dm io: use fixed initial mempool size

Replace the arbitrary calculation of an initial io struct mempool size
with a constant.

The code calculated the number of reserved structures based on the request
size and used a "magic" multiplication constant of 4.  This patch changes
it to reserve a fixed number - itself still chosen quite arbitrarily.
Further testing might show if there is a better number to choose.

Note that if there is no memory pressure, we can still allocate an
arbitrary number of "struct io" structures.  One structure is enough to
process the whole request.

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

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 976ad4688afc..53089aa11387 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -22,7 +22,6 @@
 #define DM_MSG_PREFIX "raid1"
 
 #define MAX_RECOVERY 1  /* Maximum number of regions recovered in parallel. */
-#define DM_IO_PAGES 64
 #define DM_KCOPYD_PAGES 64
 
 #define DM_RAID1_HANDLE_ERRORS 0x01
@@ -887,7 +886,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
                 return NULL;
         }
 
-        ms->io_client = dm_io_client_create(DM_IO_PAGES);
+        ms->io_client = dm_io_client_create();
         if (IS_ERR(ms->io_client)) {
                 ti->error = "Error creating dm_io client";
                 mempool_destroy(ms->read_record_pool);