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 static void lzo_init_workspace_manager(void)
68 btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
71 static void lzo_cleanup_workspace_manager(void)
73 btrfs_cleanup_workspace_manager(&wsm);
76 static struct list_head *lzo_get_workspace(unsigned int level)
78 return btrfs_get_workspace(&wsm, level);
81 static void lzo_put_workspace(struct list_head *ws)
83 btrfs_put_workspace(&wsm, ws);
86 static void lzo_free_workspace(struct list_head *ws)
88 struct workspace *workspace = list_entry(ws, struct workspace, list);
90 kvfree(workspace->buf);
91 kvfree(workspace->cbuf);
92 kvfree(workspace->mem);
96 static struct list_head *lzo_alloc_workspace(unsigned int level)
98 struct workspace *workspace;
100 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
102 return ERR_PTR(-ENOMEM);
104 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
105 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
106 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
107 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
110 INIT_LIST_HEAD(&workspace->list);
112 return &workspace->list;
114 lzo_free_workspace(&workspace->list);
115 return ERR_PTR(-ENOMEM);
118 static inline void write_compress_length(char *buf, size_t len)
122 dlen = cpu_to_le32(len);
123 memcpy(buf, &dlen, LZO_LEN);
126 static inline size_t read_compress_length(const char *buf)
130 memcpy(&dlen, buf, LZO_LEN);
131 return le32_to_cpu(dlen);
134 static int lzo_compress_pages(struct list_head *ws,
135 struct address_space *mapping,
138 unsigned long *out_pages,
139 unsigned long *total_in,
140 unsigned long *total_out)
142 struct workspace *workspace = list_entry(ws, struct workspace, list);
147 struct page *in_page = NULL;
148 struct page *out_page = NULL;
149 unsigned long bytes_left;
150 unsigned long len = *total_out;
151 unsigned long nr_dest_pages = *out_pages;
152 const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
156 unsigned long tot_in = 0;
157 unsigned long tot_out = 0;
158 unsigned long pg_bytes_left;
159 unsigned long out_offset;
166 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
167 data_in = kmap(in_page);
170 * store the size of all chunks of compressed data in
173 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
174 if (out_page == NULL) {
178 cpage_out = kmap(out_page);
179 out_offset = LZO_LEN;
183 pg_bytes_left = PAGE_SIZE - LZO_LEN;
185 /* compress at most one page of data each time */
186 in_len = min(len, PAGE_SIZE);
187 while (tot_in < len) {
188 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
189 &out_len, workspace->mem);
190 if (ret != LZO_E_OK) {
191 pr_debug("BTRFS: lzo in loop returned %d\n",
197 /* store the size of this chunk of compressed data */
198 write_compress_length(cpage_out + out_offset, out_len);
200 out_offset += LZO_LEN;
201 pg_bytes_left -= LZO_LEN;
206 /* copy bytes from the working buffer into the pages */
207 buf = workspace->cbuf;
209 bytes = min_t(unsigned long, pg_bytes_left, out_len);
211 memcpy(cpage_out + out_offset, buf, bytes);
214 pg_bytes_left -= bytes;
219 * we need another page for writing out.
221 * Note if there's less than 4 bytes left, we just
222 * skip to a new page.
224 if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
225 pg_bytes_left == 0) {
227 memset(cpage_out + out_offset, 0,
229 tot_out += pg_bytes_left;
232 /* we're done, don't allocate new page */
233 if (out_len == 0 && tot_in >= len)
237 if (nr_pages == nr_dest_pages) {
243 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
244 if (out_page == NULL) {
248 cpage_out = kmap(out_page);
249 pages[nr_pages++] = out_page;
251 pg_bytes_left = PAGE_SIZE;
256 /* we're making it bigger, give up */
257 if (tot_in > 8192 && tot_in < tot_out) {
266 if (tot_out > max_out)
269 bytes_left = len - tot_in;
274 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
275 data_in = kmap(in_page);
276 in_len = min(bytes_left, PAGE_SIZE);
279 if (tot_out >= tot_in) {
284 /* store the size of all chunks of compressed data */
285 cpage_out = kmap(pages[0]);
286 write_compress_length(cpage_out, tot_out);
291 *total_out = tot_out;
294 *out_pages = nr_pages;
306 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
308 struct workspace *workspace = list_entry(ws, struct workspace, list);
311 unsigned long page_in_index = 0;
312 size_t srclen = cb->compressed_len;
313 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
314 unsigned long buf_start;
315 unsigned long buf_offset = 0;
317 unsigned long working_bytes;
320 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
321 unsigned long in_offset;
322 unsigned long in_page_bytes_left;
323 unsigned long tot_in;
324 unsigned long tot_out;
325 unsigned long tot_len;
327 bool may_late_unmap, need_unmap;
328 struct page **pages_in = cb->compressed_pages;
329 u64 disk_start = cb->start;
330 struct bio *orig_bio = cb->orig_bio;
332 data_in = kmap(pages_in[0]);
333 tot_len = read_compress_length(data_in);
335 * Compressed data header check.
337 * The real compressed size can't exceed the maximum extent length, and
338 * all pages should be used (whole unused page with just the segment
339 * header is not possible). If this happens it means the compressed
340 * extent is corrupted.
342 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
343 tot_len < srclen - PAGE_SIZE) {
350 in_page_bytes_left = PAGE_SIZE - LZO_LEN;
354 while (tot_in < tot_len) {
355 in_len = read_compress_length(data_in + in_offset);
356 in_page_bytes_left -= LZO_LEN;
357 in_offset += LZO_LEN;
361 * Segment header check.
363 * The segment length must not exceed the maximum LZO
364 * compression size, nor the total compressed size.
366 if (in_len > max_segment_len || tot_in + in_len > tot_len) {
372 working_bytes = in_len;
373 may_late_unmap = need_unmap = false;
375 /* fast path: avoid using the working buffer */
376 if (in_page_bytes_left >= in_len) {
377 buf = data_in + in_offset;
379 may_late_unmap = true;
383 /* copy bytes from the pages into the working buffer */
384 buf = workspace->cbuf;
386 while (working_bytes) {
387 bytes = min(working_bytes, in_page_bytes_left);
389 memcpy(buf + buf_offset, data_in + in_offset, bytes);
392 working_bytes -= bytes;
393 in_page_bytes_left -= bytes;
396 /* check if we need to pick another page */
397 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
398 || in_page_bytes_left == 0) {
399 tot_in += in_page_bytes_left;
401 if (working_bytes == 0 && tot_in >= tot_len)
404 if (page_in_index + 1 >= total_pages_in) {
412 kunmap(pages_in[page_in_index]);
414 data_in = kmap(pages_in[++page_in_index]);
416 in_page_bytes_left = PAGE_SIZE;
421 out_len = max_segment_len;
422 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
425 kunmap(pages_in[page_in_index - 1]);
426 if (ret != LZO_E_OK) {
427 pr_warn("BTRFS: decompress failed\n");
435 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
436 tot_out, disk_start, orig_bio);
441 kunmap(pages_in[page_in_index]);
443 zero_fill_bio(orig_bio);
447 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
448 struct page *dest_page,
449 unsigned long start_byte,
450 size_t srclen, size_t destlen)
452 struct workspace *workspace = list_entry(ws, struct workspace, list);
455 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
460 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
463 in_len = read_compress_length(data_in);
464 if (in_len != srclen)
468 in_len = read_compress_length(data_in);
469 if (in_len != srclen - LZO_LEN * 2) {
476 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
477 if (ret != LZO_E_OK) {
478 pr_warn("BTRFS: decompress failed!\n");
483 if (out_len < start_byte) {
489 * the caller is already checking against PAGE_SIZE, but lets
490 * move this check closer to the memcpy/memset
492 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
493 bytes = min_t(unsigned long, destlen, out_len - start_byte);
495 kaddr = kmap_atomic(dest_page);
496 memcpy(kaddr, workspace->buf + start_byte, bytes);
499 * btrfs_getblock is doing a zero on the tail of the page too,
500 * but this will cover anything missing from the decompressed
504 memset(kaddr+bytes, 0, destlen-bytes);
505 kunmap_atomic(kaddr);
510 static unsigned int lzo_set_level(unsigned int level)
515 const struct btrfs_compress_op btrfs_lzo_compress = {
516 .init_workspace_manager = lzo_init_workspace_manager,
517 .cleanup_workspace_manager = lzo_cleanup_workspace_manager,
518 .get_workspace = lzo_get_workspace,
519 .put_workspace = lzo_put_workspace,
520 .alloc_workspace = lzo_alloc_workspace,
521 .free_workspace = lzo_free_workspace,
522 .compress_pages = lzo_compress_pages,
523 .decompress_bio = lzo_decompress_bio,
524 .decompress = lzo_decompress,
525 .set_level = lzo_set_level,