bcachefs: Build fixes for 32bit x86

PAGE_SIZE and size_t are not unsigned longs on 32 bit, annoying...

also switch to atomic64_cmpxchg instead of cmpxchg() for
journal_seq_copy, as atomic64_cmpxchg has a fallback that uses spinlocks
for when it's not supported.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/ec.c

@@ -1586,7 +1586,7 @@ void bch2_stripes_heap_to_text(struct printbuf *out, struct bch_fs *c)
 	size_t i;
 
 	spin_lock(&c->ec_stripes_heap_lock);
-	for (i = 0; i < min(h->used, 20UL); i++) {
+	for (i = 0; i < min_t(size_t, h->used, 20); i++) {
 		m = genradix_ptr(&c->stripes[0], h->data[i].idx);
 
 		pr_buf(out, "%zu %u/%u+%u\n", h->data[i].idx,

fs/bcachefs/fs.c

@@ -44,6 +44,11 @@ static void journal_seq_copy(struct bch_fs *c,
 			     struct bch_inode_info *dst,
 			     u64 journal_seq)
 {
+	/*
+	 * atomic64_cmpxchg has a fallback for archs that don't support it,
+	 * cmpxchg does not:
+	 */
+	atomic64_t *dst_seq = (void *) &dst->ei_journal_seq;
 	u64 old, v = READ_ONCE(dst->ei_journal_seq);
 
 	do {
@@ -51,7 +56,7 @@ static void journal_seq_copy(struct bch_fs *c,
 
 		if (old >= journal_seq)
 			break;
-	} while ((v = cmpxchg(&dst->ei_journal_seq, old, journal_seq)) != old);
+	} while ((v = atomic64_cmpxchg(dst_seq, old, journal_seq)) != old);
 
 	bch2_journal_set_has_inum(&c->journal, dst->v.i_ino, journal_seq);
 }

fs/bcachefs/io.c

@@ -180,7 +180,7 @@ void bch2_bio_alloc_pages_pool(struct bch_fs *c, struct bio *bio,
 
 	while (size) {
 		struct page *page = __bio_alloc_page_pool(c, &using_mempool);
-		unsigned len = min(PAGE_SIZE, size);
+		unsigned len = min_t(size_t, PAGE_SIZE, size);
 
 		BUG_ON(!bio_add_page(bio, page, len, 0));
 		size -= len;