xfs: create a incompat flag for atomic file mapping exchanges

Create a incompat flag so that we only attempt to process file mapping
exchange 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>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_format.h

@@ -367,18 +367,19 @@ xfs_sb_has_ro_compat_feature(
 	return (sbp->sb_features_ro_compat & feature) != 0;
 }
 
-#define XFS_SB_FEAT_INCOMPAT_FTYPE	(1 << 0)	/* filetype in dirent */
-#define XFS_SB_FEAT_INCOMPAT_SPINODES	(1 << 1)	/* sparse inode chunks */
-#define XFS_SB_FEAT_INCOMPAT_META_UUID	(1 << 2)	/* metadata UUID */
-#define XFS_SB_FEAT_INCOMPAT_BIGTIME	(1 << 3)	/* large timestamps */
-#define XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR (1 << 4)	/* needs xfs_repair */
-#define XFS_SB_FEAT_INCOMPAT_NREXT64	(1 << 5)	/* large extent counters */
+#define XFS_SB_FEAT_INCOMPAT_FTYPE	(1 << 0)  /* filetype in dirent */
+#define XFS_SB_FEAT_INCOMPAT_SPINODES	(1 << 1)  /* sparse inode chunks */
+#define XFS_SB_FEAT_INCOMPAT_META_UUID	(1 << 2)  /* metadata UUID */
+#define XFS_SB_FEAT_INCOMPAT_BIGTIME	(1 << 3)  /* large timestamps */
+#define XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR (1 << 4) /* needs xfs_repair */
+#define XFS_SB_FEAT_INCOMPAT_NREXT64	(1 << 5)  /* large extent counters */
+#define XFS_SB_FEAT_INCOMPAT_EXCHRANGE	(1 << 6)  /* exchangerange supported */
 #define XFS_SB_FEAT_INCOMPAT_ALL \
-		(XFS_SB_FEAT_INCOMPAT_FTYPE|	\
-		 XFS_SB_FEAT_INCOMPAT_SPINODES|	\
-		 XFS_SB_FEAT_INCOMPAT_META_UUID| \
-		 XFS_SB_FEAT_INCOMPAT_BIGTIME| \
-		 XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR| \
+		(XFS_SB_FEAT_INCOMPAT_FTYPE | \
+		 XFS_SB_FEAT_INCOMPAT_SPINODES | \
+		 XFS_SB_FEAT_INCOMPAT_META_UUID | \
+		 XFS_SB_FEAT_INCOMPAT_BIGTIME | \
+		 XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR | \
 		 XFS_SB_FEAT_INCOMPAT_NREXT64)
 
 #define XFS_SB_FEAT_INCOMPAT_UNKNOWN	~XFS_SB_FEAT_INCOMPAT_ALL

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_EXCHANGE_RANGE (1 << 24) /* exchange range */
 
 /*
  * Minimum and maximum sizes need for growth checks.

fs/xfs/libxfs/xfs_sb.c

@@ -26,6 +26,7 @@
 #include "xfs_health.h"
 #include "xfs_ag.h"
 #include "xfs_rtbitmap.h"
+#include "xfs_exchrange.h"
 
 /*
  * Physical superblock buffer manipulations. Shared with libxfs in userspace.
@@ -175,6 +176,8 @@ xfs_sb_version_to_features(
 		features |= XFS_FEAT_NEEDSREPAIR;
 	if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_NREXT64)
 		features |= XFS_FEAT_NREXT64;
+	if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_EXCHRANGE)
+		features |= XFS_FEAT_EXCHANGE_RANGE;
 
 	return features;
 }
@@ -1259,6 +1262,8 @@ xfs_fs_geometry(
 	}
 	if (xfs_has_large_extent_counts(mp))
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_NREXT64;
+	if (xfs_has_exchange_range(mp))
+		geo->flags |= XFS_FSOP_GEOM_FLAGS_EXCHANGE_RANGE;
 	geo->rtsectsize = sbp->sb_blocksize;
 	geo->dirblocksize = xfs_dir2_dirblock_bytes(sbp);
 

fs/xfs/xfs_mount.h

@@ -292,6 +292,7 @@ typedef struct xfs_mount {
 #define XFS_FEAT_BIGTIME	(1ULL << 24)	/* large timestamps */
 #define XFS_FEAT_NEEDSREPAIR	(1ULL << 25)	/* needs xfs_repair */
 #define XFS_FEAT_NREXT64	(1ULL << 26)	/* large extent counters */
+#define XFS_FEAT_EXCHANGE_RANGE	(1ULL << 27)	/* exchange range */
 
 /* Mount features */
 #define XFS_FEAT_NOATTR2	(1ULL << 48)	/* disable attr2 creation */
@@ -355,6 +356,7 @@ __XFS_HAS_FEAT(inobtcounts, INOBTCNT)
 __XFS_HAS_FEAT(bigtime, BIGTIME)
 __XFS_HAS_FEAT(needsrepair, NEEDSREPAIR)
 __XFS_HAS_FEAT(large_extent_counts, NREXT64)
+__XFS_HAS_FEAT(exchange_range, EXCHANGE_RANGE)
 
 /*
  * Mount features

fs/xfs/xfs_super.c

@@ -1727,6 +1727,10 @@ xfs_fs_fill_super(
 		goto out_filestream_unmount;
 	}
 
+	if (xfs_has_exchange_range(mp))
+		xfs_warn(mp,
+	"EXPERIMENTAL exchange-range feature enabled. Use at your own risk!");
+
 	error = xfs_mountfs(mp);
 	if (error)
 		goto out_filestream_unmount;