[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, 4 insertions, 103 deletions

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 31002093bfb7..074f7f6aa27c 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -387,16 +387,17 @@ xfs_btree_dup_cursor(
 
         tp = cur->bc_tp;
         mp = cur->bc_mp;
+
         /*
          * Allocate a new cursor like the old one.
          */
-        new = xfs_btree_init_cursor(mp, tp, cur->bc_private.a.agbp,
-                cur->bc_private.a.agno, cur->bc_btnum, cur->bc_private.b.ip,
-                cur->bc_private.b.whichfork);
+        new = cur->bc_ops->dup_cursor(cur);
+
         /*
          * Copy the record currently in the cursor.
          */
         new->bc_rec = cur->bc_rec;
+
         /*
          * For each level current, re-get the buffer and copy the ptr value.
          */
@@ -416,15 +417,6 @@ xfs_btree_dup_cursor(
                 } else
                         new->bc_bufs[i] = NULL;
         }
-        /*
-         * For bmap btrees, copy the firstblock, flist, and flags values,
-         * since init cursor doesn't get them.
-         */
-        if (new->bc_btnum == XFS_BTNUM_BMAP) {
-                new->bc_private.b.firstblock = cur->bc_private.b.firstblock;
-                new->bc_private.b.flist = cur->bc_private.b.flist;
-                new->bc_private.b.flags = cur->bc_private.b.flags;
-        }
         *ncur = new;
         return 0;
 }
@@ -505,97 +497,6 @@ xfs_btree_get_bufs(
 }
 
 /*
- * Allocate a new btree cursor.
- * The cursor is either for allocation (A) or bmap (B) or inodes (I).
- */
-xfs_btree_cur_t *                       /* new btree cursor */
-xfs_btree_init_cursor(
-        xfs_mount_t     *mp,            /* file system mount point */
-        xfs_trans_t     *tp,            /* transaction pointer */
-        xfs_buf_t       *agbp,          /* (A only) buffer for agf structure */
-                                        /* (I only) buffer for agi structure */
-        xfs_agnumber_t  agno,           /* (AI only) allocation group number */
-        xfs_btnum_t     btnum,          /* btree identifier */
-        xfs_inode_t     *ip,            /* (B only) inode owning the btree */
-        int             whichfork)      /* (B only) data or attr fork */
-{
-        xfs_agf_t       *agf;           /* (A) allocation group freespace */
-        xfs_agi_t       *agi;           /* (I) allocation group inodespace */
-        xfs_btree_cur_t *cur;           /* return value */
-        xfs_ifork_t     *ifp;           /* (I) inode fork pointer */
-        int             nlevels=0;      /* number of levels in the btree */
-
-        ASSERT(xfs_btree_cur_zone != NULL);
-        /*
-         * Allocate a new cursor.
-         */
-        cur = kmem_zone_zalloc(xfs_btree_cur_zone, KM_SLEEP);
-        /*
-         * Deduce the number of btree levels from the arguments.
-         */
-        switch (btnum) {
-        case XFS_BTNUM_BNO:
-        case XFS_BTNUM_CNT:
-                agf = XFS_BUF_TO_AGF(agbp);
-                nlevels = be32_to_cpu(agf->agf_levels[btnum]);
-                break;
-        case XFS_BTNUM_BMAP:
-                ifp = XFS_IFORK_PTR(ip, whichfork);
-                nlevels = be16_to_cpu(ifp->if_broot->bb_level) + 1;
-                break;
-        case XFS_BTNUM_INO:
-                agi = XFS_BUF_TO_AGI(agbp);
-                nlevels = be32_to_cpu(agi->agi_level);
-                break;
-        default:
-                ASSERT(0);
-        }
-        /*
-         * Fill in the common fields.
-         */
-        cur->bc_tp = tp;
-        cur->bc_mp = mp;
-        cur->bc_nlevels = nlevels;
-        cur->bc_btnum = btnum;
-        cur->bc_blocklog = mp->m_sb.sb_blocklog;
-        /*
-         * Fill in private fields.
-         */
-        switch (btnum) {
-        case XFS_BTNUM_BNO:
-        case XFS_BTNUM_CNT:
-                /*
-                 * Allocation btree fields.
-                 */
-                cur->bc_private.a.agbp = agbp;
-                cur->bc_private.a.agno = agno;
-                break;
-        case XFS_BTNUM_INO:
-                /*
-                 * Inode allocation btree fields.
-                 */
-                cur->bc_private.a.agbp = agbp;
-                cur->bc_private.a.agno = agno;
-                break;
-        case XFS_BTNUM_BMAP:
-                /*
-                 * Bmap btree fields.
-                 */
-                cur->bc_private.b.forksize = XFS_IFORK_SIZE(ip, whichfork);
-                cur->bc_private.b.ip = ip;
-                cur->bc_private.b.firstblock = NULLFSBLOCK;
-                cur->bc_private.b.flist = NULL;
-                cur->bc_private.b.allocated = 0;
-                cur->bc_private.b.flags = 0;
-                cur->bc_private.b.whichfork = whichfork;
-                break;
-        default:
-                ASSERT(0);
-        }
-        return cur;
-}
-
-/*
  * Check for the cursor referring to the last block at the given level.
  */
 int                                     /* 1=is last block, 0=not last block */