[PATCH v1 18/29] virtio-mem: factor out calculation of the bit number within the sb_states bitmap

[David Hildenbrand]

The calculation is already complicated enough, let's limit it to one
location.

Cc: "Michael S. Tsirkin" <m...@redhat.com>
Cc: Jason Wang <jasow...@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.li...@gmail.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 drivers/virtio/virtio_mem.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 2cc497ad8298..73ff6e9ba839 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -327,6 +327,16 @@ static int virtio_mem_sbm_mb_states_prepare_next_mb(struct 
virtio_mem *vm)
             _mb_id--) \
                if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
 
+/*
+ * Calculate the bit number in the sb_states bitmap for the given subblock
+ * inside the given memory block.
+ */
+static int virtio_mem_sbm_sb_state_bit_nr(struct virtio_mem *vm,
+                                         unsigned long mb_id, int sb_id)
+{
+       return (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+}
+
 /*
  * Mark all selected subblocks plugged.
  *
@@ -336,7 +346,7 @@ static void virtio_mem_sbm_set_sb_plugged(struct virtio_mem 
*vm,
                                          unsigned long mb_id, int sb_id,
                                          int count)
 {
-       const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+       const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
 
        __bitmap_set(vm->sbm.sb_states, bit, count);
 }
@@ -350,7 +360,7 @@ static void virtio_mem_sbm_set_sb_unplugged(struct 
virtio_mem *vm,
                                            unsigned long mb_id, int sb_id,
                                            int count)
 {
-       const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+       const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
 
        __bitmap_clear(vm->sbm.sb_states, bit, count);
 }
@@ -362,7 +372,7 @@ static bool virtio_mem_sbm_test_sb_plugged(struct 
virtio_mem *vm,
                                           unsigned long mb_id, int sb_id,
                                           int count)
 {
-       const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+       const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
 
        if (count == 1)
                return test_bit(bit, vm->sbm.sb_states);
@@ -379,7 +389,7 @@ static bool virtio_mem_sbm_test_sb_unplugged(struct 
virtio_mem *vm,
                                             unsigned long mb_id, int sb_id,
                                             int count)
 {
-       const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id;
+       const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
 
        /* TODO: Helper similar to bitmap_set() */
        return find_next_bit(vm->sbm.sb_states, bit + count, bit) >=
@@ -393,7 +403,7 @@ static bool virtio_mem_sbm_test_sb_unplugged(struct 
virtio_mem *vm,
 static int virtio_mem_sbm_first_unplugged_sb(struct virtio_mem *vm,
                                            unsigned long mb_id)
 {
-       const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb;
+       const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, 0);
 
        return find_next_zero_bit(vm->sbm.sb_states,
                                  bit + vm->nb_sb_per_mb, bit) - bit;
-- 
2.26.2