[XFS] Allow xfs_bmbt_split() to fallback to the lowspace allocator

algorithm

If xfs_bmbt_split() cannot find an AG with sufficient free space to
satisfy a full extent btree split then fall back to the lowspace allocator
algorithm.

SGI-PV: 983338

SGI-Modid: xfs-linux-melb:xfs-kern:31359a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chinner <dgc@sgi.com>

diff --git a/fs/xfs/xfs_bmap_btree.c b/fs/xfs/xfs_bmap_btree.c
index 1140cef4ba994d99ab56cf2e1e96584723eefabb..23efad29a5cd680b1229ae32a3e56fa9b78d50a8 100644 (file)
--- a/fs/xfs/xfs_bmap_btree.c
+++ b/fs/xfs/xfs_bmap_btree.c
@@ -1525,6 +1525,21 @@ xfs_bmbt_split(
                XFS_BMBT_TRACE_CURSOR(cur, ERROR);
                return error;
        }
+       if (args.fsbno == NULLFSBLOCK && args.minleft) {
+               /*
+                * Could not find an AG with enough free space to satisfy
+                * a full btree split.  Try again without minleft and if
+                * successful activate the lowspace algorithm.
+                */
+               args.fsbno = 0;
+               args.type = XFS_ALLOCTYPE_FIRST_AG;
+               args.minleft = 0;
+               if ((error = xfs_alloc_vextent(&args))) {
+                       XFS_BMBT_TRACE_CURSOR(cur, ERROR);
+                       return error;
+               }
+               cur->bc_private.b.flist->xbf_low = 1;
+       }
        if (args.fsbno == NULLFSBLOCK) {
                XFS_BMBT_TRACE_CURSOR(cur, EXIT);
                *stat = 0;