1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
  2/*
  3 * FS_IOC_GETFSMAP ioctl infrastructure.
  4 *
  5 * Copyright (C) 2017 Oracle.  All Rights Reserved.
  6 *
  7 * Author: Darrick J. Wong <darrick.wong@oracle.com>
  8 */
  9#ifndef _LINUX_FSMAP_H
 10#define _LINUX_FSMAP_H
 11
 12#include <linux/types.h>
 13
 14/*
 15 *	Structure for FS_IOC_GETFSMAP.
 16 *
 17 *	The memory layout for this call are the scalar values defined in
 18 *	struct fsmap_head, followed by two struct fsmap that describe
 19 *	the lower and upper bound of mappings to return, followed by an
 20 *	array of struct fsmap mappings.
 21 *
 22 *	fmh_iflags control the output of the call, whereas fmh_oflags report
 23 *	on the overall record output.  fmh_count should be set to the
 24 *	length of the fmh_recs array, and fmh_entries will be set to the
 25 *	number of entries filled out during each call.  If fmh_count is
 26 *	zero, the number of reverse mappings will be returned in
 27 *	fmh_entries, though no mappings will be returned.  fmh_reserved
 28 *	must be set to zero.
 29 *
 30 *	The two elements in the fmh_keys array are used to constrain the
 31 *	output.  The first element in the array should represent the
 32 *	lowest disk mapping ("low key") that the user wants to learn
 33 *	about.  If this value is all zeroes, the filesystem will return
 34 *	the first entry it knows about.  For a subsequent call, the
 35 *	contents of fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
 36 *	copied into fmh_keys[0] to have the kernel start where it left off.
 37 *
 38 *	The second element in the fmh_keys array should represent the
 39 *	highest disk mapping ("high key") that the user wants to learn
 40 *	about.  If this value is all ones, the filesystem will not stop
 41 *	until it runs out of mapping to return or runs out of space in
 42 *	fmh_recs.
 43 *
 44 *	fmr_device can be either a 32-bit cookie representing a device, or
 45 *	a 32-bit dev_t if the FMH_OF_DEV_T flag is set.  fmr_physical,
 46 *	fmr_offset, and fmr_length are expressed in units of bytes.
 47 *	fmr_owner is either an inode number, or a special value if
 48 *	FMR_OF_SPECIAL_OWNER is set in fmr_flags.
 49 */
 50struct fsmap {
 51	__u32		fmr_device;	/* device id */
 52	__u32		fmr_flags;	/* mapping flags */
 53	__u64		fmr_physical;	/* device offset of segment */
 54	__u64		fmr_owner;	/* owner id */
 55	__u64		fmr_offset;	/* file offset of segment */
 56	__u64		fmr_length;	/* length of segment */
 57	__u64		fmr_reserved[3];	/* must be zero */
 58};
 59
 60struct fsmap_head {
 61	__u32		fmh_iflags;	/* control flags */
 62	__u32		fmh_oflags;	/* output flags */
 63	__u32		fmh_count;	/* # of entries in array incl. input */
 64	__u32		fmh_entries;	/* # of entries filled in (output). */
 65	__u64		fmh_reserved[6];	/* must be zero */
 66
 67	struct fsmap	fmh_keys[2];	/* low and high keys for the mapping search */
 68	struct fsmap	fmh_recs[];	/* returned records */
 69};
 70
 71/* Size of an fsmap_head with room for nr records. */
 72static __inline__ __kernel_size_t
 73fsmap_sizeof(
 74	unsigned int	nr)
 75{
 76	return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
 77}
 78
 79/* Start the next fsmap query at the end of the current query results. */
 80static __inline__ void
 81fsmap_advance(
 82	struct fsmap_head	*head)
 83{
 84	head->fmh_keys[0] = head->fmh_recs[head->fmh_entries - 1];
 85}
 86
 87/*	fmh_iflags values - set by FS_IOC_GETFSMAP caller in the header. */
 88/* no flags defined yet */
 89#define FMH_IF_VALID		0
 90
 91/*	fmh_oflags values - returned in the header segment only. */
 92#define FMH_OF_DEV_T		0x1	/* fmr_device values will be dev_t */
 93
 94/*	fmr_flags values - returned for each non-header segment */
 95#define FMR_OF_PREALLOC		0x1	/* segment = unwritten pre-allocation */
 96#define FMR_OF_ATTR_FORK	0x2	/* segment = attribute fork */
 97#define FMR_OF_EXTENT_MAP	0x4	/* segment = extent map */
 98#define FMR_OF_SHARED		0x8	/* segment = shared with another file */
 99#define FMR_OF_SPECIAL_OWNER	0x10	/* owner is a special value */
100#define FMR_OF_LAST		0x20	/* segment is the last in the dataset */
101
102/* Each FS gets to define its own special owner codes. */
103#define FMR_OWNER(type, code)	(((__u64)type << 32) | \
104				 ((__u64)code & 0xFFFFFFFFULL))
105#define FMR_OWNER_TYPE(owner)	((__u32)((__u64)owner >> 32))
106#define FMR_OWNER_CODE(owner)	((__u32)(((__u64)owner & 0xFFFFFFFFULL)))
107#define FMR_OWN_FREE		FMR_OWNER(0, 1) /* free space */
108#define FMR_OWN_UNKNOWN		FMR_OWNER(0, 2) /* unknown owner */
109#define FMR_OWN_METADATA	FMR_OWNER(0, 3) /* metadata */
110
111#define FS_IOC_GETFSMAP		_IOWR('X', 59, struct fsmap_head)
112
113#endif /* _LINUX_FSMAP_H */