[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, 17 insertions, 0 deletions

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 6bda0ae26c2a..875e1bae1941 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -136,6 +136,23 @@ xfs_alloc_lookup_le(
         return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
 }
 
+/*
+ * Update the record referred to by cur to the value given
+ * by [bno, len].
+ * This either works (return 0) or gets an EFSCORRUPTED error.
+ */
+STATIC int                              /* error */
+xfs_alloc_update(
+        struct xfs_btree_cur    *cur,   /* btree cursor */
+        xfs_agblock_t           bno,    /* starting block of extent */
+        xfs_extlen_t            len)    /* length of extent */
+{
+        union xfs_btree_rec     rec;
+
+        rec.alloc.ar_startblock = cpu_to_be32(bno);
+        rec.alloc.ar_blockcount = cpu_to_be32(len);
+        return xfs_btree_update(cur, &rec);
+}
 
 /*
  * Compute aligned version of the found extent.