btrfs: cleanup 64bit/32bit divs, provably bounded values

The divisor is derived from nodesize or PAGE_SIZE, fits into 32bit type.
Get rid of a few more do_div instances.

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 5b77982..d712c46 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3021,7 +3021,7 @@
 
 		stripe_offset = btrfs_stripe_offset(leaf, stripe);
 		stripe_length = btrfs_chunk_length(leaf, chunk);
-		do_div(stripe_length, factor);
+		stripe_length = div_u64(stripe_length, factor);
 
 		if (stripe_offset < bargs->pend &&
 		    stripe_offset + stripe_length > bargs->pstart)
@@ -4399,8 +4399,8 @@
 	 */
 	if (stripe_size * data_stripes > max_chunk_size) {
 		u64 mask = (1ULL << 24) - 1;
-		stripe_size = max_chunk_size;
-		do_div(stripe_size, data_stripes);
+
+		stripe_size = div_u64(max_chunk_size, data_stripes);
 
 		/* bump the answer up to a 16MB boundary */
 		stripe_size = (stripe_size + mask) & ~mask;
@@ -4412,10 +4412,10 @@
 			stripe_size = devices_info[ndevs-1].max_avail;
 	}
 
-	do_div(stripe_size, dev_stripes);
+	stripe_size = div_u64(stripe_size, dev_stripes);
 
 	/* align to BTRFS_STRIPE_LEN */
-	do_div(stripe_size, raid_stripe_len);
+	stripe_size = div_u64(stripe_size, raid_stripe_len);
 	stripe_size *= raid_stripe_len;
 
 	map = kmalloc(map_lookup_size(num_stripes), GFP_NOFS);
@@ -5135,7 +5135,7 @@
 	stripe_index = 0;
 	stripe_nr_orig = stripe_nr;
 	stripe_nr_end = ALIGN(offset + *length, map->stripe_len);
-	do_div(stripe_nr_end, map->stripe_len);
+	stripe_nr_end = div_u64(stripe_nr_end, map->stripe_len);
 	stripe_end_offset = stripe_nr_end * map->stripe_len -
 			    (offset + *length);
 
@@ -5197,8 +5197,8 @@
 		    ((rw & (REQ_WRITE | REQ_GET_READ_MIRRORS)) ||
 		     mirror_num > 1)) {
 			/* push stripe_nr back to the start of the full stripe */
-			stripe_nr = raid56_full_stripe_start;
-			do_div(stripe_nr, stripe_len * nr_data_stripes(map));
+			stripe_nr = div_u64(raid56_full_stripe_start,
+					stripe_len * nr_data_stripes(map));
 
 			/* RAID[56] write or recovery. Return all stripes */
 			num_stripes = map->num_stripes;
@@ -5534,11 +5534,11 @@
 	rmap_len = map->stripe_len;
 
 	if (map->type & BTRFS_BLOCK_GROUP_RAID10)
-		do_div(length, map->num_stripes / map->sub_stripes);
+		length = div_u64(length, map->num_stripes / map->sub_stripes);
 	else if (map->type & BTRFS_BLOCK_GROUP_RAID0)
-		do_div(length, map->num_stripes);
+		length = div_u64(length, map->num_stripes);
 	else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) {
-		do_div(length, nr_data_stripes(map));
+		length = div_u64(length, nr_data_stripes(map));
 		rmap_len = map->stripe_len * nr_data_stripes(map);
 	}
 
@@ -5553,11 +5553,11 @@
 			continue;
 
 		stripe_nr = physical - map->stripes[i].physical;
-		do_div(stripe_nr, map->stripe_len);
+		stripe_nr = div_u64(stripe_nr, map->stripe_len);
 
 		if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
 			stripe_nr = stripe_nr * map->num_stripes + i;
-			do_div(stripe_nr, map->sub_stripes);
+			stripe_nr = div_u64(stripe_nr, map->sub_stripes);
 		} else if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
 			stripe_nr = stripe_nr * map->num_stripes + i;
 		} /* else if RAID[56], multiply by nr_data_stripes().