From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Thu, 28 Jun 2018 20:11:56 +0000 (-0500)
Subject: xfs: superblock scrub should use short-lived buffers
X-Git-Tag: v4.18.0-rc0~42
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=17d741a856e72330d7b1cf923b7e94d496a647b0;p=thirdparty%2Fxfsprogs-dev.git

xfs: superblock scrub should use short-lived buffers

Source kernel commit: 689e11c84b15866619e7582486acacaf79d7e3e2

Secondary superblocks are rarely used, so create a helper to read a
given non-primary AG's superblock and ensure that it won't stick around
hogging memory.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/libxfs/xfs_sb.c b/libxfs/xfs_sb.c
index 20314c181..c5e9dbae9 100644
--- a/libxfs/xfs_sb.c
+++ b/libxfs/xfs_sb.c
@@ -954,3 +954,25 @@ xfs_fs_geometry(
 
 	return 0;
 }
+
+/* Read a secondary superblock. */
+int
+xfs_sb_read_secondary(
+	struct xfs_mount	*mp,
+	struct xfs_trans	*tp,
+	xfs_agnumber_t		agno,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_buf		*bp;
+	int			error;
+
+	ASSERT(agno != 0 && agno != NULLAGNUMBER);
+	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
+			XFS_FSS_TO_BB(mp, 1), 0, &bp, &xfs_sb_buf_ops);
+	if (error)
+		return error;
+	xfs_buf_set_ref(bp, XFS_SSB_REF);
+	*bpp = bp;
+	return 0;
+}
diff --git a/libxfs/xfs_sb.h b/libxfs/xfs_sb.h
index 63dcd2a1a..5166d78b2 100644
--- a/libxfs/xfs_sb.h
+++ b/libxfs/xfs_sb.h
@@ -37,5 +37,8 @@ extern void	xfs_sb_quota_from_disk(struct xfs_sb *sbp);
 #define XFS_FS_GEOM_MAX_STRUCT_VER	(4)
 extern int	xfs_fs_geometry(struct xfs_sb *sbp, struct xfs_fsop_geom *geo,
 				int struct_version);
+extern int	xfs_sb_read_secondary(struct xfs_mount *mp,
+				struct xfs_trans *tp, xfs_agnumber_t agno,
+				struct xfs_buf **bpp);
 
 #endif	/* __XFS_SB_H__ */
diff --git a/libxfs/xfs_shared.h b/libxfs/xfs_shared.h
index 8efc06e62..ae99c260a 100644
--- a/libxfs/xfs_shared.h
+++ b/libxfs/xfs_shared.h
@@ -112,6 +112,7 @@ void	xfs_log_get_max_trans_res(struct xfs_mount *mp,
 #define	XFS_ATTR_BTREE_REF	1
 #define	XFS_DQUOT_REF		1
 #define	XFS_REFC_BTREE_REF	1
+#define	XFS_SSB_REF		0
 
 /*
  * Flags for xfs_trans_ichgtime().