1 files changed, 10 insertions, 3 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index cf1821784a16..2f2e0da1a6b7 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -358,7 +358,7 @@ void ext4_validate_block_bitmap(struct super_block *sb,
 }
 
 /**
- * ext4_read_block_bitmap()
+ * ext4_read_block_bitmap_nowait()
  * @sb:                 super block
  * @block_group:        given block group
  *
@@ -457,6 +457,8 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
         struct buffer_head *bh;
 
         bh = ext4_read_block_bitmap_nowait(sb, block_group);
+        if (!bh)
+                return NULL;
         if (ext4_wait_block_bitmap(sb, block_group, bh)) {
                 put_bh(bh);
                 return NULL;
@@ -482,11 +484,16 @@ static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
 
         free_clusters  = percpu_counter_read_positive(fcc);
         dirty_clusters = percpu_counter_read_positive(dcc);
-        root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es));
+
+        /*
+         * r_blocks_count should always be multiple of the cluster ratio so
+         * we are safe to do a plane bit shift only.
+         */
+        root_clusters = ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits;
 
         if (free_clusters - (nclusters + root_clusters + dirty_clusters) <
                                         EXT4_FREECLUSTERS_WATERMARK) {
-                free_clusters  = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc));
+                free_clusters  = percpu_counter_sum_positive(fcc);
                 dirty_clusters = percpu_counter_sum_positive(dcc);
         }
         /* Check whether we have space after accounting for current