[PATCH 077/145] xfs: account for the refcount btree in the alloc/free log reservation

["Darrick J. Wong" <darrick.wong@xxxxxxxxxx>]

Every time we allocate or free an extent, we might need to split the
refcount btree.  Reserve some blocks in the transaction to handle
this possibility.

(Reproduced by generic/167 over NFS atop XFS)

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
[darrick.wong@xxxxxxxxxx: add commit message]
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
 libxfs/xfs_trans_resv.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)


diff --git a/libxfs/xfs_trans_resv.c b/libxfs/xfs_trans_resv.c
index 10234bb..5b6bbcd 100644
--- a/libxfs/xfs_trans_resv.c
+++ b/libxfs/xfs_trans_resv.c
@@ -66,7 +66,8 @@ xfs_calc_buf_res(
  * Per-extent log reservation for the btree changes involved in freeing or
  * allocating an extent.  In classic XFS there were two trees that will be
  * modified (bnobt + cntbt).  With rmap enabled, there are three trees
- * (rmapbt).  The number of blocks reserved is based on the formula:
+ * (rmapbt).  With reflink, there are four trees (refcountbt).  The number of
+ * blocks reserved is based on the formula:
  *
  * num trees * ((2 blocks/level * max depth) - 1)
  *
@@ -82,6 +83,8 @@ xfs_allocfree_log_count(
        blocks = num_ops * 2 * (2 * mp->m_ag_maxlevels - 1);
        if (xfs_sb_version_hasrmapbt(&mp->m_sb))
                blocks += num_ops * (2 * mp->m_rmap_maxlevels - 1);
+       if (xfs_sb_version_hasreflink(&mp->m_sb))
+               blocks += num_ops * (2 * mp->m_refc_maxlevels - 1);
 
        return blocks;
 }