On Wed, Jan 10, 2018 at 02:03:36PM -0800, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Eryu Guan reported seeing occasional hangs when running generic/269 with > a new fsstress that supports clonerange/deduperange. The cause of this > hang is an infinite loop when we convert the CoW fork extents from > unwritten to real just prior to writing the pages out; the infinite > loop happens because there's nothing in the CoW fork to convert, and so > it spins forever. > > The underlying issue here is that when we go to perform these CoW fork > conversions, we're supposed to have an extent waiting for us, but the > low space CoW reaper has snuck in and blown them away! There are four > conditions that can dissuade the reaper from touching our file -- no > reflink iflag; dirty page cache; writeback in progress; or directio in > progress. We check the four conditions prior to taking the locks, but > we neglect to recheck them once we have the locks, which is how we end > up whacking the writeback that's in progress. > > Therefore, refactor the four checks into a helper function and call it > once again once we have the locks to make sure we really want to reap > the inode. While we're at it, add an ASSERT for this weird condition so > that we'll fail noisily if we ever screw this up again. > > Reported-by: Eryu Guan <eguan@xxxxxxxxxx> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> I applied this patch on top of v4.15-rc5 kernel, and ran generic/083 generic/269 and generic/270 (where I hit the soft lockup and hang before) multiple times and tests all passed. I also ran all tests in 'enospc' group on 1k/2k/4k XFS with reflink enabled, tests passed too. So Tested-by: Eryu Guan <eguan@xxxxxxxxxx> Thanks! Eryu -- 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
