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f2fs: add bitmaps for empty or full NAT blocks

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This patches adds bitmaps to represent empty or full NAT blocks containing
free nid entries.

If we can find valid crc|cp_ver in the last block of checkpoint pack, we'll
use these bitmaps when building free nids. In order to avoid checkpointing
burden, up-to-date bitmaps will be flushed only during umount time. So,
normally we can get this gain, but when power-cut happens, we rely on fsck.f2fs
which recovers this bitmap again.

After this patch, we build free nids from nid #0 at mount time to make more
full NAT blocks, but in runtime, we check empty NAT blocks to load free nids
without loading any NAT pages from disk.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Jaegeuk Kim
2017-02-09 10:38:09 -08:00
parent 5e8256ac2e
commit 22ad0b6ab4
6 changed files with 231 additions and 20 deletions
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28
fs/f2fs/checkpoint.c
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@@ -1024,6 +1024,10 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
spin_lock(&sbi->cp_lock);
if (cpc->reason == CP_UMOUNT && ckpt->cp_pack_total_block_count >
sbi->blocks_per_seg - NM_I(sbi)->nat_bits_blocks)
disable_nat_bits(sbi, false);
if (cpc->reason == CP_UMOUNT)
__set_ckpt_flags(ckpt, CP_UMOUNT_FLAG);
else
@@ -1136,6 +1140,28 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
start_blk = __start_cp_next_addr(sbi);
/* write nat bits */
if (enabled_nat_bits(sbi, cpc)) {
__u64 cp_ver = cur_cp_version(ckpt);
unsigned int i;
block_t blk;
cp_ver |= ((__u64)crc32 << 32);
*(__le64 *)nm_i->nat_bits = cpu_to_le64(cp_ver);
blk = start_blk + sbi->blocks_per_seg - nm_i->nat_bits_blocks;
for (i = 0; i < nm_i->nat_bits_blocks; i++)
update_meta_page(sbi, nm_i->nat_bits +
(i << F2FS_BLKSIZE_BITS), blk + i);
/* Flush all the NAT BITS pages */
while (get_pages(sbi, F2FS_DIRTY_META)) {
sync_meta_pages(sbi, META, LONG_MAX);
if (unlikely(f2fs_cp_error(sbi)))
return -EIO;
}
}
/* need to wait for end_io results */
wait_on_all_pages_writeback(sbi);
if (unlikely(f2fs_cp_error(sbi)))
@@ -1272,7 +1298,7 @@ int write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
ckpt->checkpoint_ver = cpu_to_le64(++ckpt_ver);
/* write cached NAT/SIT entries to NAT/SIT area */
flush_nat_entries(sbi);
flush_nat_entries(sbi, cpc);
flush_sit_entries(sbi, cpc);
/* unlock all the fs_lock[] in do_checkpoint() */