On 2017/10/13 21:21, Yunlong Song wrote: > Without this patch, it will cause all the free segments using up in some > corner case. For example, there are 100 segments, and 20 of them are > reserved for ovp. If 79 segments are full of data, segment 80 becomes > CURSEG segment, write 512 blocks and then delete 511 blocks. Since it is > CURSEG segment, the __locate_dirty_segment will not update its dirty > status. Then the dirty_segments(sbi) is 0, f2fs_gc will fail to > get_victim, and f2fs_balance_fs will fail to trigger gc action. After > f2fs_balance_fs returns, f2fs can continue to write data to segment 81. > Again, segment 81 becomes CURSEG segment, write 512 blocks and delete > 511 blocks, the dirty_segments(sbi) is 0 and f2fs_gc fail again. This > can finally use up all the free segments and cause panic. Look into this patch again, I found refresh_sit_entry is called after ->allocate_segment, so if all 512 blocks were allocated, log header should have been moved to another segment, so locate_dirty_segment in refresh_sit_entry should update dirty status of previous segment correctly, anything I'm missing? Thanks, > > Signed-off-by: Yunlong Song <yunlong.song@xxxxxxxxxx> > --- > fs/f2fs/segment.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index bfbcff8..0fce076 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -687,7 +687,7 @@ static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno, > struct dirty_seglist_info *dirty_i = DIRTY_I(sbi); > > /* need not be added */ > - if (IS_CURSEG(sbi, segno)) > + if (IS_CURSEG(sbi, segno) && dirty_type == PRE) > return; > > if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type])) > @@ -737,7 +737,7 @@ static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno) > struct dirty_seglist_info *dirty_i = DIRTY_I(sbi); > unsigned short valid_blocks; > > - if (segno == NULL_SEGNO || IS_CURSEG(sbi, segno)) > + if (segno == NULL_SEGNO) > return; > > mutex_lock(&dirty_i->seglist_lock); >
