bcachefs: bch2_kvmalloc()

Add a version of kvmalloc() that doesn't have the INT_MAX limit; large
filesystems do hit this.

We'll want to get rid of the in-memory bucket gens array, but we're not
there quite yet.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

fs/bcachefs/buckets.c

@@ -1258,7 +1258,7 @@ int bch2_buckets_nouse_alloc(struct bch_fs *c)
 	for_each_member_device(c, ca) {
 		BUG_ON(ca->buckets_nouse);
 
-		ca->buckets_nouse = kvmalloc(BITS_TO_LONGS(ca->mi.nbuckets) *
+		ca->buckets_nouse = bch2_kvmalloc(BITS_TO_LONGS(ca->mi.nbuckets) *
 					    sizeof(unsigned long),
 					    GFP_KERNEL|__GFP_ZERO);
 		if (!ca->buckets_nouse) {
@@ -1290,8 +1290,8 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 	if (resize && ca->buckets_nouse)
 		return -BCH_ERR_no_resize_with_buckets_nouse;
 
-	bucket_gens = kvmalloc(struct_size(bucket_gens, b, nbuckets),
-			       GFP_KERNEL|__GFP_ZERO);
+	bucket_gens = bch2_kvmalloc(struct_size(bucket_gens, b, nbuckets),
+				    GFP_KERNEL|__GFP_ZERO);
 	if (!bucket_gens) {
 		ret = -BCH_ERR_ENOMEM_bucket_gens;
 		goto err;

fs/bcachefs/util.h

@@ -55,6 +55,16 @@ static inline size_t buf_pages(void *p, size_t len)
 			    PAGE_SIZE);
 }
 
+static inline void *bch2_kvmalloc(size_t n, gfp_t flags)
+{
+	void *p = unlikely(n >= INT_MAX)
+		? vmalloc(n)
+		: kvmalloc(n, flags & ~__GFP_ZERO);
+	if (p && (flags & __GFP_ZERO))
+		memset(p, 0, n);
+	return p;
+}
+
 #define init_heap(heap, _size, gfp)					\
 ({									\
 	(heap)->nr = 0;						\