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"
21 * Btrfs LZO compression format
23 * Regular and inlined LZO compressed data extents consist of:
26 * Fixed size. LZO_LEN (4) bytes long, LE32.
27 * Records the total size (including the header) of compressed data.
30 * Variable size. Each segment includes one segment header, followed by data
32 * One regular LZO compressed extent can have one or more segments.
33 * For inlined LZO compressed extent, only one segment is allowed.
34 * One segment represents at most one page of uncompressed data.
37 * Fixed size. LZO_LEN (4) bytes long, LE32.
38 * Records the total size of the segment (not including the header).
39 * Segment header never crosses page boundary, thus it's possible to
40 * have at most 3 padding zeros at the end of the page.
43 * Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
44 * which is 4419 for a 4KiB page.
48 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
49 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
51 * 0x0ff0 | SegHdr N | Data payload N ... |00|
54 * 0x1000 | SegHdr N+1| Data payload N+1 ... |
59 void *buf; /* where decompressed data goes */
60 void *cbuf; /* where compressed data goes */
61 struct list_head list;
64 static struct workspace_manager wsm;
66 void lzo_free_workspace(struct list_head *ws)
68 struct workspace *workspace = list_entry(ws, struct workspace, list);
70 kvfree(workspace->buf);
71 kvfree(workspace->cbuf);
72 kvfree(workspace->mem);
76 struct list_head *lzo_alloc_workspace(unsigned int level)
78 struct workspace *workspace;
80 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
82 return ERR_PTR(-ENOMEM);
84 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
85 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
86 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
87 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
90 INIT_LIST_HEAD(&workspace->list);
92 return &workspace->list;
94 lzo_free_workspace(&workspace->list);
95 return ERR_PTR(-ENOMEM);
98 static inline void write_compress_length(char *buf, size_t len)
102 dlen = cpu_to_le32(len);
103 memcpy(buf, &dlen, LZO_LEN);
106 static inline size_t read_compress_length(const char *buf)
110 memcpy(&dlen, buf, LZO_LEN);
111 return le32_to_cpu(dlen);
114 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
115 u64 start, struct page **pages, unsigned long *out_pages,
116 unsigned long *total_in, unsigned long *total_out)
118 struct workspace *workspace = list_entry(ws, struct workspace, list);
121 char *cpage_out, *sizes_ptr;
123 struct page *in_page = NULL;
124 struct page *out_page = NULL;
125 unsigned long bytes_left;
126 unsigned long len = *total_out;
127 unsigned long nr_dest_pages = *out_pages;
128 const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
132 unsigned long tot_in = 0;
133 unsigned long tot_out = 0;
134 unsigned long pg_bytes_left;
135 unsigned long out_offset;
142 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
143 data_in = kmap(in_page);
146 * store the size of all chunks of compressed data in
149 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
150 if (out_page == NULL) {
154 cpage_out = kmap(out_page);
155 out_offset = LZO_LEN;
159 pg_bytes_left = PAGE_SIZE - LZO_LEN;
161 /* compress at most one page of data each time */
162 in_len = min(len, PAGE_SIZE);
163 while (tot_in < len) {
164 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
165 &out_len, workspace->mem);
166 if (ret != LZO_E_OK) {
167 pr_debug("BTRFS: lzo in loop returned %d\n",
173 /* store the size of this chunk of compressed data */
174 write_compress_length(cpage_out + out_offset, out_len);
176 out_offset += LZO_LEN;
177 pg_bytes_left -= LZO_LEN;
182 /* copy bytes from the working buffer into the pages */
183 buf = workspace->cbuf;
185 bytes = min_t(unsigned long, pg_bytes_left, out_len);
187 memcpy(cpage_out + out_offset, buf, bytes);
190 pg_bytes_left -= bytes;
195 * we need another page for writing out.
197 * Note if there's less than 4 bytes left, we just
198 * skip to a new page.
200 if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
201 pg_bytes_left == 0) {
203 memset(cpage_out + out_offset, 0,
205 tot_out += pg_bytes_left;
208 /* we're done, don't allocate new page */
209 if (out_len == 0 && tot_in >= len)
213 if (nr_pages == nr_dest_pages) {
219 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
220 if (out_page == NULL) {
224 cpage_out = kmap(out_page);
225 pages[nr_pages++] = out_page;
227 pg_bytes_left = PAGE_SIZE;
232 /* we're making it bigger, give up */
233 if (tot_in > 8192 && tot_in < tot_out) {
242 if (tot_out > max_out)
245 bytes_left = len - tot_in;
250 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
251 data_in = kmap(in_page);
252 in_len = min(bytes_left, PAGE_SIZE);
255 if (tot_out >= tot_in) {
260 /* store the size of all chunks of compressed data */
261 sizes_ptr = kmap_local_page(pages[0]);
262 write_compress_length(sizes_ptr, tot_out);
263 kunmap_local(sizes_ptr);
266 *total_out = tot_out;
269 *out_pages = nr_pages;
281 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
283 struct workspace *workspace = list_entry(ws, struct workspace, list);
286 unsigned long page_in_index = 0;
287 size_t srclen = cb->compressed_len;
288 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
289 unsigned long buf_start;
290 unsigned long buf_offset = 0;
292 unsigned long working_bytes;
295 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
296 unsigned long in_offset;
297 unsigned long in_page_bytes_left;
298 unsigned long tot_in;
299 unsigned long tot_out;
300 unsigned long tot_len;
302 bool may_late_unmap, need_unmap;
303 struct page **pages_in = cb->compressed_pages;
304 u64 disk_start = cb->start;
305 struct bio *orig_bio = cb->orig_bio;
307 data_in = kmap(pages_in[0]);
308 tot_len = read_compress_length(data_in);
310 * Compressed data header check.
312 * The real compressed size can't exceed the maximum extent length, and
313 * all pages should be used (whole unused page with just the segment
314 * header is not possible). If this happens it means the compressed
315 * extent is corrupted.
317 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
318 tot_len < srclen - PAGE_SIZE) {
325 in_page_bytes_left = PAGE_SIZE - LZO_LEN;
329 while (tot_in < tot_len) {
330 in_len = read_compress_length(data_in + in_offset);
331 in_page_bytes_left -= LZO_LEN;
332 in_offset += LZO_LEN;
336 * Segment header check.
338 * The segment length must not exceed the maximum LZO
339 * compression size, nor the total compressed size.
341 if (in_len > max_segment_len || tot_in + in_len > tot_len) {
347 working_bytes = in_len;
348 may_late_unmap = need_unmap = false;
350 /* fast path: avoid using the working buffer */
351 if (in_page_bytes_left >= in_len) {
352 buf = data_in + in_offset;
354 may_late_unmap = true;
358 /* copy bytes from the pages into the working buffer */
359 buf = workspace->cbuf;
361 while (working_bytes) {
362 bytes = min(working_bytes, in_page_bytes_left);
364 memcpy(buf + buf_offset, data_in + in_offset, bytes);
367 working_bytes -= bytes;
368 in_page_bytes_left -= bytes;
371 /* check if we need to pick another page */
372 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
373 || in_page_bytes_left == 0) {
374 tot_in += in_page_bytes_left;
376 if (working_bytes == 0 && tot_in >= tot_len)
379 if (page_in_index + 1 >= total_pages_in) {
387 kunmap(pages_in[page_in_index]);
389 data_in = kmap(pages_in[++page_in_index]);
391 in_page_bytes_left = PAGE_SIZE;
396 out_len = max_segment_len;
397 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
400 kunmap(pages_in[page_in_index - 1]);
401 if (ret != LZO_E_OK) {
402 pr_warn("BTRFS: decompress failed\n");
410 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
411 tot_out, disk_start, orig_bio);
416 kunmap(pages_in[page_in_index]);
418 zero_fill_bio(orig_bio);
422 int lzo_decompress(struct list_head *ws, unsigned char *data_in,
423 struct page *dest_page, unsigned long start_byte, size_t srclen,
426 struct workspace *workspace = list_entry(ws, struct workspace, list);
429 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
434 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
437 in_len = read_compress_length(data_in);
438 if (in_len != srclen)
442 in_len = read_compress_length(data_in);
443 if (in_len != srclen - LZO_LEN * 2) {
450 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
451 if (ret != LZO_E_OK) {
452 pr_warn("BTRFS: decompress failed!\n");
457 if (out_len < start_byte) {
463 * the caller is already checking against PAGE_SIZE, but lets
464 * move this check closer to the memcpy/memset
466 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
467 bytes = min_t(unsigned long, destlen, out_len - start_byte);
469 kaddr = kmap_local_page(dest_page);
470 memcpy(kaddr, workspace->buf + start_byte, bytes);
473 * btrfs_getblock is doing a zero on the tail of the page too,
474 * but this will cover anything missing from the decompressed
478 memset(kaddr+bytes, 0, destlen-bytes);
484 const struct btrfs_compress_op btrfs_lzo_compress = {
485 .workspace_manager = &wsm,