[PATCH] xfs: always invalidate buffer in xfs_refcountbt_free_block

[Christoph Hellwig <hch@xxxxxx>]

Simplify the return value from xfs_perag_pool_free_block to a bool so that
we can easily call xfs_trans_binval for both the per-AG pool and the real
freeing case.  Without this we fail to invalidate the btree buffer and
will trip over the write verifier on a shrinking refcount btree.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/libxfs/xfs_perag_pool.c     | 22 ++++++++++------------
 fs/xfs/libxfs/xfs_perag_pool.h     |  2 +-
 fs/xfs/libxfs/xfs_refcount_btree.c | 20 +++++++-------------
 3 files changed, 18 insertions(+), 26 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_perag_pool.c b/fs/xfs/libxfs/xfs_perag_pool.c
index b49ffd2..41c4e5e 100644
--- a/fs/xfs/libxfs/xfs_perag_pool.c
+++ b/fs/xfs/libxfs/xfs_perag_pool.c
@@ -338,7 +338,7 @@ err:
  * @tp: Transaction to record the free operation.
  * @bno: Block to put back.
  */
-int
+bool
 xfs_perag_pool_free_block(
        struct xfs_perag_pool           *p,
        struct xfs_trans                *tp,
@@ -348,7 +348,7 @@ xfs_perag_pool_free_block(
        struct xfs_perag_pool_entry     *ppe;
 
        if (p == NULL)
-               return -EINVAL;
+               return false;
 
        mp = p->pp_mount;
        mp = mp;
@@ -356,18 +356,12 @@ xfs_perag_pool_free_block(
 
        list_for_each_entry(ppe, &p->pp_entries, ppe_list) {
                if (ppe->ppe_bno - 1 == bno) {
-
                        /* Adjust bookkeeping. */
-                       p->pp_inuse--;
                        ppe->ppe_bno--;
-                       ppe->ppe_len++;
-                       return 0;
-               }
-               if (ppe->ppe_bno + ppe->ppe_len == bno) {
-                       p->pp_inuse--;
-                       ppe->ppe_len++;
-                       return 0;
+                       goto adjust;
                }
+               if (ppe->ppe_bno + ppe->ppe_len == bno)
+                       goto adjust;
        }
        ppe = kmem_alloc(sizeof(struct xfs_perag_pool_entry), KM_SLEEP);
        ppe->ppe_bno = bno;
@@ -375,5 +369,9 @@ xfs_perag_pool_free_block(
        p->pp_inuse--;
 
        list_add_tail(&ppe->ppe_list, &p->pp_entries);
-       return 0;
+       return true;
+adjust:
+       p->pp_inuse--;
+       ppe->ppe_len++;
+       return true;
 }
diff --git a/fs/xfs/libxfs/xfs_perag_pool.h b/fs/xfs/libxfs/xfs_perag_pool.h
index ecdcd2a..665ea16 100644
--- a/fs/xfs/libxfs/xfs_perag_pool.h
+++ b/fs/xfs/libxfs/xfs_perag_pool.h
@@ -43,5 +43,5 @@ int xfs_perag_pool_ensure_capacity(struct xfs_perag_pool *p, 
xfs_extlen_t sz);
 
 int xfs_perag_pool_alloc_block(struct xfs_perag_pool *p, struct xfs_trans *tp,
                xfs_agblock_t *bno);
-int xfs_perag_pool_free_block(struct xfs_perag_pool *p, struct xfs_trans *tp,
+bool xfs_perag_pool_free_block(struct xfs_perag_pool *p, struct xfs_trans *tp,
                xfs_agblock_t bno);
diff --git a/fs/xfs/libxfs/xfs_refcount_btree.c 
b/fs/xfs/libxfs/xfs_refcount_btree.c
index 2379488..4a31164 100644
--- a/fs/xfs/libxfs/xfs_refcount_btree.c
+++ b/fs/xfs/libxfs/xfs_refcount_btree.c
@@ -141,27 +141,21 @@ xfs_refcountbt_free_block(
        struct xfs_perag        *pag;
        xfs_fsblock_t           fsbno = XFS_DADDR_TO_FSB(mp, XFS_BUF_ADDR(bp));
        struct xfs_owner_info   oinfo;
-       int                     error;
+       bool                    freed;
 
        /* Try to give it back to the pool. */
        pag = xfs_perag_get(cur->bc_mp, cur->bc_private.a.agno);
-       error = xfs_perag_pool_free_block(pag->pagf_refcountbt_pool, cur->bc_tp,
+       freed = xfs_perag_pool_free_block(pag->pagf_refcountbt_pool, cur->bc_tp,
                        XFS_FSB_TO_AGBNO(cur->bc_mp, fsbno));
        xfs_perag_put(pag);
 
-       switch (error) {
-       case 0:
-               return 0;
-       case -EINVAL:
-               break;
-       default:
-               return error;
+       if (!freed) {
+               /* Return it to the AG. */
+               XFS_RMAP_AG_OWNER(&oinfo, XFS_RMAP_OWN_REFC);
+               xfs_bmap_add_free(mp, cur->bc_private.a.flist, fsbno, 1,
+                               &oinfo);
        }
 
-       /* Return it to the AG. */
-       XFS_RMAP_AG_OWNER(&oinfo, XFS_RMAP_OWN_REFC);
-       xfs_bmap_add_free(mp, cur->bc_private.a.flist, fsbno, 1,
-                       &oinfo);
        xfs_trans_binval(tp, bp);
        return 0;
 }
-- 
1.9.1