[XFS] implement generic xfs_btree_update

From: Dave Chinner <dgc@sgi.com>

The most complicated part here is the lastrec tracking for the alloc
btree. Most logic is in the update_lastrec method which has to do some
hopefully good enough dirty magic to maintain it.

[hch: split out from bigger patch and a rework of the lastrec

logic]

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32194a

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, 121 insertions, 0 deletions

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index 1459a2b9a729..205272f282d9 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -988,6 +988,30 @@ xfs_btree_get_sibling(
         }
 }
 
+/*
+ * Return true if ptr is the last record in the btree and
+ * we need to track updateѕ to this record.  The decision
+ * will be further refined in the update_lastrec method.
+ */
+STATIC int
+xfs_btree_is_lastrec(
+        struct xfs_btree_cur    *cur,
+        struct xfs_btree_block  *block,
+        int                     level)
+{
+        union xfs_btree_ptr     ptr;
+
+        if (level > 0)
+                return 0;
+        if (!(cur->bc_flags & XFS_BTREE_LASTREC_UPDATE))
+                return 0;
+
+        xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
+        if (!xfs_btree_ptr_is_null(cur, &ptr))
+                return 0;
+        return 1;
+}
+
 STATIC xfs_daddr_t
 xfs_btree_ptr_to_daddr(
         struct xfs_btree_cur    *cur,
@@ -1080,6 +1104,20 @@ xfs_btree_copy_keys(
 }
 
 /*
+ * Copy records from one btree block to another.
+ */
+STATIC void
+xfs_btree_copy_recs(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_rec     *dst_rec,
+        union xfs_btree_rec     *src_rec,
+        int                     numrecs)
+{
+        ASSERT(numrecs >= 0);
+        memcpy(dst_rec, src_rec, numrecs * cur->bc_ops->rec_len);
+}
+
+/*
  * Log key values from the btree block.
  */
 STATIC void
@@ -1105,6 +1143,26 @@ xfs_btree_log_keys(
 }
 
 /*
+ * Log record values from the btree block.
+ */
+STATIC void
+xfs_btree_log_recs(
+        struct xfs_btree_cur    *cur,
+        struct xfs_buf          *bp,
+        int                     first,
+        int                     last)
+{
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);
+
+        xfs_trans_log_buf(cur->bc_tp, bp,
+                          xfs_btree_rec_offset(cur, first),
+                          xfs_btree_rec_offset(cur, last + 1) - 1);
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+}
+
+/*
  * Increment cursor by one record at the level.
  * For nonzero levels the leaf-ward information is untouched.
  */
@@ -1576,3 +1634,66 @@ xfs_btree_updkey(
         XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
         return 0;
 }
+
+/*
+ * Update the record referred to by cur to the value in the
+ * given record. This either works (return 0) or gets an
+ * EFSCORRUPTED error.
+ */
+int
+xfs_btree_update(
+        struct xfs_btree_cur    *cur,
+        union xfs_btree_rec     *rec)
+{
+        struct xfs_btree_block  *block;
+        struct xfs_buf          *bp;
+        int                     error;
+        int                     ptr;
+        union xfs_btree_rec     *rp;
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
+        XFS_BTREE_TRACE_ARGR(cur, rec);
+
+        /* Pick up the current block. */
+        block = xfs_btree_get_block(cur, 0, &bp);
+
+#ifdef DEBUG
+        error = xfs_btree_check_block(cur, block, 0, bp);
+        if (error)
+                goto error0;
+#endif
+        /* Get the address of the rec to be updated. */
+        ptr = cur->bc_ptrs[0];
+        rp = xfs_btree_rec_addr(cur, ptr, block);
+
+        /* Fill in the new contents and log them. */
+        xfs_btree_copy_recs(cur, rp, rec, 1);
+        xfs_btree_log_recs(cur, bp, ptr, ptr);
+
+        /*
+         * If we are tracking the last record in the tree and
+         * we are at the far right edge of the tree, update it.
+         */
+        if (xfs_btree_is_lastrec(cur, block, 0)) {
+                cur->bc_ops->update_lastrec(cur, block, rec,
+                                            ptr, LASTREC_UPDATE);
+        }
+
+        /* Updating first rec in leaf. Pass new key value up to our parent. */
+        if (ptr == 1) {
+                union xfs_btree_key     key;
+
+                cur->bc_ops->init_key_from_rec(&key, rec);
+                error = xfs_btree_updkey(cur, &key, 1);
+                if (error)
+                        goto error0;
+        }
+
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
+        return 0;
+
+error0:
+        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
+        return error;
+}
+