dm kcopyd: reserve fewer pages

Reserve just the minimum of pages needed to process one job.

Because we allocate pages from page allocator, we don't need to reserve
a large number of pages.  The maximum job size is SUB_JOB_SIZE and we
calculate the number of reserved pages based on this.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 719693340d1d..579647f8b4d2 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -30,6 +30,7 @@
 #define SUB_JOB_SIZE    128
 #define SPLIT_COUNT     8
 #define MIN_JOBS        8
+#define RESERVE_PAGES   (DIV_ROUND_UP(SUB_JOB_SIZE << SECTOR_SHIFT, PAGE_SIZE))
 
 /*-----------------------------------------------------------------
  * Each kcopyd client has its own little pool of preallocated
@@ -636,8 +637,7 @@ int kcopyd_cancel(struct kcopyd_job *job, int block)
 /*-----------------------------------------------------------------
  * Client setup
  *---------------------------------------------------------------*/
-int dm_kcopyd_client_create(unsigned min_pages,
-                            struct dm_kcopyd_client **result)
+int dm_kcopyd_client_create(struct dm_kcopyd_client **result)
 {
         int r = -ENOMEM;
         struct dm_kcopyd_client *kc;
@@ -663,7 +663,7 @@ int dm_kcopyd_client_create(unsigned min_pages,
 
         kc->pages = NULL;
         kc->nr_reserved_pages = kc->nr_free_pages = 0;
-        r = client_reserve_pages(kc, min_pages);
+        r = client_reserve_pages(kc, RESERVE_PAGES);
         if (r)
                 goto bad_client_pages;