On Mon, 4 Jan 2021, Mike Snitzer wrote: > On Sun, Dec 20 2020 at 8:02am -0500, > Lukas Straub <lukasstraub2@xxxxxx> wrote: > > > With an external metadata device, flush requests aren't passed down > > to the data device. > > > > Fix this by issuing flush in the right places: In integrity_commit > > when not in journal mode, in do_journal_write after writing the > > contents of the journal to the disk and in dm_integrity_postsuspend. > > > > Signed-off-by: Lukas Straub <lukasstraub2@xxxxxx> > > --- > > drivers/md/dm-integrity.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c > > index 5a7a1b90e671..a26ed65869f6 100644 > > --- a/drivers/md/dm-integrity.c > > +++ b/drivers/md/dm-integrity.c > > @@ -2196,6 +2196,8 @@ static void integrity_commit(struct work_struct *w) > > if (unlikely(ic->mode != 'J')) { > > spin_unlock_irq(&ic->endio_wait.lock); > > dm_integrity_flush_buffers(ic); > > + if (ic->meta_dev) > > + blkdev_issue_flush(ic->dev->bdev, GFP_NOIO); > > goto release_flush_bios; > > } > > > > @@ -2410,6 +2412,9 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start, > > wait_for_completion_io(&comp.comp); > > > > dm_integrity_flush_buffers(ic); > > + if (ic->meta_dev) > > + blkdev_issue_flush(ic->dev->bdev, GFP_NOIO); > > + > > } > > > > static void integrity_writer(struct work_struct *w) > > @@ -2949,6 +2954,9 @@ static void dm_integrity_postsuspend(struct dm_target *ti) > > #endif > > } > > > > + if (ic->meta_dev) > > + blkdev_issue_flush(ic->dev->bdev, GFP_NOIO); > > + > > BUG_ON(!RB_EMPTY_ROOT(&ic->in_progress)); > > > > ic->journal_uptodate = true; > > -- > > 2.20.1 > > > Seems like a pretty bad oversight... but shouldn't you also make sure to > flush the data device _before_ the metadata is flushed? > > Mike I think, ordering is not a problem. A disk may flush its cache spontaneously anytime, so it doesn't matter in which order do we flush them. Similarly a dm-bufio buffer may be flushed anytime - if the machine is running out of memory and a dm-bufio shrinker is called. I'll send another patch for this - I've created a patch that flushes the metadata device cache and data device cache in parallel, so that performance degradation is reduced. My patch also doesn't use GFP_NOIO allocation - which can in theory deadlock if we are swapping on dm-integrity device. Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel