1) Introduce DM_TARGET_ZONED_HM feature flag:
The target drivers currently available will not operate correctly if a
table target maps onto a host-managed zoned block device.
To avoid problems, introduce the new feature flag DM_TARGET_ZONED_HM to
allow a target to explicitly state that it supports host-managed zoned
block devices. This feature is checked for all targets in a table if
any of the table's block devices are host-managed.
Note that as host-aware zoned block devices are backward compatible with
regular block devices, they can be used by any of the current target
types. This new feature is thus restricted to host-managed zoned block
devices.
2) Check device area zone alignment:
If a target maps to a zoned block device, check that the device area is
aligned on zone boundaries to avoid problems with REQ_OP_ZONE_RESET
operations (resetting a partially mapped sequential zone would not be
possible). This also facilitates the processing of zone report with
REQ_OP_ZONE_REPORT bios.
3) Check block devices zone model compatibility
When setting the DM device's queue limits, several possibilities exists
for zoned block devices:
1) The DM target driver may want to expose a different zone model
(e.g. host-managed device emulation or regular block device on top of
host-managed zoned block devices)
2) Expose the underlying zone model of the devices as-is
To allow both cases, the underlying block device zone model must be set
in the target limits in dm_set_device_limits() and the compatibility of
all devices checked similarly to the logical block size alignment. For
this last check, introduce validate_hardware_zoned_model() to check that
all targets of a table have the same zone model and that the zone size
of the target devices are equal.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
[Mike Snitzer refactored Damien's original work to simplify the code]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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