[dm-devel] fstrim discarding too many or wrong blocks on Linux 5.1, leading to data loss
snitzer at redhat.com
Tue May 21 20:12:27 UTC 2019
On Tue, May 21 2019 at 3:00pm -0400,
Andrea Gelmini <andrea.gelmini at linux.it> wrote:
> On Tue, May 21, 2019 at 06:46:20PM +0200, Michael Laß wrote:
> > > I finished bisecting. Here’s the responsible commit:
> > >
> > > commit 61697a6abd24acba941359c6268a94f4afe4a53d
> > > Author: Mike Snitzer <snitzer at redhat.com>
> > > Date: Fri Jan 18 14:19:26 2019 -0500
> > >
> > > dm: eliminate 'split_discard_bios' flag from DM target interface
> > >
> > > There is no need to have DM core split discards on behalf of a DM target
> > > now that blk_queue_split() handles splitting discards based on the
> > > queue_limits. A DM target just needs to set max_discard_sectors,
> > > discard_granularity, etc, in queue_limits.
> > >
> > > Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> > Reverting that commit solves the issue for me on Linux 5.1.3. Would
> that be an option until the root cause has been identified? I’d rather
> not let more people run into this issue.
> Thanks a lot Michael, for your time/work.
> This kind of bisecting are very boring and time consuming.
> I CC: also the patch author.
Thanks for cc'ing me, this thread didn't catch my eye.
Sorry for your troubles. Can you please try this patch?
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 1fb1333fefec..997385c1ca54 100644
@@ -1469,7 +1469,7 @@ static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
- unsigned len = ci->sector_count;
+ unsigned len;
* Even though the device advertised support for this type of
@@ -1480,6 +1480,8 @@ static int __send_changing_extent_only(struct clone_info *ci, struct dm_target *
+ len = min((sector_t)ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
__send_duplicate_bios(ci, ti, num_bios, &len);
ci->sector += len;
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