Btrfs: Add efficient dirty accounting to the extent_map tree

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

3 files changed, 36 insertions, 4 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index de0552532d23..eef4ab56b9ca 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -210,7 +210,7 @@ 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 && current_is_pdflush()) {
+        if (wbc->sync_mode == WB_SYNC_NONE) {
                 u64 num_dirty;
                 u64 start = 0;
                 unsigned long thresh = 96 * 1024 * 1024;
@@ -218,6 +218,11 @@ static int btree_writepages(struct address_space *mapping,
                 if (wbc->for_kupdate)
                         return 0;
 
+                if (current_is_pdflush()) {
+                        thresh = 96 * 1024 * 1024;
+                } else {
+                        thresh = 8 * 1024 * 1024;
+                }
                 num_dirty = count_range_bits(tree, &start, thresh, EXTENT_DIRTY);
                 if (num_dirty < thresh) {
                         return 0;
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index b6a4974ecc23..06e437723dc3 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -42,6 +42,7 @@ struct extent_page_data {
         struct extent_map_tree *tree;
         get_extent_t *get_extent;
 };
+
 int __init extent_map_init(void)
 {
         extent_map_cache = btrfs_cache_create("extent_map",
@@ -94,6 +95,7 @@ void extent_map_tree_init(struct extent_map_tree *tree,
         tree->map.rb_node = NULL;
         tree->state.rb_node = NULL;
         tree->ops = NULL;
+        tree->dirty_bytes = 0;
         rwlock_init(&tree->lock);
         spin_lock_init(&tree->lru_lock);
         tree->mapping = mapping;
@@ -414,6 +416,8 @@ static int insert_state(struct extent_map_tree *tree,
                 printk("end < start %Lu %Lu\n", end, start);
                 WARN_ON(1);
         }
+        if (bits & EXTENT_DIRTY)
+                tree->dirty_bytes += end - start + 1;
         state->state |= bits;
         state->start = start;
         state->end = end;
@@ -476,6 +480,12 @@ static int clear_state_bit(struct extent_map_tree *tree,
                             int delete)
 {
         int ret = state->state & bits;
+
+        if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
+                u64 range = state->end - state->start + 1;
+                WARN_ON(range > tree->dirty_bytes);
+                tree->dirty_bytes -= range;
+        }
         state->state &= ~bits;
         if (wake)
                 wake_up(&state->wq);
@@ -668,6 +678,17 @@ out:
 }
 EXPORT_SYMBOL(wait_extent_bit);
 
+static void set_state_bits(struct extent_map_tree *tree,
+                           struct extent_state *state,
+                           int bits)
+{
+        if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
+                u64 range = state->end - state->start + 1;
+                tree->dirty_bytes += range;
+        }
+        state->state |= bits;
+}
+
 /*
  * set some bits on a range in the tree.  This may require allocations
  * or sleeping, so the gfp mask is used to indicate what is allowed.
@@ -727,7 +748,7 @@ again:
                         err = -EEXIST;
                         goto out;
                 }
-                state->state |= bits;
+                set_state_bits(tree, state, bits);
                 start = state->end + 1;
                 merge_state(tree, state);
                 goto search_again;
@@ -762,7 +783,7 @@ again:
                 if (err)
                         goto out;
                 if (state->end <= end) {
-                        state->state |= bits;
+                        set_state_bits(tree, state, bits);
                         start = state->end + 1;
                         merge_state(tree, state);
                 } else {
@@ -808,7 +829,7 @@ again:
                 err = split_state(tree, state, prealloc, end + 1);
                 BUG_ON(err == -EEXIST);
 
-                prealloc->state |= bits;
+                set_state_bits(tree, prealloc, bits);
                 merge_state(tree, prealloc);
                 prealloc = NULL;
                 goto out;
@@ -1116,6 +1137,11 @@ u64 count_range_bits(struct extent_map_tree *tree,
         int found = 0;
 
         write_lock_irq(&tree->lock);
+        if (bits == EXTENT_DIRTY) {
+                *start = 0;
+                total_bytes = tree->dirty_bytes;
+                goto out;
+        }
         /*
          * this search will find all the extents that end after
          * our range starts.
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 13c562f7cb6f..2ffc0c76338c 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -40,6 +40,7 @@ struct extent_map_tree {
         struct rb_root map;
         struct rb_root state;
         struct address_space *mapping;
+        u64 dirty_bytes;
         rwlock_t lock;
         struct extent_map_ops *ops;
         spinlock_t lru_lock;