[XFS] implement semi-generic xfs_btree_new_root

From: Dave Chinner <dgc@sgi.com>

Add a xfs_btree_new_root helper for the alloc and ialloc btrees. The bmap
btree needs it's own version and is not converted.

[hch: split out from bigger patch and minor adaptions]

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32200a

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, 129 insertions, 0 deletions

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 80576695fbe5..8de884c4dab7 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -2467,3 +2467,132 @@ error0:
         XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
         return error;
 }
+
+/*
+ * Allocate a new root block, fill it in.
+ */
+int                             /* error */
+xfs_btree_new_root(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        int                     *stat)  /* success/failure */
+{
+        struct xfs_btree_block  *block; /* one half of the old root block */
+        struct xfs_buf          *bp;    /* buffer containing block */
+        int                     error;  /* error return value */
+        struct xfs_buf          *lbp;   /* left buffer pointer */
+        struct xfs_btree_block  *left;  /* left btree block */
+        struct xfs_buf          *nbp;   /* new (root) buffer */
+        struct xfs_btree_block  *new;   /* new (root) btree block */
+        int                     nptr;   /* new value for key index, 1 or 2 */
+        struct xfs_buf          *rbp;   /* right buffer pointer */
+        struct xfs_btree_block  *right; /* right btree block */
+        union xfs_btree_ptr     rptr;
+        union xfs_btree_ptr     lptr;
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_STATS_INC(cur, newroot);
+
+        /* initialise our start point from the cursor */
+        cur->bc_ops->init_ptr_from_cur(cur, &rptr);
+
+        /* Allocate the new block. If we can't do it, we're toast. Give up. */
+        error = cur->bc_ops->alloc_block(cur, &rptr, &lptr, 1, stat);
+        if (error)
+                goto error0;
+        if (*stat == 0)
+                goto out0;
+        XFS_BTREE_STATS_INC(cur, alloc);
+
+        /* Set up the new block. */
+        error = xfs_btree_get_buf_block(cur, &lptr, 0, &new, &nbp);
+        if (error)
+                goto error0;
+
+        /* Set the root in the holding structure  increasing the level by 1. */
+        cur->bc_ops->set_root(cur, &lptr, 1);
+
+        /*
+         * At the previous root level there are now two blocks: the old root,
+         * and the new block generated when it was split.  We don't know which
+         * one the cursor is pointing at, so we set up variables "left" and
+         * "right" for each case.
+         */
+        block = xfs_btree_get_block(cur, cur->bc_nlevels - 1, &bp);
+
+#ifdef DEBUG
+        error = xfs_btree_check_block(cur, block, cur->bc_nlevels - 1, bp);
+        if (error)
+                goto error0;
+#endif
+
+        xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
+        if (!xfs_btree_ptr_is_null(cur, &rptr)) {
+                /* Our block is left, pick up the right block. */
+                lbp = bp;
+                xfs_btree_buf_to_ptr(cur, lbp, &lptr);
+                left = block;
+                error = xfs_btree_read_buf_block(cur, &rptr,
+                                        cur->bc_nlevels - 1, 0, &right, &rbp);
+                if (error)
+                        goto error0;
+                bp = rbp;
+                nptr = 1;
+        } else {
+                /* Our block is right, pick up the left block. */
+                rbp = bp;
+                xfs_btree_buf_to_ptr(cur, rbp, &rptr);
+                right = block;
+                xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
+                error = xfs_btree_read_buf_block(cur, &lptr,
+                                        cur->bc_nlevels - 1, 0, &left, &lbp);
+                if (error)
+                        goto error0;
+                bp = lbp;
+                nptr = 2;
+        }
+        /* Fill in the new block's btree header and log it. */
+        xfs_btree_init_block(cur, cur->bc_nlevels, 2, new);
+        xfs_btree_log_block(cur, nbp, XFS_BB_ALL_BITS);
+        ASSERT(!xfs_btree_ptr_is_null(cur, &lptr) &&
+                        !xfs_btree_ptr_is_null(cur, &rptr));
+
+        /* Fill in the key data in the new root. */
+        if (xfs_btree_get_level(left) > 0) {
+                xfs_btree_copy_keys(cur,
+                                xfs_btree_key_addr(cur, 1, new),
+                                xfs_btree_key_addr(cur, 1, left), 1);
+                xfs_btree_copy_keys(cur,
+                                xfs_btree_key_addr(cur, 2, new),
+                                xfs_btree_key_addr(cur, 1, right), 1);
+        } else {
+                cur->bc_ops->init_key_from_rec(
+                                xfs_btree_key_addr(cur, 1, new),
+                                xfs_btree_rec_addr(cur, 1, left));
+                cur->bc_ops->init_key_from_rec(
+                                xfs_btree_key_addr(cur, 2, new),
+                                xfs_btree_rec_addr(cur, 1, right));
+        }
+        xfs_btree_log_keys(cur, nbp, 1, 2);
+
+        /* Fill in the pointer data in the new root. */
+        xfs_btree_copy_ptrs(cur,
+                xfs_btree_ptr_addr(cur, 1, new), &lptr, 1);
+        xfs_btree_copy_ptrs(cur,
+                xfs_btree_ptr_addr(cur, 2, new), &rptr, 1);
+        xfs_btree_log_ptrs(cur, nbp, 1, 2);
+
+        /* Fix up the cursor. */
+        xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
+        cur->bc_ptrs[cur->bc_nlevels] = nptr;
+        cur->bc_nlevels++;
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        *stat = 1;
+        return 0;
+error0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+        return error;
+out0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        *stat = 0;
+        return 0;
+}