4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Darrick J. Wong <darrick.w...@oracle.com>
commit 9789dd9e1d939232e8ff4c50ef8e75aa6781b3fb upstream.
We call __xfs_ag_resv_init to make a per-AG reservation for each AG.
This makes the reservation per-AG, not per-filesystem. Therefore, it
is incorrect to adjust m_ag_max_usable for each AG. Adjust it only
when we're reserving AG 0's blocks so that we only do it once per fs.
Signed-off-by: Darrick J. Wong <darrick.w...@oracle.com>
Reviewed-by: Brian Foster <bfos...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
fs/xfs/libxfs/xfs_ag_resv.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -157,7 +157,8 @@ __xfs_ag_resv_free(
trace_xfs_ag_resv_free(pag, type, 0);
resv = xfs_perag_resv(pag, type);
- pag->pag_mount->m_ag_max_usable += resv->ar_asked;
+ if (pag->pag_agno == 0)
+ pag->pag_mount->m_ag_max_usable += resv->ar_asked;
/*
* AGFL blocks are always considered "free", so whatever
* was reserved at mount time must be given back at umount.
@@ -217,7 +218,14 @@ __xfs_ag_resv_init(
return error;
}
- mp->m_ag_max_usable -= ask;
+ /*
+ * Reduce the maximum per-AG allocation length by however much we're
+ * trying to reserve for an AG. Since this is a filesystem-wide
+ * counter, we only make the adjustment for AG 0. This assumes that
+ * there aren't any AGs hungrier for per-AG reservation than AG 0.
+ */
+ if (pag->pag_agno == 0)
+ mp->m_ag_max_usable -= ask;
resv = xfs_perag_resv(pag, type);
resv->ar_asked = ask;
