On Wed, Mar 25, 2020 at 11:29 AM Jaegeuk Kim <jaeg...@kernel.org> wrote: > It seems dm-crypt has discard-related support, ie., "allow_discards", in ctrl. > But, FWIW, the target simply doesn't support discard at all. > > # grep discards_supported drivers/md/* > drivers/md/dm-cache-target.c: ti->discards_supported = true; > drivers/md/dm-clone-target.c: ti->discards_supported = true; > drivers/md/dm-log-writes.c: ti->discards_supported = true; > drivers/md/dm-table.c: if (!tgt->num_discard_bios && tgt->discards_supported) > drivers/md/dm-table.c: DMWARN("%s: %s: ignoring discards_supported > because num_discard_bios is zero.", > drivers/md/dm-table.c: * 'discards_supported') or it relies on > _all_ data devices having > drivers/md/dm-table.c: if (!ti->discards_supported && > drivers/md/dm-thin.c: * Setting 'discards_supported' circumvents > the normal > drivers/md/dm-thin.c: ti->discards_supported = true; > drivers/md/dm-thin.c: ti->discards_supported = true; > drivers/md/dm-zoned-target.c: ti->discards_supported = true;
I can confirm that it is true with an encrypted ext4 partition. I get the same error, "fstrim: /mnt/test: the discard operation is not supported" when I try it there on the same device. Unless there is a good reason for it, not having discard on LUKS encrypted partitions seems like a pretty serious omission. Perhaps it is intentional. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel