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target: Convert se_node_acl->device_list[] to RCU hlist

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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 <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: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger
2015-03-22 20:42:19 -07:00
parent d2c27f0d0b
commit 29a05deebf
12 changed files with 413 additions and 442 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/target/target_core_backend.h
View File

@@ -101,7 +101,7 @@ int target_alloc_sgl(struct scatterlist **, unsigned int *, u32, bool);
sense_reason_t transport_generic_map_mem_to_cmd(struct se_cmd *,
struct scatterlist *, u32, struct scatterlist *, u32);
void array_free(void *array, int n);
bool target_lun_is_rdonly(struct se_cmd *);
/* From target_core_configfs.c to setup default backend config_item_types */
void target_core_setup_sub_cits(struct se_subsystem_api *);

27
include/target/target_core_base.h
View File

@@ -160,10 +160,8 @@ enum se_cmd_flags_table {
/* struct se_dev_entry->lun_flags and struct se_lun->lun_access */
enum transport_lunflags_table {
TRANSPORT_LUNFLAGS_NO_ACCESS = 0x00,
TRANSPORT_LUNFLAGS_INITIATOR_ACCESS = 0x01,
TRANSPORT_LUNFLAGS_READ_ONLY = 0x02,
TRANSPORT_LUNFLAGS_READ_WRITE = 0x04,
TRANSPORT_LUNFLAGS_READ_ONLY = 0x01,
TRANSPORT_LUNFLAGS_READ_WRITE = 0x02,
};
/*
@@ -584,10 +582,10 @@ struct se_node_acl {
char acl_tag[MAX_ACL_TAG_SIZE];
/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
atomic_t acl_pr_ref_count;
struct se_dev_entry **device_list;
struct hlist_head lun_entry_hlist;
struct se_session *nacl_sess;
struct se_portal_group *se_tpg;
spinlock_t device_list_lock;
struct mutex lun_entry_mutex;
spinlock_t nacl_sess_lock;
struct config_group acl_group;
struct config_group acl_attrib_group;
@@ -644,20 +642,23 @@ struct se_dev_entry {
/* See transport_lunflags_table */
u32 lun_flags;
u32 mapped_lun;
u32 total_cmds;
u64 pr_res_key;
u64 creation_time;
u32 attach_count;
u64 read_bytes;
u64 write_bytes;
atomic_long_t total_cmds;
atomic_long_t read_bytes;
atomic_long_t write_bytes;
atomic_t ua_count;
/* Used for PR SPEC_I_PT=1 and REGISTER_AND_MOVE */
atomic_t pr_ref_count;
struct se_lun_acl *se_lun_acl;
struct kref pr_kref;
struct completion pr_comp;
struct se_lun_acl __rcu *se_lun_acl;
spinlock_t ua_lock;
struct se_lun *se_lun;
struct se_lun __rcu *se_lun;
struct list_head alua_port_list;
struct list_head ua_list;
struct hlist_node link;
struct rcu_head rcu_head;
};
struct se_dev_attrib {
@@ -703,6 +704,7 @@ struct se_port_stat_grps {
};
struct se_lun {
u16 lun_rtpi;
#define SE_LUN_LINK_MAGIC 0xffff7771
u32 lun_link_magic;
/* See transport_lun_status_table */
@@ -710,6 +712,7 @@ struct se_lun {
u32 lun_access;
u32 lun_flags;
u32 unpacked_lun;
u32 lun_index;
atomic_t lun_acl_count;
spinlock_t lun_acl_lock;
spinlock_t lun_sep_lock;