path: root/fs/f2fs/compress.c

// SPDX-License-Identifier: GPL-2.0
/*
 * f2fs compress support
 *
 * Copyright (c) 2019 Chao Yu <chao@kernel.org>
 */

#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/lzo.h>
#include <linux/lz4.h>
#include <linux/zstd.h>

#include "f2fs.h"
#include "node.h"
#include <trace/events/f2fs.h>

static struct kmem_cache *cic_entry_slab;
static struct kmem_cache *dic_entry_slab;

static void *page_array_alloc(struct inode *inode, int nr)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	unsigned int size = sizeof(struct page *) * nr;

	if (likely(size <= sbi->page_array_slab_size))
		return kmem_cache_zalloc(sbi->page_array_slab, GFP_NOFS);
	return f2fs_kzalloc(sbi, size, GFP_NOFS);
}

static void page_array_free(struct inode *inode, void *pages, int nr)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	unsigned int size = sizeof(struct page *) * nr;

	if (!pages)
		return;

	if (likely(size <= sbi->page_array_slab_size))
		kmem_cache_free(sbi->page_array_slab, pages);
	else
		kfree(pages);
}

struct f2fs_compress_ops {
	int (*init_compress_ctx)(struct compress_ctx *cc);
	void (*destroy_compress_ctx)(struct compress_ctx *cc);
	int (*compress_pages)(struct compress_ctx *cc);
	int (*init_decompress_ctx)(struct decompress_io_ctx *dic);
	void (*destroy_decompress_ctx)(struct decompress_io_ctx *dic);
	int (*decompress_pages)(struct decompress_io_ctx *dic);
};

static unsigned int offset_in_cluster(struct compress_ctx *cc, pgoff_t index)
{
	return index & (cc->cluster_size - 1);
}

static pgoff_t cluster_idx(struct compress_ctx *cc, pgoff_t index)
{
	return index >> cc->log_cluster_size;
}

static pgoff_t start_idx_of_cluster(struct compress_ctx *cc)
{
	return cc->cluster_idx << cc->log_cluster_size;
}

bool f2fs_is_compressed_page(struct page *page)
{
	if (!PagePrivate(page))
		return false;
	if (!page_private(page))
		return false;
	if (IS_ATOMIC_WRITTEN_PAGE(page) || IS_DUMMY_WRITTEN_PAGE(page))
		return false;
	/*
	 * page->private may be set with pid.
	 * pid_max is enough to check if it is traced.
	 */
	if (IS_IO_TRACED_PAGE(page))
		return false;

	f2fs_bug_on(F2FS_M_SB(page->mapping),
		*((u32 *)page_private(page)) != F2FS_COMPRESSED_PAGE_MAGIC);
	return true;
}

static void f2fs_set_compressed_page(struct page *page,
		struct inode *inode, pgoff_t index, void *data)
{
	SetPagePrivate(page);
	set_page_private(page, (unsigned long)data);

	/* i_crypto_info and iv index */
	page->index = index;
	page->mapping = inode->i_mapping;
}

static void f2fs_drop_rpages(struct compress_ctx *cc, int len, bool unlock)
{
	int i;

	for (i = 0; i < len; i++) {
		if (!cc->rpages[i])
			continue;
		if (unlock)
			unlock_page(cc->rpages[i]);
		else
			put_page(cc->rpages[i]);
	}
}

static void f2fs_put_rpages(struct compress_ctx *cc)
{
	f2fs_drop_rpages(cc, cc->cluster_size, false);
}

static void f2fs_unlock_rpages(struct compress_ctx *cc, int len)
{
	f2fs_drop_rpages(cc, len, true);
}

static void f2fs_put_rpages_wbc(struct compress_ctx *cc,
		struct writeback_control *wbc, bool redirty, int unlock)
{
	unsigned int i;

	for (i = 0; i < cc->cluster_size; i++) {
		if (!cc->rpages[i])
			continue;
		if (redirty)
			redirty_page_for_writepage(wbc, cc->rpages[i]);
		f2fs_put_page(cc->rpages[i], unlock);
	}
}

struct page *f2fs_compress_control_page(struct page *page)
{
	return ((struct compress_io_ctx *)page_private(page))->rpages[0];
}

int f2fs_init_compress_ctx(struct compress_ctx *cc)
{
	if (cc->rpages)
		return 0;

	cc->rpages = page_array_alloc(cc->inode, cc->cluster_size);
	return cc->rpages ? 0 : -ENOMEM;
}

void f2fs_destroy_compress_ctx(struct compress_ctx *cc, bool reuse)
{