lightnvm: pblk: fix write amplificiation calculation

When the user data counter exceeds 32 bits, the write amplification
calculation does not provide the right value. Fix this by using
div64_u64 in stead of div64.

Fixes: 76758390 ("lightnvm: pblk: export write amplification counters to sysfs")
Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/lightnvm/pblk-sysfs.c

@@ -337,7 +337,6 @@ static ssize_t pblk_get_write_amp(u64 user, u64 gc, u64 pad,
 {
 	int sz;
 
-
 	sz = snprintf(page, PAGE_SIZE,
 			"user:%lld gc:%lld pad:%lld WA:",
 			user, gc, pad);
@@ -349,7 +348,7 @@ static ssize_t pblk_get_write_amp(u64 user, u64 gc, u64 pad,
 		u32 wa_frac;
 
 		wa_int = (user + gc + pad) * 100000;
-		wa_int = div_u64(wa_int, user);
+		wa_int = div64_u64(wa_int, user);
 		wa_int = div_u64_rem(wa_int, 100000, &wa_frac);
 
 		sz += snprintf(page + sz, PAGE_SIZE - sz, "%llu.%05u\n",