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Commit 3b7885bf authored by Chris Mason's avatar Chris Mason
Browse files

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: default avatarChris Mason <chris.mason@oracle.com>
parent 771ed689

fs/btrfs/extent-tree.c

+17 −0
Original line number Diff line number Diff line
@@ -2195,6 +2195,23 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 
			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)) {

fs/btrfs/extent_io.c

+0 −7
Original line number Diff line number Diff line
@@ -2494,13 +2494,6 @@ int extent_write_cache_pages(struct extent_io_tree *tree, 
		index = 0;

		goto retry;

	}

	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))

		mapping->writeback_index = index;

		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)

			range_whole = 1;



	if (wbc->range_cont)

		wbc->range_start = index << PAGE_CACHE_SHIFT;

	return ret;

}

EXPORT_SYMBOL(extent_write_cache_pages);