dm space map: optimise sm_ll_dec and sm_ll_inc
Prior to this patch these methods did a lookup followed by an insert.
Instead they now call a common mutate function that adjusts the value
according to a callback function. This avoids traversing the data
structures twice and hence improves performance.
Also factor out sm_ll_lookup_big_ref_count() for use by both
sm_ll_lookup() and sm_ll_mutate().
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
index 3e7a88d..6058569 100644
--- a/drivers/md/persistent-data/dm-space-map-common.c
+++ b/drivers/md/persistent-data/dm-space-map-common.c
@@ -292,16 +292,11 @@
return dm_tm_unlock(ll->tm, blk);
}
-int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+static int sm_ll_lookup_big_ref_count(struct ll_disk *ll, dm_block_t b,
+ uint32_t *result)
{
__le32 le_rc;
- int r = sm_ll_lookup_bitmap(ll, b, result);
-
- if (r)
- return r;
-
- if (*result != 3)
- return r;
+ int r;
r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root, &b, &le_rc);
if (r < 0)
@@ -312,6 +307,19 @@
return r;
}
+int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+{
+ int r = sm_ll_lookup_bitmap(ll, b, result);
+
+ if (r)
+ return r;
+
+ if (*result != 3)
+ return r;
+
+ return sm_ll_lookup_big_ref_count(ll, b, result);
+}
+
int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
dm_block_t end, dm_block_t *result)
{
@@ -372,11 +380,12 @@
return -ENOSPC;
}
-int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
- uint32_t ref_count, enum allocation_event *ev)
+static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
+ uint32_t (*mutator)(void *context, uint32_t old),
+ void *context, enum allocation_event *ev)
{
int r;
- uint32_t bit, old;
+ uint32_t bit, old, ref_count;
struct dm_block *nb;
dm_block_t index = b;
struct disk_index_entry ie_disk;
@@ -399,6 +408,14 @@
bm_le = dm_bitmap_data(nb);
old = sm_lookup_bitmap(bm_le, bit);
+ if (old > 2) {
+ r = sm_ll_lookup_big_ref_count(ll, b, &old);
+ if (r < 0)
+ return r;
+ }
+
+ ref_count = mutator(context, old);
+
if (ref_count <= 2) {
sm_set_bitmap(bm_le, bit, ref_count);
@@ -448,31 +465,35 @@
return ll->save_ie(ll, index, &ie_disk);
}
+static uint32_t set_ref_count(void *context, uint32_t old)
+{
+ return *((uint32_t *) context);
+}
+
+int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
+ uint32_t ref_count, enum allocation_event *ev)
+{
+ return sm_ll_mutate(ll, b, set_ref_count, &ref_count, ev);
+}
+
+static uint32_t inc_ref_count(void *context, uint32_t old)
+{
+ return old + 1;
+}
+
int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
- int r;
- uint32_t rc;
+ return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev);
+}
- r = sm_ll_lookup(ll, b, &rc);
- if (r)
- return r;
-
- return sm_ll_insert(ll, b, rc + 1, ev);
+static uint32_t dec_ref_count(void *context, uint32_t old)
+{
+ return old - 1;
}
int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
{
- int r;
- uint32_t rc;
-
- r = sm_ll_lookup(ll, b, &rc);
- if (r)
- return r;
-
- if (!rc)
- return -EINVAL;
-
- return sm_ll_insert(ll, b, rc - 1, ev);
+ return sm_ll_mutate(ll, b, dec_ref_count, NULL, ev);
}
int sm_ll_commit(struct ll_disk *ll)
