path: root/fs/btrfs/compression.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/highmem.h>
#include <linux/kthread.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/writeback.h>
#include <linux/psi.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include <linux/log2.h>
#include <linux/shrinker.h>
#include <crypto/hash.h>
#include "misc.h"
#include "ctree.h"
#include "fs.h"
#include "btrfs_inode.h"
#include "bio.h"
#include "ordered-data.h"
#include "compression.h"
#include "extent_io.h"
#include "extent_map.h"
#include "subpage.h"
#include "messages.h"
#include "super.h"

static struct bio_set btrfs_compressed_bioset;

static const char* const btrfs_compress_types[] = { "", "zlib", "lzo", "zstd" };

const char* btrfs_compress_type2str(enum btrfs_compression_type type)
{
	switch (type) {
	case BTRFS_COMPRESS_ZLIB:
	case BTRFS_COMPRESS_LZO:
	case BTRFS_COMPRESS_ZSTD:
	case BTRFS_COMPRESS_NONE:
		return btrfs_compress_types[type];
	default:
		break;
	}

	return NULL;
}

static inline struct compressed_bio *to_compressed_bio(struct btrfs_bio *bbio)
{
	return container_of(bbio, struct compressed_bio, bbio);
}

static struct compressed_bio *alloc_compressed_bio(struct btrfs_inode *inode,
						   u64 start, blk_opf_t op,
						   btrfs_bio_end_io_t end_io)
{
	struct btrfs_bio *bbio;

	bbio = btrfs_bio(bio_alloc_bioset(NULL, BTRFS_MAX_COMPRESSED_PAGES, op,
					  GFP_NOFS, &btrfs_compressed_bioset));
	btrfs_bio_init(bbio, inode->root->fs_info, end_io, NULL);
	bbio->inode = inode;
	bbio->file_offset = start;
	return to_compressed_bio(bbio);
}

bool btrfs_compress_is_valid_type(const char *str, size_t len)
{
	int i;

	for (i = 1; i < ARRAY_SIZE(btrfs_compress_types); i++) {
		size_t comp_len = strlen(btrfs_compress_types[i]);

		if (len < comp_len)
			continue;

		if (!strncmp(btrfs_compress_types[i], str, comp_len))
			return true;
	}
	return false;
}

static int compression_compress_pages(int type, struct list_head *ws,
				      struct address_space *mapping, u64 start,
				      struct folio **folios, unsigned long *out_folios,
				      unsigned long *total_in, unsigned long *total_out)
{
	switch (type) {
	case BTRFS_COMPRESS_ZLIB:
		return zlib_compress_folios(ws, mapping, start, folios,
					    out_folios, total_in, total_out);
	case BTRFS_COMPRESS_LZO:
		return lzo_compress_folios(ws, mapping, start, folios,
					   out_folios, total_in, total_out);
	case BTRFS_COMPRESS_ZSTD:
		return zstd_compress_folios(ws, mapping, start, folios,
					    out_folios, total_in, total_out);
	case BTRFS_COMPRESS_NONE:
	default:
		/*
		 * This can happen when compression races with remount setting
		 * it to 'no compress', while caller doesn't call
		 * inode_need_compress() to check if we really need to
		 * compress.
		 *
		 * Not a big deal, just need to inform caller that we
		 * haven't allocated any pages yet.
		 */
		*out_folios = 0;
		return -E2BIG;
	}
}

static int compression_decompress_bio(struct list_head *ws,
				      struct compressed_bio *cb)
{
	switch (cb->compress_type) {
	case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb);
	case BTRFS_COMPRESS_LZO:  return lzo_decompress_bio(ws, cb);
	case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb);
	case BTRFS_COMPRESS_NONE:
	default:
		/*
		 * This can't happen, the type is validated several times
		 * before we get here.
		 */
		BUG();
	}
}

static int compression_decompress(int type, struct list_head *ws,
		const u8 *data_in, struct folio *dest_folio,
		unsigned long dest_pgoff, size_t srclen, size_t destlen)
{
	switch (type) {
	case BTRFS_COMPRESS_ZLIB: return zlib_decompres