Merge pull request #12 from versity/ben/punch-hole

add PunchHole() to convert offline range to sparse

c_defs_linux.go

@@ -72,6 +72,7 @@ package scoutfs
 // typedef struct scoutfs_ioctl_xattr_index_entry scoutfs_ioctl_xattr_index_entry_t;
 // typedef struct scoutfs_ioctl_read_xattr_index scoutfs_ioctl_read_xattr_index_t;
 // typedef struct scoutfs_ioctl_inode_attr_x scoutfs_ioctl_inode_attr_x_t;
+// typedef struct scoutfs_ioctl_punch_offline scoutfs_ioctl_punch_offline_t;
 import "C"
 
 const IOCQUERYINODES = C.SCOUTFS_IOC_WALK_INODES
@@ -122,6 +123,7 @@ const IOCIAXPROJECTID = C.SCOUTFS_IOC_IAX_PROJECT_ID
 const IOCIAXBITS = C.SCOUTFS_IOC_IAX__BITS
 const IOCGETATTRX = C.SCOUTFS_IOC_GET_ATTR_X
 const IOCSETATTRX = C.SCOUTFS_IOC_SET_ATTR_X
+const IOCPUNCHOFFLINE = C.SCOUTFS_IOC_PUNCH_OFFLINE
 
 type InodesEntry C.scoutfs_ioctl_walk_inodes_entry_t
 type queryInodes C.scoutfs_ioctl_walk_inodes_t
@@ -148,6 +150,7 @@ type getQuotaRules C.scoutfs_ioctl_get_quota_rules_t
 type indexEntry C.scoutfs_ioctl_xattr_index_entry_t
 type readXattrIndex C.scoutfs_ioctl_read_xattr_index_t
 type inodeAttrX C.scoutfs_ioctl_inode_attr_x_t
+type punchOffline C.scoutfs_ioctl_punch_offline_t
 
 const sizeofstatfsMore = C.sizeof_scoutfs_ioctl_statfs_more_t
 const sizeofxattrTotal = C.sizeof_scoutfs_ioctl_xattr_total_t

scoutfs.go

@@ -905,11 +905,7 @@ func StageMoveAt(from, to *os.File, len, fromOffset, toOffset, version uint64) e
 	}
 
 	_, err := scoutfsctl(to, IOCMOVEBLOCKS, unsafe.Pointer(&mb))
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return err
 }
 
 // XattrTotal has the total values matching id triple
@@ -1807,3 +1803,30 @@ func (i indexEntry) increment() indexEntry {
 	}
 	return i
 }
+
+// PunchHole is a limited and specific version of hole punching.  It's an
+// archive layer operation that only converts unmapped offline extents
+// into sparse extents.  It is intended to be used when restoring sparse
+// files after the initial creation set the entire file size offline.
+//
+// The offset and len fields are in units of bytes and must be aligned
+// to the small (4KiB) block size.  All regions of offline extents
+// covered by the region will be converted into sparse online extents,
+// including regions that straddle the boundaries of the region.  Any
+// existing sparse extents in the region are ignored.
+//
+// The data_version must match the inode or EINVAL is returned.  The
+// data_version is not modified by this operation.
+//
+// EINVAL is returned if any mapped extents are found in the region.  If
+// an error is returned then partial progress may have been made.
+func PunchHole(f *os.File, length, offset, version uint64) error {
+	po := punchOffline{
+		Offset:  offset,
+		Len:     length,
+		Version: version,
+	}
+
+	_, err := scoutfsctl(f, IOCPUNCHOFFLINE, unsafe.Pointer(&po))
+	return err
+}

scoutfsdefs.go

@@ -51,6 +51,7 @@ const IOCIAXPROJECTID = 0x200
 const IOCIAXBITS = 0x100
 const IOCGETATTRX = 0x4068e812
 const IOCSETATTRX = 0x4068e813
+const IOCPUNCHOFFLINE = 0x4020e818
 
 type InodesEntry struct {
 	Major	uint64
@@ -241,6 +242,12 @@ type inodeAttrX struct {
 	Bits		uint64
 	Project_id	uint64
 }
+type punchOffline struct {
+	Offset	uint64
+	Len	uint64
+	Version	uint64
+	Flags	uint64
+}
 
 const sizeofstatfsMore = 0x30
 const sizeofxattrTotal = 0x28