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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: Jaegeuk Kim <jaegeuk.kim@samsung.com>
wifi-calibration
Jaegeuk Kim 2013-11-12 14:49:56 +09:00
parent 7fd9e544fb
commit b29555505d
1 changed files with 60 additions and 0 deletions
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60
fs/f2fs/segment.c
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@ -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;