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linux/fs/btrfs/zlib.c
Ira Weiny 3590ec5899 btrfs: use memcpy_[to|from]_page() and kmap_local_page() 
There are many places where the pattern kmap/memcpy/kunmap occurs.

This pattern was lifted to the core common functions
memcpy_[to|from]_page().

Use these new functions to reduce the code, eliminate direct uses of
kmap, and leverage the new core functions use of kmap_local_page().

Also, there is 1 place where a kmap/memcpy is followed by an
optional memset.  Here we leave the kmap open coded to avoid remapping
the page but use kmap_local_page() directly.

Development of this patch was aided by the coccinelle script:

// <smpl>
// SPDX-License-Identifier: GPL-2.0-only
// Find kmap/memcpy/kunmap pattern and replace with memcpy*page calls
//
// NOTE: Offsets and other expressions may be more complex than what the script
// will automatically generate.  Therefore a catchall rule is provided to find
// the pattern which then must be evaluated by hand.
//
// Confidence: Low
// Copyright: (C) 2021 Intel Corporation
// URL: http://coccinelle.lip6.fr/
// Comments:
// Options:

//
// simple memcpy version
//
@ memcpy_rule1 @
expression page, T, F, B, Off;
identifier ptr;
type VP;
@@

(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
-memcpy(ptr + Off, F, B);
+memcpy_to_page(page, Off, F, B);
|
-memcpy(ptr, F, B);
+memcpy_to_page(page, 0, F, B);
|
-memcpy(T, ptr + Off, B);
+memcpy_from_page(T, page, Off, B);
|
-memcpy(T, ptr, B);
+memcpy_from_page(T, page, 0, B);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)

// Remove any pointers left unused
@
depends on memcpy_rule1
@
identifier memcpy_rule1.ptr;
type VP, VP1;
@@

-VP ptr;
	... when != ptr;
? VP1 ptr;

//
// Some callers kmap without a temp pointer
//
@ memcpy_rule2 @
expression page, T, Off, F, B;
@@

<+...
(
-memcpy(kmap(page) + Off, F, B);
+memcpy_to_page(page, Off, F, B);
|
-memcpy(kmap(page), F, B);
+memcpy_to_page(page, 0, F, B);
|
-memcpy(T, kmap(page) + Off, B);
+memcpy_from_page(T, page, Off, B);
|
-memcpy(T, kmap(page), B);
+memcpy_from_page(T, page, 0, B);
)
...+>
-kunmap(page);
// No need for the ptr variable removal

//
// Catch all
//
@ memcpy_rule3 @
expression page;
expression GenTo, GenFrom, GenSize;
identifier ptr;
type VP;
@@

(
-VP ptr = kmap(page);
|
-ptr = kmap(page);
|
-VP ptr = kmap_atomic(page);
|
-ptr = kmap_atomic(page);
)
<+...
(
//
// Some call sites have complex expressions within the memcpy
// match a catch all to be evaluated by hand.
//
-memcpy(GenTo, GenFrom, GenSize);
+memcpy_to_pageExtra(page, GenTo, GenFrom, GenSize);
+memcpy_from_pageExtra(GenTo, page, GenFrom, GenSize);
)
...+>
(
-kunmap(page);
|
-kunmap_atomic(ptr);
)

// Remove any pointers left unused
@
depends on memcpy_rule3
@
identifier memcpy_rule3.ptr;
type VP, VP1;
@@

-VP ptr;
	... when != ptr;
? VP1 ptr;

// <smpl>

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-02-26 12:45:15 +01:00

470 lines
12 KiB
C
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2008 Oracle. All rights reserved.
*
* 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/mm.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/bio.h>
#include <linux/refcount.h>
#include "compression.h"
/* workspace buffer size for s390 zlib hardware support */
#define ZLIB_DFLTCC_BUF_SIZE (4 * PAGE_SIZE)
struct workspace {
z_stream strm;
char *buf;
unsigned int buf_size;
struct list_head list;
int level;
};
static struct workspace_manager wsm;
struct list_head *zlib_get_workspace(unsigned int level)
{
struct list_head *ws = btrfs_get_workspace(BTRFS_COMPRESS_ZLIB, level);
struct workspace *workspace = list_entry(ws, struct workspace, list);
workspace->level = level;
return ws;
}
void zlib_free_workspace(struct list_head *ws)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
kvfree(workspace->strm.workspace);
kfree(workspace->buf);
kfree(workspace);
}
struct list_head *zlib_alloc_workspace(unsigned int level)
{
struct workspace *workspace;
int workspacesize;
workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
if (!workspace)
return ERR_PTR(-ENOMEM);
workspacesize = max(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
zlib_inflate_workspacesize());
workspace->strm.workspace = kvmalloc(workspacesize, GFP_KERNEL);
workspace->level = level;
workspace->buf = NULL;
/*
* In case of s390 zlib hardware support, allocate lager workspace
* buffer. If allocator fails, fall back to a single page buffer.
*/
if (zlib_deflate_dfltcc_enabled()) {
workspace->buf = kmalloc(ZLIB_DFLTCC_BUF_SIZE,
__GFP_NOMEMALLOC | __GFP_NORETRY |
__GFP_NOWARN | GFP_NOIO);
workspace->buf_size = ZLIB_DFLTCC_BUF_SIZE;
}
if (!workspace->buf) {
workspace->buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
workspace->buf_size = PAGE_SIZE;
}
if (!workspace->strm.workspace || !workspace->buf)
goto fail;
INIT_LIST_HEAD(&workspace->list);
return &workspace->list;
fail:
zlib_free_workspace(&workspace->list);
return ERR_PTR(-ENOMEM);
}
int zlib_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;
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 int in_buf_pages;
unsigned long len = *total_out;
unsigned long nr_dest_pages = *out_pages;
const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
*out_pages = 0;
*total_out = 0;
*total_in = 0;
if (Z_OK != zlib_deflateInit(&workspace->strm, workspace->level)) {
pr_warn("BTRFS: deflateInit failed\n");
ret = -EIO;
goto out;
}
workspace->strm.total_in = 0;
workspace->strm.total_out = 0;
out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (out_page == NULL) {
ret = -ENOMEM;
goto out;
}
cpage_out = kmap(out_page);
pages[0] = out_page;
nr_pages = 1;
workspace->strm.next_in = workspace->buf;
workspace->strm.avail_in = 0;
workspace->strm.next_out = cpage_out;
workspace->strm.avail_out = PAGE_SIZE;
while (workspace->strm.total_in < len) {
/*
* Get next input pages and copy the contents to
* the workspace buffer if required.
*/
if (workspace->strm.avail_in == 0) {
bytes_left = len - workspace->strm.total_in;
in_buf_pages = min(DIV_ROUND_UP(bytes_left, PAGE_SIZE),
workspace->buf_size / PAGE_SIZE);
if (in_buf_pages > 1) {
int i;
for (i = 0; i < in_buf_pages; i++) {
if (in_page) {
kunmap(in_page);
put_page(in_page);
}
in_page = find_get_page(mapping,
start >> PAGE_SHIFT);
data_in = kmap(in_page);
memcpy(workspace->buf + i * PAGE_SIZE,
data_in, PAGE_SIZE);
start += PAGE_SIZE;
}
workspace->strm.next_in = workspace->buf;
} else {
if (in_page) {
kunmap(in_page);
put_page(in_page);
}
in_page = find_get_page(mapping,
start >> PAGE_SHIFT);
data_in = kmap(in_page);
start += PAGE_SIZE;
workspace->strm.next_in = data_in;
}
workspace->strm.avail_in = min(bytes_left,
(unsigned long) workspace->buf_size);
}
ret = zlib_deflate(&workspace->strm, Z_SYNC_FLUSH);
if (ret != Z_OK) {
pr_debug("BTRFS: deflate in loop returned %d\n",
ret);
zlib_deflateEnd(&workspace->strm);
ret = -EIO;
goto out;
}
/* we're making it bigger, give up */
if (workspace->strm.total_in > 8192 &&
workspace->strm.total_in <
workspace->strm.total_out) {
ret = -E2BIG;
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->strm.avail_out == 0) {
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;
nr_pages++;
workspace->strm.avail_out = PAGE_SIZE;
workspace->strm.next_out = cpage_out;
}
/* we're all done */
if (workspace->strm.total_in >= len)
break;
if (workspace->strm.total_out > max_out)
break;
}
workspace->strm.avail_in = 0;
/*
* Call deflate with Z_FINISH flush parameter providing more output
* space but no more input data, until it returns with Z_STREAM_END.
*/
while (ret != Z_STREAM_END) {
ret = zlib_deflate(&workspace->strm, Z_FINISH);
if (ret == Z_STREAM_END)
break;
if (ret != Z_OK && ret != Z_BUF_ERROR) {
zlib_deflateEnd(&workspace->strm);
ret = -EIO;
goto out;
} else if (workspace->strm.avail_out == 0) {
/* get another page for the stream end */
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;
nr_pages++;
workspace->strm.avail_out = PAGE_SIZE;
workspace->strm.next_out = cpage_out;
}
}
zlib_deflateEnd(&workspace->strm);
if (workspace->strm.total_out >= workspace->strm.total_in) {
ret = -E2BIG;
goto out;
}
ret = 0;
*total_out = workspace->strm.total_out;
*total_in = workspace->strm.total_in;
out:
*out_pages = nr_pages;
if (out_page)
kunmap(out_page);
if (in_page) {
kunmap(in_page);
put_page(in_page);
}
return ret;
}
int zlib_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
struct workspace *workspace = list_entry(ws, struct workspace, list);
int ret = 0, ret2;
int wbits = MAX_WBITS;
char *data_in;
size_t total_out = 0;
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;
struct page **pages_in = cb->compressed_pages;
u64 disk_start = cb->start;
struct bio *orig_bio = cb->orig_bio;
data_in = kmap(pages_in[page_in_index]);
workspace->strm.next_in = data_in;
workspace->strm.avail_in = min_t(size_t, srclen, PAGE_SIZE);
workspace->strm.total_in = 0;
workspace->strm.total_out = 0;
workspace->strm.next_out = workspace->buf;
workspace->strm.avail_out = workspace->buf_size;
/* 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->strm.next_in += 2;
workspace->strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
pr_warn("BTRFS: inflateInit failed\n");
kunmap(pages_in[page_in_index]);
return -EIO;
}
while (workspace->strm.total_in < srclen) {
ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;
buf_start = total_out;
total_out = workspace->strm.total_out;
/* we didn't make progress in this inflate call, we're done */
if (buf_start == total_out)
break;
ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
total_out, disk_start,
orig_bio);
if (ret2 == 0) {
ret = 0;
goto done;
}
workspace->strm.next_out = workspace->buf;
workspace->strm.avail_out = workspace->buf_size;
if (workspace->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->strm.next_in = data_in;
tmp = srclen - workspace->strm.total_in;
workspace->strm.avail_in = min(tmp,
PAGE_SIZE);
}
}
if (ret != Z_STREAM_END)
ret = -EIO;
else
ret = 0;
done:
zlib_inflateEnd(&workspace->strm);
if (data_in)
kunmap(pages_in[page_in_index]);
if (!ret)
zero_fill_bio(orig_bio);
return ret;
}
int zlib_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);
int ret = 0;
int wbits = MAX_WBITS;
unsigned long bytes_left;
unsigned long total_out = 0;
unsigned long pg_offset = 0;
char *kaddr;
destlen = min_t(unsigned long, destlen, PAGE_SIZE);
bytes_left = destlen;
workspace->strm.next_in = data_in;
workspace->strm.avail_in = srclen;
workspace->strm.total_in = 0;
workspace->strm.next_out = workspace->buf;
workspace->strm.avail_out = workspace->buf_size;
workspace->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->strm.next_in += 2;
workspace->strm.avail_in -= 2;
}
if (Z_OK != zlib_inflateInit2(&workspace->strm, wbits)) {
pr_warn("BTRFS: inflateInit failed\n");
return -EIO;
}
while (bytes_left > 0) {
unsigned long buf_start;
unsigned long buf_offset;
unsigned long bytes;
ret = zlib_inflate(&workspace->strm, Z_NO_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
break;
buf_start = total_out;
total_out = workspace->strm.total_out;
if (total_out == buf_start) {
ret = -EIO;
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_SIZE - pg_offset,
PAGE_SIZE - (buf_offset % PAGE_SIZE));
bytes = min(bytes, bytes_left);
memcpy_to_page(dest_page, pg_offset,
workspace->buf + buf_offset, bytes);
pg_offset += bytes;
bytes_left -= bytes;
next:
workspace->strm.next_out = workspace->buf;
workspace->strm.avail_out = workspace->buf_size;
}
if (ret != Z_STREAM_END && bytes_left != 0)
ret = -EIO;
else
ret = 0;
zlib_inflateEnd(&workspace->strm);
/*
* this should only happen if zlib returned fewer bytes than we
* expected. btrfs_get_block is responsible for zeroing from the
* end of the inline extent (destlen) to the end of the page
*/
if (pg_offset < destlen) {
kaddr = kmap_atomic(dest_page);
memset(kaddr + pg_offset, 0, destlen - pg_offset);
kunmap_atomic(kaddr);
}
return ret;
}
const struct btrfs_compress_op btrfs_zlib_compress = {
.workspace_manager = &wsm,
.max_level = 9,
.default_level = BTRFS_ZLIB_DEFAULT_LEVEL,
};
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