On Thu, Apr 19, 2018 at 10:25:48AM -0700, Darrick J. Wong wrote: > On Thu, Apr 19, 2018 at 08:55:47AM -0400, Brian Foster wrote: > > On Tue, Apr 17, 2018 at 07:40:20PM -0700, Darrick J. Wong wrote: > > > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > > > > > We've never cached buffers when reading or writing superblocks, so we > > > need to change scrub to do likewise or risk screwing up the uncached sb > > > buffer usage everywhere else. > > > > > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > > --- > > > > Hmm, so this goes back to this[1] thread, right? > > Yep. > > > IIRC, we wanted to end up with an lru-bypassing uncached buffer lookup > > mechanism to provide uncached behavior for resource-saving purposes > > but without introducing serialization issues between multiple users of > > uncached buffers. > > Right. > > > On a quick look back, growfs currently uses cached buffers for secondary > > superblocks and the associated patch was looking to change that to > > something like the above. Don't we have the same requirement here (since > > growfs currently still uses cached buffers)? > > Correct, this patch is contingent on landing Dave's "tableise growfs" > series that converts growfs to use uncached buffers for writing out the > new secondary supers. If I manage to land Dave's growfs thing before > repair then I'll keep this; if repair goes first I'll defer it to that > series. I plan on changing that patch set to use single-use cached buffers rather than uncached buffers. So I'd just drop this patch, or replace it with a patch that adds this: #define XFS_SINGLE_USE_REF 0 and this after the xfs_trans_read_buf() call: xfs_buf_set_ref(bp, XFS_SINGLE_USE_REF); Which will result in it being reclaimed when it is released rather than being put on the LRU. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
