[PATCH] add xfs_map_buffer helper

[Christoph Hellwig <hch@xxxxxx>]

Add a xfs_map_buffer helper to factor out common code from
xfs_map_at_offset and __linvfs_get_block.  For some delalloc
changes I'm working on I'll need it in even more places.


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs-2.6.x/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- xfs-2.6.x.orig/fs/xfs/linux-2.6/xfs_aops.c  2006-02-21 21:20:21.000000000 
+0100
+++ xfs-2.6.x/fs/xfs/linux-2.6/xfs_aops.c       2006-02-21 21:28:19.000000000 
+0100
@@ -487,28 +487,37 @@
 }
 
 STATIC void
+xfs_map_buffer(
+       struct buffer_head      *bh,
+       xfs_iomap_t             *mp,
+       xfs_off_t               offset,
+       uint                    block_bits)
+{
+       sector_t                bn;
+
+       ASSERT(mp->iomap_bn != IOMAP_DADDR_NULL);
+
+       bn = (mp->iomap_bn >> (block_bits - BBSHIFT)) +
+             ((offset - mp->iomap_offset) >> block_bits);
+
+       ASSERT(bn || (mp->iomap_flags & IOMAP_REALTIME));
+
+       bh->b_blocknr = bn;
+       set_buffer_mapped(bh);
+}
+
+STATIC void
 xfs_map_at_offset(
        struct buffer_head      *bh,
        loff_t                  offset,
        int                     block_bits,
        xfs_iomap_t             *iomapp)
 {
-       xfs_daddr_t             bn;
-       int                     sector_shift;
-
        ASSERT(!(iomapp->iomap_flags & IOMAP_HOLE));
        ASSERT(!(iomapp->iomap_flags & IOMAP_DELAY));
-       ASSERT(iomapp->iomap_bn != IOMAP_DADDR_NULL);
-
-       sector_shift = block_bits - BBSHIFT;
-       bn = (iomapp->iomap_bn >> sector_shift) +
-             ((offset - iomapp->iomap_offset) >> block_bits);
-
-       ASSERT(bn || (iomapp->iomap_flags & IOMAP_REALTIME));
-       ASSERT((bn << sector_shift) >= iomapp->iomap_bn);
 
        lock_buffer(bh);
-       bh->b_blocknr = bn;
+       xfs_map_buffer(bh, iomapp, offset, block_bits);
        bh->b_bdev = iomapp->iomap_target->bt_bdev;
        set_buffer_mapped(bh);
        clear_buffer_delay(bh);
@@ -1246,21 +1255,13 @@
                return 0;
 
        if (iomap.iomap_bn != IOMAP_DADDR_NULL) {
-               xfs_daddr_t     bn;
-               xfs_off_t       delta;
-
-               /* For unwritten extents do not report a disk address on
+               /*
+                * For unwritten extents do not report a disk address on
                 * the read case (treat as if we're reading into a hole).
                 */
                if (create || !(iomap.iomap_flags & IOMAP_UNWRITTEN)) {
-                       delta = offset - iomap.iomap_offset;
-                       delta >>= inode->i_blkbits;
-
-                       bn = iomap.iomap_bn >> (inode->i_blkbits - BBSHIFT);
-                       bn += delta;
-                       BUG_ON(!bn && !(iomap.iomap_flags & IOMAP_REALTIME));
-                       bh_result->b_blocknr = bn;
-                       set_buffer_mapped(bh_result);
+                       xfs_map_buffer(bh_result, &iomap, offset,
+                                      inode->i_blkbits);
                }
                if (create && (iomap.iomap_flags & IOMAP_UNWRITTEN)) {
                        if (direct)