);
287         tot_len = read_compress_length(data_in);
288 
289         tot_in = LZO_LEN;
290         in_offset = LZO_LEN;
291         tot_len = min_t(size_t, srclen, tot_len);
292         in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
293 
294         tot_out = 0;
295         pg_offset = 0;
296 
297         while (tot_in < tot_len) {
298                 in_len = read_compress_length(data_in + in_offset);
299                 in_page_bytes_left -= LZO_LEN;
300                 in_offset += LZO_LEN;
301                 tot_in += LZO_LEN;
302 
303                 tot_in += in_len;
304                 working_bytes = in_len;
305                 may_late_unmap = need_unmap = false;
306 
307                 /* fast path: avoid using the working buffer */
308                 if (in_page_bytes_left >= in_len) {
309                         buf = data_in + in_offset;
310                         bytes = in_len;
311                         may_late_unmap = true;
312                         goto cont;
313                 }
314 
315                 /* copy bytes from the pages into the working buffer */
316                 buf = workspace->cbuf;
317                 buf_offset = 0;
318                 while (working_bytes) {
319                         bytes = min(working_bytes, in_page_bytes_left);
320 
321                         memcpy(buf + buf_offset, data_in + in_offset, bytes);
322                         buf_offset += bytes;
323 cont:
324                         working_bytes -= bytes;
325                         in_page_bytes_left -= bytes;
326                         in_offset += bytes;
327 
328                         /* check if we need to pick another page */
329                         if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
330                             || in_page_bytes_left == 0) {
331                                 tot_in += in_page_bytes_left;
332 
333                                 if (working_bytes == 0 && tot_in >= tot_len)
334                                         break;
335 
336                                 if (page_in_index + 1 >= total_pages_in) {
337                                         ret = -EIO;
338                                         goto done;
339                                 }
340 
341                                 if (may_late_unmap)
342                                         need_unmap = true;
343                                 else
344                                         kunmap(pages_in[page_in_index]);
345 
346                                 data_in = kmap(pages_in[++page_in_index]);
347 
348                                 in_page_bytes_left = PAGE_CACHE_SIZE;
349                                 in_offset = 0;
350                         }
351                 }
352 
353                 out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
354                 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
355                                             &out_len);
356                 if (need_unmap)
357                         kunmap(pages_in[page_in_index - 1]);
358                 if (ret != LZO_E_OK) {
359                         printk(KERN_WARNING "BTRFS: decompress failed\n");
360                         ret = -EIO;
361                         break;
362                 }
363 
364                 buf_start = tot_out;
365                 tot_out += out_len;
366 
367                 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
368                                                  tot_out, disk_start,
369                                                  bvec, vcnt,
370                                                  &page_out_index, &pg_offset);
371                 if (ret2 == 0)
372                         break;
373         }
374 done:
375         kunmap(pages_in[page_in_index]);
376         if (!ret)
377                 btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
378         return ret;
379 }
380 
381 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
382                           struct page *dest_page,
383                           unsigned long start_byte,
384                           size_t srclen, size_t destlen)
385 {
386         struct workspace *workspace = list_entry(ws, struct workspace, list);
387         size_t in_len;
388         size_t out_len;
389         size_t tot_len;
390         int ret = 0;
391         char *kaddr;
392         unsigned long bytes;
393 
394         BUG_ON(srclen < LZO_LEN);
395 
396         tot_len = read_compress_length(data_in);
397         data_in += LZO_LEN;
398 
399         in_len = read_compress_length(data_in);
400         data_in += LZO_LEN;
401 
402         out_len = PAGE_CACHE_SIZE;
403         ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
404         if (ret != LZO_E_OK) {
405                 printk(KERN_WARNING "BTRFS: decompress failed!\n");
406                 ret = -EIO;
407                 goto out;
408         }
409 
410         if (out_len < start_byte) {
411                 ret = -EIO;
412                 goto out;
413         }
414 
415         /*
416          * the caller is already checking against PAGE_SIZE, but lets
417          * move this check closer to the memcpy/memset
418          */
419         destlen = min_t(unsigned long, destlen, PAGE_SIZE);
420         bytes = min_t(unsigned long, destlen, out_len - start_byte);
421 
422         kaddr = kmap_atomic(dest_page);
423         memcpy(kaddr, workspace->buf + start_byte, bytes);
424 
425         /*
426          * btrfs_getblock is doing a zero on the tail of the page too,
427          * but this will cover anything missing from the decompressed
428          * data.
429          */
430         if (bytes < destlen)
431                 memset(kaddr+bytes, 0, destlen-bytes);
432         kunmap_atomic(kaddr);
433 out:
434         return ret;
435 }
436 
437 const struct btrfs_compress_op btrfs_lzo_compress = {
438         .alloc_workspace        = lzo_alloc_workspace,
439         .free_workspace         = lzo_free_workspace,
440         .compress_pages         = lzo_compress_pages,
441         .decompress_biovec      = lzo_decompress_biovec,
442         .decompress             = lzo_decompress,
443 };
444 

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