xfs: create rmap update intent log items

Create rmap update intent/done log items to record redo information in
the log.  Because we need to roll transactions between updating the
bmbt mapping and updating the reverse mapping, we also have to track
the status of the metadata updates that will be recorded in the
post-roll transactions, just in case we crash before committing the
final transaction.  This mechanism enables log recovery to finish what
was already started.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/fs/xfs/xfs_rmap_item.h b/fs/xfs/xfs_rmap_item.h
new file mode 100644
index 000000000000..bd36ab50c0fe
--- /dev/null
+++ b/fs/xfs/xfs_rmap_item.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2016 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#ifndef	__XFS_RMAP_ITEM_H__
+#define	__XFS_RMAP_ITEM_H__
+
+/*
+ * There are (currently) three pairs of rmap btree redo item types: map, unmap,
+ * and convert.  The common abbreviations for these are RUI (rmap update
+ * intent) and RUD (rmap update done).  The redo item type is encoded in the
+ * flags field of each xfs_map_extent.
+ *
+ * *I items should be recorded in the *first* of a series of rolled
+ * transactions, and the *D items should be recorded in the same transaction
+ * that records the associated rmapbt updates.  Typically, the first
+ * transaction will record a bmbt update, followed by some number of
+ * transactions containing rmapbt updates, and finally transactions with any
+ * bnobt/cntbt updates.
+ *
+ * Should the system crash after the commit of the first transaction but
+ * before the commit of the final transaction in a series, log recovery will
+ * use the redo information recorded by the intent items to replay the
+ * (rmapbt/bnobt/cntbt) metadata updates in the non-first transaction.
+ */
+
+/* kernel only RUI/RUD definitions */
+
+struct xfs_mount;
+struct kmem_zone;
+
+/*
+ * Max number of extents in fast allocation path.
+ */
+#define	XFS_RUI_MAX_FAST_EXTENTS	16
+
+/*
+ * Define RUI flag bits. Manipulated by set/clear/test_bit operators.
+ */
+#define	XFS_RUI_RECOVERED		1
+
+/*
+ * This is the "rmap update intent" log item.  It is used to log the fact that
+ * some reverse mappings need to change.  It is used in conjunction with the
+ * "rmap update done" log item described below.
+ *
+ * These log items follow the same rules as struct xfs_efi_log_item; see the
+ * comments about that structure (in xfs_extfree_item.h) for more details.
+ */
+struct xfs_rui_log_item {
+	struct xfs_log_item		rui_item;
+	atomic_t			rui_refcount;
+	atomic_t			rui_next_extent;
+	unsigned long			rui_flags;	/* misc flags */
+	struct xfs_rui_log_format	rui_format;
+};
+
+/*
+ * This is the "rmap update done" log item.  It is used to log the fact that
+ * some rmapbt updates mentioned in an earlier rui item have been performed.
+ */
+struct xfs_rud_log_item {
+	struct xfs_log_item		rud_item;
+	struct xfs_rui_log_item		*rud_ruip;
+	uint				rud_next_extent;
+	struct xfs_rud_log_format	rud_format;
+};
+
+/*
+ * Max number of extents in fast allocation path.
+ */
+#define	XFS_RUD_MAX_FAST_EXTENTS	16
+
+extern struct kmem_zone	*xfs_rui_zone;
+extern struct kmem_zone	*xfs_rud_zone;
+
+struct xfs_rui_log_item *xfs_rui_init(struct xfs_mount *, uint);
+struct xfs_rud_log_item *xfs_rud_init(struct xfs_mount *,
+		struct xfs_rui_log_item *, uint);
+int xfs_rui_copy_format(struct xfs_log_iovec *buf,
+		struct xfs_rui_log_format *dst_rui_fmt);
+void xfs_rui_item_free(struct xfs_rui_log_item *);
+void xfs_rui_release(struct xfs_rui_log_item *);
+
+#endif	/* __XFS_RMAP_ITEM_H__ */