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Commit f5a31e16 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Try harder while searching for free space 



The loop searching for free space would exit out too soon when
metadata clustering was trying to allocate a large extent.  This makes
sure a full scan of the free space is done searching for only the
minimum extent size requested by the higher layers.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent e04ca626

fs/btrfs/extent-tree.c

+30 −8
Original line number Diff line number Diff line
@@ -2123,6 +2123,7 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 
	int allowed_chunk_alloc = 0;

	struct list_head *head = NULL, *cur = NULL;

	int loop = 0;

	int extra_loop = 0;

	struct btrfs_space_info *space_info;



	WARN_ON(num_bytes < root->sectorsize);
@@ -2191,6 +2192,9 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 


		free_space = btrfs_find_free_space(block_group, search_start,

						   total_needed);

		if (empty_size)

			extra_loop = 1;



		if (free_space) {

			u64 start = block_group->key.objectid;

			u64 end = block_group->key.objectid +
@@ -2254,11 +2258,11 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 
new_group:

		mutex_unlock(&block_group->alloc_mutex);

new_group_no_lock:

		/* don't try to compare new allocations against the

		 * last allocation any more

		 */

		last_wanted = 0;

		if (!allowed_chunk_alloc) {

			total_needed -= empty_size;

			empty_size = 0;

		}



		/*

		 * Here's how this works.

		 * loop == 0: we were searching a block group via a hint
@@ -2276,9 +2280,21 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 
			cur = head->next;

			loop++;

		} else if (loop == 1 && cur == head) {

			int keep_going;



			/* at this point we give up on the empty_size

			 * allocations and just try to allocate the min

			 * space.

			 *

			 * The extra_loop field was set if an empty_size

			 * allocation was attempted above, and if this

			 * is try we need to try the loop again without

			 * the additional empty_size.

			 */

			total_needed -= empty_size;

			empty_size = 0;

			keep_going = extra_loop;

			loop++;



			if (allowed_chunk_alloc && !chunk_alloc_done) {

				up_read(&space_info->groups_sem);
@@ -2287,13 +2303,19 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans, 
				if (ret < 0)

					break;

				down_read(&space_info->groups_sem);

				loop++;

				head = &space_info->block_groups;

				cur = head->next;

				/*

				 * we've allocated a new chunk, keep

				 * trying

				 */

				keep_going = 1;

				chunk_alloc_done = 1;

			} else if (!allowed_chunk_alloc) {

				space_info->force_alloc = 1;

				break;

			}

			if (keep_going) {

				cur = head->next;

				extra_loop = 0;

			} else {

				break;

			}