// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2008 Oracle. All rights reserved. */ #include #include #include #include #include #include #include #include #include #include #include "compression.h" #include "ctree.h" #define LZO_LEN 4 /* * Btrfs LZO compression format * * Regular and inlined LZO compressed data extents consist of: * * 1. Header * Fixed size. LZO_LEN (4) bytes long, LE32. * Records the total size (including the header) of compressed data. * * 2. Segment(s) * Variable size. Each segment includes one segment header, followed by data * payload. * One regular LZO compressed extent can have one or more segments. * For inlined LZO compressed extent, only one segment is allowed. * One segment represents at most one sector of uncompressed data. * * 2.1 Segment header * Fixed size. LZO_LEN (4) bytes long, LE32. * Records the total size of the segment (not including the header). * Segment header never crosses sector boundary, thus it's possible to * have at most 3 padding zeros at the end of the sector. * * 2.2 Data Payload * Variable size. Size up limit should be lzo1x_worst_compress(sectorsize) * which is 4419 for a 4KiB sectorsize. * * Example with 4K sectorsize: * Page 1: * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... | * ... * 0x0ff0 | SegHdr N | Data payload N ... |00| * ^^ padding zeros * Page 2: * 0x1000 | SegHdr N+1| Data payload N+1 ... | */ struct workspace { void *mem; void *buf; /* where decompressed data goes */ void *cbuf; /* where compressed data goes */ struct list_head list; }; static struct workspace_manager wsm; void lzo_free_workspace(struct list_head *ws) { struct workspace *workspace = list_entry(ws, struct workspace, list); kvfree(workspace->buf); kvfree(workspace->cbuf); kvfree(workspace->mem); kfree(workspace); } struct list_head *lzo_alloc_workspace(unsigned int level) { struct workspace *workspace; workspace = kzalloc(sizeof(*workspace), GFP_KERNEL); if (!workspace) return ERR_PTR(-ENOMEM); workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL); if (!workspace->mem || !workspace->buf || !workspace->cbuf) goto fail; INIT_LIST_HEAD(&workspace->list); return &workspace->list; fail: lzo_free_workspace(&workspace->list); return ERR_PTR(-ENOMEM); } static inline void write_compress_length(char *buf, size_t len) { __le32 dlen; dlen = cpu_to_le32(len); memcpy(buf, &dlen, LZO_LEN); } static inline size_t read_compress_length(const char *buf) { __le32 dlen; memcpy(&dlen, buf, LZO_LEN); return le32_to_cpu(dlen); } /* * Will do: * * - Write a segment header into the destination * - Copy the compressed buffer into the destination * - Make sure we have enough space in the last sector to fit a segment header * If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros. * * Will allocate new pages when needed. */ static int copy_compressed_data_to_page(char *compressed_data, size_t compressed_size, struct page **out_pages, unsigned long max_nr_page, u32 *cur_out, const u32 sectorsize) { u32 sector_bytes_left; u32 orig_out; struct page *cur_page; char *kaddr; if ((*cur_out / PAGE_SIZE) >= max_nr_page) return -E2BIG; /* * We never allow a segment header crossing sector boundary, previous * run should ensure we have enough space left inside the sector. */ ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize); cur_page = out_pages[*cur_out / PAGE_SIZE]; /* Allocate a new page */ if (!cur_page) { cur_page = alloc_page(GFP_NOFS); if (!cur_page) return -ENOMEM; out_pages[*cur_out / PAGE_SIZE] = cur_page; } kaddr = kmap(cur_page); write_compress_length(kaddr + offset_in_page(*cur_out), compressed_size); *cur_out += LZO_LEN; orig_out = *cur_out; /* Copy compressed data */ while (*cur_out - orig_out < compressed_size) { u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize, orig_out + compressed_size - *cur_out); kunmap(cur_page); if ((*cur_out / PAGE_SIZE) >= max_nr_page) return -E2BIG; cur_page = out_pages[*cur_out / PAGE_SIZE]; /* Allocate a new page */ if (!cur_page) { cur_page = alloc_page(GFP_NOFS); if (!cur_page) return -ENOMEM; out_pages[*cur_out / PAGE_SIZE] = cur_page; } kaddr = kmap(cur_page); memcpy(kaddr + offset_in_page(*cur_out), compressed_data + *cur_out - orig_out, copy_len); *cur_out += copy_len; } /* * Check if we can fit the next segment header into the remaining space * of the sector. */ sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out; if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0) goto out; /* The remaining size is not enough, pad it with zeros */ memset(kaddr + offset_in_page(*cur_out), 0, sector_bytes_left); *cur_out += sector_bytes_left; out: kunmap(cur_page); return 0; } int lzo_compress_pages(struct list_head *ws, struct address_space *mapping, u64 start, struct page **pages, unsigned long *out_pages, unsigned long *total_in, unsigned long *total_out) { struct workspace *workspace = list_entry(ws, struct workspace, list); const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize; struct page *page_in = NULL; char *sizes_ptr; const unsigned long max_nr_page = *out_pages; int ret = 0; /* Points to the file offset of input data */ u64 cur_in = start; /* Points to the current output byte */ u32 cur_out = 0; u32 len = *total_out; ASSERT(max_nr_page > 0); *out_pages = 0; *total_out = 0; *total_in = 0; /* * Skip the header for now, we will later come back and write the total * compressed size */ cur_out += LZO_LEN; while (cur_in < start + len) { char *data_in; const u32 sectorsize_mask = sectorsize - 1; u32 sector_off = (cur_in - start) & sectorsize_mask; u32 in_len; size_t out_len; /* Get the input page first */ if (!page_in) { page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT); ASSERT(page_in); } /* Compress at most one sector of data each time */ in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off); ASSERT(in_len); data_in = kmap(page_in); ret = lzo1x_1_compress(data_in + offset_in_page(cur_in), in_len, workspace->cbuf, &out_len, workspace->mem); kunmap(page_in); if (ret < 0) { pr_debug("BTRFS: lzo in loop returned %d\n", ret); ret = -EIO; goto out; } ret = copy_compressed_data_to_page(workspace->cbuf, out_len, pages, max_nr_page, &cur_out, sectorsize); if (ret < 0) goto out; cur_in += in_len; /* * Check if we're making it bigger after two sectors. And if * it is so, give up. */ if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) { ret = -E2BIG; goto out; } /* Check if we have reached page boundary */ if (IS_ALIGNED(cur_in, PAGE_SIZE)) { put_page(page_in); page_in = NULL; } } /* Store the size of all chunks of compressed data */ sizes_ptr = kmap_local_page(pages[0]); write_compress_length(sizes_ptr, cur_out); kunmap_local(sizes_ptr); ret = 0; *total_out = cur_out; *total_in = cur_in - start; out: if (page_in) put_page(page_in); *out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE); return ret; } /* * Copy the compressed segment payload into @dest. * * For the payload there will be no padding, just need to do page switching. */ static void copy_compressed_segment(struct compressed_bio *cb, char *dest, u32 len, u32 *cur_in) { u32 orig_in = *cur_in; while (*cur_in < orig_in + len) { char *kaddr; struct page *cur_page; u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in), orig_in + len - *cur_in); ASSERT(copy_len); cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE]; kaddr = kmap(cur_page); memcpy(dest + *cur_in - orig_in, kaddr + offset_in_page(*cur_in), copy_len); kunmap(cur_page); *cur_in += copy_len; } } int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) { struct workspace *workspace = list_entry(ws, struct workspace, list); const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb); const u32 sectorsize = fs_info->sectorsize; char *kaddr; int ret; /* Compressed data length, can be unaligned */ u32 len_in; /* Offset inside the compressed data */ u32 cur_in = 0; /* Bytes decompressed so far */ u32 cur_out = 0; kaddr = kmap(cb->compressed_pages[0]); len_in = read_compress_length(kaddr); kunmap(cb->compressed_pages[0]); cur_in += LZO_LEN; /* * LZO header length check * * The total length should not exceed the maximum extent length, * and all sectors should be used. * If this happens, it means the compressed extent is corrupted. */ if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) || round_up(len_in, sectorsize) < cb->compressed_len) { btrfs_err(fs_info, "invalid lzo header, lzo len %u compressed len %u", len_in, cb->compressed_len); return -EUCLEAN; } /* Go through each lzo segment */ while (cur_in < len_in) { struct page *cur_page; /* Length of the compressed segment */ u32 seg_len; u32 sector_bytes_left; size_t out_len = lzo1x_worst_compress(sectorsize); /* * We should always have enough space for one segment header * inside current sector. */ ASSERT(cur_in / sectorsize == (cur_in + LZO_LEN - 1) / sectorsize); cur_page = cb->compressed_pages[cur_in / PAGE_SIZE]; ASSERT(cur_page); kaddr = kmap(cur_page); seg_len = read_compress_length(kaddr + offset_in_page(cur_in)); kunmap(cur_page); cur_in += LZO_LEN; /* Copy the compressed segment payload into workspace */ copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in); /* Decompress the data */ ret = lzo1x_decompress_safe(workspace->cbuf, seg_len, workspace->buf, &out_len); if (ret != LZO_E_OK) { btrfs_err(fs_info, "failed to decompress"); ret = -EIO; goto out; } /* Copy the data into inode pages */ ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out); cur_out += out_len; /* All data read, exit */ if (ret == 0) goto out; ret = 0; /* Check if the sector has enough space for a segment header */ sector_bytes_left = sectorsize - (cur_in % sectorsize); if (sector_bytes_left >= LZO_LEN) continue; /* Skip the padding zeros */ cur_in += sector_bytes_left; } out: if (!ret) zero_fill_bio(cb->orig_bio); return ret; } int lzo_decompress(struct list_head *ws, unsigned char *data_in, struct page *dest_page, unsigned long start_byte, size_t srclen, size_t destlen) { struct workspace *workspace = list_entry(ws, struct workspace, list); size_t in_len; size_t out_len; size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); int ret = 0; char *kaddr; unsigned long bytes; if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2) return -EUCLEAN; in_len = read_compress_length(data_in); if (in_len != srclen) return -EUCLEAN; data_in += LZO_LEN; in_len = read_compress_length(data_in); if (in_len != srclen - LZO_LEN * 2) { ret = -EUCLEAN; goto out; } data_in += LZO_LEN; out_len = PAGE_SIZE; ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); if (ret != LZO_E_OK) { pr_warn("BTRFS: decompress failed!\n"); ret = -EIO; goto out; } if (out_len < start_byte) { ret = -EIO; goto out; } /* * the caller is already checking against PAGE_SIZE, but lets * move this check closer to the memcpy/memset */ destlen = min_t(unsigned long, destlen, PAGE_SIZE); bytes = min_t(unsigned long, destlen, out_len - start_byte); kaddr = kmap_local_page(dest_page); memcpy(kaddr, workspace->buf + start_byte, bytes); /* * btrfs_getblock is doing a zero on the tail of the page too, * but this will cover anything missing from the decompressed * data. */ if (bytes < destlen) memset(kaddr+bytes, 0, destlen-bytes); kunmap_local(kaddr); out: return ret; } const struct btrfs_compress_op btrfs_lzo_compress = { .workspace_manager = &wsm, .max_level = 1, .default_level = 1, };