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. > > --- > fs/f2fs/segment.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index ebbadde6cbced..f67cffc38975e 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -3095,6 +3095,14 @@ void f2fs_allocate_data_block(struct f2fs_sb_info > *sbi, struct page *page, > struct curseg_info *curseg = CURSEG_I(sbi, type); > bool put_pin_sem = false; > > + /* > + * 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))
type is CURSEG_COLD_DATA_PINNED, IS_DATASEG(CURSEG_COLD_DATA_PINNED) should be false, then node_write lock will not be held, later type will be updated to CURSEG_COLD_DATA, then we will try to release node_write. Thanks, > + down_write(&sbi->node_write); > + > if (type == CURSEG_COLD_DATA) { > /* GC during CURSEG_COLD_DATA_PINNED allocation */ > if (down_read_trylock(&sbi->pin_sem)) { > @@ -3174,6 +3182,9 @@ void f2fs_allocate_data_block(struct f2fs_sb_info *sbi, > struct page *page, > > 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) >