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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: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2017-03-28 18:18:50 +08:00 committed by Jaegeuk Kim
parent f099405fc8
commit a7eeb82385
2 changed files with 43 additions and 35 deletions
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6
fs/f2fs/f2fs.h
View File

@ -182,11 +182,11 @@ struct inode_entry {
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 list_head list; /* list head */
block_t blkaddr; /* block address to be discarded */
int len; /* # of consecutive blocks of the discard */
block_t start_blkaddr; /* start blockaddr of current segment */
unsigned char discard_map[SIT_VBLOCK_MAP_SIZE]; /* segment discard bitmap */
};
enum {

72
fs/f2fs/segment.c
View File

@ -962,32 +962,6 @@ static int f2fs_issue_discard(struct f2fs_sb_info *sbi,
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,
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 int start = 0, end = -1;
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;
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)
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;
}
@ -1117,13 +1103,35 @@ next:
/* send small discards */
list_for_each_entry_safe(entry, this, head, list) {
if (force && entry->len < cpc->trim_minlen)
goto skip;
f2fs_issue_discard(sbi, entry->blkaddr, entry->len);
cpc->trimmed += entry->len;
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;
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:
cur_pos = next_pos;
is_valid = !is_valid;
if (cur_pos < sbi->blocks_per_seg)
goto find_next;
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);
}
}