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/highmem.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/writeback.h>
#include <linux/slab.h>
#include <linux/sched/mm.h>
#include <linux/log2.h>
#include <crypto/hash.h>
#include "misc.h"
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "volumes.h"
#include "ordered-data.h"
#include "compression.h"
#include "extent_io.h"
#include "extent_map.h"

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];
	}

	return NULL;
}

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 btrfs_decompress_bio(struct compressed_bio *cb);

static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
				      unsigned long disk_size)
{
	u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);

	return sizeof(struct compressed_bio) +
		(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
}

static int check_compressed_csum(struct btrfs_inode *inode,
				 struct compressed_bio *cb,
				 u64 disk_start)
{
	struct btrfs_fs_info *fs_info = inode->root->fs_info;
	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
	const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
	int ret;
	struct page *page;
	unsigned long i;
	char *kaddr;
	u8 csum[BTRFS_CSUM_SIZE];
	u8 *cb_sum = cb->sums;

	if (inode->flags & BTRFS_INODE_NODATASUM)
		return 0;

	shash->tfm = fs_info->csum_shash;

	for (i = 0; i < cb->nr_pages; i++) {
		page = cb->compressed_pages[i];

		crypto_shash_init(shash);
		kaddr = kmap_atomic(page);
		crypto_shash_update(shash, kaddr, PAGE_SIZE);
		kunmap_atomic(kaddr);
		crypto_shash_final(shash, (u8 *)&csum);

		if (memcmp(&csum, cb_sum, csum_size)) {
			btrfs_print_data_csum_error(inode, disk_start,
					csum, cb_sum, cb->mirror_num);
			ret = -EIO;
			goto fail;
		}
		cb_sum += csum_size;

	}
	ret = 0;
fail:
	return ret;
}

/* when we finish reading compressed pages from the disk, we
 * decompress them and then run the bio end_io routines on the
 * decompressed pages (in the inode address space).
 *
 * This allows the checksumming and other IO error handling routines
 * to work normally
 *
 * The compressed pages are freed here, and it must be run
 * in process context
 */
static void end_compressed_bio_read(struct bio *bio)
{
	struct compressed_bio *cb = bio->bi_private;
	struct inode *inode;
	struct page *page;
	unsigned long index;
	unsigned int mirror = btrfs_io_bio(bio)->mirror_num;
	int ret = 0;

	if (bio->bi_status)
		cb->errors = 1;

	/* if there are more bios still pending for this compressed
	 * extent, just exit
	 */
	if (!refcount_dec_and_test(&cb->pending_bios))
		goto out;

	/*
	 * Record the correct mirror_num in cb->orig_bio so that
	 * read-repair can work properly.
	 */
	ASSERT(btrfs_io_bio(cb->orig_bio));
	btrfs_io_bio(cb->orig_bio)->mirror_num = mirror;
	cb->mirror_num = mirror;

	/*
	 * Some IO in this cb have failed, just skip checksum as there
	 * is no way it could be correct.
	 */
	if (cb->errors == 1)
		goto csum_failed;

	inode = cb->inode;
	ret = check_compressed_csum(BTRFS_I(inode), cb,
				    (u64)bio->bi_iter.bi_sector << 9);
	if (ret)
		goto csum_failed;

	/* ok, we're the last bio for this extent, lets start
	 * the decompression.
	 */
	ret = btrfs_deco