Messages in this thread | | | Subject | Re: [dm-devel] [PATCH 0/3] dm raid/raid1: enable discard support when any devices support discard | From | Ondrej Kozina <> | Date | Mon, 20 Apr 2020 09:35:38 +0200 |
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On 4/19/20 4:48 PM, Paul Wise wrote: > On Sun, 2020-04-19 at 09:19 -0400, Mike Snitzer wrote: > >> You went overboard with implementation before checking to see if your >> work would be well received. Your 2/3 patch header shows you're >> capable of analyzing past commits to explain the evolution of code, >> etc. But yet you make no mention of this commit header which explicitly >> speaks to why what you're proposing is _not_ acceptable: >> >> commit 8a74d29d541cd86569139c6f3f44b2d210458071 >> Author: Mike Snitzer <snitzer@redhat.com> >> Date: Tue Nov 14 15:40:52 2017 -0500 >> >> dm: discard support requires all targets in a table support discards > > I do remember seeing this commit while working on this, I guess I > ignored it in my attempts to get fstrim working on my rootfs, woops. > >> I haven't looked closely at MD raid in this area but if you trully think >> underlying MD raid can cope with issuing discards to devices that don't >> support them (or that it avoids issuing them?) then please update >> dm-raid.c to conditionally set ti->discard_supported (if not all devices >> support discard). That is how to inform DM core that the target knows >> better and it will manage discards issued to it. It keeps the change >> local to dm-raid.c without the flag-day you're proposing. > > On my system I have a HDD and an SSD, with /boot on MD RAID and / on > ext4 on DM RAID on 2 DM crypt volumes. In this setup fstrim works on > /boot but does not work on / and with my patches it works on / again. > In addition I don't see any messages in dmesg or other issues when > doing fstrim / with my patches.
Did you have discard allowed on both dm-crypt devices? dm-crypt (kernel) does not allow discards by default.
Regards O.
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