On 03/25, Chao Yu wrote:
> Hi Jaegeuk,
>
> On 2017/3/25 15:59, Jaegeuk Kim wrote:
> > - has_not_enough_free_secs
> > node_secs: 0 dent_secs: 0 freed:0 free_segments:103 reserved:104
> >
> > - f2fs_gc
> > - get_victim_by_default
> > alloc_mode 0, gc_mode 1, max_search 2672, offset 4654, ofs_unit 1
> >
> > - do_garbage_collect
> > start_segno 3976, end_segno 3977 type 0
> >
> > - is_alive
> > nid 22797, blkaddr 2131882, ofs_in_node 0, version 0x8/0x0
> >
> > - gc_data_segment 766, segno 3976, block 512/426 not alive
> >
> > So, this patch fixes subtle corrupted case where node version does not match
> > to summary version which results in infinite loop by gc.
> >
> > Reported-by: Yunlei He <heyunlei@xxxxxxxxxx>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> > fs/f2fs/gc.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index 939be88a8833..bbeee41aaf73 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -551,8 +551,10 @@ static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
> > get_node_info(sbi, nid, dni);
> >
> > if (sum->version != dni->version) {
>
> If the node was been truncated, we will increase its version number, since it
> was been truncated, so it will never be writebacked to storage, so the version
> in summary will not be updated.
That's covered by node page lock, so we shouldn't be reached out to this point.
Let's think more about this.
Thanks,
> So this case can happen, shouldn't we just set SBI_NEED_FSCK for the case:
> sum->version != dni->version - 1
>
> Thanks,
>
> > - f2fs_put_page(node_page, 1);
> > - return false;
> > + f2fs_msg(sbi->sb, KERN_WARNING,
> > + "%s: valid data with mismatched node version.",
> > + __func__);
> > + set_sbi_flag(sbi, SBI_NEED_FSCK);
> > }
> >
> > *nofs = ofs_of_node(node_page);
> >
