xref: /openbmc/linux/include/uapi/linux/fsmap.h (revision cbf28203)
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  */
50 struct 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 
60 struct 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. */
72 static inline __kernel_size_t
fsmap_sizeof(unsigned int nr)73 fsmap_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. */
80 static inline void
fsmap_advance(struct fsmap_head * head)81 fsmap_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 */
114