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? Thanks, > >> >> Thanks, >> >>> >>>> >>>> Thanks, >>>> >>>>> >>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> >>>>> --- >>>>> 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-devel@xxxxxxxxxxxxxxxxxxxxx >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>>
