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Commit a7eeb823 authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
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f2fs: use bitmap in discard_entry 



This patch changes to use bitmap instead of extent in struct discard_entry
to indicate discard range in one segment, for fragmented space, this
implementation can save memory footprint.

Signed-off-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent f099405f

fs/f2fs/f2fs.h

+3 −3
Original line number Original line Diff line number Diff line
@@ -182,11 +182,11 @@ struct inode_entry { 
	struct inode *inode;	/* vfs inode pointer */

	struct inode *inode;	/* vfs inode pointer */

};

};





/* for the list of blockaddresses to be discarded */

/* for the bitmap indicate blocks to be discarded */

struct discard_entry {

struct discard_entry {

	struct list_head list;	/* list head */

	struct list_head list;	/* list head */

	block_t blkaddr;	/* block address to be discarded */

	block_t start_blkaddr;	/* start blockaddr of current segment */

	int len;		/* # of consecutive blocks of the discard */

	unsigned char discard_map[SIT_VBLOCK_MAP_SIZE];	/* segment discard bitmap */

};

};





enum {

enum {

fs/f2fs/segment.c

+40 −32
Original line number Original line Diff line number Diff line
@@ -962,32 +962,6 @@ static int f2fs_issue_discard(struct f2fs_sb_info *sbi, 
	return err;

	return err;

}

}





static void __add_discard_entry(struct f2fs_sb_info *sbi,

		struct cp_control *cpc, struct seg_entry *se,

		unsigned int start, unsigned int end)

{

	struct list_head *head = &SM_I(sbi)->dcc_info->discard_entry_list;

	struct discard_entry *new, *last;



	if (!list_empty(head)) {

		last = list_last_entry(head, struct discard_entry, list);

		if (START_BLOCK(sbi, cpc->trim_start) + start ==

				last->blkaddr + last->len &&

				last->len < MAX_DISCARD_BLOCKS(sbi)) {

			last->len += end - start;

			goto done;

		}

	}



	new = f2fs_kmem_cache_alloc(discard_entry_slab, GFP_NOFS);

	INIT_LIST_HEAD(&new->list);

	new->blkaddr = START_BLOCK(sbi, cpc->trim_start) + start;

	new->len = end - start;

	list_add_tail(&new->list, head);

done:

	SM_I(sbi)->dcc_info->nr_discards += end - start;

}



static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,

static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,

							bool check_only)

							bool check_only)

{

{
@@ -1000,6 +974,8 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, 
	unsigned long *dmap = SIT_I(sbi)->tmp_map;

	unsigned long *dmap = SIT_I(sbi)->tmp_map;

	unsigned int start = 0, end = -1;

	unsigned int start = 0, end = -1;

	bool force = (cpc->reason == CP_DISCARD);

	bool force = (cpc->reason == CP_DISCARD);

	struct discard_entry *de = NULL;

	struct list_head *head = &SM_I(sbi)->dcc_info->discard_entry_list;

	int i;

	int i;





	if (se->valid_blocks == max_blocks || !f2fs_discard_en(sbi))

	if (se->valid_blocks == max_blocks || !f2fs_discard_en(sbi))
@@ -1031,7 +1007,17 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, 
		if (check_only)

		if (check_only)

			return true;

			return true;





		__add_discard_entry(sbi, cpc, se, start, end);

		if (!de) {

			de = f2fs_kmem_cache_alloc(discard_entry_slab,

								GFP_F2FS_ZERO);

			de->start_blkaddr = START_BLOCK(sbi, cpc->trim_start);

			list_add_tail(&de->list, head);

		}



		for (i = start; i < end; i++)

			__set_bit_le(i, (void *)de->discard_map);



		SM_I(sbi)->dcc_info->nr_discards += end - start;

	}

	}

	return false;

	return false;

}

}
@@ -1117,13 +1103,35 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc) 




	/* send small discards */

	/* send small discards */

	list_for_each_entry_safe(entry, this, head, list) {

	list_for_each_entry_safe(entry, this, head, list) {

		if (force && entry->len < cpc->trim_minlen)

		unsigned int cur_pos = 0, next_pos, len, total_len = 0;

		bool is_valid = test_bit_le(0, entry->discard_map);



find_next:

		if (is_valid) {

			next_pos = find_next_zero_bit_le(entry->discard_map,

					sbi->blocks_per_seg, cur_pos);

			len = next_pos - cur_pos;



			if (force && len < cpc->trim_minlen)

				goto skip;

				goto skip;

		f2fs_issue_discard(sbi, entry->blkaddr, entry->len);



		cpc->trimmed += entry->len;

			f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos,

									len);

			cpc->trimmed += len;

			total_len += len;

		} else {

			next_pos = find_next_bit_le(entry->discard_map,

					sbi->blocks_per_seg, cur_pos);

		}

skip:

skip:

		cur_pos = next_pos;

		is_valid = !is_valid;



		if (cur_pos < sbi->blocks_per_seg)

			goto find_next;



		list_del(&entry->list);

		list_del(&entry->list);

		SM_I(sbi)->dcc_info->nr_discards -= entry->len;

		SM_I(sbi)->dcc_info->nr_discards -= total_len;

		kmem_cache_free(discard_entry_slab, entry);

		kmem_cache_free(discard_entry_slab, entry);

	}

	}

}

}