From: Dan Williams <dan.j.willi...@intel.com>

If BLK_CGROUP is disabled, still enable ionice to set advice on bios.

Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Jason B. Akers <jason.b.ak...@intel.com>
---
 block/bio.c         |   43 +++++++++++---------------------
 block/blk.h         |    2 ++
 include/linux/bio.h |   68 +++++++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 79 insertions(+), 34 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index e133b5c..b93ae04 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1980,7 +1980,6 @@ struct bio_set *bioset_create_nobvec(unsigned int 
pool_size, unsigned int front_
 }
 EXPORT_SYMBOL(bioset_create_nobvec);
 
-#ifdef CONFIG_BLK_CGROUP
 /**
  * bio_associate_current - associate a bio with %current
  * @bio: target bio
@@ -1989,34 +1988,28 @@ EXPORT_SYMBOL(bioset_create_nobvec);
  * layer will treat @bio as if it were issued by %current no matter which
  * task actually issues it.
  *
- * This function takes an extra reference of @task's io_context and blkcg
- * which will be put when @bio is released.  The caller must own @bio,
- * ensure %current->io_context exists, and is responsible for synchronizing
- * calls to this function.
+ * When BLK_CGROUP=y this function takes an extra reference of @task's
+ * io_context and blkcg which will be put when @bio is released.  The caller
+ * must own @bio, ensure %current->io_context exists, and is responsible for
+ * synchronizing calls to this function.
+ *
+ * When BLK_CGROUP=n this function simply sets the bio priority and cache 
advice
  */
 int bio_associate_current(struct bio *bio)
 {
        struct io_context *ioc;
-       struct cgroup_subsys_state *css;
-
-       if (bio->bi_ioc)
-               return -EBUSY;
+       int rc;
 
        ioc = current->io_context;
        if (!ioc)
                return -ENOENT;
 
-       /* acquire active ref on @ioc and associate */
-       get_io_context_active(ioc);
-       bio->bi_ioc = ioc;
-       bio_set_prio(bio, ioprio_best(ioc->ioprio, bio_prio(bio)));
+       rc = bio_associate_ioc(bio, ioc);
+       if (rc)
+               return rc;
 
-       /* associate blkcg if exists */
-       rcu_read_lock();
-       css = task_css(current, blkio_cgrp_id);
-       if (css && css_tryget_online(css))
-               bio->bi_css = css;
-       rcu_read_unlock();
+       bio_associate_blkcg(bio, current);
+       bio_set_prio(bio, ioprio_best(ioc->ioprio, bio_prio(bio)));
 
        return 0;
 }
@@ -2027,18 +2020,10 @@ int bio_associate_current(struct bio *bio)
  */
 void bio_disassociate_task(struct bio *bio)
 {
-       if (bio->bi_ioc) {
-               put_io_context(bio->bi_ioc);
-               bio->bi_ioc = NULL;
-       }
-       if (bio->bi_css) {
-               css_put(bio->bi_css);
-               bio->bi_css = NULL;
-       }
+       bio_disassociate_ioc(bio);
+       bio_disassociate_blkcg(bio);
 }
 
-#endif /* CONFIG_BLK_CGROUP */
-
 static void __init biovec_init_slabs(void)
 {
        int i;
diff --git a/block/blk.h b/block/blk.h
index 43b0361..6d7c4df 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -274,6 +274,8 @@ extern void blk_throtl_exit(struct request_queue *q);
 #else /* CONFIG_BLK_DEV_THROTTLING */
 static inline bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 {
+       /* set prio, but don't throttle */
+       bio_associate_current(bio);
        return false;
 }
 static inline void blk_throtl_drain(struct request_queue *q) { }
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 7347f48..8419319 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -22,6 +22,7 @@
 
 #include <linux/highmem.h>
 #include <linux/mempool.h>
+#include <linux/cgroup.h>
 #include <linux/ioprio.h>
 #include <linux/bug.h>
 
@@ -469,13 +470,70 @@ extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned 
long *, mempool_t *);
 extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 extern unsigned int bvec_nr_vecs(unsigned short idx);
 
-#ifdef CONFIG_BLK_CGROUP
 int bio_associate_current(struct bio *bio);
 void bio_disassociate_task(struct bio *bio);
-#else  /* CONFIG_BLK_CGROUP */
-static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
-static inline void bio_disassociate_task(struct bio *bio) { }
-#endif /* CONFIG_BLK_CGROUP */
+
+#ifdef CONFIG_BLK_CGROUP
+static inline int bio_associate_ioc(struct bio *bio, struct io_context *ioc)
+{
+       if (bio->bi_ioc)
+               return -EBUSY;
+
+       /* acquire active ref on @ioc and associate */
+       get_io_context_active(ioc);
+       bio->bi_ioc = ioc;
+
+       return 0;
+}
+
+static inline void bio_associate_blkcg(struct bio *bio,
+                                       struct task_struct *task)
+{
+       struct cgroup_subsys_state *css;
+
+       /* associate blkcg if exists */
+       rcu_read_lock();
+       css = task_css(task, blkio_cgrp_id);
+       if (css && css_tryget(css))
+               bio->bi_css = css;
+       rcu_read_unlock();
+}
+
+static inline void bio_disassociate_ioc(struct bio *bio)
+{
+       if (bio->bi_ioc) {
+               put_io_context(bio->bi_ioc);
+               bio->bi_ioc = NULL;
+       }
+}
+
+static inline void bio_disassociate_blkcg(struct bio *bio)
+{
+       if (bio->bi_css) {
+               css_put(bio->bi_css);
+               bio->bi_css = NULL;
+       }
+}
+#else
+static inline int bio_associate_ioc(struct bio *bio, struct io_context *ioc)
+{
+       return 0;
+}
+
+static inline void bio_associate_blkcg(struct bio *bio,
+                                       struct task_struct *task)
+{
+}
+
+static inline void bio_disassociate_ioc(struct bio *bio)
+{
+}
+
+static inline void bio_disassociate_blkcg(struct bio *bio)
+{
+}
+
+#endif
 
 #ifdef CONFIG_HIGHMEM
 /*

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