• Nicholas Bellinger's avatar
    target: Convert se_node_acl->device_list[] to RCU hlist · 29a05dee
    Nicholas Bellinger authored
    This patch converts se_node_acl->device_list[] table for mappedluns
    to modern RCU hlist_head usage in order to support an arbitrary number
    of node_acl lun mappings.
    It converts transport_lookup_*_lun() fast-path code to use RCU read path
    primitives when looking up se_dev_entry.  It adds a new hlist_head at
    se_node_acl->lun_entry_hlist for this purpose.
    For transport_lookup_cmd_lun() code, it works with existing per-cpu
    se_lun->lun_ref when associating se_cmd with se_lun + se_device.
    Also, go ahead and update core_create_device_list_for_node() +
    core_free_device_list_for_node() to use ->lun_entry_hlist.
    It also converts se_dev_entry->pr_ref_count access to use modern
    struct kref counting, and updates core_disable_device_list_for_node()
    to kref_put() and block on se_deve->pr_comp waiting for outstanding PR
    special-case PR references to drop, then invoke kfree_rcu() to wait
    for the RCU grace period to complete before releasing memory.
    So now that se_node_acl->lun_entry_hlist fast path access uses RCU
    protected pointers, go ahead and convert remaining non-fast path
    RCU updater code using ->lun_entry_lock to struct mutex to allow
    callers to block while walking se_node_acl->lun_entry_hlist.
    Finally drop the left-over core_clear_initiator_node_from_tpg() that
    originally cleared lun_access during se_node_acl shutdown, as post
    RCU conversion it now becomes duplicated logic.
    Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Sagi Grimberg <sagig@mellanox.com>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
target_core_base.h 26.4 KB