Merge branch 'raid56-experimental' into for-linus-3.9

[deliverable/linux.git] / fs / btrfs / free-space-cache.c

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index e067cae15e3d4a98ec1db07b683559ed409bdf5c..1f84fc09c1a8e74c5d4b063160e60bdbded44417 100644 (file)
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1356,6 +1356,8 @@ static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
        u64 bytes_per_bg = BITS_PER_BITMAP * ctl->unit;
        int max_bitmaps = div64_u64(size + bytes_per_bg - 1, bytes_per_bg);
 
+       max_bitmaps = max(max_bitmaps, 1);
+
        BUG_ON(ctl->total_bitmaps > max_bitmaps);
 
        /*
@@ -1659,10 +1661,14 @@ static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
        }
 
        /*
-        * some block groups are so tiny they can't be enveloped by a bitmap, so
-        * don't even bother to create a bitmap for this
+        * The original block groups from mkfs can be really small, like 8
+        * megabytes, so don't bother with a bitmap for those entries.  However
+        * some block groups can be smaller than what a bitmap would cover but
+        * are still large enough that they could overflow the 32k memory limit,
+        * so allow those block groups to still be allowed to have a bitmap
+        * entry.
         */
-       if (BITS_PER_BITMAP * ctl->unit > block_group->key.offset)
+       if (((BITS_PER_BITMAP * ctl->unit) >> 1) > block_group->key.offset)
                return false;
 
        return true;