[XFS] move xfs_bmbt_killroot to common code

xfs_bmbt_killroot is a mostly generic implementation of moving from a real
block based root to an inode based root. So move it to xfs_btree.c where
it can use all the nice infrastructure there and make it pointer size
agnostic

The new name for it is xfs_btree_kill_iroot, following the old naming but
making it clear we're dealing with the root in inode case here, and to
avoid confusion with xfs_btree_new_root which is used for the not inode
rooted case. I've also added a comment describing what it does and why
it's named the way it is.

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32203a

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, 112 insertions, 0 deletions

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 36477aae77df..75a8a7b00dfb 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -3059,3 +3059,115 @@ error0:
         XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
         return error;
 }
+
+/*
+ * Try to merge a non-leaf block back into the inode root.
+ *
+ * Note: the killroot names comes from the fact that we're effectively
+ * killing the old root block.  But because we can't just delete the
+ * inode we have to copy the single block it was pointing to into the
+ * inode.
+ */
+int
+xfs_btree_kill_iroot(
+        struct xfs_btree_cur    *cur)
+{
+        int                     whichfork = cur->bc_private.b.whichfork;
+        struct xfs_inode        *ip = cur->bc_private.b.ip;
+        struct xfs_ifork        *ifp = XFS_IFORK_PTR(ip, whichfork);
+        struct xfs_btree_block  *block;
+        struct xfs_btree_block  *cblock;
+        union xfs_btree_key     *kp;
+        union xfs_btree_key     *ckp;
+        union xfs_btree_ptr     *pp;
+        union xfs_btree_ptr     *cpp;
+        struct xfs_buf          *cbp;
+        int                     level;
+        int                     index;
+        int                     numrecs;
+#ifdef DEBUG
+        union xfs_btree_ptr     ptr;
+        int                     i;
+#endif
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+
+        ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);
+        ASSERT(cur->bc_nlevels > 1);
+
+        /*
+         * Don't deal with the root block needs to be a leaf case.
+         * We're just going to turn the thing back into extents anyway.
+         */
+        level = cur->bc_nlevels - 1;
+        if (level == 1)
+                goto out0;
+
+        /*
+         * Give up if the root has multiple children.
+         */
+        block = xfs_btree_get_iroot(cur);
+        if (xfs_btree_get_numrecs(block) != 1)
+                goto out0;
+
+        cblock = xfs_btree_get_block(cur, level - 1, &cbp);
+        numrecs = xfs_btree_get_numrecs(cblock);
+
+        /*
+         * Only do this if the next level will fit.
+         * Then the data must be copied up to the inode,
+         * instead of freeing the root you free the next level.
+         */
+        if (numrecs > cur->bc_ops->get_dmaxrecs(cur, level))
+                goto out0;
+
+        XFS_BTREE_STATS_INC(cur, killroot);
+
+#ifdef DEBUG
+        xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB);
+        ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
+        xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
+        ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
+#endif
+
+        index = numrecs - cur->bc_ops->get_maxrecs(cur, level);
+        if (index) {
+                xfs_iroot_realloc(cur->bc_private.b.ip, index,
+                                  cur->bc_private.b.whichfork);
+                block = (struct xfs_btree_block *)ifp->if_broot;
+        }
+
+        be16_add_cpu(&block->bb_numrecs, index);
+        ASSERT(block->bb_numrecs == cblock->bb_numrecs);
+
+        kp = xfs_btree_key_addr(cur, 1, block);
+        ckp = xfs_btree_key_addr(cur, 1, cblock);
+        xfs_btree_copy_keys(cur, kp, ckp, numrecs);
+
+        pp = xfs_btree_ptr_addr(cur, 1, block);
+        cpp = xfs_btree_ptr_addr(cur, 1, cblock);
+#ifdef DEBUG
+        for (i = 0; i < numrecs; i++) {
+                int             error;
+
+                error = xfs_btree_check_ptr(cur, cpp, i, level - 1);
+                if (error) {
+                        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+                        return error;
+                }
+        }
+#endif
+        xfs_btree_copy_ptrs(cur, pp, cpp, numrecs);
+
+        cur->bc_ops->free_block(cur, cbp);
+        XFS_BTREE_STATS_INC(cur, free);
+
+        cur->bc_bufs[level - 1] = NULL;
+        be16_add_cpu(&block->bb_level, -1);
+        xfs_trans_log_inode(cur->bc_tp, ip,
+                XFS_ILOG_CORE | XFS_ILOG_FBROOT(cur->bc_private.b.whichfork));
+        cur->bc_nlevels--;
+out0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        return 0;
+}