[PATCH 1/2] set minleft in xfs_bmbt_split()

[Lachlan McIlroy <lachlan@xxxxxxx>]

The bmap btree split code relies on a previous data extent allocation
(from xfs_bmap_btalloc()) to find an AG that has sufficient space
to perform a full btree split, when inserting the extent.  When
converting unwritten extents we don't allocate a data extent so a
btree split will be the first allocation.  In this case we need to
set minleft so the allocator will pick an AG that has space to
complete the split(s).

Lachlan

--- 2.6.x-agno2.orig/fs/xfs/xfs_bmap_btree.c
+++ 2.6.x-agno2/fs/xfs/xfs_bmap_btree.c
@@ -1493,12 +1493,20 @@ xfs_bmbt_split(
        left = XFS_BUF_TO_BMBT_BLOCK(lbp);
        args.fsbno = cur->bc_private.b.firstblock;
        args.firstblock = args.fsbno;
+       args.minleft = 0;
        if (args.fsbno == NULLFSBLOCK) {
                args.fsbno = lbno;
                args.type = XFS_ALLOCTYPE_START_BNO;
+               /*
+                * Make sure there is sufficient room left in the AG to
+                * complete a full tree split for an extent insert.  If
+                * we are converting the middle part of an extent then
+                * we may need space for two tree splits.
+                */
+               args.minleft = xfs_trans_get_block_res(args.tp);
        } else
                args.type = XFS_ALLOCTYPE_NEAR_BNO;
-       args.mod = args.minleft = args.alignment = args.total = args.isfl =
+       args.mod = args.alignment = args.total = args.isfl =
                args.userdata = args.minalignslop = 0;
        args.minlen = args.maxlen = args.prod = 1;
        args.wasdel = cur->bc_private.b.flags & XFS_BTCUR_BPRV_WASDEL;