So far the feature of BLK_CGROUP_FC_APPID is only used for LPFC, and
only when it is setup via sysfs. It is very likely for one system to
never use the feature, so allocate the application id buffer in case
that someone starts to use it, then we save 129 bytes in each blkcg
if no one uses the feature.
Cc: Muneendra Kumar <muneendra.kumar@xxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Himanshu Madhani <himanshu.madhani@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-cgroup.c | 3 +++
include/linux/blk-cgroup.h | 15 ++++++++++++---
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 38b9f7684952..e452adf5f4f6 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1061,6 +1061,9 @@ static void blkcg_css_free(struct cgroup_subsys_state *css)
mutex_unlock(&blkcg_pol_mutex);
+#ifdef CONFIG_BLK_CGROUP_FC_APPID
+ kfree(blkcg->fc_app_id);
+#endif
kfree(blkcg);
}
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index b4de2010fba5..75094c0a752b 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -58,7 +58,7 @@ struct blkcg {
struct list_head all_blkcgs_node;
#ifdef CONFIG_BLK_CGROUP_FC_APPID
- char fc_app_id[FC_APPID_LEN];
+ char *fc_app_id;
#endif
#ifdef CONFIG_CGROUP_WRITEBACK
struct list_head cgwb_list;
@@ -699,7 +699,16 @@ static inline int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_le
* the vmid from the fabric.
* Adding the overhead of a lock is not necessary.
*/
- strlcpy(blkcg->fc_app_id, app_id, app_id_len);
+ if (!blkcg->fc_app_id) {
+ char *buf = kzalloc(FC_APPID_LEN, GFP_KERNEL);
+
+ if (cmpxchg(&blkcg->fc_app_id, NULL, buf))
+ kfree(buf);
+ }
+ if (blkcg->fc_app_id)
+ strlcpy(blkcg->fc_app_id, app_id, app_id_len);
+ else
+ ret = -ENOMEM;
css_put(css);
out_cgrp_put:
cgroup_put(cgrp);
@@ -714,7 +723,7 @@ static inline int blkcg_set_fc_appid(char *app_id, u64 cgrp_id, size_t app_id_le
*/
static inline char *blkcg_get_fc_appid(struct bio *bio)
{
- if (bio && bio->bi_blkg &&
+ if (bio && bio->bi_blkg && bio->bi_blkg->blkcg->fc_app_id &&
(bio->bi_blkg->blkcg->fc_app_id[0] != '\0'))
return bio->bi_blkg->blkcg->fc_app_id;
return NULL;
--
2.31.1
