[XFS] split up xfs_btree_init_cursor

xfs_btree_init_cursor contains close to little shared code for the
different btrees and will get even more non-common code in the future.
Split it up into one routine per btree type.

Because xfs_btree_dup_cursor needs to call the init routine for a generic
btree cursor add a new btree operation vector that contains a dup_cursor
method that initializes a new cursor based on an existing one.

The btree operations vector is based on an idea and code from Dave Chinner
and will grow more entries later during this series.

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32176a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c
index 3ce2645508ae..60c121f1e81b 100644
--- a/fs/xfs/xfs_alloc_btree.c
+++ b/fs/xfs/xfs_alloc_btree.c
@@ -2209,3 +2209,48 @@ xfs_alloc_update(
         }
         return 0;
 }
+
+STATIC struct xfs_btree_cur *
+xfs_allocbt_dup_cursor(
+        struct xfs_btree_cur    *cur)
+{
+        return xfs_allocbt_init_cursor(cur->bc_mp, cur->bc_tp,
+                        cur->bc_private.a.agbp, cur->bc_private.a.agno,
+                        cur->bc_btnum);
+}
+
+static const struct xfs_btree_ops xfs_allocbt_ops = {
+        .dup_cursor             = xfs_allocbt_dup_cursor,
+};
+
+/*
+ * Allocate a new allocation btree cursor.
+ */
+struct xfs_btree_cur *                  /* new alloc btree cursor */
+xfs_allocbt_init_cursor(
+        struct xfs_mount        *mp,            /* file system mount point */
+        struct xfs_trans        *tp,            /* transaction pointer */
+        struct xfs_buf          *agbp,          /* buffer for agf structure */
+        xfs_agnumber_t          agno,           /* allocation group number */
+        xfs_btnum_t             btnum)          /* btree identifier */
+{
+        struct xfs_agf          *agf = XFS_BUF_TO_AGF(agbp);
+        struct xfs_btree_cur    *cur;
+
+        ASSERT(btnum == XFS_BTNUM_BNO || btnum == XFS_BTNUM_CNT);
+
+        cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
+
+        cur->bc_tp = tp;
+        cur->bc_mp = mp;
+        cur->bc_nlevels = be32_to_cpu(agf->agf_levels[btnum]);
+        cur->bc_btnum = btnum;
+        cur->bc_blocklog = mp->m_sb.sb_blocklog;
+
+        cur->bc_ops = &xfs_allocbt_ops;
+
+        cur->bc_private.a.agbp = agbp;
+        cur->bc_private.a.agno = agno;
+
+        return cur;
+}