Hi Chao,
On Sat, Jan 31, 2015 at 05:06:59PM +0800, Chao Yu wrote:
> Previously, discard_next_dnode is added before a checkpoint to prevent that we
> may meet a garbage dnode page readed from next free blkaddr in recover flow.
>
> Since f2fs will skip recovery flow for a clean umount image, this condition
> will
> never happen.
>
> So it's safe for us to leave next free dnode as it is in an umount checkpoint.
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/checkpoint.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index f7cdcad..991fd0a 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -905,8 +905,12 @@ static void do_checkpoint(struct f2fs_sb_info *sbi,
> struct cp_control *cpc)
> /*
> * This avoids to conduct wrong roll-forward operations and uses
> * metapages, so should be called prior to sync_meta_pages below.
> + * But if we are in an umount checkpoint, we'd better skip this
> + * because we will not enter recovery flow to use the next free
> + * blkaddr when mounting it.
> */
> - discard_next_dnode(sbi, NEXT_FREE_BLKADDR(sbi, curseg));
> + if (cpc->reason != CP_UMOUNT)
> + discard_next_dnode(sbi, NEXT_FREE_BLKADDR(sbi, curseg));
The reason for discard_next_dnode is to avoid wrong execution due to old
mkfs.f2fs which remains gabage data.
It needs to do all the time.
Thanks,
>
> /* Flush all the NAT/SIT pages */
> while (get_pages(sbi, F2FS_DIRTY_META)) {
> --
> 2.2.1
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