s390/dasd: Re-enable discard support for ESE volumes

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Re-enable block-layer discard for ESE ECKD volumes, releasing thin space
via release allocated space (RAS).
This is based on
commit 7e64db1597 ("s390/dasd: Add discard support for ESE volumes")
but adapted to the current code and fixed.

REQ_OP_DISCARD is routed to a RAS release over the request's track range,
and discard requests run on the base device only. Discard limits use extent
granularity via the disc_limits discipline hook so the block layer only
issues extent-aligned discards.

Discard is gated on the DASD_FEATURE_DISCARD device feature rather than a
per-discipline flag: the driver sets the feature when the volume is on ESE
hardware (i.e. RAS is available), and the block-layer setup enables discard
limits for a device that has it.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://patch.msgid.link/20260805111612.1285190-19-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

...

This commit is contained in:

Stefan Haberland 2026-08-05 13:16:11 +02:00 • committed by Jens Axboe

parent 6c1be943fd

commit 04ea1579bc

3 changed files with 166 additions and 43 deletions

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34

drivers/s390/block/dasd.c

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173

drivers/s390/block/dasd_eckd.c

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2

drivers/s390/block/dasd_int.h

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