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 size_t
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
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 */