xfs: add xfs_remount_rw() helper

Factor the remount read write code into a helper to simplify the
subsequent change from the super block method .remount_fs to the
mount-api fs_context_operations method .reconfigure.
Signed-off-by: NIan Kent <raven@themaw.net>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_super.c

@@ -1184,6 +1184,68 @@ xfs_test_remount_options(
 	return error;
 }
 
+static int
+xfs_remount_rw(
+	struct xfs_mount	*mp)
+{
+	struct xfs_sb		*sbp = &mp->m_sb;
+	int error;
+
+	if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
+		xfs_warn(mp,
+			"ro->rw transition prohibited on norecovery mount");
+		return -EINVAL;
+	}
+
+	if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
+	    xfs_sb_has_ro_compat_feature(sbp, XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
+		xfs_warn(mp,
+	"ro->rw transition prohibited on unknown (0x%x) ro-compat filesystem",
+			(sbp->sb_features_ro_compat &
+				XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
+		return -EINVAL;
+	}
+
+	mp->m_flags &= ~XFS_MOUNT_RDONLY;
+
+	/*
+	 * If this is the first remount to writeable state we might have some
+	 * superblock changes to update.
+	 */
+	if (mp->m_update_sb) {
+		error = xfs_sync_sb(mp, false);
+		if (error) {
+			xfs_warn(mp, "failed to write sb changes");
+			return error;
+		}
+		mp->m_update_sb = false;
+	}
+
+	/*
+	 * Fill out the reserve pool if it is empty. Use the stashed value if
+	 * it is non-zero, otherwise go with the default.
+	 */
+	xfs_restore_resvblks(mp);
+	xfs_log_work_queue(mp);
+
+	/* Recover any CoW blocks that never got remapped. */
+	error = xfs_reflink_recover_cow(mp);
+	if (error) {
+		xfs_err(mp,
+			"Error %d recovering leftover CoW allocations.", error);
+			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+		return error;
+	}
+	xfs_start_block_reaping(mp);
+
+	/* Create the per-AG metadata reservation pool .*/
+	error = xfs_fs_reserve_ag_blocks(mp);
+	if (error && error != -ENOSPC)
+		return error;
+
+	return 0;
+}
+
 STATIC int
 xfs_fs_remount(
 	struct super_block	*sb,
@@ -1247,57 +1309,8 @@ xfs_fs_remount(
 
 	/* ro -> rw */
 	if ((mp->m_flags & XFS_MOUNT_RDONLY) && !(*flags & SB_RDONLY)) {
-		if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
-			xfs_warn(mp,
-		"ro->rw transition prohibited on norecovery mount");
-			return -EINVAL;
-		}
-
-		if (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
-		    xfs_sb_has_ro_compat_feature(sbp,
-					XFS_SB_FEAT_RO_COMPAT_UNKNOWN)) {
-			xfs_warn(mp,
-"ro->rw transition prohibited on unknown (0x%x) ro-compat filesystem",
-				(sbp->sb_features_ro_compat &
-					XFS_SB_FEAT_RO_COMPAT_UNKNOWN));
-			return -EINVAL;
-		}
-
-		mp->m_flags &= ~XFS_MOUNT_RDONLY;
-
-		/*
-		 * If this is the first remount to writeable state we
-		 * might have some superblock changes to update.
-		 */
-		if (mp->m_update_sb) {
-			error = xfs_sync_sb(mp, false);
-			if (error) {
-				xfs_warn(mp, "failed to write sb changes");
-				return error;
-			}
-			mp->m_update_sb = false;
-		}
-
-		/*
-		 * Fill out the reserve pool if it is empty. Use the stashed
-		 * value if it is non-zero, otherwise go with the default.
-		 */
-		xfs_restore_resvblks(mp);
-		xfs_log_work_queue(mp);
-
-		/* Recover any CoW blocks that never got remapped. */
-		error = xfs_reflink_recover_cow(mp);
-		if (error) {
-			xfs_err(mp,
-	"Error %d recovering leftover CoW allocations.", error);
-			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
-			return error;
-		}
-		xfs_start_block_reaping(mp);
-
-		/* Create the per-AG metadata reservation pool .*/
-		error = xfs_fs_reserve_ag_blocks(mp);
-		if (error && error != -ENOSPC)
+		error = xfs_remount_rw(mp);
+		if (error)
 			return error;
 	}