Merge tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device-mapper updates from Mike Snitzer:
 "Add the ability to collect I/O statistics on user-defined regions of a
  device-mapper device.  This dm-stats code required the reintroduction
  of a div64_u64_rem() helper, but as a separate method that doesn't
  slow down div64_u64() -- especially on 32-bit systems.

  Allow the error target to replace request-based DM devices (e.g.
  multipath) in addition to bio-based DM devices.

  Various other small code fixes and improvements to thin-provisioning,
  DM cache and the DM ioctl interface"

* tag 'dm-3.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm stripe: silence a couple sparse warnings
  dm: add statistics support
  dm thin: always return -ENOSPC if no_free_space is set
  dm ioctl: cleanup error handling in table_load
  dm ioctl: increase granularity of type_lock when loading table
  dm ioctl: prevent rename to empty name or uuid
  dm thin: set pool read-only if breaking_sharing fails block allocation
  dm thin: prefix pool error messages with pool device name
  dm: allow error target to replace bio-based and request-based targets
  math64: New separate div64_u64_rem helper
  dm space map: optimise sm_ll_dec and sm_ll_inc
  dm btree: prefetch child nodes when walking tree for a dm_btree_del
  dm btree: use pop_frame in dm_btree_del to cleanup code
  dm cache: eliminate holes in cache structure
  dm cache: fix stacking of geometry limits
  dm thin: fix stacking of geometry limits
  dm thin: add data block size limits to Documentation
  dm cache: add data block size limits to code and Documentation
  dm cache: document metadata device is exclussive to a cache
  dm: stop using WQ_NON_REENTRANT

1 files changed, 49 insertions, 28 deletions

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 @@ int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
 	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 @@ int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
 	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 @@ int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
 	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 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
 	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 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
 	return ll->save_ie(ll, index, &ie_disk);
 }
 
-int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
+static uint32_t set_ref_count(void *context, uint32_t old)
 {
-	int r;
-	uint32_t rc;
-
-	r = sm_ll_lookup(ll, b, &rc);
-	if (r)
-		return r;
+	return *((uint32_t *) context);
+}
 
-	return sm_ll_insert(ll, b, rc + 1, ev);
+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);
 }
 
-int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
+static uint32_t inc_ref_count(void *context, uint32_t old)
 {
-	int r;
-	uint32_t rc;
+	return old + 1;
+}
 
-	r = sm_ll_lookup(ll, b, &rc);
-	if (r)
-		return r;
+int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
+{
+	return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev);
+}
 
-	if (!rc)
-		return -EINVAL;
+static uint32_t dec_ref_count(void *context, uint32_t old)
+{
+	return old - 1;
+}
 
-	return sm_ll_insert(ll, b, rc - 1, ev);
+int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
+{
+	return sm_ll_mutate(ll, b, dec_ref_count, NULL, ev);
 }
 
 int sm_ll_commit(struct ll_disk *ll)