hugetlb: remove duplicated code

Remove duplicated code between region_chg and region_add, and refactor
it into a common function, add_reservation_in_range.  This is mostly
done because there is a follow up change in another series that disables
region coalescing in region_add, and I want to make that change in one
place only.  It should improve maintainability anyway on its own.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/20190919200428.188797-3-almasrymina@google.com
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 17178dbd1167047d31d3330210297f9e302c47e3..a8e43aa9c6709ef271165652670acd14655282e7 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -244,6 +244,60 @@ struct file_region {
        long to;
 };
 
+/* Must be called with resv->lock held. Calling this with count_only == true
+ * will count the number of pages to be added but will not modify the linked
+ * list.
+ */
+static long add_reservation_in_range(struct resv_map *resv, long f, long t,
+                                    bool count_only)
+{
+       long chg = 0;
+       struct list_head *head = &resv->regions;
+       struct file_region *rg = NULL, *trg = NULL, *nrg = NULL;
+
+       /* Locate the region we are before or in. */
+       list_for_each_entry(rg, head, link)
+               if (f <= rg->to)
+                       break;
+
+       /* Round our left edge to the current segment if it encloses us. */
+       if (f > rg->from)
+               f = rg->from;
+
+       chg = t - f;
+
+       /* Check for and consume any regions we now overlap with. */
+       nrg = rg;
+       list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
+               if (&rg->link == head)
+                       break;
+               if (rg->from > t)
+                       break;
+
+               /* We overlap with this area, if it extends further than
+                * us then we must extend ourselves.  Account for its
+                * existing reservation.
+                */
+               if (rg->to > t) {
+                       chg += rg->to - t;
+                       t = rg->to;
+               }
+               chg -= rg->to - rg->from;
+
+               if (!count_only && rg != nrg) {
+                       list_del(&rg->link);
+                       kfree(rg);
+               }
+       }
+
+       if (!count_only) {
+               nrg->from = f;
+               nrg->to = t;
+       }
+
+       return chg;
+}
+
 /*
  * Add the huge page range represented by [f, t) to the reserve
  * map.  Existing regions will be expanded to accommodate the specified
@@ -257,7 +311,7 @@ struct file_region {
 static long region_add(struct resv_map *resv, long f, long t)
 {
        struct list_head *head = &resv->regions;
-       struct file_region *rg, *nrg, *trg;
+       struct file_region *rg, *nrg;
        long add = 0;
 
        spin_lock(&resv->lock);
@@ -287,38 +341,7 @@ static long region_add(struct resv_map *resv, long f, long t)
                goto out_locked;
        }
 
-       /* Round our left edge to the current segment if it encloses us. */
-       if (f > rg->from)
-               f = rg->from;
-
-       /* Check for and consume any regions we now overlap with. */
-       nrg = rg;
-       list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
-               if (&rg->link == head)
-                       break;
-               if (rg->from > t)
-                       break;
-
-               /* If this area reaches higher then extend our area to
-                * include it completely.  If this is not the first area
-                * which we intend to reuse, free it. */
-               if (rg->to > t)
-                       t = rg->to;
-               if (rg != nrg) {
-                       /* Decrement return value by the deleted range.
-                        * Another range will span this area so that by
-                        * end of routine add will be >= zero
-                        */
-                       add -= (rg->to - rg->from);
-                       list_del(&rg->link);
-                       kfree(rg);
-               }
-       }
-
-       add += (nrg->from - f);         /* Added to beginning of region */
-       nrg->from = f;
-       add += t - nrg->to;             /* Added to end of region */
-       nrg->to = t;
+       add = add_reservation_in_range(resv, f, t, false);
 
 out_locked:
        resv->adds_in_progress--;
@@ -345,8 +368,6 @@ static long region_add(struct resv_map *resv, long f, long t)
  */
 static long region_chg(struct resv_map *resv, long f, long t)
 {
-       struct list_head *head = &resv->regions;
-       struct file_region *rg;
        long chg = 0;
 
        spin_lock(&resv->lock);
@@ -375,34 +396,8 @@ static long region_chg(struct resv_map *resv, long f, long t)
                goto retry_locked;
        }
 
-       /* Locate the region we are before or in. */
-       list_for_each_entry(rg, head, link)
-               if (f <= rg->to)
-                       break;
-
-       /* Round our left edge to the current segment if it encloses us. */
-       if (f > rg->from)
-               f = rg->from;
-       chg = t - f;
-
-       /* Check for and consume any regions we now overlap with. */
-       list_for_each_entry(rg, rg->link.prev, link) {
-               if (&rg->link == head)
-                       break;
-               if (rg->from > t)
-                       goto out;
+       chg = add_reservation_in_range(resv, f, t, true);
 
-               /* We overlap with this area, if it extends further than
-                * us then we must extend ourselves.  Account for its
-                * existing reservation. */
-               if (rg->to > t) {
-                       chg += rg->to - t;
-                       t = rg->to;
-               }
-               chg -= rg->to - rg->from;
-       }
-
-out:
        spin_unlock(&resv->lock);
        return chg;
 }