xfs: exact busy extent tracking

Update the extent tree in case we have to reuse a busy extent, so that it
always is kept uptodate.  This is done by replacing the busy list searches
with a new xfs_alloc_busy_reuse helper, which updates the busy extent tree
in case of a reuse.  This allows us to allow reusing metadata extents
unconditionally, and thus avoid log forces especially for allocation btree
blocks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 2 insertions, 13 deletions

diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c
index bcfe92f47edd..8b469d53599f 100644
--- a/fs/xfs/xfs_alloc_btree.c
+++ b/fs/xfs/xfs_alloc_btree.c
@@ -94,8 +94,8 @@ xfs_allocbt_alloc_block(
 		*stat = 0;
 		return 0;
 	}
-	if (xfs_alloc_busy_search(cur->bc_mp, cur->bc_private.a.agno, bno, 1))
-		xfs_trans_set_sync(cur->bc_tp);
+
+	xfs_alloc_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1, false);
 
 	xfs_trans_agbtree_delta(cur->bc_tp, 1);
 	new->s = cpu_to_be32(bno);
@@ -120,17 +120,6 @@ xfs_allocbt_free_block(
 	if (error)
 		return error;
 
-	/*
-	 * Since blocks move to the free list without the coordination used in
-	 * xfs_bmap_finish, we can't allow block to be available for
-	 * reallocation and non-transaction writing (user data) until we know
-	 * that the transaction that moved it to the free list is permanently
-	 * on disk. We track the blocks by declaring these blocks as "busy";
-	 * the busy list is maintained on a per-ag basis and each transaction
-	 * records which entries should be removed when the iclog commits to
-	 * disk. If a busy block is allocated, the iclog is pushed up to the
-	 * LSN that freed the block.
-	 */
 	xfs_alloc_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1);
 	xfs_trans_agbtree_delta(cur->bc_tp, -1);
 	return 0;