flex_array: flex_array_prealloc takes a number of elements, not an end

Change flex_array_prealloc to take the number of elements for which space
should be allocated instead of the last (inclusive) element. Users
and documentation are updated accordingly.  flex_arrays got introduced before
they had users.  When folks started using it, they ended up needing a
different API than was coded up originally.  This swaps over to the API that
folks apparently need.

Based-on-patch-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Tested-by: Chris Richards <gizmo@giz-works.com>
Acked-by: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: stable@kernel.org [2.6.38+]

1 files changed, 8 insertions, 5 deletions

diff --git a/lib/flex_array.c b/lib/flex_array.c
index c0ea40ba2082..0c33b24498ba 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -232,10 +232,10 @@ EXPORT_SYMBOL(flex_array_clear);
 
 /**
  * flex_array_prealloc - guarantee that array space exists
- * @fa:         the flex array for which to preallocate parts
- * @start:      index of first array element for which space is allocated
- * @end:        index of last (inclusive) element for which space is allocated
- * @flags:      page allocation flags
+ * @fa:                 the flex array for which to preallocate parts
+ * @start:              index of first array element for which space is allocated
+ * @nr_elements:        number of elements for which space is allocated
+ * @flags:              page allocation flags
  *
  * This will guarantee that no future calls to flex_array_put()
  * will allocate memory.  It can be used if you are expecting to
@@ -245,13 +245,16 @@ EXPORT_SYMBOL(flex_array_clear);
  * Locking must be provided by the caller.
  */
 int flex_array_prealloc(struct flex_array *fa, unsigned int start,
-                        unsigned int end, gfp_t flags)
+                        unsigned int nr_elements, gfp_t flags)
 {
         int start_part;
         int end_part;
         int part_nr;
+        unsigned int end;
         struct flex_array_part *part;
 
+        end = start + nr_elements - 1;
+
         if (start >= fa->total_nr_elements || end >= fa->total_nr_elements)
                 return -ENOSPC;
         if (elements_fit_in_base(fa))