[PATCH] xfs: move xfs_sync_sb_buf() out of libxfs into xfs_ioctl.c

[Yun Zhou <yun.zhou@windriver.com>]

xfs_sync_sb_buf() dereferences mp->m_sb_bp and mp->m_rtsb_bp, which
only exist in the kernel's struct xfs_mount, not in xfsprogs' libxfs.
Keeping it in libxfs is a porting hazard.

Its only caller, xfs_ioc_setlabel(), is kernel-only, so move it there
and make it static.

Fixes: c1351fb48eee ("xfs: don't hold buffer locks across sync transaction commit in xfs_sync_sb_buf")
Suggested-by: Darrick J. Wong <djwong@kernel.org>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
---
 fs/xfs/libxfs/xfs_sb.c | 40 ----------------------------------------
 fs/xfs/libxfs/xfs_sb.h |  1 -
 fs/xfs/xfs_ioctl.c     | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 41 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 2664728f2d8f..2c976b9d343d 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -1460,46 +1460,6 @@ xfs_update_secondary_sbs(
 	return saved_error ? saved_error : error;
 }
 
-/*
- * Same behavior as xfs_sync_sb, except that it is always synchronous and it
- * also writes the superblock buffer to disk sector 0 immediately.
- */
-int
-xfs_sync_sb_buf(
-	struct xfs_mount	*mp,
-	bool			update_rtsb)
-{
-	struct xfs_trans	*tp;
-	int			error;
-
-	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_sb, 0, 0, 0, &tp);
-	if (error)
-		return error;
-
-	xfs_log_sb(tp);
-	if (update_rtsb)
-		xfs_log_rtsb(tp, xfs_trans_getsb(tp));
-	xfs_trans_set_sync(tp);
-	error = xfs_trans_commit(tp);
-	if (error)
-		return error;
-
-	/* Re-acquire and write the sb and rtsb to disk. */
-	xfs_buf_lock(mp->m_sb_bp);
-	error = xfs_bwrite(mp->m_sb_bp);
-	xfs_buf_unlock(mp->m_sb_bp);
-	if (error)
-		return error;
-
-	if (update_rtsb && mp->m_rtsb_bp) {
-		xfs_buf_lock(mp->m_rtsb_bp);
-		error = xfs_bwrite(mp->m_rtsb_bp);
-		xfs_buf_unlock(mp->m_rtsb_bp);
-	}
-
-	return error;
-}
-
 void
 xfs_fs_geometry(
 	struct xfs_mount	*mp,
diff --git a/fs/xfs/libxfs/xfs_sb.h b/fs/xfs/libxfs/xfs_sb.h
index 34d0dd374e9b..77de65922213 100644
--- a/fs/xfs/libxfs/xfs_sb.h
+++ b/fs/xfs/libxfs/xfs_sb.h
@@ -15,7 +15,6 @@ struct xfs_perag;
 
 extern void	xfs_log_sb(struct xfs_trans *tp);
 extern int	xfs_sync_sb(struct xfs_mount *mp, bool wait);
-extern int	xfs_sync_sb_buf(struct xfs_mount *mp, bool update_rtsb);
 extern void	xfs_sb_mount_common(struct xfs_mount *mp, struct xfs_sb *sbp);
 void		xfs_sb_mount_rextsize(struct xfs_mount *mp, struct xfs_sb *sbp);
 void		xfs_mount_sb_set_rextsize(struct xfs_mount *mp,
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 1b53701bebea..fc8c59d2879c 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1035,6 +1035,46 @@ xfs_ioc_getlabel(
 	return 0;
 }
 
+/*
+ * Same behavior as xfs_sync_sb, except that it is always synchronous and it
+ * also writes the superblock buffer to disk sector 0 immediately.
+ */
+static int
+xfs_sync_sb_buf(
+	struct xfs_mount	*mp,
+	bool			update_rtsb)
+{
+	struct xfs_trans	*tp;
+	int			error;
+
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_sb, 0, 0, 0, &tp);
+	if (error)
+		return error;
+
+	xfs_log_sb(tp);
+	if (update_rtsb)
+		xfs_log_rtsb(tp, xfs_trans_getsb(tp));
+	xfs_trans_set_sync(tp);
+	error = xfs_trans_commit(tp);
+	if (error)
+		return error;
+
+	/* Re-acquire and write the sb and rtsb to disk. */
+	xfs_buf_lock(mp->m_sb_bp);
+	error = xfs_bwrite(mp->m_sb_bp);
+	xfs_buf_unlock(mp->m_sb_bp);
+	if (error)
+		return error;
+
+	if (update_rtsb && mp->m_rtsb_bp) {
+		xfs_buf_lock(mp->m_rtsb_bp);
+		error = xfs_bwrite(mp->m_rtsb_bp);
+		xfs_buf_unlock(mp->m_rtsb_bp);
+	}
+
+	return error;
+}
+
 static int
 xfs_ioc_setlabel(
 	struct file		*filp,
-- 
2.43.0