On 05/30, Chao Yu wrote:
> On 2020/5/30 9:49, Jaegeuk Kim wrote:
> > On 05/30, Chao Yu wrote:
> >> On 2020/5/30 6:34, Jaegeuk Kim wrote:
> >>> On 05/29, Chao Yu wrote:
> >>>> Under heavy fsstress, we may triggle panic while issuing discard,
> >>>> because __check_sit_bitmap() detects that discard command may earse
> >>>> valid data blocks, the root cause is as below race stack described,
> >>>> since we removed lock when flushing quota data, quota data writeback
> >>>> may race with write_checkpoint(), so that it causes inconsistency in
> >>>> between cached discard entry and segment bitmap.
> >>>>
> >>>> - f2fs_write_checkpoint
> >>>> - block_operations
> >>>> - set_sbi_flag(sbi, SBI_QUOTA_SKIP_FLUSH)
> >>>> - f2fs_flush_sit_entries
> >>>> - add_discard_addrs
> >>>> - __set_bit_le(i, (void *)de->discard_map);
> >>>> - f2fs_write_data_pages
> >>>> - f2fs_write_single_data_page
> >>>> : inode is quota one,
> >>>> cp_rwsem won't be locked
> >>>> - f2fs_do_write_data_page
> >>>> - f2fs_allocate_data_block
> >>>> - f2fs_wait_discard_bio
> >>>> : discard entry has not
> >>>> been added yet.
> >>>> - update_sit_entry
> >>>> - f2fs_clear_prefree_segments
> >>>> - f2fs_issue_discard
> >>>> : add discard entry
> >>>>
> >>>> This patch fixes this issue by reverting 435cbab95e39 ("f2fs: fix
> >>>> quota_sync
> >>>> failure due to f2fs_lock_op").
> >>>>
> >>>> Fixes: 435cbab95e39 ("f2fs: fix quota_sync failure due to f2fs_lock_op")
> >>>
> >>> The previous patch fixes quota_sync gets EAGAIN all the time.
> >>> How about this? It seems this works for fsstress test.
> >>>
> >
> > Then this?
> >
> > ---
> > fs/f2fs/segment.c | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index ebbadde6cbced..ed11dcf2d69ed 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -3107,6 +3107,14 @@ void f2fs_allocate_data_block(struct f2fs_sb_info
> > *sbi, struct page *page,
> > type = CURSEG_COLD_DATA;
> > }
> >
> > + /*
> > + * We need to wait for node_write to avoid block allocation during
> > + * checkpoint. This can only happen to quota writes which can cause
> > + * the below discard race condition.
> > + */
> > + if (IS_DATASEG(type))
> > + down_write(&sbi->node_write);
> > +
> > down_read(&SM_I(sbi)->curseg_lock);
> >
> > mutex_lock(&curseg->curseg_mutex);
> > @@ -3174,6 +3182,9 @@ void f2fs_allocate_data_block(struct f2fs_sb_info
> > *sbi, struct page *page,
>
> Minor thing: unlock order.
>
> if (IS_DATASEG(type))
> up_write(&sbi->node_write);
>
> Could you merge the diff into this patch?
Pushed in dev branch. Thanks.
>
> >
> > if (put_pin_sem)
> > up_read(&sbi->pin_sem);
> > +
> > + if (IS_DATASEG(type))
> > + up_write(&sbi->node_write);
> > }
> >
> > static void update_device_state(struct f2fs_io_info *fio)
> >
