These are helpers to send pages down to the zlib API.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
new file mode 100644
index 0000000..ecfbce8
--- /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@xxxxxxxxxxxxx>
+ */
+
+#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();
+}
--
1.6.0.2
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