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Commit b2955550 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: add key functions for small discards 



This patch adds key functions to activate the small discard feature.

Note that this procedure is conducted during the checkpoint only.

In flush_sit_entries(), when a new dirty sit entry is flushed, f2fs calls
add_discard_addrs() which searches candidates to be discarded.
The candidates should be marked *invalidated* and also previous checkpoint
recognizes it as *valid*.

At the end of a checkpoint procedure, f2fs throws discards based on the
discard entry list.

Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent 7fd9e544

fs/f2fs/segment.c

+60 −0
Original line number Diff line number Diff line
@@ -266,6 +266,47 @@ static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno) 
	mutex_unlock(&dirty_i->seglist_lock);

}



static void add_discard_addrs(struct f2fs_sb_info *sbi,

			unsigned int segno, struct seg_entry *se)

{

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

	struct discard_entry *new;

	int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);

	int max_blocks = sbi->blocks_per_seg;

	unsigned long *cur_map = (unsigned long *)se->cur_valid_map;

	unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;

	unsigned long dmap[entries];

	unsigned int start = 0, end = -1;

	int i;



	if (!test_opt(sbi, DISCARD))

		return;



	/* zero block will be discarded through the prefree list */

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

		return;



	/* SIT_VBLOCK_MAP_SIZE should be multiple of sizeof(unsigned long) */

	for (i = 0; i < entries; i++)

		dmap[i] = (cur_map[i] ^ ckpt_map[i]) & ckpt_map[i];



	while (SM_I(sbi)->nr_discards <= SM_I(sbi)->max_discards) {

		start = __find_rev_next_bit(dmap, max_blocks, end + 1);

		if (start >= max_blocks)

			break;



		end = __find_rev_next_zero_bit(dmap, max_blocks, start + 1);



		new = f2fs_kmem_cache_alloc(discard_entry_slab, GFP_NOFS);

		INIT_LIST_HEAD(&new->list);

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

		new->len = end - start;



		list_add_tail(&new->list, head);

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

	}

}



/*

 * Should call clear_prefree_segments after checkpoint is done.

 */
@@ -288,6 +329,9 @@ static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi) 


void clear_prefree_segments(struct f2fs_sb_info *sbi)

{

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

	struct list_head *this, *next;

	struct discard_entry *entry;

	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

	unsigned long *prefree_map = dirty_i->dirty_segmap[PRE];

	unsigned int total_segs = TOTAL_SEGS(sbi);
@@ -318,6 +362,18 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi) 
				GFP_NOFS, 0);

	}

	mutex_unlock(&dirty_i->seglist_lock);



	/* send small discards */

	list_for_each_safe(this, next, head) {

		entry = list_entry(this, struct discard_entry, list);

		blkdev_issue_discard(sbi->sb->s_bdev,

				entry->blkaddr << sbi->log_sectors_per_block,

				(1 << sbi->log_sectors_per_block) * entry->len,

				GFP_NOFS, 0);

		list_del(&entry->list);

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

		kmem_cache_free(discard_entry_slab, entry);

	}

}



static void __mark_sit_entry_dirty(struct f2fs_sb_info *sbi, unsigned int segno)
@@ -1469,6 +1525,10 @@ void flush_sit_entries(struct f2fs_sb_info *sbi) 


		sit_offset = SIT_ENTRY_OFFSET(sit_i, segno);



		/* add discard candidates */

		if (SM_I(sbi)->nr_discards < SM_I(sbi)->max_discards)

			add_discard_addrs(sbi, segno, se);



		if (flushed)

			goto to_sit_page;