[PATCH 10 of 33] DM Snapshot: exception function changes 2

[Jonathan Brassow <jbrassow@redhat.com>]

Patch name: dm-snap-exception-function-changes-2.patch

This patch makes exception [de]allocation functions deal specifically
with the dm_exception type.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>

Index: linux-2.6/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap.c
+++ linux-2.6/drivers/md/dm-snap.c
@@ -436,7 +436,7 @@ static void free_completed_exception(str
 	kmem_cache_free(exception_cache, e);
 }
 
-static struct dm_snap_pending_exception *alloc_pending_exception(void *context)
+static struct dm_exception *alloc_pending_exception(void *context)
 {
 	struct dm_snapshot *s = context;
 	struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
@@ -445,13 +445,16 @@ static struct dm_snap_pending_exception 
 	atomic_inc(&s->pending_exceptions_count);
 	pe->snap = s;
 
-	return pe;
+	return &pe->e;
 }
 
-static void free_pending_exception(struct dm_snap_pending_exception *pe,
-				   void *unused)
+static void free_pending_exception(struct dm_exception *e, void *unused)
 {
-	struct dm_snapshot *s = pe->snap;
+	struct dm_snap_pending_exception *pe;
+	struct dm_snapshot *s;
+
+	pe = container_of(e, struct dm_snap_pending_exception, e);
+	s = pe->snap;
 
 	mempool_free(pe, s->pending_pool);
 	smp_mb__before_atomic_dec();
@@ -907,7 +910,7 @@ static struct bio *put_pending_exception
 	if (primary_pe &&
 	    atomic_dec_and_test(&primary_pe->ref_count)) {
 		origin_bios = bio_list_get(&primary_pe->origin_bios);
-		free_pending_exception(primary_pe, NULL);
+		free_pending_exception(&primary_pe->e, NULL);
 	}
 
 	/*
@@ -915,7 +918,7 @@ static struct bio *put_pending_exception
 	 * it's not itself a primary pe.
 	 */
 	if (!primary_pe || primary_pe != pe)
-		free_pending_exception(pe, NULL);
+		free_pending_exception(&pe->e, NULL);
 
 	return origin_bios;
 }
@@ -1058,7 +1061,7 @@ __find_pending_exception(struct dm_snaps
 
 	pe2 = __lookup_pending_exception(s, chunk);
 	if (pe2) {
-		free_pending_exception(pe, NULL);
+		free_pending_exception(&pe->e, NULL);
 		return pe2;
 	}
 
@@ -1070,7 +1073,7 @@ __find_pending_exception(struct dm_snaps
 	pe->started = 0;
 
 	if (s->store->type->prepare_exception(s->store, &pe->e)) {
-		free_pending_exception(pe, NULL);
+		free_pending_exception(&pe->e, NULL);
 		return NULL;
 	}
 
@@ -1094,7 +1097,7 @@ static void remap_exception(struct dm_sn
 static int snapshot_map(struct dm_target *ti, struct bio *bio,
 			union map_info *map_context)
 {
-	struct dm_exception *e;
+	struct dm_exception *e, *tmp_e;
 	struct dm_snapshot *s = ti->private;
 	int r = DM_MAPIO_REMAPPED;
 	chunk_t chunk;
@@ -1132,18 +1135,20 @@ static int snapshot_map(struct dm_target
 		pe = __lookup_pending_exception(s, chunk);
 		if (!pe) {
 			up_write(&s->lock);
-			pe = alloc_pending_exception(s);
+			tmp_e = alloc_pending_exception(s);
+			pe = container_of(tmp_e,
+					  struct dm_snap_pending_exception, e);
 			down_write(&s->lock);
 
 			if (!s->valid) {
-				free_pending_exception(pe, NULL);
+				free_pending_exception(&pe->e, NULL);
 				r = -EIO;
 				goto out_unlock;
 			}
 
 			e = dm_lookup_exception(&s->complete, chunk);
 			if (e) {
-				free_pending_exception(pe, NULL);
+				free_pending_exception(&pe->e, NULL);
 				remap_exception(s, e, bio, chunk);
 				goto out_unlock;
 			}
@@ -1247,7 +1252,7 @@ static int __origin_write(struct list_he
 {
 	int r = DM_MAPIO_REMAPPED, first = 0;
 	struct dm_snapshot *snap;
-	struct dm_exception *e;
+	struct dm_exception *e, *tmp_e;
 	struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL;
 	chunk_t chunk;
 	LIST_HEAD(pe_queue);
@@ -1286,17 +1291,19 @@ static int __origin_write(struct list_he
 		pe = __lookup_pending_exception(snap, chunk);
 		if (!pe) {
 			up_write(&snap->lock);
-			pe = alloc_pending_exception(snap);
+			tmp_e = alloc_pending_exception(snap);
+			pe = container_of(tmp_e,
+					  struct dm_snap_pending_exception, e);
 			down_write(&snap->lock);
 
 			if (!snap->valid) {
-				free_pending_exception(pe, NULL);
+				free_pending_exception(&pe->e, NULL);
 				goto next_snapshot;
 			}
 
 			e = dm_lookup_exception(&snap->complete, chunk);
 			if (e) {
-				free_pending_exception(pe, NULL);
+				free_pending_exception(&pe->e, NULL);
 				goto next_snapshot;
 			}
 
@@ -1350,7 +1357,7 @@ static int __origin_write(struct list_he
 
 	if (first && atomic_dec_and_test(&primary_pe->ref_count)) {
 		flush_bios(bio_list_get(&primary_pe->origin_bios));
-		free_pending_exception(primary_pe, NULL);
+		free_pending_exception(&primary_pe->e, NULL);
 		/* If we got here, pe_queue is necessarily empty. */
 		return r;
 	}