scsi: sbitmap: Add helpers for updating allocation hint

Add helpers for updating allocation hint so that we can avoid duplicate
code.

Prepare for moving allocation hint into sbitmap.

Link: https://lore.kernel.org/r/20210122023317.687987-4-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 7000636933b3ef1f675d590438fa3ba20a3198f3..2b43a6aefec3ac560748aef1dc4ba376d9a58931 100644 (file)
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -9,6 +9,55 @@
 #include <linux/sbitmap.h>
 #include <linux/seq_file.h>
 
+static int init_alloc_hint(struct sbitmap_queue *sbq, gfp_t flags)
+{
+       unsigned depth = sbq->sb.depth;
+
+       sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
+       if (!sbq->alloc_hint)
+               return -ENOMEM;
+
+       if (depth && !sbq->sb.round_robin) {
+               int i;
+
+               for_each_possible_cpu(i)
+                       *per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
+       }
+
+       return 0;
+}
+
+static inline unsigned update_alloc_hint_before_get(struct sbitmap_queue *sbq,
+                                                   unsigned int depth)
+{
+       unsigned hint;
+
+       hint = this_cpu_read(*sbq->alloc_hint);
+       if (unlikely(hint >= depth)) {
+               hint = depth ? prandom_u32() % depth : 0;
+               this_cpu_write(*sbq->alloc_hint, hint);
+       }
+
+       return hint;
+}
+
+static inline void update_alloc_hint_after_get(struct sbitmap_queue *sbq,
+                                              unsigned int depth,
+                                              unsigned int hint,
+                                              unsigned int nr)
+{
+       if (nr == -1) {
+               /* If the map is full, a hint won't do us much good. */
+               this_cpu_write(*sbq->alloc_hint, 0);
+       } else if (nr == hint || unlikely(sbq->sb.round_robin)) {
+               /* Only update the hint if we used it. */
+               hint = nr + 1;
+               if (hint >= depth - 1)
+                       hint = 0;
+               this_cpu_write(*sbq->alloc_hint, hint);
+       }
+}
+
 /*
  * See if we have deferred clears that we can batch move
  */
@@ -355,17 +404,11 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
        if (ret)
                return ret;
 
-       sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
-       if (!sbq->alloc_hint) {
+       if (init_alloc_hint(sbq, flags) != 0) {
                sbitmap_free(&sbq->sb);
                return -ENOMEM;
        }
 
-       if (depth && !round_robin) {
-               for_each_possible_cpu(i)
-                       *per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
-       }
-
        sbq->min_shallow_depth = UINT_MAX;
        sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
        atomic_set(&sbq->wake_index, 0);
@@ -418,24 +461,10 @@ int __sbitmap_queue_get(struct sbitmap_queue *sbq)
        unsigned int hint, depth;
        int nr;
 
-       hint = this_cpu_read(*sbq->alloc_hint);
        depth = READ_ONCE(sbq->sb.depth);
-       if (unlikely(hint >= depth)) {
-               hint = depth ? prandom_u32() % depth : 0;
-               this_cpu_write(*sbq->alloc_hint, hint);
-       }
+       hint = update_alloc_hint_before_get(sbq, depth);
        nr = sbitmap_get(&sbq->sb, hint);
-
-       if (nr == -1) {
-               /* If the map is full, a hint won't do us much good. */
-               this_cpu_write(*sbq->alloc_hint, 0);
-       } else if (nr == hint || unlikely(sbq->sb.round_robin)) {
-               /* Only update the hint if we used it. */
-               hint = nr + 1;
-               if (hint >= depth - 1)
-                       hint = 0;
-               this_cpu_write(*sbq->alloc_hint, hint);
-       }
+       update_alloc_hint_after_get(sbq, depth, hint, nr);
 
        return nr;
 }
@@ -449,24 +478,10 @@ int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
 
        WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
 
-       hint = this_cpu_read(*sbq->alloc_hint);
        depth = READ_ONCE(sbq->sb.depth);
-       if (unlikely(hint >= depth)) {
-               hint = depth ? prandom_u32() % depth : 0;
-               this_cpu_write(*sbq->alloc_hint, hint);
-       }
+       hint = update_alloc_hint_before_get(sbq, depth);
        nr = sbitmap_get_shallow(&sbq->sb, hint, shallow_depth);
-
-       if (nr == -1) {
-               /* If the map is full, a hint won't do us much good. */
-               this_cpu_write(*sbq->alloc_hint, 0);
-       } else if (nr == hint || unlikely(sbq->sb.round_robin)) {
-               /* Only update the hint if we used it. */
-               hint = nr + 1;
-               if (hint >= depth - 1)
-                       hint = 0;
-               this_cpu_write(*sbq->alloc_hint, hint);
-       }
+       update_alloc_hint_after_get(sbq, depth, hint, nr);
 
        return nr;
 }