Btrfs: Limit btree writeback to prevent seeks

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

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3e16cca..28e9ef8 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -210,6 +210,15 @@ static int btree_writepages(struct address_space *mapping,
 {
        struct extent_map_tree *tree;
        tree = &BTRFS_I(mapping->host)->extent_tree;
+       if (wbc->sync_mode == WB_SYNC_NONE) {
+               u64 num_dirty;
+               u64 start = 0;
+               unsigned long thresh = 96 * 1024 * 1024;
+               num_dirty = count_range_bits(tree, &start, thresh, EXTENT_DIRTY);
+               if (num_dirty < thresh) {
+                       return 0;
+               }
+       }
        return extent_writepages(tree, mapping, btree_get_extent, wbc);
 }
 

diff --cc fs/btrfs/extent_map.c
Simple merge

diff --cc fs/btrfs/extent_map.h
Simple merge