2 * Copyright (C) 2008 Oracle. All rights reserved.
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.
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.
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.
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"
34 void *buf
; /* where decompressed data goes */
35 void *cbuf
; /* where compressed data goes */
36 struct list_head list
;
39 static void lzo_free_workspace(struct list_head
*ws
)
41 struct workspace
*workspace
= list_entry(ws
, struct workspace
, list
);
43 vfree(workspace
->buf
);
44 vfree(workspace
->cbuf
);
45 vfree(workspace
->mem
);
49 static struct list_head
*lzo_alloc_workspace(void)
51 struct workspace
*workspace
;
53 workspace
= kzalloc(sizeof(*workspace
), GFP_NOFS
);
55 return ERR_PTR(-ENOMEM
);
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
)
63 INIT_LIST_HEAD(&workspace
->list
);
65 return &workspace
->list
;
67 lzo_free_workspace(&workspace
->list
);
68 return ERR_PTR(-ENOMEM
);
71 static inline void write_compress_length(char *buf
, size_t len
)
75 dlen
= cpu_to_le32(len
);
76 memcpy(buf
, &dlen
, LZO_LEN
);
79 static inline size_t read_compress_length(char *buf
)
83 memcpy(&dlen
, buf
, LZO_LEN
);
84 return le32_to_cpu(dlen
);
87 static int lzo_compress_pages(struct list_head
*ws
,
88 struct address_space
*mapping
,
89 u64 start
, unsigned long len
,
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
)
97 struct workspace
*workspace
= list_entry(ws
, struct workspace
, list
);
102 struct page
*in_page
= NULL
;
103 struct page
*out_page
= NULL
;
104 unsigned long bytes_left
;
109 unsigned long tot_in
= 0;
110 unsigned long tot_out
= 0;
111 unsigned long pg_bytes_left
;
112 unsigned long out_offset
;
119 in_page
= find_get_page(mapping
, start
>> PAGE_CACHE_SHIFT
);
120 data_in
= kmap(in_page
);
123 * store the size of all chunks of compressed data in
126 out_page
= alloc_page(GFP_NOFS
| __GFP_HIGHMEM
);
127 if (out_page
== NULL
) {
131 cpage_out
= kmap(out_page
);
132 out_offset
= LZO_LEN
;
136 pg_bytes_left
= PAGE_CACHE_SIZE
- LZO_LEN
;
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",
150 /* store the size of this chunk of compressed data */
151 write_compress_length(cpage_out
+ out_offset
, out_len
);
153 out_offset
+= LZO_LEN
;
154 pg_bytes_left
-= LZO_LEN
;
159 /* copy bytes from the working buffer into the pages */
160 buf
= workspace
->cbuf
;
162 bytes
= min_t(unsigned long, pg_bytes_left
, out_len
);
164 memcpy(cpage_out
+ out_offset
, buf
, bytes
);
167 pg_bytes_left
-= bytes
;
172 * we need another page for writing out.
174 * Note if there's less than 4 bytes left, we just
175 * skip to a new page.
177 if ((out_len
== 0 && pg_bytes_left
< LZO_LEN
) ||
178 pg_bytes_left
== 0) {
180 memset(cpage_out
+ out_offset
, 0,
182 tot_out
+= pg_bytes_left
;
185 /* we're done, don't allocate new page */
186 if (out_len
== 0 && tot_in
>= len
)
190 if (nr_pages
== nr_dest_pages
) {
196 out_page
= alloc_page(GFP_NOFS
| __GFP_HIGHMEM
);
197 if (out_page
== NULL
) {
201 cpage_out
= kmap(out_page
);
202 pages
[nr_pages
++] = out_page
;
204 pg_bytes_left
= PAGE_CACHE_SIZE
;
209 /* we're making it bigger, give up */
210 if (tot_in
> 8192 && tot_in
< tot_out
) {
219 if (tot_out
> max_out
)
222 bytes_left
= len
- tot_in
;
224 page_cache_release(in_page
);
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
);
232 if (tot_out
> tot_in
)
235 /* store the size of all chunks of compressed data */
236 cpage_out
= kmap(pages
[0]);
237 write_compress_length(cpage_out
, tot_out
);
242 *total_out
= tot_out
;
245 *out_pages
= nr_pages
;
251 page_cache_release(in_page
);
257 static int lzo_decompress_biovec(struct list_head
*ws
,
258 struct page
**pages_in
,
260 struct bio_vec
*bvec
,
264 struct workspace
*workspace
= list_entry(ws
, struct workspace
, list
);
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;
273 unsigned long working_bytes
;
274 unsigned long pg_offset
;
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
;
284 bool may_late_unmap
, need_unmap
;
286 data_in
= kmap(pages_in
[0]);
287 tot_len
= read_compress_length(data_in
);
291 tot_len
= min_t(size_t, srclen
, tot_len
);
292 in_page_bytes_left
= PAGE_CACHE_SIZE
- LZO_LEN
;
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
;
304 working_bytes
= in_len
;
305 may_late_unmap
= need_unmap
= false;
307 /* fast path: avoid using the working buffer */
308 if (in_page_bytes_left
>= in_len
) {
309 buf
= data_in
+ in_offset
;
311 may_late_unmap
= true;
315 /* copy bytes from the pages into the working buffer */
316 buf
= workspace
->cbuf
;
318 while (working_bytes
) {
319 bytes
= min(working_bytes
, in_page_bytes_left
);
321 memcpy(buf
+ buf_offset
, data_in
+ in_offset
, bytes
);
324 working_bytes
-= bytes
;
325 in_page_bytes_left
-= bytes
;
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
;
333 if (working_bytes
== 0 && tot_in
>= tot_len
)
336 if (page_in_index
+ 1 >= total_pages_in
) {
344 kunmap(pages_in
[page_in_index
]);
346 data_in
= kmap(pages_in
[++page_in_index
]);
348 in_page_bytes_left
= PAGE_CACHE_SIZE
;
353 out_len
= lzo1x_worst_compress(PAGE_CACHE_SIZE
);
354 ret
= lzo1x_decompress_safe(buf
, in_len
, workspace
->buf
,
357 kunmap(pages_in
[page_in_index
- 1]);
358 if (ret
!= LZO_E_OK
) {
359 printk(KERN_WARNING
"BTRFS: decompress failed\n");
367 ret2
= btrfs_decompress_buf2page(workspace
->buf
, buf_start
,
370 &page_out_index
, &pg_offset
);
375 kunmap(pages_in
[page_in_index
]);
377 btrfs_clear_biovec_end(bvec
, vcnt
, page_out_index
, pg_offset
);
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
)
386 struct workspace
*workspace
= list_entry(ws
, struct workspace
, list
);
394 BUG_ON(srclen
< LZO_LEN
);
396 tot_len
= read_compress_length(data_in
);
399 in_len
= read_compress_length(data_in
);
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");
410 if (out_len
< start_byte
) {
416 * the caller is already checking against PAGE_SIZE, but lets
417 * move this check closer to the memcpy/memset
419 destlen
= min_t(unsigned long, destlen
, PAGE_SIZE
);
420 bytes
= min_t(unsigned long, destlen
, out_len
- start_byte
);
422 kaddr
= kmap_atomic(dest_page
);
423 memcpy(kaddr
, workspace
->buf
+ start_byte
, bytes
);
426 * btrfs_getblock is doing a zero on the tail of the page too,
427 * but this will cover anything missing from the decompressed
431 memset(kaddr
+bytes
, 0, destlen
-bytes
);
432 kunmap_atomic(kaddr
);
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
,