Btrfs: fix metadata dirty throttling limits

Once a metadata block has been written, it must be recowed, so the
btrfs dirty balancing call has a check to make sure a fair amount of metadata
was actually dirty before it started writing it back to disk.

A previous commit had changed the dirty tracking for metadata without
updating the btrfs dirty balancing checks.  This commit switches it
to use the correct counter.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7f5c6e3e999283afe78051569163c8e19a6b67a0..e572cf478a5d4daa9104c4eae36e1630cba192a3 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2378,17 +2378,14 @@ void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
         * looks as though older kernels can get into trouble with
         * this code, they end up stuck in balance_dirty_pages forever
         */
-       struct extent_io_tree *tree;
        u64 num_dirty;
-       u64 start = 0;
        unsigned long thresh = 32 * 1024 * 1024;
-       tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
 
        if (current->flags & PF_MEMALLOC)
                return;
 
-       num_dirty = count_range_bits(tree, &start, (u64)-1,
-                                    thresh, EXTENT_DIRTY);
+       num_dirty = root->fs_info->dirty_metadata_bytes;
+
        if (num_dirty > thresh) {
                balance_dirty_pages_ratelimited_nr(
                                   root->fs_info->btree_inode->i_mapping, 1);