1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2008 Oracle. All rights reserved.
6 #include <linux/kernel.h>
7 #include <linux/slab.h>
9 #include <linux/init.h>
10 #include <linux/err.h>
11 #include <linux/sched.h>
12 #include <linux/pagemap.h>
13 #include <linux/bio.h>
14 #include <linux/lzo.h>
15 #include <linux/refcount.h>
16 #include "compression.h"
22 void *buf; /* where decompressed data goes */
23 void *cbuf; /* where compressed data goes */
24 struct list_head list;
27 static void lzo_free_workspace(struct list_head *ws)
29 struct workspace *workspace = list_entry(ws, struct workspace, list);
31 kvfree(workspace->buf);
32 kvfree(workspace->cbuf);
33 kvfree(workspace->mem);
37 static struct list_head *lzo_alloc_workspace(void)
39 struct workspace *workspace;
41 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
43 return ERR_PTR(-ENOMEM);
45 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
46 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
47 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
48 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
51 INIT_LIST_HEAD(&workspace->list);
53 return &workspace->list;
55 lzo_free_workspace(&workspace->list);
56 return ERR_PTR(-ENOMEM);
59 static inline void write_compress_length(char *buf, size_t len)
63 dlen = cpu_to_le32(len);
64 memcpy(buf, &dlen, LZO_LEN);
67 static inline size_t read_compress_length(const char *buf)
71 memcpy(&dlen, buf, LZO_LEN);
72 return le32_to_cpu(dlen);
75 static int lzo_compress_pages(struct list_head *ws,
76 struct address_space *mapping,
79 unsigned long *out_pages,
80 unsigned long *total_in,
81 unsigned long *total_out)
83 struct workspace *workspace = list_entry(ws, struct workspace, list);
88 struct page *in_page = NULL;
89 struct page *out_page = NULL;
90 unsigned long bytes_left;
91 unsigned long len = *total_out;
92 unsigned long nr_dest_pages = *out_pages;
93 const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
97 unsigned long tot_in = 0;
98 unsigned long tot_out = 0;
99 unsigned long pg_bytes_left;
100 unsigned long out_offset;
107 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
108 data_in = kmap(in_page);
111 * store the size of all chunks of compressed data in
114 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
115 if (out_page == NULL) {
119 cpage_out = kmap(out_page);
120 out_offset = LZO_LEN;
124 pg_bytes_left = PAGE_SIZE - LZO_LEN;
126 /* compress at most one page of data each time */
127 in_len = min(len, PAGE_SIZE);
128 while (tot_in < len) {
129 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
130 &out_len, workspace->mem);
131 if (ret != LZO_E_OK) {
132 pr_debug("BTRFS: lzo in loop returned %d\n",
138 /* store the size of this chunk of compressed data */
139 write_compress_length(cpage_out + out_offset, out_len);
141 out_offset += LZO_LEN;
142 pg_bytes_left -= LZO_LEN;
147 /* copy bytes from the working buffer into the pages */
148 buf = workspace->cbuf;
150 bytes = min_t(unsigned long, pg_bytes_left, out_len);
152 memcpy(cpage_out + out_offset, buf, bytes);
155 pg_bytes_left -= bytes;
160 * we need another page for writing out.
162 * Note if there's less than 4 bytes left, we just
163 * skip to a new page.
165 if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
166 pg_bytes_left == 0) {
168 memset(cpage_out + out_offset, 0,
170 tot_out += pg_bytes_left;
173 /* we're done, don't allocate new page */
174 if (out_len == 0 && tot_in >= len)
178 if (nr_pages == nr_dest_pages) {
184 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
185 if (out_page == NULL) {
189 cpage_out = kmap(out_page);
190 pages[nr_pages++] = out_page;
192 pg_bytes_left = PAGE_SIZE;
197 /* we're making it bigger, give up */
198 if (tot_in > 8192 && tot_in < tot_out) {
207 if (tot_out > max_out)
210 bytes_left = len - tot_in;
215 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
216 data_in = kmap(in_page);
217 in_len = min(bytes_left, PAGE_SIZE);
220 if (tot_out >= tot_in) {
225 /* store the size of all chunks of compressed data */
226 cpage_out = kmap(pages[0]);
227 write_compress_length(cpage_out, tot_out);
232 *total_out = tot_out;
235 *out_pages = nr_pages;
247 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
249 struct workspace *workspace = list_entry(ws, struct workspace, list);
252 unsigned long page_in_index = 0;
253 size_t srclen = cb->compressed_len;
254 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
255 unsigned long buf_start;
256 unsigned long buf_offset = 0;
258 unsigned long working_bytes;
261 unsigned long in_offset;
262 unsigned long in_page_bytes_left;
263 unsigned long tot_in;
264 unsigned long tot_out;
265 unsigned long tot_len;
267 bool may_late_unmap, need_unmap;
268 struct page **pages_in = cb->compressed_pages;
269 u64 disk_start = cb->start;
270 struct bio *orig_bio = cb->orig_bio;
272 data_in = kmap(pages_in[0]);
273 tot_len = read_compress_length(data_in);
277 tot_len = min_t(size_t, srclen, tot_len);
278 in_page_bytes_left = PAGE_SIZE - LZO_LEN;
282 while (tot_in < tot_len) {
283 in_len = read_compress_length(data_in + in_offset);
284 in_page_bytes_left -= LZO_LEN;
285 in_offset += LZO_LEN;
289 working_bytes = in_len;
290 may_late_unmap = need_unmap = false;
292 /* fast path: avoid using the working buffer */
293 if (in_page_bytes_left >= in_len) {
294 buf = data_in + in_offset;
296 may_late_unmap = true;
300 /* copy bytes from the pages into the working buffer */
301 buf = workspace->cbuf;
303 while (working_bytes) {
304 bytes = min(working_bytes, in_page_bytes_left);
306 memcpy(buf + buf_offset, data_in + in_offset, bytes);
309 working_bytes -= bytes;
310 in_page_bytes_left -= bytes;
313 /* check if we need to pick another page */
314 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
315 || in_page_bytes_left == 0) {
316 tot_in += in_page_bytes_left;
318 if (working_bytes == 0 && tot_in >= tot_len)
321 if (page_in_index + 1 >= total_pages_in) {
329 kunmap(pages_in[page_in_index]);
331 data_in = kmap(pages_in[++page_in_index]);
333 in_page_bytes_left = PAGE_SIZE;
338 out_len = lzo1x_worst_compress(PAGE_SIZE);
339 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
342 kunmap(pages_in[page_in_index - 1]);
343 if (ret != LZO_E_OK) {
344 pr_warn("BTRFS: decompress failed\n");
352 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
353 tot_out, disk_start, orig_bio);
358 kunmap(pages_in[page_in_index]);
360 zero_fill_bio(orig_bio);
364 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
365 struct page *dest_page,
366 unsigned long start_byte,
367 size_t srclen, size_t destlen)
369 struct workspace *workspace = list_entry(ws, struct workspace, list);
376 BUG_ON(srclen < LZO_LEN);
380 in_len = read_compress_length(data_in);
384 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
385 if (ret != LZO_E_OK) {
386 pr_warn("BTRFS: decompress failed!\n");
391 if (out_len < start_byte) {
397 * the caller is already checking against PAGE_SIZE, but lets
398 * move this check closer to the memcpy/memset
400 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
401 bytes = min_t(unsigned long, destlen, out_len - start_byte);
403 kaddr = kmap_atomic(dest_page);
404 memcpy(kaddr, workspace->buf + start_byte, bytes);
407 * btrfs_getblock is doing a zero on the tail of the page too,
408 * but this will cover anything missing from the decompressed
412 memset(kaddr+bytes, 0, destlen-bytes);
413 kunmap_atomic(kaddr);
418 static void lzo_set_level(struct list_head *ws, unsigned int type)
422 const struct btrfs_compress_op btrfs_lzo_compress = {
423 .alloc_workspace = lzo_alloc_workspace,
424 .free_workspace = lzo_free_workspace,
425 .compress_pages = lzo_compress_pages,
426 .decompress_bio = lzo_decompress_bio,
427 .decompress = lzo_decompress,
428 .set_level = lzo_set_level,