xfs: fix per-ag reference counting in inode reclaim tree walking

The walk fails to decrement the per-ag reference count when the
non-blocking walk fails to obtain the per-ag reclaim lock, leading
to an assert failure on debug kernels when unmounting a filesystem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 37d3325..afb0d7c 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -853,6 +853,7 @@ restart:
                if (trylock) {
                        if (!mutex_trylock(&pag->pag_ici_reclaim_lock)) {
                                skipped++;
+                               xfs_perag_put(pag);
                                continue;
                        }
                        first_index = pag->pag_ici_reclaim_cursor;

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index b1498ab..19e9dfa 100644 (file)
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -275,6 +275,7 @@ xfs_free_perag(
                pag = radix_tree_delete(&mp->m_perag_tree, agno);
                spin_unlock(&mp->m_perag_lock);
                ASSERT(pag);
+               ASSERT(atomic_read(&pag->pag_ref) == 0);
                call_rcu(&pag->rcu_head, __xfs_free_perag);
        }
 }