[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, 6 insertions, 14 deletions

diff --git a/fs/xfs/xfs_btree.h b/fs/xfs/xfs_btree.h
index 332b9f1da203..d30ee7498606 100644
--- a/fs/xfs/xfs_btree.h
+++ b/fs/xfs/xfs_btree.h
@@ -131,6 +131,11 @@ extern const __uint32_t	xfs_magics[];
 
 #define XFS_BTREE_MAXLEVELS     8       /* max of all btrees */
 
+struct xfs_btree_ops {
+        /* cursor operations */
+        struct xfs_btree_cur *(*dup_cursor)(struct xfs_btree_cur *);
+};
+
 /*
  * Btree cursor structure.
  * This collects all information needed by the btree code in one place.
@@ -139,6 +144,7 @@ typedef struct xfs_btree_cur
 {
         struct xfs_trans        *bc_tp; /* transaction we're in, if any */
         struct xfs_mount        *bc_mp; /* file system mount struct */
+        const struct xfs_btree_ops *bc_ops;
         union {
                 xfs_alloc_rec_incore_t  a;
                 xfs_bmbt_irec_t         b;
@@ -308,20 +314,6 @@ xfs_btree_get_bufs(
         uint                    lock);  /* lock flags for get_buf */
 
 /*
- * Allocate a new btree cursor.
- * The cursor is either for allocation (A) or bmap (B).
- */
-xfs_btree_cur_t *                       /* new btree cursor */
-xfs_btree_init_cursor(
-        struct xfs_mount        *mp,    /* file system mount point */
-        struct xfs_trans        *tp,    /* transaction pointer */
-        struct xfs_buf          *agbp,  /* (A only) buffer for agf structure */
-        xfs_agnumber_t          agno,   /* (A only) allocation group number */
-        xfs_btnum_t             btnum,  /* btree identifier */
-        struct xfs_inode        *ip,    /* (B only) inode owning the btree */
-        int                     whichfork); /* (B only) data/attr fork */
-
-/*
  * Check for the cursor referring to the last block at the given level.
  */
 int                                     /* 1=is last block, 0=not last block */