The following patches were built over Linus's tree and this patchset which fixes some scsi error handling issues: https://lore.kernel.org/linux-scsi/1136e369-49b0-c3ef-340a-ab337f514fc5@xxxxxxxxxx/T/#meebd5040bc360f8c86532b792b48dbe3efe88619 The patches allow us to use the block pr_ops with LIO's target_core_iblock module to support cluster applications in VMs. Currently, to use windows clustering or linux clustering (pacemaker + cluster labs scsi fence agents) in VMs with LIO and vhost-scsi, you have to use tcmu or pscsi or use a cluster aware FS/framework for the LIO pr file. Setting up a cluster FS/framework is pain and waste when your real backend device is already a distributed device, and pscsi and tcmu are nice for specific use cases, but iblock gives you the best performance and allows you to use stacked devices like dm-multipath. So these patches allow iblock to work like pscsi/tcmu where they can pass a PR command to the backend module. And then iblock will use the pr_ops to pass the PR command to the real devices similar to what we do for unmap today. The patches are separated in the following groups: patches 1 - 11 - Add callouts to read a reservation and it's keys. patches 12 - 16 - Have pr_ops return a blk_status_t. patches 17 - 20 - Support for target_core_iblock to bypass the emulate PR code and call the pr_ops. This patchset has been tested with the libiscsi PGR ops and with window's failover cluster verification test. v2: - Drop BLK_STS_NEXUS rename changes. Will do separately. - Add NVMe support. - Fixed bug in target_core_iblock where a variable was not initialized mentioned by Christoph. - Fixed sd pr_ops UA handling issue found when running libiscsi PGR tests. - Added patches to allow pr_ops to pass up a BLK_STS so we could return a RESERVATION_CONFLICT status when a pr_ops callout fails.
