diff options
Diffstat (limited to 'fs/btrfs/zlib.c')
| -rw-r--r-- | fs/btrfs/zlib.c | 632 |
1 files changed, 632 insertions, 0 deletions
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c new file mode 100644 index 00000000000..ecfbce836d3 --- /dev/null +++ b/fs/btrfs/zlib.c @@ -0,0 +1,632 @@ +/* + * 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. + * + * Based on jffs2 zlib code: + * Copyright © 2001-2007 Red Hat, Inc. + * Created by David Woodhouse <dwmw2@infradead.org> + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/zlib.h> +#include <linux/zutil.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 "compression.h" + +/* Plan: call deflate() with avail_in == *sourcelen, + avail_out = *dstlen - 12 and flush == Z_FINISH. + If it doesn't manage to finish, call it again with + avail_in == 0 and avail_out set to the remaining 12 + bytes for it to clean up. + Q: Is 12 bytes sufficient? +*/ +#define STREAM_END_SPACE 12 + +struct workspace { + z_stream inf_strm; + z_stream def_strm; + char *buf; + struct list_head list; +}; + +static LIST_HEAD(idle_workspace); +static DEFINE_SPINLOCK(workspace_lock); +static unsigned long num_workspace; +static atomic_t alloc_workspace = ATOMIC_INIT(0); +static DECLARE_WAIT_QUEUE_HEAD(workspace_wait); + +/* + * this finds an available zlib workspace or allocates a new one + * NULL or an ERR_PTR is returned if things go bad. + */ +static struct workspace *find_zlib_workspace(void) +{ + struct workspace *workspace; + int ret; + int cpus = num_online_cpus(); + +again: + spin_lock(&workspace_lock); + if (!list_empty(&idle_workspace)) { + workspace = list_entry(idle_workspace.next, struct workspace, + list); + list_del(&workspace->list); + num_workspace--; + spin_unlock(&workspace_lock); + return workspace; + + } + spin_unlock(&workspace_lock); + if (atomic_read(&alloc_workspace) > cpus) { + DEFINE_WAIT(wait); + prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE); + if (atomic_read(&alloc_workspace) > cpus) + schedule(); + finish_wait(&workspace_wait, &wait); + goto again; + } + atomic_inc(&alloc_workspace); + workspace = kzalloc(sizeof(*workspace), GFP_NOFS); + if (!workspace) { + ret = -ENOMEM; + goto fail; + } + + workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize()); + if (!workspace->def_strm.workspace) { + ret = -ENOMEM; + goto fail; + } + workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize()); + if (!workspace->inf_strm.workspace) { + ret = -ENOMEM; + goto fail_inflate; + } + workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS); + if (!workspace->buf) { + ret = -ENOMEM; + goto fail_kmalloc; + } + return workspace; + +fail_kmalloc: + vfree(workspace->inf_strm.workspace); +fail_inflate: + vfree(workspace->def_strm.workspace); +fail: + kfree(workspace); + atomic_dec(&alloc_workspace); + wake_up(&workspace_wait); + return ERR_PTR(ret); +} + +/* + * put a workspace struct back on the list or free it if we have enough + * idle ones sitting around + */ +static int free_workspace(struct workspace *workspace) +{ + spin_lock(&workspace_lock); + if (num_workspace < num_online_cpus()) { + list_add_tail(&workspace->list, &idle_workspace); + num_workspace++; + spin_unlock(&workspace_lock); + if (waitqueue_active(&workspace_wait)) + wake_up(&workspace_wait); + return 0; + } + spin_unlock(&workspace_lock); + vfree(workspace->def_strm.workspace); + vfree(workspace->inf_strm.workspace); + kfree(workspace->buf); + kfree(workspace); + + atomic_dec(&alloc_workspace); + if (waitqueue_active(&workspace_wait)) + wake_up(&workspace_wait); + return 0; +} + +/* + * cleanup function for module exit + */ +static void free_workspaces(void) +{ + struct workspace *workspace; + while (!list_empty(&idle_workspace)) { + workspace = list_entry(idle_workspace.next, struct workspace, + list); + list_del(&workspace->list); + vfree(workspace->def_strm.workspace); + vfree(workspace->inf_strm.workspace); + kfree(workspace->buf); + kfree(workspace); + atomic_dec(&alloc_workspace); + } +} + +/* + * given an address space and start/len, compress the bytes. + * + * pages are allocated to hold the compressed result and stored + * in 'pages' + * + * out_pages is used to return the number of pages allocated. There + * may be pages allocated even if we return an error + * + * total_in is used to return the number of bytes actually read. It + * may be smaller then len if we had to exit early because we + * ran out of room in the pages array or because we cross the + * max_out threshold. + * + * total_out is used to return the total number of compressed bytes + * + * max_out tells us the max number of bytes that we're allowed to + * stuff into pages + */ +int btrfs_zlib_compress_pages(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) +{ + int ret; + struct workspace *workspace; + char *data_in; + char *cpage_out; + int nr_pages = 0; + struct page *in_page = NULL; + struct page *out_page = NULL; + int out_written = 0; + int in_read = 0; + unsigned long bytes_left; + + *out_pages = 0; + *total_out = 0; + *total_in = 0; + + workspace = find_zlib_workspace(); + if (!workspace) + return -1; + + if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) { + printk(KERN_WARNING "deflateInit failed\n"); + ret = -1; + goto out; + } + + workspace->def_strm.total_in = 0; + workspace->def_strm.total_out = 0; + + in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT); + data_in = kmap(in_page); + + out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + cpage_out = kmap(out_page); + pages[0] = out_page; + nr_pages = 1; + + workspace->def_strm.next_in = data_in; + workspace->def_strm.next_out = cpage_out; + workspace->def_strm.avail_out = PAGE_CACHE_SIZE; + workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE); + + out_written = 0; + in_read = 0; + + while (workspace->def_strm.total_in < len) { + ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH); + if (ret != Z_OK) { + printk(KERN_DEBUG "btrfs deflate in loop returned %d\n", + ret); + zlib_deflateEnd(&workspace->def_strm); + ret = -1; + goto out; + } + + /* we're making it bigger, give up */ + if (workspace->def_strm.total_in > 8192 && + workspace->def_strm.total_in < + workspace->def_strm.total_out) { + ret = -1; + goto out; + } + /* we need another page for writing out. Test this + * before the total_in so we will pull in a new page for + * the stream end if required + */ + if (workspace->def_strm.avail_out == 0) { + kunmap(out_page); + if (nr_pages == nr_dest_pages) { + out_page = NULL; + ret = -1; + goto out; + } + out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + cpage_out = kmap(out_page); + pages[nr_pages] = out_page; + nr_pages++; + workspace->def_strm.avail_out = PAGE_CACHE_SIZE; + workspace->def_strm.next_out = cpage_out; + } + /* we're all done */ + if (workspace->def_strm.total_in >= len) + break; + + /* we've read in a full page, get a new one */ + if (workspace->def_strm.avail_in == 0) { + if (workspace->def_strm.total_out > max_out) + break; + + bytes_left = len - workspace->def_strm.total_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); + workspace->def_strm.avail_in = min(bytes_left, + PAGE_CACHE_SIZE); + workspace->def_strm.next_in = data_in; + } + } + workspace->def_strm.avail_in = 0; + ret = zlib_deflate(&workspace->def_strm, Z_FINISH); + zlib_deflateEnd(&workspace->def_strm); + + if (ret != Z_STREAM_END) { + ret = -1; + goto out; + } + + if (workspace->def_strm.total_out >= workspace->def_strm.total_in) { + ret = -1; + goto out; + } + + ret = 0; + *total_out = workspace->def_strm.total_out; + *total_in = workspace->def_strm.total_in; +out: + *out_pages = nr_pages; + if (out_page) + kunmap(out_page); + + if (in_page) { + kunmap(in_page); + page_cache_release(in_page); + } + free_workspace(workspace); + return ret; +} + +/* + * pages_in is an array of pages with compressed data. + * + * disk_start is the starting logical offset of this array in the file + * + * bvec is a bio_vec of pages from the file that we want to decompress into + * + * vcnt is the count of pages in the biovec + * + * srclen is the number of bytes in pages_in + * + * The basic idea is that we have a bio that was created by readpages. + * The pages in the bio are for the uncompressed data, and they may not + * be contiguous. They all correspond to the range of bytes covered by + * the compressed extent. + */ +int btrfs_zlib_decompress_biovec(struct page **pages_in, + u64 disk_start, + struct bio_vec *bvec, + int vcnt, + size_t srclen) +{ + int ret = 0; + int wbits = MAX_WBITS; + struct workspace *workspace; + char *data_in; + size_t total_out = 0; + unsigned long page_bytes_left; + unsigned long page_in_index = 0; + unsigned long page_out_index = 0; + struct page *page_out; + unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) / + PAGE_CACHE_SIZE; + unsigned long buf_start; + unsigned long buf_offset; + unsigned long bytes; + unsigned long working_bytes; + unsigned long pg_offset; + unsigned long start_byte; + unsigned long current_buf_start; + char *kaddr; + + workspace = find_zlib_workspace(); + if (!workspace) + return -ENOMEM; + + data_in = kmap(pages_in[page_in_index]); + workspace->inf_strm.next_in = data_in; + workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE); + workspace->inf_strm.total_in = 0; + + workspace->inf_strm.total_out = 0; + workspace->inf_strm.next_out = workspace->buf; + workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; + page_out = bvec[page_out_index].bv_page; + page_bytes_left = PAGE_CACHE_SIZE; + pg_offset = 0; + + /* If it's deflate, and it's got no preset dictionary, then + we can tell zlib to skip the adler32 check. */ + if (srclen > 2 && !(data_in[1] & PRESET_DICT) && + ((data_in[0] & 0x0f) == Z_DEFLATED) && + !(((data_in[0]<<8) + data_in[1]) % 31)) { + + wbits = -((data_in[0] >> 4) + 8); + workspace->inf_strm.next_in += 2; + workspace->inf_strm.avail_in -= 2; + } + + if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) { + printk(KERN_WARNING "inflateInit failed\n"); + ret = -1; + goto out; + } + while (workspace->inf_strm.total_in < srclen) { + ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH); + if (ret != Z_OK && ret != Z_STREAM_END) + break; + /* + * buf start is the byte offset we're of the start of + * our workspace buffer + */ + buf_start = total_out; + + /* total_out is the last byte of the workspace buffer */ + total_out = workspace->inf_strm.total_out; + + working_bytes = total_out - buf_start; + + /* + * start byte is the first byte of the page we're currently + * copying into relative to the start of the compressed data. + */ + start_byte = page_offset(page_out) - disk_start; + + if (working_bytes == 0) { + /* we didn't make progress in this inflate + * call, we're done + */ + if (ret != Z_STREAM_END) + ret = -1; + break; + } + + /* we haven't yet hit data corresponding to this page */ + if (total_out <= start_byte) + goto next; + + /* + * the start of the data we care about is offset into + * the middle of our working buffer + */ + if (total_out > start_byte && buf_start < start_byte) { + buf_offset = start_byte - buf_start; + working_bytes -= buf_offset; + } else { + buf_offset = 0; + } + current_buf_start = buf_start; + + /* copy bytes from the working buffer into the pages */ + while (working_bytes > 0) { + bytes = min(PAGE_CACHE_SIZE - pg_offset, + PAGE_CACHE_SIZE - buf_offset); + bytes = min(bytes, working_bytes); + kaddr = kmap_atomic(page_out, KM_USER0); + memcpy(kaddr + pg_offset, workspace->buf + buf_offset, + bytes); + kunmap_atomic(kaddr, KM_USER0); + flush_dcache_page(page_out); + + pg_offset += bytes; + page_bytes_left -= bytes; + buf_offset += bytes; + working_bytes -= bytes; + current_buf_start += bytes; + + /* check if we need to pick another page */ + if (page_bytes_left == 0) { + page_out_index++; + if (page_out_index >= vcnt) { + ret = 0; + goto done; + } + + page_out = bvec[page_out_index].bv_page; + pg_offset = 0; + page_bytes_left = PAGE_CACHE_SIZE; + start_byte = page_offset(page_out) - disk_start; + + /* + * make sure our new page is covered by this + * working buffer + */ + if (total_out <= start_byte) + goto next; + + /* the next page in the biovec might not + * be adjacent to the last page, but it + * might still be found inside this working + * buffer. bump our offset pointer + */ + if (total_out > start_byte && + current_buf_start < start_byte) { + buf_offset = start_byte - buf_start; + working_bytes = total_out - start_byte; + current_buf_start = buf_start + + buf_offset; + } + } + } +next: + workspace->inf_strm.next_out = workspace->buf; + workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; + + if (workspace->inf_strm.avail_in == 0) { + unsigned long tmp; + kunmap(pages_in[page_in_index]); + page_in_index++; + if (page_in_index >= total_pages_in) { + data_in = NULL; + break; + } + data_in = kmap(pages_in[page_in_index]); + workspace->inf_strm.next_in = data_in; + tmp = srclen - workspace->inf_strm.total_in; + workspace->inf_strm.avail_in = min(tmp, + PAGE_CACHE_SIZE); + } + } + if (ret != Z_STREAM_END) + ret = -1; + else + ret = 0; +done: + zlib_inflateEnd(&workspace->inf_strm); + if (data_in) + kunmap(pages_in[page_in_index]); +out: + free_workspace(workspace); + return ret; +} + +/* + * a less complex decompression routine. Our compressed data fits in a + * single page, and we want to read a single page out of it. + * start_byte tells us the offset into the compressed data we're interested in + */ +int btrfs_zlib_decompress(unsigned char *data_in, + struct page *dest_page, + unsigned long start_byte, + size_t srclen, size_t destlen) +{ + int ret = 0; + int wbits = MAX_WBITS; + struct workspace *workspace; + unsigned long bytes_left = destlen; + unsigned long total_out = 0; + char *kaddr; + + if (destlen > PAGE_CACHE_SIZE) + return -ENOMEM; + + workspace = find_zlib_workspace(); + if (!workspace) + return -ENOMEM; + + workspace->inf_strm.next_in = data_in; + workspace->inf_strm.avail_in = srclen; + workspace->inf_strm.total_in = 0; + + workspace->inf_strm.next_out = workspace->buf; + workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; + workspace->inf_strm.total_out = 0; + /* If it's deflate, and it's got no preset dictionary, then + we can tell zlib to skip the adler32 check. */ + if (srclen > 2 && !(data_in[1] & PRESET_DICT) && + ((data_in[0] & 0x0f) == Z_DEFLATED) && + !(((data_in[0]<<8) + data_in[1]) % 31)) { + + wbits = -((data_in[0] >> 4) + 8); + workspace->inf_strm.next_in += 2; + workspace->inf_strm.avail_in -= 2; + } + + if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) { + printk(KERN_WARNING "inflateInit failed\n"); + ret = -1; + goto out; + } + + while (bytes_left > 0) { + unsigned long buf_start; + unsigned long buf_offset; + unsigned long bytes; + unsigned long pg_offset = 0; + + ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH); + if (ret != Z_OK && ret != Z_STREAM_END) + break; + + buf_start = total_out; + total_out = workspace->inf_strm.total_out; + + if (total_out == buf_start) { + ret = -1; + break; + } + + if (total_out <= start_byte) + goto next; + + if (total_out > start_byte && buf_start < start_byte) + buf_offset = start_byte - buf_start; + else + buf_offset = 0; + + bytes = min(PAGE_CACHE_SIZE - pg_offset, + PAGE_CACHE_SIZE - buf_offset); + bytes = min(bytes, bytes_left); + + kaddr = kmap_atomic(dest_page, KM_USER0); + memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes); + kunmap_atomic(kaddr, KM_USER0); + + pg_offset += bytes; + bytes_left -= bytes; +next: + workspace->inf_strm.next_out = workspace->buf; + workspace->inf_strm.avail_out = PAGE_CACHE_SIZE; + } + + if (ret != Z_STREAM_END && bytes_left != 0) + ret = -1; + else + ret = 0; + + zlib_inflateEnd(&workspace->inf_strm); +out: + free_workspace(workspace); + return ret; +} + +void btrfs_zlib_exit(void) +{ + free_workspaces(); +} |