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 * Btrfs LZO compression format
24 * Regular and inlined LZO compressed data extents consist of:
27 * Fixed size. LZO_LEN (4) bytes long, LE32.
28 * Records the total size (including the header) of compressed data.
31 * Variable size. Each segment includes one segment header, followed by data
33 * One regular LZO compressed extent can have one or more segments.
34 * For inlined LZO compressed extent, only one segment is allowed.
35 * One segment represents at most one sector of uncompressed data.
38 * Fixed size. LZO_LEN (4) bytes long, LE32.
39 * Records the total size of the segment (not including the header).
40 * Segment header never crosses sector boundary, thus it's possible to
41 * have at most 3 padding zeros at the end of the sector.
44 * Variable size. Size up limit should be lzo1x_worst_compress(sectorsize)
45 * which is 4419 for a 4KiB sectorsize.
47 * Example with 4K sectorsize:
49 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
50 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
52 * 0x0ff0 | SegHdr N | Data payload N ... |00|
55 * 0x1000 | SegHdr N+1| Data payload N+1 ... |
58 #define WORKSPACE_BUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
59 #define WORKSPACE_CBUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
63 void *buf; /* where decompressed data goes */
64 void *cbuf; /* where compressed data goes */
65 struct list_head list;
68 static struct workspace_manager wsm;
70 void lzo_free_workspace(struct list_head *ws)
72 struct workspace *workspace = list_entry(ws, struct workspace, list);
74 kvfree(workspace->buf);
75 kvfree(workspace->cbuf);
76 kvfree(workspace->mem);
80 struct list_head *lzo_alloc_workspace(unsigned int level)
82 struct workspace *workspace;
84 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
86 return ERR_PTR(-ENOMEM);
88 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
89 workspace->buf = kvmalloc(WORKSPACE_BUF_LENGTH, GFP_KERNEL);
90 workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, GFP_KERNEL);
91 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
94 INIT_LIST_HEAD(&workspace->list);
96 return &workspace->list;
98 lzo_free_workspace(&workspace->list);
99 return ERR_PTR(-ENOMEM);
102 static inline void write_compress_length(char *buf, size_t len)
106 dlen = cpu_to_le32(len);
107 memcpy(buf, &dlen, LZO_LEN);
110 static inline size_t read_compress_length(const char *buf)
114 memcpy(&dlen, buf, LZO_LEN);
115 return le32_to_cpu(dlen);
121 * - Write a segment header into the destination
122 * - Copy the compressed buffer into the destination
123 * - Make sure we have enough space in the last sector to fit a segment header
124 * If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
126 * Will allocate new pages when needed.
128 static int copy_compressed_data_to_page(char *compressed_data,
129 size_t compressed_size,
130 struct page **out_pages,
131 unsigned long max_nr_page,
133 const u32 sectorsize)
135 u32 sector_bytes_left;
137 struct page *cur_page;
140 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
144 * We never allow a segment header crossing sector boundary, previous
145 * run should ensure we have enough space left inside the sector.
147 ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);
149 cur_page = out_pages[*cur_out / PAGE_SIZE];
150 /* Allocate a new page */
152 cur_page = alloc_page(GFP_NOFS);
155 out_pages[*cur_out / PAGE_SIZE] = cur_page;
158 kaddr = kmap_local_page(cur_page);
159 write_compress_length(kaddr + offset_in_page(*cur_out),
165 /* Copy compressed data */
166 while (*cur_out - orig_out < compressed_size) {
167 u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
168 orig_out + compressed_size - *cur_out);
172 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
175 cur_page = out_pages[*cur_out / PAGE_SIZE];
176 /* Allocate a new page */
178 cur_page = alloc_page(GFP_NOFS);
181 out_pages[*cur_out / PAGE_SIZE] = cur_page;
183 kaddr = kmap_local_page(cur_page);
185 memcpy(kaddr + offset_in_page(*cur_out),
186 compressed_data + *cur_out - orig_out, copy_len);
188 *cur_out += copy_len;
192 * Check if we can fit the next segment header into the remaining space
195 sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
196 if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
199 /* The remaining size is not enough, pad it with zeros */
200 memset(kaddr + offset_in_page(*cur_out), 0,
202 *cur_out += sector_bytes_left;
209 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
210 u64 start, struct page **pages, unsigned long *out_pages,
211 unsigned long *total_in, unsigned long *total_out)
213 struct workspace *workspace = list_entry(ws, struct workspace, list);
214 const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
215 struct page *page_in = NULL;
217 const unsigned long max_nr_page = *out_pages;
219 /* Points to the file offset of input data */
221 /* Points to the current output byte */
223 u32 len = *total_out;
225 ASSERT(max_nr_page > 0);
231 * Skip the header for now, we will later come back and write the total
235 while (cur_in < start + len) {
237 const u32 sectorsize_mask = sectorsize - 1;
238 u32 sector_off = (cur_in - start) & sectorsize_mask;
242 /* Get the input page first */
244 page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
248 /* Compress at most one sector of data each time */
249 in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
251 data_in = kmap_local_page(page_in);
252 ret = lzo1x_1_compress(data_in +
253 offset_in_page(cur_in), in_len,
254 workspace->cbuf, &out_len,
256 kunmap_local(data_in);
258 pr_debug("BTRFS: lzo in loop returned %d\n", ret);
263 ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
265 &cur_out, sectorsize);
272 * Check if we're making it bigger after two sectors. And if
275 if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
280 /* Check if we have reached page boundary */
281 if (IS_ALIGNED(cur_in, PAGE_SIZE)) {
287 /* Store the size of all chunks of compressed data */
288 sizes_ptr = kmap_local_page(pages[0]);
289 write_compress_length(sizes_ptr, cur_out);
290 kunmap_local(sizes_ptr);
293 *total_out = cur_out;
294 *total_in = cur_in - start;
298 *out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
303 * Copy the compressed segment payload into @dest.
305 * For the payload there will be no padding, just need to do page switching.
307 static void copy_compressed_segment(struct compressed_bio *cb,
308 char *dest, u32 len, u32 *cur_in)
310 u32 orig_in = *cur_in;
312 while (*cur_in < orig_in + len) {
313 struct page *cur_page;
314 u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
315 orig_in + len - *cur_in);
318 cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
320 memcpy_from_page(dest + *cur_in - orig_in, cur_page,
321 offset_in_page(*cur_in), copy_len);
327 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
329 struct workspace *workspace = list_entry(ws, struct workspace, list);
330 const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
331 const u32 sectorsize = fs_info->sectorsize;
334 /* Compressed data length, can be unaligned */
336 /* Offset inside the compressed data */
338 /* Bytes decompressed so far */
341 kaddr = kmap_local_page(cb->compressed_pages[0]);
342 len_in = read_compress_length(kaddr);
347 * LZO header length check
349 * The total length should not exceed the maximum extent length,
350 * and all sectors should be used.
351 * If this happens, it means the compressed extent is corrupted.
353 if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
354 round_up(len_in, sectorsize) < cb->compressed_len) {
356 "invalid lzo header, lzo len %u compressed len %u",
357 len_in, cb->compressed_len);
361 /* Go through each lzo segment */
362 while (cur_in < len_in) {
363 struct page *cur_page;
364 /* Length of the compressed segment */
366 u32 sector_bytes_left;
367 size_t out_len = lzo1x_worst_compress(sectorsize);
370 * We should always have enough space for one segment header
371 * inside current sector.
373 ASSERT(cur_in / sectorsize ==
374 (cur_in + LZO_LEN - 1) / sectorsize);
375 cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
377 kaddr = kmap_local_page(cur_page);
378 seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
382 if (seg_len > WORKSPACE_CBUF_LENGTH) {
384 * seg_len shouldn't be larger than we have allocated
385 * for workspace->cbuf
387 btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
393 /* Copy the compressed segment payload into workspace */
394 copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
396 /* Decompress the data */
397 ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
398 workspace->buf, &out_len);
399 if (ret != LZO_E_OK) {
400 btrfs_err(fs_info, "failed to decompress");
405 /* Copy the data into inode pages */
406 ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
409 /* All data read, exit */
414 /* Check if the sector has enough space for a segment header */
415 sector_bytes_left = sectorsize - (cur_in % sectorsize);
416 if (sector_bytes_left >= LZO_LEN)
419 /* Skip the padding zeros */
420 cur_in += sector_bytes_left;
424 zero_fill_bio(cb->orig_bio);
428 int lzo_decompress(struct list_head *ws, unsigned char *data_in,
429 struct page *dest_page, unsigned long start_byte, size_t srclen,
432 struct workspace *workspace = list_entry(ws, struct workspace, list);
435 size_t max_segment_len = WORKSPACE_BUF_LENGTH;
440 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
443 in_len = read_compress_length(data_in);
444 if (in_len != srclen)
448 in_len = read_compress_length(data_in);
449 if (in_len != srclen - LZO_LEN * 2) {
456 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
457 if (ret != LZO_E_OK) {
458 pr_warn("BTRFS: decompress failed!\n");
463 if (out_len < start_byte) {
469 * the caller is already checking against PAGE_SIZE, but lets
470 * move this check closer to the memcpy/memset
472 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
473 bytes = min_t(unsigned long, destlen, out_len - start_byte);
475 kaddr = kmap_local_page(dest_page);
476 memcpy(kaddr, workspace->buf + start_byte, bytes);
479 * btrfs_getblock is doing a zero on the tail of the page too,
480 * but this will cover anything missing from the decompressed
484 memset(kaddr+bytes, 0, destlen-bytes);
490 const struct btrfs_compress_op btrfs_lzo_compress = {
491 .workspace_manager = &wsm,