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authorChris Mason <chris.mason@oracle.com>2007-11-26 16:34:41 -0800
committerChris Mason <chris.mason@oracle.com>2008-09-25 11:03:58 -0400
commit793955bca66c99defdffc857ae6eb7e8431d6bbe (patch)
tree2f8376247033fced7289038b8d82e10a6cc55f22 /fs/btrfs/extent_map.c
parent015a739c7c238768fbfa4eea8ea2ebc1a35e7bb1 (diff)
Btrfs: Limit btree writeback to prevent seeks
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/extent_map.c')
-rw-r--r--fs/btrfs/extent_map.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 55f272c335c..b6a4974ecc2 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1106,6 +1106,45 @@ out:
return found;
}
+u64 count_range_bits(struct extent_map_tree *tree,
+ u64 *start, u64 max_bytes, unsigned long bits)
+{
+ struct rb_node *node;
+ struct extent_state *state;
+ u64 cur_start = *start;
+ u64 total_bytes = 0;
+ int found = 0;
+
+ write_lock_irq(&tree->lock);
+ /*
+ * this search will find all the extents that end after
+ * our range starts.
+ */
+ node = tree_search(&tree->state, cur_start);
+ if (!node || IS_ERR(node)) {
+ goto out;
+ }
+
+ while(1) {
+ state = rb_entry(node, struct extent_state, rb_node);
+ if ((state->state & bits)) {
+ total_bytes += state->end - state->start + 1;
+ if (total_bytes >= max_bytes)
+ break;
+ if (!found) {
+ *start = state->start;
+ found = 1;
+ }
+ }
+ node = rb_next(node);
+ if (!node)
+ break;
+ }
+out:
+ write_unlock_irq(&tree->lock);
+ return total_bytes;
+}
+
/*
* helper function to lock both pages and extents in the tree.
* pages must be locked first.