On 07/01, Chao Yu wrote: > On 2017/7/1 15:28, Jaegeuk Kim wrote: > > On 06/26, Chao Yu wrote: > >> Hi Jaegeuk, > >> > >> On 2017/6/26 22:54, Jaegeuk Kim wrote: > >>> Hi Chao, > >>> > >>> On 06/26, Chao Yu wrote: > >>>> Hi Jaegeuk, > >>>> > >>>> On 2017/6/25 0:25, Jaegeuk Kim wrote: > >>>>> - punch_hole > >>>>> - fill_zero > >>>>> - f2fs_lock_op > >>>>> - get_new_data_page > >>>>> - lock_page > >>>>> > >>>>> - f2fs_write_data_pages > >>>>> - lock_page > >>>>> - do_write_data_page > >>>>> - f2fs_lock_op > >>>> > >>>> Good catch! > >>>> > >>>> With this implementation, page writeback can fail due to concurrent > >>>> checkpoint, > >>>> this will make fsync/atomic_commit which trigger synchronous write > >>>> failed randomly. > >>>> > >>>> How about unifying the lock order in punch_hole as one in writepages for > >>>> regular > >>>> inode? We can add one more parameter in get_new_data_page to indicate > >>>> whether > >>>> callee needs to lock cp_rwsem. > >>> > >>> Currently, there would be some places to keep cp_rwsem -> page.lock, > >>> which seems > >>> not simple to change the lock order with page.lock -> cp_rwsem. IMO, we > >>> can retry > >>> flushing data in f2fs_sync_file, once it gets -EAGAIN. > >>> > >>> Any thoughts? > >> > >> What about adding inode_lock in f2fs_sync_file to exclude other > >> foreground operation which have reversed lock order? Atomic_commit is OK > >> since it has inode_lock in its path. > > > > I have concerned about performance regression, if we do that. > > I think fsync vs write or fsync vs fsync scenarios are unusual, so is > there any usecase?
Well, that'd be common to call multiple fsync calls at the same time. Like dbench or tiotest? > > Thanks, > > > > >> > >> Thanks, > >> > >>> > >>>> > >>>> Thanks, > >>>> > >>>>> > >>>>> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org> > >>>>> --- > >>>>> fs/f2fs/data.c | 5 +++-- > >>>>> 1 file changed, 3 insertions(+), 2 deletions(-) > >>>>> > >>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c > >>>>> index 7d3af48d34a9..9141bd19a902 100644 > >>>>> --- a/fs/f2fs/data.c > >>>>> +++ b/fs/f2fs/data.c > >>>>> @@ -1404,8 +1404,9 @@ int do_write_data_page(struct f2fs_io_info *fio) > >>>>> } > >>>>> } > >>>>> > >>>>> - if (fio->need_lock == LOCK_REQ) > >>>>> - f2fs_lock_op(fio->sbi); > >>>>> + /* Deadlock due to between page->lock and f2fs_lock_op */ > >>>>> + if (fio->need_lock == LOCK_REQ && !f2fs_trylock_op(fio->sbi)) > >>>>> + return -EAGAIN; > >>>>> > >>>>> err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE); > >>>>> if (err) > >>>>> > >>> > >>> ------------------------------------------------------------------------------ > >>> Check out the vibrant tech community on one of the world's most > >>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot > >>> _______________________________________________ > >>> Linux-f2fs-devel mailing list > >>> linux-f2fs-de...@lists.sourceforge.net > >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > >>>
