Btrfs: Add efficient dirty accounting to the extent_map tree

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

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index de05525..eef4ab5 100644 (file)
--- 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 b6a4974..06e4377 100644 (file)
--- 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 13c562f..2ffc0c7 100644 (file)
--- 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;