On 2018/2/9 21:29, Yunlong Song wrote: > Back to the problem, if we skip out, then the f2fs_gc will go > into dead loop if the apps only atomic start but never atomic
That's another issue, which I have suggest to set a threshold time to release atomic/volatile pages by balance_fs_bg. Thanks, > commit. The main aim of my two patches is to remove the skip > action to avoid the dead loop. > > On 2018/2/9 21:26, Chao Yu wrote: >> On 2018/2/9 20:56, Yunlong Song wrote: >>> As what I point in last mail, if the atomic file is not committed >>> yet, gc_data_segment will register_inmem_page the GCed data pages. >> >> We will skip GCing that page as below check: >> >> - move_data_{page,block} >> - f2fs_is_atomic_file() >> skip out; >> >> No? >> >> Thanks, >> >>> This will cause these data pages written twice, the first write >>> happens in move_data_page->do_write_data_page, and the second >>> write happens in later __commit_inmem_pages->do_write_data_page. >>> >>> On 2018/2/9 20:44, Chao Yu wrote: >>>> On 2018/2/8 11:11, Yunlong Song wrote: >>>>> Then the GCed data pages are totally mixed with the inmem atomic pages, >>>> >>>> If we add dio_rwsem, GC flow is exclude with atomic write flow. There >>>> will be not race case to mix GCed page into atomic pages. >>>> >>>> Or you mean: >>>> >>>> - gc_data_segment >>>> - move_data_page >>>> - f2fs_is_atomic_file >>>> - f2fs_ioc_start_atomic_write >>>> - set_inode_flag(inode, FI_ATOMIC_FILE); >>>> - f2fs_set_data_page_dirty >>>> - register_inmem_page >>>> >>>> In this case, GCed page can be mixed into database transaction, but could >>>> it cause any problem except break rule of isolation for transaction. >>>> >>>>> this will cause the atomic commit ops write the GCed data pages twice >>>>> (the first write happens in GC). >>>>> >>>>> How about using the early two patches to separate the inmem data pages >>>>> and GCed data pages, and use dio_rwsem instead of this patch to fix the >>>>> dnode page problem (dnode page commited but data page are not committed >>>>> for the GCed page)? >>>> >>>> Could we fix the race case first, based on that fixing, and then find the >>>> place that we can improve? >>>> >>>>> >>>>> >>>>> On 2018/2/7 20:16, Chao Yu wrote: >>>>>> On 2018/2/6 11:49, Yunlong Song wrote: >>>>>>> This patch adds fi->commit_lock to avoid the case that GCed node pages >>>>>>> are committed but GCed data pages are not committed. This can avoid the >>>>>>> db file run into inconsistent state when sudden-power-off happens if >>>>>>> data pages of atomic file is allowed to be GCed before. >>>>>> >>>>>> do_fsync: GC: >>>>>> - mutex_lock(&fi->commit_lock); >>>>>> - lock_page() >>>>>> - mutex_lock(&fi->commit_lock); >>>>>> - lock_page() >>>>>> >>>>>> >>>>>> Well, please consider lock dependency & code complexity, IMO, reuse >>>>>> fi->dio_rwsem[WRITE] will be enough as below: >>>>>> >>>>>> --- >>>>>> fs/f2fs/file.c | 3 +++ >>>>>> fs/f2fs/gc.c | 5 ----- >>>>>> 2 files changed, 3 insertions(+), 5 deletions(-) >>>>>> >>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>>>>> index 672a542e5464..1bdc11feb8d0 100644 >>>>>> --- a/fs/f2fs/file.c >>>>>> +++ b/fs/f2fs/file.c >>>>>> @@ -1711,6 +1711,8 @@ static int f2fs_ioc_commit_atomic_write(struct >>>>>> file *filp) >>>>>> >>>>>> inode_lock(inode); >>>>>> >>>>>> + down_write(&F2FS_I(inode)->dio_rwsem[WRITE]); >>>>>> + >>>>>> if (f2fs_is_volatile_file(inode)) >>>>>> goto err_out; >>>>>> >>>>>> @@ -1729,6 +1731,7 @@ static int f2fs_ioc_commit_atomic_write(struct >>>>>> file *filp) >>>>>> ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); >>>>>> } >>>>>> err_out: >>>>>> + up_write(&F2FS_I(inode)->dio_rwsem[WRITE]); >>>>>> inode_unlock(inode); >>>>>> mnt_drop_write_file(filp); >>>>>> return ret; >>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>>>>> index b9d93fd532a9..e49416283563 100644 >>>>>> --- a/fs/f2fs/gc.c >>>>>> +++ b/fs/f2fs/gc.c >>>>>> @@ -622,9 +622,6 @@ static void move_data_block(struct inode *inode, >>>>>> block_t bidx, >>>>>> if (!check_valid_map(F2FS_I_SB(inode), segno, off)) >>>>>> goto out; >>>>>> >>>>>> - if (f2fs_is_atomic_file(inode)) >>>>>> - goto out; >>>> >>>> Seems that we need this check. >>>> >>>>>> - >>>>>> if (f2fs_is_pinned_file(inode)) { >>>>>> f2fs_pin_file_control(inode, true); >>>>>> goto out; >>>>>> @@ -729,8 +726,6 @@ static void move_data_page(struct inode *inode, >>>>>> block_t bidx, int gc_type, >>>>>> if (!check_valid_map(F2FS_I_SB(inode), segno, off)) >>>>>> goto out; >>>>>> >>>>>> - if (f2fs_is_atomic_file(inode)) >>>>>> - goto out; >>>> >>>> Ditto. >>>> >>>> Thanks, >>>> >>>>>> if (f2fs_is_pinned_file(inode)) { >>>>>> if (gc_type == FG_GC) >>>>>> f2fs_pin_file_control(inode, true); >>>>>> >>>>> >>>> >>>> . >>>> >>> >> >> . >> >