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 <crypto/hash.h>
#include "misc.h"
#include "ctree.h"
#include "fs.h"
#include "disk-io.h"
#include "transaction.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 "zoned.h"
#include "file-item.h"
#include "super.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];
	default:
		break;
	}

	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 compression_compress_pages(int type, 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)
{
	switch (type) {
	case BTRFS_COMPRESS_ZLIB:
		return zlib_compress_pages(ws, mapping, start, pages,
				out_pages, total_in, total_out);
	case BTRFS_COMPRESS_LZO:
		return lzo_compress_pages(ws, mapping, start, pages,
				out_pages, total_in, total_out);
	case BTRFS_COMPRESS_ZSTD:
		return zstd_compress_pages(ws, mapping, start, pages,
				out_pages, 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_pages = 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 page *dest_page,
               unsigned long start_byte, size_t srclen, size_t destlen)
{
	switch (type) {
	case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page,
						start_byte, srclen, destlen);
	case BTRFS_COMPRESS_LZO:  return lzo_decompress(ws, data_in, dest_page,
						start_byte, srclen, destlen);
	case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page,
						start_byte, srclen, destlen);
	case BTRFS_COMPRESS_NONE:
	default:
		/*
		 * This can't happen, the type is validated several times
		 * before we get here.
		 */
		BUG();
	}
}

static int btrfs_decompress_bio(struct compressed_bio *cb);

static void end_compressed_bio_read(struct btrfs_bio *bbio)
{
	struct compressed_bio *cb = bbio->private;
	unsigned int index;
	struct page *page;

	if (bbio->bio.bi_status)
		cb->status = bbio->bio.bi_status;
	else
		cb->status = errno_to_blk_status(btrfs_decompress_bio(cb));

	/* Release the compressed pages */
	for (index = 0; index < cb->nr_pages; index++) {
		page = cb->compressed_pages[index];
		page->mapping = NULL;
		put_page(page);
	}

	/* Do io completion on the original bio */
	btrfs_bio_end_io(btrfs_bio(cb->orig_bio), cb->status);

	/* Finally free the cb struct */
	kfree(cb->compressed_pages);
	kfree(cb);
	bio_put(&bbio->bio);
}

/*
 * Clear the writeback bits on all of the file
 * pages for a compressed write
 */
static noinline void end_compressed_writeback(struct inode *inode,
					      const struct compressed_bio *cb)
{
	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
	unsigned long index = cb->start >> PAGE_SHIFT;
	unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
	struct folio_batch fbatch;
	const int errno = blk_status_to_errno(cb->status);
	int i;
	int ret;

	if (errno)
		mapping_set_error(inode->i_mapping, errno);

	folio_batch_init(&fbatch);
	while (index <= end_index) {
		ret = filemap_get_folios(inode->i_mapping, &index, end_index,
				&fbatch);

		if (ret == 0)
			return;

		for (i = 0; i < ret; i++) {
			struct folio *folio = fbatch.folios[i];

			if (errno)
				folio_set_error(folio);
			btrfs_page_clamp_clear_writeback(fs_info, &folio->page,
							 cb->start, cb->len);
		}
		folio_batch_release(&fbatch);
	}
	/* the inode may be gone now */
}

static void finish_compressed_bio_write(struct compressed_bio *cb)
{
	struct inode *inode = cb->inode;
	unsigned int index;

	/*
	 * Ok, we're the last bio for this extent, step one is to call back
	 * into the FS and do all the end_io operations.
	 */
	btrfs_writepage_endio_finish_ordered(BTRFS_I(inode), NULL,
			cb->start, cb->start + cb->len - 1,
			cb->status == BLK_STS_OK);

	if (cb->writeback)
		end_compressed_writeback(inode, cb);
	/* Note, our inode could be gone now */

	/*
	 * Release the compressed pages, these came from alloc_page and
	 * are not attached to the inode at all
	 */
	for (index = 0; index < cb->nr_pages; index++) {
		struct page *page = cb->compressed_pages[index];

		page->mapping = NULL;
		put_page(page);
	}

	/* Finally free the cb struct */
	kfree(cb->compressed_pages);
	kfree(cb);
}

static void btrfs_finish_compressed_write_work(struct work_struct *work)
{
	struct compressed_bio *cb =
		container_of(work, struct compressed_bio, write_end_work);

	finish_compressed_bio_write(cb);
}

/*
 * Do the cleanup once all the compressed pages hit the disk.  This will clear
 * writeback on the