[PATCH 4.13 74/85] xfs: perag initialization should only touch m_ag_max_usable for AG 0
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2017-10-24 13:18:15
Also in:
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4.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Darrick J. Wong <redacted> 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 <redacted> Reviewed-by: Brian Foster <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@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@@ -156,7 +156,8 @@ __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.
@@ -216,7 +217,14 @@ __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;