Re: [PATCH-v2 0/9] target: se_node_acl + se_lun RCU conversions

Hannes Reinecke
2015-05-22T06:23:32Z

On 05/22/2015 08:11 AM, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
>
> Hi all,
>
> Here is -v2 series for converting LIO target se_node_acl + se_lun
> mapping tables from fixed size arrays to dynamic RCU hlist_heads.
>
> This turns fast-path I/O into a lock-less RCU reader using existing
> percpu based se_lun->lun_ref logic, and converts the RCU updater
> path to allow for an arbitrary number of LUNs for both types of
> mappings within target-core.
>
> This series also squashes a number of previous se_node_acl RCU
> related changes into a single commit (#1) for easier review,
> and to avoid potential bisect issues.
>
> There have been a number of changes since -v1, including:
>
> - Mirror port->sep_rtpi in lun->lun_rtpi for RCU
> - Drop unnecessary synchronize_rcu() usage
> - Convert call_rcu() to kfree_rcu() usage
> - Move hlist_del_rcu head of rcu_assign_pointer in se_dev_entry
> - Drop unnecessary lookup deve in target_fabric_mappedlun_unlink()
> - Add target_lun_is_rdonly helper
> - Acquire lun_entry_mutex during core_disable_device_list_for_node
> - Drop TRANSPORT_LUNFLAGS_*_ACCESS usage
> - Pass se_dev_entry directly to core_disable_device_list_for_node
> - Convert sbp-target se_lun usage to use ->login_lun
> - Fix se_session dereference in spc_emulate_report_luns
> - Fix testing for NULL instead of IS_ERR in fabric_make_lun()
> - Convert BUG_ON to EINVAL for wrong dynamic -> explicit ACL conversion
> - Add missing hlist_del_rcu when swapping orig with new
> - Add HBA_FLAGS_INTERNAL_USE checks in add/remove lun
>
> Please review.
>
Very nice.

Reviewed-by: Hannes Reinecke <hare@suse.de>

Although it would be _perfect_ if you could move to full 64-bit
LUNs; now that the LUN array is gone there is no need to have a
limitation on the number of LUNs, and we can trivially support
64-bit LUNs ...

But then, I can easily send a patch once this one is in.

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)