From 29a05deebf6c2e3010934fb78ee65cab3d329470 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Sun, 22 Mar 2015 20:42:19 -0700 Subject: target: Convert se_node_acl->device_list[] to RCU hlist 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: Hannes Reinecke Cc: Christoph Hellwig Cc: Sagi Grimberg Cc: Paul E. McKenney Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_fabric_configfs.c | 43 +++++++++++----------------- 1 file changed, 17 insertions(+), 26 deletions(-) (limited to 'drivers/target/target_core_fabric_configfs.c') diff --git a/drivers/target/target_core_fabric_configfs.c b/drivers/target/target_core_fabric_configfs.c index 6cb4828308e9..0939a5492c16 100644 --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -123,16 +123,16 @@ static int target_fabric_mappedlun_link( * which be will write protected (READ-ONLY) when * tpg_1/attrib/demo_mode_write_protect=1 */ - spin_lock_irq(&lacl->se_lun_nacl->device_list_lock); - deve = lacl->se_lun_nacl->device_list[lacl->mapped_lun]; - if (deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS) + rcu_read_lock(); + deve = target_nacl_find_deve(lacl->se_lun_nacl, lacl->mapped_lun); + if (deve) lun_access = deve->lun_flags; else lun_access = (se_tpg->se_tpg_tfo->tpg_check_prod_mode_write_protect( se_tpg)) ? TRANSPORT_LUNFLAGS_READ_ONLY : TRANSPORT_LUNFLAGS_READ_WRITE; - spin_unlock_irq(&lacl->se_lun_nacl->device_list_lock); + rcu_read_unlock(); /* * Determine the actual mapped LUN value user wants.. * @@ -149,23 +149,13 @@ static int target_fabric_mappedlun_unlink( struct config_item *lun_acl_ci, struct config_item *lun_ci) { - struct se_lun *lun; struct se_lun_acl *lacl = container_of(to_config_group(lun_acl_ci), struct se_lun_acl, se_lun_group); - struct se_node_acl *nacl = lacl->se_lun_nacl; - struct se_dev_entry *deve = nacl->device_list[lacl->mapped_lun]; - struct se_portal_group *se_tpg; - /* - * Determine if the underlying MappedLUN has already been released.. - */ - if (!deve->se_lun) - return 0; - - lun = container_of(to_config_group(lun_ci), struct se_lun, lun_group); - se_tpg = lun->lun_sep->sep_tpg; + struct se_lun *lun = container_of(to_config_group(lun_ci), + struct se_lun, lun_group); + struct se_portal_group *se_tpg = lun->lun_sep->sep_tpg; - core_dev_del_initiator_node_lun_acl(se_tpg, lun, lacl); - return 0; + return core_dev_del_initiator_node_lun_acl(se_tpg, lun, lacl); } CONFIGFS_EATTR_STRUCT(target_fabric_mappedlun, se_lun_acl); @@ -181,14 +171,15 @@ static ssize_t target_fabric_mappedlun_show_write_protect( { struct se_node_acl *se_nacl = lacl->se_lun_nacl; struct se_dev_entry *deve; - ssize_t len; - - spin_lock_irq(&se_nacl->device_list_lock); - deve = se_nacl->device_list[lacl->mapped_lun]; - len = sprintf(page, "%d\n", - (deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY) ? - 1 : 0); - spin_unlock_irq(&se_nacl->device_list_lock); + ssize_t len = 0; + + rcu_read_lock(); + deve = target_nacl_find_deve(se_nacl, lacl->mapped_lun); + if (deve) { + len = sprintf(page, "%d\n", + (deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY) ? 1 : 0); + } + rcu_read_unlock(); return len; } -- cgit