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>
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 <linux/refcount.h>
29 #include "compression.h"
35 void *buf; /* where decompressed data goes */
36 void *cbuf; /* where compressed data goes */
37 struct list_head list;
40 static void lzo_free_workspace(struct list_head *ws)
42 struct workspace *workspace = list_entry(ws, struct workspace, list);
44 kvfree(workspace->buf);
45 kvfree(workspace->cbuf);
46 kvfree(workspace->mem);
50 static struct list_head *lzo_alloc_workspace(void)
52 struct workspace *workspace;
54 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
56 return ERR_PTR(-ENOMEM);
58 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
59 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
60 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
61 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
64 INIT_LIST_HEAD(&workspace->list);
66 return &workspace->list;
68 lzo_free_workspace(&workspace->list);
69 return ERR_PTR(-ENOMEM);
72 static inline void write_compress_length(char *buf, size_t len)
76 dlen = cpu_to_le32(len);
77 memcpy(buf, &dlen, LZO_LEN);
80 static inline size_t read_compress_length(const char *buf)
84 memcpy(&dlen, buf, LZO_LEN);
85 return le32_to_cpu(dlen);
88 static int lzo_compress_pages(struct list_head *ws,
89 struct address_space *mapping,
92 unsigned long *out_pages,
93 unsigned long *total_in,
94 unsigned long *total_out)
96 struct workspace *workspace = list_entry(ws, struct workspace, list);
101 struct page *in_page = NULL;
102 struct page *out_page = NULL;
103 unsigned long bytes_left;
104 unsigned long len = *total_out;
105 unsigned long nr_dest_pages = *out_pages;
106 const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
110 unsigned long tot_in = 0;
111 unsigned long tot_out = 0;
112 unsigned long pg_bytes_left;
113 unsigned long out_offset;
120 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
121 data_in = kmap(in_page);
124 * store the size of all chunks of compressed data in
127 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
128 if (out_page == NULL) {
132 cpage_out = kmap(out_page);
133 out_offset = LZO_LEN;
137 pg_bytes_left = PAGE_SIZE - LZO_LEN;
139 /* compress at most one page of data each time */
140 in_len = min(len, PAGE_SIZE);
141 while (tot_in < len) {
142 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
143 &out_len, workspace->mem);
144 if (ret != LZO_E_OK) {
145 pr_debug("BTRFS: lzo in loop returned %d\n",
151 /* store the size of this chunk of compressed data */
152 write_compress_length(cpage_out + out_offset, out_len);
154 out_offset += LZO_LEN;
155 pg_bytes_left -= LZO_LEN;
160 /* copy bytes from the working buffer into the pages */
161 buf = workspace->cbuf;
163 bytes = min_t(unsigned long, pg_bytes_left, out_len);
165 memcpy(cpage_out + out_offset, buf, bytes);
168 pg_bytes_left -= bytes;
173 * we need another page for writing out.
175 * Note if there's less than 4 bytes left, we just
176 * skip to a new page.
178 if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
179 pg_bytes_left == 0) {
181 memset(cpage_out + out_offset, 0,
183 tot_out += pg_bytes_left;
186 /* we're done, don't allocate new page */
187 if (out_len == 0 && tot_in >= len)
191 if (nr_pages == nr_dest_pages) {
197 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
198 if (out_page == NULL) {
202 cpage_out = kmap(out_page);
203 pages[nr_pages++] = out_page;
205 pg_bytes_left = PAGE_SIZE;
210 /* we're making it bigger, give up */
211 if (tot_in > 8192 && tot_in < tot_out) {
220 if (tot_out > max_out)
223 bytes_left = len - tot_in;
228 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
229 data_in = kmap(in_page);
230 in_len = min(bytes_left, PAGE_SIZE);
233 if (tot_out >= tot_in) {
238 /* store the size of all chunks of compressed data */
239 cpage_out = kmap(pages[0]);
240 write_compress_length(cpage_out, tot_out);
245 *total_out = tot_out;
248 *out_pages = nr_pages;
260 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
262 struct workspace *workspace = list_entry(ws, struct workspace, list);
265 unsigned long page_in_index = 0;
266 size_t srclen = cb->compressed_len;
267 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
268 unsigned long buf_start;
269 unsigned long buf_offset = 0;
271 unsigned long working_bytes;
274 unsigned long in_offset;
275 unsigned long in_page_bytes_left;
276 unsigned long tot_in;
277 unsigned long tot_out;
278 unsigned long tot_len;
280 bool may_late_unmap, need_unmap;
281 struct page **pages_in = cb->compressed_pages;
282 u64 disk_start = cb->start;
283 struct bio *orig_bio = cb->orig_bio;
285 data_in = kmap(pages_in[0]);
286 tot_len = read_compress_length(data_in);
290 tot_len = min_t(size_t, srclen, tot_len);
291 in_page_bytes_left = PAGE_SIZE - LZO_LEN;
295 while (tot_in < tot_len) {
296 in_len = read_compress_length(data_in + in_offset);
297 in_page_bytes_left -= LZO_LEN;
298 in_offset += LZO_LEN;
302 working_bytes = in_len;
303 may_late_unmap = need_unmap = false;
305 /* fast path: avoid using the working buffer */
306 if (in_page_bytes_left >= in_len) {
307 buf = data_in + in_offset;
309 may_late_unmap = true;
313 /* copy bytes from the pages into the working buffer */
314 buf = workspace->cbuf;
316 while (working_bytes) {
317 bytes = min(working_bytes, in_page_bytes_left);
319 memcpy(buf + buf_offset, data_in + in_offset, bytes);
322 working_bytes -= bytes;
323 in_page_bytes_left -= bytes;
326 /* check if we need to pick another page */
327 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
328 || in_page_bytes_left == 0) {
329 tot_in += in_page_bytes_left;
331 if (working_bytes == 0 && tot_in >= tot_len)
334 if (page_in_index + 1 >= total_pages_in) {
342 kunmap(pages_in[page_in_index]);
344 data_in = kmap(pages_in[++page_in_index]);
346 in_page_bytes_left = PAGE_SIZE;
351 out_len = lzo1x_worst_compress(PAGE_SIZE);
352 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
355 kunmap(pages_in[page_in_index - 1]);
356 if (ret != LZO_E_OK) {
357 pr_warn("BTRFS: decompress failed\n");
365 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
366 tot_out, disk_start, orig_bio);
371 kunmap(pages_in[page_in_index]);
373 zero_fill_bio(orig_bio);
377 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
378 struct page *dest_page,
379 unsigned long start_byte,
380 size_t srclen, size_t destlen)
382 struct workspace *workspace = list_entry(ws, struct workspace, list);
390 BUG_ON(srclen < LZO_LEN);
392 tot_len = read_compress_length(data_in);
395 in_len = read_compress_length(data_in);
399 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
400 if (ret != LZO_E_OK) {
401 pr_warn("BTRFS: decompress failed!\n");
406 if (out_len < start_byte) {
412 * the caller is already checking against PAGE_SIZE, but lets
413 * move this check closer to the memcpy/memset
415 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
416 bytes = min_t(unsigned long, destlen, out_len - start_byte);
418 kaddr = kmap_atomic(dest_page);
419 memcpy(kaddr, workspace->buf + start_byte, bytes);
422 * btrfs_getblock is doing a zero on the tail of the page too,
423 * but this will cover anything missing from the decompressed
427 memset(kaddr+bytes, 0, destlen-bytes);
428 kunmap_atomic(kaddr);
433 const struct btrfs_compress_op btrfs_lzo_compress = {
434 .alloc_workspace = lzo_alloc_workspace,
435 .free_workspace = lzo_free_workspace,
436 .compress_pages = lzo_compress_pages,
437 .decompress_bio = lzo_decompress_bio,
438 .decompress = lzo_decompress,