[PATCH v3 1/2] xfs: set a mount flag when perag reservation is active

[Brian Foster <bfoster@redhat.com>]

perag reservation is enabled at mount time on a per AG basis. The
upcoming in-core allocation btree accounting mechanism needs to know
when reservation is enabled and that all perag AGF contexts are
initialized. As a preparation step, set a flag in the mount
structure and unconditionally initialize the pagf on all mounts
where at least one reservation is active.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/xfs/libxfs/xfs_ag_resv.c | 24 ++++++++++++++----------
 fs/xfs/xfs_mount.h          |  1 +
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
index fdfe6dc0d307..8e454097b905 100644
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -250,6 +250,7 @@ xfs_ag_resv_init(
 	xfs_extlen_t			ask;
 	xfs_extlen_t			used;
 	int				error = 0;
+	bool				has_resv = false;
 
 	/* Create the metadata reservation. */
 	if (pag->pag_meta_resv.ar_asked == 0) {
@@ -287,6 +288,8 @@ xfs_ag_resv_init(
 			if (error)
 				goto out;
 		}
+		if (ask)
+			has_resv = true;
 	}
 
 	/* Create the RMAPBT metadata reservation */
@@ -300,18 +303,19 @@ xfs_ag_resv_init(
 		error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used);
 		if (error)
 			goto out;
+		if (ask)
+			has_resv = true;
 	}
 
-#ifdef DEBUG
-	/* need to read in the AGF for the ASSERT below to work */
-	error = xfs_alloc_pagf_init(pag->pag_mount, tp, pag->pag_agno, 0);
-	if (error)
-		return error;
-
-	ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
-	       xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
-	       pag->pagf_freeblks + pag->pagf_flcount);
-#endif
+	if (has_resv) {
+		mp->m_has_agresv = true;
+		error = xfs_alloc_pagf_init(mp, tp, pag->pag_agno, 0);
+		if (error)
+			return error;
+		ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved +
+		       xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <=
+		       pag->pagf_freeblks + pag->pagf_flcount);
+	}
 out:
 	return error;
 }
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 659ad95fe3e0..489d9b2c53d9 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -139,6 +139,7 @@ typedef struct xfs_mount {
 	bool			m_fail_unmount;
 	bool			m_finobt_nores; /* no per-AG finobt resv. */
 	bool			m_update_sb;	/* sb needs update in mount */
+	bool			m_has_agresv;	/* perag reservations active */
 
 	/*
 	 * Bitsets of per-fs metadata that have been checked and/or are sick.
-- 
2.26.2