bcachefs: properly initialize used values

 - Ensure the second key value in bch_hash_info is initialized to zero
   if the info type is of type BCH_STR_HASH_SIPHASH.

 - Initialize the possibly returned value in bch2_inode_create. Assuming
   bch2_btree_iter_peek returns bkey_s_c_null, the uninitialized value
   of ret could be returned to the user as an error pointer.

 - Fix compiler warning in initialization of bkey_s_c_stripe

fs/bcachefs/buckets.c:1646:35: warning: suggest braces around initialization
of subobject [-Wmissing-braces]
        struct bkey_s_c_stripe new_s = { NULL };
                                         ^~~~
Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/buckets.c

@@ -1646,8 +1646,8 @@ static int bch2_trans_mark_stripe(struct btree_trans *trans,
 				  struct bkey_s_c old, struct bkey_s_c new,
 				  unsigned flags)
 {
-	struct bkey_s_c_stripe old_s = { NULL };
-	struct bkey_s_c_stripe new_s = { NULL };
+	struct bkey_s_c_stripe old_s = { .k = NULL };
+	struct bkey_s_c_stripe new_s = { .k = NULL };
 	struct bch_replicas_padded r;
 	unsigned i;
 	int ret = 0;

fs/bcachefs/inode.c

@@ -478,7 +478,7 @@ struct btree_iter *bch2_inode_create(struct btree_trans *trans,
 	struct btree_iter *iter = NULL;
 	struct bkey_s_c k;
 	u64 min, max, start, pos, *hint;
-	int ret;
+	int ret = 0;
 
 	u64 cpu = raw_smp_processor_id();
 	unsigned bits = (c->opts.inodes_32bit

fs/bcachefs/str_hash.h

@@ -33,10 +33,11 @@ bch2_str_hash_opt_to_type(struct bch_fs *c, enum bch_str_hash_opts opt)
 
 struct bch_hash_info {
 	u8			type;
-	union {
-		__le64		crc_key;
-		SIPHASH_KEY	siphash_key;
-	};
+	/*
+	 * For crc32 or crc64 string hashes the first key value of
+	 * the siphash_key (k0) is used as the key.
+	 */
+	SIPHASH_KEY	siphash_key;
 };
 
 static inline struct bch_hash_info
@@ -46,7 +47,7 @@ bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
 	struct bch_hash_info info = {
 		.type = (bi->bi_flags >> INODE_STR_HASH_OFFSET) &
 			~(~0U << INODE_STR_HASH_BITS),
-		.crc_key = bi->bi_hash_seed,
+		.siphash_key = { .k0 = bi->bi_hash_seed }
 	};
 
 	if (unlikely(info.type == BCH_STR_HASH_SIPHASH_OLD)) {
@@ -76,10 +77,12 @@ static inline void bch2_str_hash_init(struct bch_str_hash_ctx *ctx,
 {
 	switch (info->type) {
 	case BCH_STR_HASH_CRC32C:
-		ctx->crc32c = crc32c(~0, &info->crc_key, sizeof(info->crc_key));
+		ctx->crc32c = crc32c(~0, &info->siphash_key.k0,
+				     sizeof(info->siphash_key.k0));
 		break;
 	case BCH_STR_HASH_CRC64:
-		ctx->crc64 = crc64_be(~0, &info->crc_key, sizeof(info->crc_key));
+		ctx->crc64 = crc64_be(~0, &info->siphash_key.k0,
+				      sizeof(info->siphash_key.k0));
 		break;
 	case BCH_STR_HASH_SIPHASH_OLD:
 	case BCH_STR_HASH_SIPHASH: