[Btrfs-devel] [PATCH 1/2] Make btrfs-progs compile with -fstrict-aliasing (included in -O2) again.

[Jan Engelhardt]

From: Jan Engelhardt <jengelh at computergmbh.de>

Make btrfs-progs compile with -fstrict-aliasing (included in -O2) again.

This is done by doing a two-step conversion (rather than a one-step).
First, the variable goes from type * to void *, and then to 
implicitly to void **.
(Not sure if this is "good practice", but it shuts up the compiler,
so it seems the compiler takes into account that we are actually punning
it this way.)

---
 bit-radix.c   |    2 +-
 btrfsck.c     |    2 +-
 extent-tree.c |   10 +++++-----
 radix-tree.c  |    2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

Index: btrfs-progs-0.8/bit-radix.c
===================================================================
--- btrfs-progs-0.8.orig/bit-radix.c
+++ btrfs-progs-0.8/bit-radix.c
@@ -186,7 +186,7 @@ int find_first_radix_bit(struct radix_tr
 	unsigned long slot;
 
 	slot = start / BIT_RADIX_BITS_PER_ARRAY;
-	ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
+	ret = radix_tree_gang_lookup(radix, (void *)gang, slot,
 				     ARRAY_SIZE(gang));
 	found = start % BIT_RADIX_BITS_PER_ARRAY;
 	for (i = 0; i < ret && nr > 0; i++) {
Index: btrfs-progs-0.8/btrfsck.c
===================================================================
--- btrfs-progs-0.8.orig/btrfsck.c
+++ btrfs-progs-0.8/btrfsck.c
@@ -413,7 +413,7 @@ int check_extent_refs(struct btrfs_root 
 	int err = 0;
 
 	while(1) {
-		ret = radix_tree_gang_lookup(extent_radix, (void **)rec, 0,
+		ret = radix_tree_gang_lookup(extent_radix, (void *)rec, 0,
 					     ARRAY_SIZE(rec));
 		if (!ret)
 			break;
Index: btrfs-progs-0.8/extent-tree.c
===================================================================
--- btrfs-progs-0.8.orig/extent-tree.c
+++ btrfs-progs-0.8/extent-tree.c
@@ -164,7 +164,7 @@ int btrfs_write_dirty_block_groups(struc
 	btrfs_init_path(&path);
 
 	while(1) {
-		ret = radix_tree_gang_lookup_tag(radix, (void **)cache,
+		ret = radix_tree_gang_lookup_tag(radix, (void *)cache,
 						 0, ARRAY_SIZE(cache),
 						 BTRFS_BLOCK_GROUP_DIRTY);
 		if (!ret)
@@ -195,7 +195,7 @@ static int update_block_group(struct btr
 
 	while(total) {
 		ret = radix_tree_gang_lookup(&info->block_group_radix,
-					     (void **)&cache, blocknr, 1);
+					     (void *)&cache, blocknr, 1);
 		if (!ret)
 			return -1;
 		radix_tree_tag_set(&info->block_group_radix,
@@ -229,7 +229,7 @@ int btrfs_finish_extent_commit(struct bt
 
 	while(1) {
 		ret = radix_tree_gang_lookup(&root->fs_info->pinned_radix,
-					     (void **)gang, 0,
+					     (void *)gang, 0,
 					     ARRAY_SIZE(gang));
 		if (!ret)
 			break;
@@ -362,7 +362,7 @@ static int del_pending_extents(struct bt
 	while(1) {
 		ret = radix_tree_gang_lookup_tag(
 					&extent_root->fs_info->cache_radix,
-					(void **)gang, 0,
+					(void *)gang, 0,
 					ARRAY_SIZE(gang),
 					CTREE_EXTENT_PENDING_DEL);
 		if (!ret)
@@ -738,7 +738,7 @@ int btrfs_free_block_groups(struct btrfs
 
 	while(1) {
 		ret = radix_tree_gang_lookup(&info->block_group_radix,
-					     (void **)cache, 0,
+					     (void *)cache, 0,
 					     ARRAY_SIZE(cache));
 		if (!ret)
 			break;
Index: btrfs-progs-0.8/radix-tree.c
===================================================================
--- btrfs-progs-0.8.orig/radix-tree.c
+++ btrfs-progs-0.8/radix-tree.c
@@ -314,7 +314,7 @@ static inline void **__lookup_slot(struc
 		return NULL;
 
 	if (height == 0 && root->rnode)
-		return (void **)&root->rnode;
+		return (void *)&root->rnode;
 
 	shift = (height-1) * RADIX_TREE_MAP_SHIFT;
 	slot = &root->rnode;