diff options
Diffstat (limited to '')
-rw-r--r-- | fs/btrfs/lzo.c | 494 |
1 files changed, 494 insertions, 0 deletions
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c new file mode 100644 index 000000000..89bc5f825 --- /dev/null +++ b/fs/btrfs/lzo.c @@ -0,0 +1,494 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2008 Oracle. All rights reserved. + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/mm.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/sched.h> +#include <linux/pagemap.h> +#include <linux/bio.h> +#include <linux/lzo.h> +#include <linux/refcount.h> +#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 ... | + */ + +#define WORKSPACE_BUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE)) +#define WORKSPACE_CBUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE)) + +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(WORKSPACE_BUF_LENGTH, GFP_KERNEL); + workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, 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_local_page(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_local(kaddr); + + 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_local_page(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_local(kaddr); + 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_local_page(page_in); + ret = lzo1x_1_compress(data_in + + offset_in_page(cur_in), in_len, + workspace->cbuf, &out_len, + workspace->mem); + kunmap_local(data_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) { + 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]; + + memcpy_from_page(dest + *cur_in - orig_in, cur_page, + offset_in_page(*cur_in), copy_len); + + *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_local_page(cb->compressed_pages[0]); + len_in = read_compress_length(kaddr); + kunmap_local(kaddr); + 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_local_page(cur_page); + seg_len = read_compress_length(kaddr + offset_in_page(cur_in)); + kunmap_local(kaddr); + cur_in += LZO_LEN; + + if (seg_len > WORKSPACE_CBUF_LENGTH) { + /* + * seg_len shouldn't be larger than we have allocated + * for workspace->cbuf + */ + btrfs_err(fs_info, "unexpectedly large lzo segment len %u", + seg_len); + ret = -EIO; + goto out; + } + + /* 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 = WORKSPACE_BUF_LENGTH; + 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, +}; |