Commit af4b6b8e authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
Browse files

f2fs: introduce check_swap_activate_fast() 



check_swap_activate() will lookup block mapping via bmap() one by one, so
its performance is very bad, this patch introduces check_swap_activate_fast()
to use f2fs_fiemap() to boost this process, since f2fs_fiemap() will lookup
block mappings in batch, therefore, it can improve swapon()'s performance
significantly.

Note that this enhancement only works when page size is equal to f2fs' block
size.

Testcase: (backend device: zram)
- touch file
- pin & fallocate file to 8GB
- mkswap file
- swapon file

Before:
real	0m2.999s
user	0m0.000s
sys	0m2.980s

After:
real	0m0.081s
user	0m0.000s
sys	0m0.064s

Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent 6ed29fe1

fs/f2fs/data.c

+80 −0
Original line number Diff line number Diff line
@@ -3883,6 +3883,83 @@ int f2fs_migrate_page(struct address_space *mapping, 
#endif



#ifdef CONFIG_SWAP

static int check_swap_activate_fast(struct swap_info_struct *sis,

				struct file *swap_file, sector_t *span)

{

	struct address_space *mapping = swap_file->f_mapping;

	struct inode *inode = mapping->host;

	sector_t cur_lblock;

	sector_t last_lblock;

	sector_t pblock;

	sector_t lowest_pblock = -1;

	sector_t highest_pblock = 0;

	int nr_extents = 0;

	unsigned long nr_pblocks;

	unsigned long len;

	int ret;



	/*

	 * Map all the blocks into the extent list.  This code doesn't try

	 * to be very smart.

	 */

	cur_lblock = 0;

	last_lblock = logical_to_blk(inode, i_size_read(inode));

	len = i_size_read(inode);



	while (cur_lblock <= last_lblock && cur_lblock < sis->max) {

		struct buffer_head map_bh;

		pgoff_t next_pgofs;



		cond_resched();



		memset(&map_bh, 0, sizeof(struct buffer_head));

		map_bh.b_size = len - cur_lblock;



		ret = get_data_block(inode, cur_lblock, &map_bh, 0,

					F2FS_GET_BLOCK_FIEMAP, &next_pgofs);

		if (ret)

			goto err_out;



		/* hole */

		if (!buffer_mapped(&map_bh))

			goto err_out;



		pblock = map_bh.b_blocknr;

		nr_pblocks = logical_to_blk(inode, map_bh.b_size);



		if (cur_lblock + nr_pblocks >= sis->max)

			nr_pblocks = sis->max - cur_lblock;



		if (cur_lblock) {	/* exclude the header page */

			if (pblock < lowest_pblock)

				lowest_pblock = pblock;

			if (pblock + nr_pblocks - 1 > highest_pblock)

				highest_pblock = pblock + nr_pblocks - 1;

		}



		/*

		 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks

		 */

		ret = add_swap_extent(sis, cur_lblock, nr_pblocks, pblock);

		if (ret < 0)

			goto out;

		nr_extents += ret;

		cur_lblock += nr_pblocks;

	}

	ret = nr_extents;

	*span = 1 + highest_pblock - lowest_pblock;

	if (cur_lblock == 0)

		cur_lblock = 1;	/* force Empty message */

	sis->max = cur_lblock;

	sis->pages = cur_lblock - 1;

	sis->highest_bit = cur_lblock - 1;

out:

	return ret;

err_out:

	pr_err("swapon: swapfile has holes\n");

	return -EINVAL;

}



/* Copied from generic_swapfile_activate() to check any holes */

static int check_swap_activate(struct swap_info_struct *sis,

				struct file *swap_file, sector_t *span)
@@ -3899,6 +3976,9 @@ static int check_swap_activate(struct swap_info_struct *sis, 
	int nr_extents = 0;

	int ret;



	if (PAGE_SIZE == F2FS_BLKSIZE)

		return check_swap_activate_fast(sis, swap_file, span);



	blkbits = inode->i_blkbits;

	blocks_per_page = PAGE_SIZE >> blkbits;

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