// 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" #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, followd 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 page 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 page boundary, thus it's possible to * have at most 3 padding zeros at the end of the page. * * 2.2 Data Payload * Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE) * which is 4419 for a 4KiB page. * * Example: * 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 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); } static struct list_head *lzo_alloc_workspace(void) { 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); } static 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); int ret = 0; char *data_in; char *cpage_out; int nr_pages = 0; struct page *in_page = NULL; struct page *out_page = NULL; unsigned long bytes_left; unsigned long len = *total_out; unsigned long nr_dest_pages = *out_pages; const unsigned long max_out = nr_dest_pages * PAGE_SIZE; size_t in_len; size_t out_len; char *buf; unsigned long tot_in = 0; unsigned long tot_out = 0; unsigned long pg_bytes_left; unsigned long out_offset; unsigned long bytes; *out_pages = 0; *total_out = 0; *total_in = 0; in_page = find_get_page(mapping, start >> PAGE_SHIFT); data_in = kmap(in_page); /* * store the size of all chunks of compressed data in * the first 4 bytes */ out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); if (out_page == NULL) { ret = -ENOMEM; goto out; } cpage_out = kmap(out_page); out_offset = LZO_LEN; tot_out = LZO_LEN; pages[0] = out_page; nr_pages = 1; pg_bytes_left = PAGE_SIZE - LZO_LEN; /* compress at most one page of data each time */ in_len = min(len, PAGE_SIZE); while (tot_in < len) { ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, &out_len, workspace->mem); if (ret != LZO_E_OK) { pr_debug("BTRFS: lzo in loop returned %d\n", ret); ret = -EIO; goto out; } /* store the size of this chunk of compressed data */ write_compress_length(cpage_out + out_offset, out_len); tot_out += LZO_LEN; out_offset += LZO_LEN; pg_bytes_left -= LZO_LEN; tot_in += in_len; tot_out += out_len; /* copy bytes from the working buffer into the pages */ buf = workspace->cbuf; while (out_len) { bytes = min_t(unsigned long, pg_bytes_left, out_len); memcpy(cpage_out + out_offset, buf, bytes); out_len -= bytes; pg_bytes_left -= bytes; buf += bytes; out_offset += bytes; /* * we need another page for writing out. * * Note if there's less than 4 bytes left, we just * skip to a new page. */ if ((out_len == 0 && pg_bytes_left < LZO_LEN) || pg_bytes_left == 0) { if (pg_bytes_left) { memset(cpage_out + out_offset, 0, pg_bytes_left); tot_out += pg_bytes_left; } /* we're done, don't allocate new page */ if (out_len == 0 && tot_in >= len) break; kunmap(out_page); if (nr_pages == nr_dest_pages) { out_page = NULL; ret = -E2BIG; goto out; } out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); if (out_page == NULL) { ret = -ENOMEM; goto out; } cpage_out = kmap(out_page); pages[nr_pages++] = out_page; pg_bytes_left = PAGE_SIZE; out_offset = 0; } } /* we're making it bigger, give up */ if (tot_in > 8192 && tot_in < tot_out) { ret = -E2BIG; goto out; } /* we're all done */ if (tot_in >= len) break; if (tot_out > max_out) break; bytes_left = len - tot_in; kunmap(in_page); put_page(in_page); start += PAGE_SIZE; in_page = find_get_page(mapping, start >> PAGE_SHIFT); data_in = kmap(in_page); in_len = min(bytes_left, PAGE_SIZE); } if (tot_out >= tot_in) { ret = -E2BIG; goto out; } /* store the size of all chunks of compressed data */ cpage_out = kmap(pages[0]); write_compress_length(cpage_out, tot_out); kunmap(pages[0]); ret = 0; *total_out = tot_out; *total_in = tot_in; out: *out_pages = nr_pages; if (out_page) kunmap(out_page); if (in_page) { kunmap(in_page); put_page(in_page); } return ret; } static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb) { struct workspace *workspace = list_entry(ws, struct workspace, list); int ret = 0, ret2; char *data_in; unsigned long page_in_index = 0; size_t srclen = cb->compressed_len; unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE); unsigned long buf_start; unsigned long buf_offset = 0; unsigned long bytes; unsigned long working_bytes; size_t in_len; size_t out_len; const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE); unsigned long in_offset; unsigned long in_page_bytes_left; unsigned long tot_in; unsigned long tot_out; unsigned long tot_len; char *buf; bool may_late_unmap, need_unmap; struct page **pages_in = cb->compressed_pages; u64 disk_start = cb->start; struct bio *orig_bio = cb->orig_bio; data_in = kmap(pages_in[0]); tot_len = read_compress_length(data_in); /* * Compressed data header check. * * The real compressed size can't exceed the maximum extent length, and * all pages should be used (whole unused page with just the segment * header is not possible). If this happens it means the compressed * extent is corrupted. */ if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) || tot_len < srclen - PAGE_SIZE) { ret = -EUCLEAN; goto done; } tot_in = LZO_LEN; in_offset = LZO_LEN; in_page_bytes_left = PAGE_SIZE - LZO_LEN; tot_out = 0; while (tot_in < tot_len) { in_len = read_compress_length(data_in + in_offset); in_page_bytes_left -= LZO_LEN; in_offset += LZO_LEN; tot_in += LZO_LEN; /* * Segment header check. * * The segment length must not exceed the maximum LZO * compression size, nor the total compressed size. */ if (in_len > max_segment_len || tot_in + in_len > tot_len) { ret = -EUCLEAN; goto done; } tot_in += in_len; working_bytes = in_len; may_late_unmap = need_unmap = false; /* fast path: avoid using the working buffer */ if (in_page_bytes_left >= in_len) { buf = data_in + in_offset; bytes = in_len; may_late_unmap = true; goto cont; } /* copy bytes from the pages into the working buffer */ buf = workspace->cbuf; buf_offset = 0; while (working_bytes) { bytes = min(working_bytes, in_page_bytes_left); memcpy(buf + buf_offset, data_in + in_offset, bytes); buf_offset += bytes; cont: working_bytes -= bytes; in_page_bytes_left -= bytes; in_offset += bytes; /* check if we need to pick another page */ if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN) || in_page_bytes_left == 0) { tot_in += in_page_bytes_left; if (working_bytes == 0 && tot_in >= tot_len) break; if (page_in_index + 1 >= total_pages_in) { ret = -EIO; goto done; } if (may_late_unmap) need_unmap = true; else kunmap(pages_in[page_in_index]); data_in = kmap(pages_in[++page_in_index]); in_page_bytes_left = PAGE_SIZE; in_offset = 0; } } out_len = max_segment_len; ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, &out_len); if (need_unmap) kunmap(pages_in[page_in_index - 1]); if (ret != LZO_E_OK) { pr_warn("BTRFS: decompress failed\n"); ret = -EIO; break; } buf_start = tot_out; tot_out += out_len; ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, tot_out, disk_start, orig_bio); if (ret2 == 0) break; } done: kunmap(pages_in[page_in_index]); if (!ret) zero_fill_bio(orig_bio); return ret; } static 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; int ret = 0; char *kaddr; unsigned long bytes; BUG_ON(srclen < LZO_LEN); data_in += LZO_LEN; in_len = read_compress_length(data_in); 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_atomic(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_atomic(kaddr); out: return ret; } static void lzo_set_level(struct list_head *ws, unsigned int type) { } const struct btrfs_compress_op btrfs_lzo_compress = { .alloc_workspace = lzo_alloc_workspace, .free_workspace = lzo_free_workspace, .compress_pages = lzo_compress_pages, .decompress_bio = lzo_decompress_bio, .decompress = lzo_decompress, .set_level = lzo_set_level, };