On Tue, Aug 18, 2015 at 05:33:05PM -0500, Eric Sandeen wrote: > On 8/18/15 5:28 PM, Dave Chinner wrote: > > On Wed, Aug 19, 2015 at 01:21:51AM +0800, Zorro Lang wrote: > >> @@ -50,6 +50,16 @@ rm -f $seqres.full > >> # For this test we use block size = 1/8 page size > >> pgsize=`$here/src/feature -s` > >> blksize=`expr $pgsize / 8` > >> +secsize=`_min_dio_alignment $SCRATCH_DEV` > >> + > >> +# The minimal blksize can't less than sector size, So if > >> +# blksize < secsize, we should adjust blksize and pgsize number. > >> +# Of course, if we adjust pgsize, pgsize won't equal to the > >> +# real page size of system. > >> +if [ $blksize -lt $secsize ];then > >> + blksize=$secsize > >> + pgsize=`expr $blksize \* 8` > >> +fi > > > > No, this is wrong. the page size stays fixed at the machine page > > size. We are testing *sub-page block sizes* here and the sector size > > must be <= page size. Increasing the "page size" to larger than the > > machine page size does not make the kernel use larger page sizes. > > > > IOWs, if you've got sector size = page size (e.g. 4k sector device) > > then no matter what you say $pgsize is, the kernel will see a block > > size = page size test. > > > > This whole chunk of code can simply be replaced with: > > > > blksize=`_min_dio_alignment $SCRATCH_DEV` > > > > Because that's what we actually need to test... > > That won't work either, because we could easily get 512 from that. If 'blockdev --getss $dev' returns 512, then the device supports 512 byte IOs and so it is fine to do 512 byte IOs in the test. > and then this test: > > # Now try the same thing but write a sector in the middle of that hole > # If things go badly stale data will be exposed either side. > # This is most interesting for block size > 512 (page size > 4096) > > # We *should* get: > # |1100|HHHH|33HH|HHHH|2222|----|----|----| > > echo "== Test 4 ==" > xfs_io \ > -c "pwrite -S 0x11 -b $pgsize 0 $pgsize" \ > -c "mmap -r 0 $blksize" -c "mread 0 $blksize" -c "munmap" \ > -c "truncate `expr $blksize / 2`" \ > -c "truncate `expr $blksize + 1`" \ > -c "pwrite -S 0x22 -b $blksize `expr $pgsize / 2` $blksize" \ > -c "pwrite -S 0x33 -b 512 `expr $blksize \* 2` 512" \ > -t -d -f $SCRATCH_MNT/testfile4 >> $seqres.full > > will be impossible. > > AFAICT everything works except for that explicit 512-byte IO. Right. That hard coded 512 needs to change to $blksize, because blksize is now equal to the sector size. I thought this would be obvious to the reader, so I didn't comment on it. > All we really need here is a sub-block-size IO, but at least as > large as the logical sector size. Yes. See above. > So we want sub-page-size blocks, an sub-block-sized IOS (here). Yes. See above. > Can't be *that* tricky to work out the scaling for various pages > and sector sizes, I hope? :) Famous last words! It's not. See above. :) Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
