On Sun, Jan 24, 2016 at 06:04:06PM +1100, Dave Chinner wrote: > Hence even for ->setattr, we can remove the IOLOCK usage if the > vfs takes the the new i_rwsem in exclusive mode because we would > still have a functional IO submission barrier.... > > > For data operations on regular files it's probably up to filesystems, as > > i_mutex is now. Not sure if IOLOCK would map well on that; can you live with > > that thing taken outside of transaction? > > Yes. IOLOCK has the same scope as i_mutex in the IO path. Umm... So e.g. xfs_create() could take IOLOCK before xfs_trans_reserve()? If so, you probably could eventually be able to use ->i_rwsem for it (and drop it in places where it's already taken by method callers). I'm nowhere near being familiar enough with details of fs/xfs locking to tell how much PITA would the last part be - e.g. a function used both inside ->lookup() and in ->read_iter() and currently taking IOLOCK shared would need to have it lifted into both callers and removed from ->lookup(), etc., which might or might not be painful. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
