On 11/15, Chao Yu wrote:
> Hi Jaegeuk,
>
> Please drop this patch first, as it still can trigger deadlock as below, sorry
> about this mistake.
Got it. Thank you.
>
> - f2fs_put_super
> - f2fs_wait_discard_bios
> - __issue_discard_cmd
> - lock(&dcc->cmd_lock); A
> - __check_sit_bitmap
> - down_read(&sit_i->sentry_lock) B
>
> - do_write_page
> - allocate_data_block
> - down_write(&sit_i->sentry_lock) B
> - locate_dirty_segment
> - lock(&dirty_i->seglist_lock) C
>
> - write_checkpoint
> - clear_prefree_segments
> - lock(&dirty_i->seglist_lock) C
> - f2fs_issue_discard
> - __issue_discard_async
> - __queue_discard_cmd
> - __update_discard_tree_range
> - lock(&dcc->cmd_lock) A
>
> Thanks,
>
> On 2017/11/13 17:54, Chao Yu wrote:
> > This patch protects sit bitmap accessing in __check_sit_bitmap with
> > sentry_lock, meanwhile, in allocate_data_block, f2fs_wait_discard_bio
> > will not access/update sit cache, let's exclude it from sentry_lock's
> > region.>
> > Signed-off-by: Chao Yu <yuch...@huawei.com>
> > ---
> > fs/f2fs/segment.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index c117e0913f2a..464696b1612a 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -894,6 +894,8 @@ void __check_sit_bitmap(struct f2fs_sb_info *sbi,
> > unsigned long offset, size, max_blocks = sbi->blocks_per_seg;
> > unsigned long *map;
> >
> > + down_read(&SIT_I(sbi)->sentry_lock);
> > +
> > while (blk < end) {
> > segno = GET_SEGNO(sbi, blk);
> > sentry = get_seg_entry(sbi, segno);
> > @@ -908,6 +910,8 @@ void __check_sit_bitmap(struct f2fs_sb_info *sbi,
> > f2fs_bug_on(sbi, offset != size);
> > blk = START_BLOCK(sbi, segno + 1);
> > }
> > +
> > + up_read(&SIT_I(sbi)->sentry_lock);
> > #endif
> > }
> >
> > @@ -2527,12 +2531,13 @@ void allocate_data_block(struct f2fs_sb_info *sbi,
> > struct page *page,
> > down_read(&SM_I(sbi)->curseg_lock);
> >
> > mutex_lock(&curseg->curseg_mutex);
> > - down_write(&sit_i->sentry_lock);
> >
> > *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
> >
> > f2fs_wait_discard_bio(sbi, *new_blkaddr);
> >
> > + down_write(&sit_i->sentry_lock);
> > +
> > /*
> > * __add_sum_entry should be resided under the curseg_mutex
> > * because, this function updates a summary entry in the
> >
