Btrfs: enforce metadata allocation clustering
The allocator uses the last allocation as a starting point for metadata
allocations, and tries to allocate in clusters of at least 256k.
If the search for a free block fails to find the expected block, this patch
forces a new cluster to be found in the free list.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index ebd8275..b8c6541 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2195,6 +2195,23 @@
if (search_start + num_bytes > end)
goto new_group;
+ if (last_ptr && *last_ptr && search_start != *last_ptr) {
+ total_needed += empty_cluster;
+ *last_ptr = 0;
+ /*
+ * if search_start is still in this block group
+ * then we just re-search this block group
+ */
+ if (search_start >= start &&
+ search_start < end) {
+ mutex_unlock(&block_group->alloc_mutex);
+ continue;
+ }
+
+ /* else we go to the next block group */
+ goto new_group;
+ }
+
if (exclude_nr > 0 &&
(search_start + num_bytes > exclude_start &&
search_start < exclude_start + exclude_nr)) {