diff options
Diffstat (limited to 'fs/btrfs/lzo.c')
| -rw-r--r-- | fs/btrfs/lzo.c | 420 |
1 files changed, 420 insertions, 0 deletions
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c new file mode 100644 index 0000000..cc9b450 --- /dev/null +++ b/fs/btrfs/lzo.c @@ -0,0 +1,420 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/vmalloc.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 "compression.h" + +#define LZO_LEN 4 + +struct workspace { + void *mem; + void *buf; /* where compressed data goes */ + void *cbuf; /* where decompressed data goes */ + struct list_head list; +}; + +static void lzo_free_workspace(struct list_head *ws) +{ + struct workspace *workspace = list_entry(ws, struct workspace, list); + + vfree(workspace->buf); + vfree(workspace->cbuf); + vfree(workspace->mem); + kfree(workspace); +} + +static struct list_head *lzo_alloc_workspace(void) +{ + struct workspace *workspace; + + workspace = kzalloc(sizeof(*workspace), GFP_NOFS); + if (!workspace) + return ERR_PTR(-ENOMEM); + + workspace->mem = vmalloc(LZO1X_MEM_COMPRESS); + workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE)); + workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE)); + 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(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, unsigned long len, + struct page **pages, + unsigned long nr_dest_pages, + unsigned long *out_pages, + unsigned long *total_in, + unsigned long *total_out, + unsigned long max_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; + + 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_CACHE_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_CACHE_SIZE - LZO_LEN; + + /* compress at most one page of data each time */ + in_len = min(len, PAGE_CACHE_SIZE); + while (tot_in < len) { + ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf, + &out_len, workspace->mem); + if (ret != LZO_E_OK) { + printk(KERN_DEBUG "btrfs deflate in loop returned %d\n", + ret); + ret = -1; + 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 = -1; + 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_CACHE_SIZE; + out_offset = 0; + } + } + + /* we're making it bigger, give up */ + if (tot_in > 8192 && tot_in < tot_out) + 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); + page_cache_release(in_page); + + start += PAGE_CACHE_SIZE; + in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT); + data_in = kmap(in_page); + in_len = min(bytes_left, PAGE_CACHE_SIZE); + } + + if (tot_out > tot_in) + 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); + page_cache_release(in_page); + } + + return ret; +} + +static int lzo_decompress_biovec(struct list_head *ws, + struct page **pages_in, + u64 disk_start, + struct bio_vec *bvec, + int vcnt, + size_t srclen) +{ + struct workspace *workspace = list_entry(ws, struct workspace, list); + int ret = 0, ret2; + char *data_in; + unsigned long page_in_index = 0; + unsigned long page_out_index = 0; + unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) / + PAGE_CACHE_SIZE; + unsigned long buf_start; + unsigned long buf_offset = 0; + unsigned long bytes; + unsigned long working_bytes; + unsigned long pg_offset; + + size_t in_len; + size_t out_len; + unsigned long in_offset; + unsigned long in_page_bytes_left; + unsigned long tot_in; + unsigned long tot_out; + unsigned long tot_len; + char *buf; + + data_in = kmap(pages_in[0]); + tot_len = read_compress_length(data_in); + + tot_in = LZO_LEN; + in_offset = LZO_LEN; + tot_len = min_t(size_t, srclen, tot_len); + in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN; + + tot_out = 0; + pg_offset = 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; + + tot_in += in_len; + working_bytes = in_len; + + /* fast path: avoid using the working buffer */ + if (in_page_bytes_left >= in_len) { + buf = data_in + in_offset; + bytes = in_len; + 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; + + kunmap(pages_in[page_in_index]); + page_in_index++; + if (page_in_index >= total_pages_in) { + ret = -1; + data_in = NULL; + goto done; + } + data_in = kmap(pages_in[page_in_index]); + + in_page_bytes_left = PAGE_CACHE_SIZE; + in_offset = 0; + } + } + + out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE); + ret = lzo1x_decompress_safe(buf, in_len, workspace->buf, + &out_len); + if (ret != LZO_E_OK) { + printk(KERN_WARNING "btrfs decompress failed\n"); + ret = -1; + break; + } + + buf_start = tot_out; + tot_out += out_len; + + ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start, + tot_out, disk_start, + bvec, vcnt, + &page_out_index, &pg_offset); + if (ret2 == 0) + break; + } +done: + if (data_in) + kunmap(pages_in[page_in_index]); + 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; + size_t tot_len; + int ret = 0; + char *kaddr; + unsigned long bytes; + + BUG_ON(srclen < LZO_LEN); + + tot_len = read_compress_length(data_in); + data_in += LZO_LEN; + + in_len = read_compress_length(data_in); + data_in += LZO_LEN; + + out_len = PAGE_CACHE_SIZE; + ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len); + if (ret != LZO_E_OK) { + printk(KERN_WARNING "btrfs decompress failed!\n"); + ret = -1; + goto out; + } + + if (out_len < start_byte) { + ret = -1; + goto out; + } + + bytes = min_t(unsigned long, destlen, out_len - start_byte); + + kaddr = kmap_atomic(dest_page, KM_USER0); + memcpy(kaddr, workspace->buf + start_byte, bytes); + kunmap_atomic(kaddr, KM_USER0); +out: + return ret; +} + +struct btrfs_compress_op btrfs_lzo_compress = { + .alloc_workspace = lzo_alloc_workspace, + .free_workspace = lzo_free_workspace, + .compress_pages = lzo_compress_pages, + .decompress_biovec = lzo_decompress_biovec, + .decompress = lzo_decompress, +}; 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