[PATCH 05/21] xfs: create a log incompat flag for atomic extent swapping

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Create a log incompat flag so that we only attempt to process swap
extent log items if the filesystem supports it, and a geometry flag to
advertise support if it's present.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_format.h  |    1 +
 fs/xfs/libxfs/xfs_fs.h      |    1 +
 fs/xfs/libxfs/xfs_sb.c      |    3 +++
 fs/xfs/libxfs/xfs_swapext.h |   24 ++++++++++++++++++++++++
 4 files changed, 29 insertions(+)
 create mode 100644 fs/xfs/libxfs/xfs_swapext.h


diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index 817adb36cb1e..1424976ec955 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -391,6 +391,7 @@ xfs_sb_has_incompat_feature(
 }
 
 #define XFS_SB_FEAT_INCOMPAT_LOG_XATTRS   (1 << 0)	/* Delayed Attributes */
+#define XFS_SB_FEAT_INCOMPAT_LOG_SWAPEXT  (1U << 31)	/* file extent swap */
 #define XFS_SB_FEAT_INCOMPAT_LOG_ALL \
 	(XFS_SB_FEAT_INCOMPAT_LOG_XATTRS)
 #define XFS_SB_FEAT_INCOMPAT_LOG_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_LOG_ALL
diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 210c17f5a16c..a39fd65e6ee0 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -239,6 +239,7 @@ typedef struct xfs_fsop_resblks {
 #define XFS_FSOP_GEOM_FLAGS_BIGTIME	(1 << 21) /* 64-bit nsec timestamps */
 #define XFS_FSOP_GEOM_FLAGS_INOBTCNT	(1 << 22) /* inobt btree counter */
 #define XFS_FSOP_GEOM_FLAGS_NREXT64	(1 << 23) /* large extent counters */
+#define XFS_FSOP_GEOM_FLAGS_ATOMIC_SWAP	(1U << 31) /* atomic file extent swap */
 
 /*
  * Minimum and maximum sizes need for growth checks.
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index b3e8ab247b28..5b6f5939fda1 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -25,6 +25,7 @@
 #include "xfs_da_format.h"
 #include "xfs_health.h"
 #include "xfs_ag.h"
+#include "xfs_swapext.h"
 
 /*
  * Physical superblock buffer manipulations. Shared with libxfs in userspace.
@@ -1197,6 +1198,8 @@ xfs_fs_geometry(
 	}
 	if (xfs_has_large_extent_counts(mp))
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_NREXT64;
+	if (xfs_swapext_supported(mp))
+		geo->flags |= XFS_FSOP_GEOM_FLAGS_ATOMIC_SWAP;
 	geo->rtsectsize = sbp->sb_blocksize;
 	geo->dirblocksize = xfs_dir2_dirblock_bytes(sbp);
 
diff --git a/fs/xfs/libxfs/xfs_swapext.h b/fs/xfs/libxfs/xfs_swapext.h
new file mode 100644
index 000000000000..316323339d76
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_swapext.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SWAPEXT_H_
+#define __XFS_SWAPEXT_H_ 1
+
+/*
+ * Decide if this filesystem supports using log items to swap file extents and
+ * restart the operation if the system fails before the operation completes.
+ *
+ * This can be done to individual file extents by using the block mapping log
+ * intent items introduced with reflink and rmap; or to entire file ranges
+ * using swapext log intent items to track the overall progress across multiple
+ * extent mappings.  Realtime is not supported yet.
+ */
+static inline bool xfs_swapext_supported(struct xfs_mount *mp)
+{
+	return (xfs_has_reflink(mp) || xfs_has_rmapbt(mp)) &&
+	       !xfs_has_realtime(mp);
+}
+
+#endif /* __XFS_SWAPEXT_H_ */