xfs: implement swapext for rmap filesystems

Source kernel commit: 1f08af52e7c981e9877796a2d90b0e0f08666945

Implement swapext for filesystems that have reverse mapping.  Back in
the reflink patches, we augmented the bmap code with a 'REMAP' flag
that updates only the bmbt and doesn't touch the allocator and
implemented log redo items for those two operations.  Now we can
rewrite extent swapping as a (looong) series of remap operations.

This is far less efficient than the fork swapping method implemented
in the past, so we only switch this on for rmap.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/libxfs/xfs_trans_space.h b/libxfs/xfs_trans_space.h
index 41e0428d8175a2ab7ea4be8d7f67ce932a7e3a3f..7917f6e44286a4591e9109138a7be07dc1a18eb1 100644 (file)
--- a/libxfs/xfs_trans_space.h
+++ b/libxfs/xfs_trans_space.h
@@ -21,6 +21,8 @@
 /*
  * Components of space reservations.
  */
+#define XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp)    \
+               (((mp)->m_rmap_mxr[0]) - ((mp)->m_rmap_mnr[0]))
 #define XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp)    \
                (((mp)->m_alloc_mxr[0]) - ((mp)->m_alloc_mnr[0]))
 #define        XFS_EXTENTADD_SPACE_RES(mp,w)   (XFS_BM_MAXLEVELS(mp,w) - 1)
@@ -28,6 +30,13 @@
        (((b + XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp) - 1) / \
          XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp)) * \
          XFS_EXTENTADD_SPACE_RES(mp,w))
+#define XFS_SWAP_RMAP_SPACE_RES(mp,b,w)\
+       (((b + XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp) - 1) / \
+         XFS_MAX_CONTIG_EXTENTS_PER_BLOCK(mp)) * \
+         XFS_EXTENTADD_SPACE_RES(mp,w) + \
+        ((b + XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp) - 1) / \
+         XFS_MAX_CONTIG_RMAPS_PER_BLOCK(mp)) * \
+         (mp)->m_rmap_maxlevels)
 #define        XFS_DAENTER_1B(mp,w)    \
        ((w) == XFS_DATA_FORK ? (mp)->m_dir_geo->fsbcount : 1)
 #define        XFS_DAENTER_DBS(mp,w)   \