btrfs_diskformat/core/
inode_item.rs

1use crate::Time;
2use bitflags::bitflags;
3use static_assertions::const_assert_eq;
4use zerocopy::little_endian::{U32 as U32LE, U64 as U64LE};
5use zerocopy_derive::*;
6
7/// Contains traditional inode data and attributes.
8#[derive(Copy, Clone, Debug, Hash, IntoBytes, FromBytes, Unaligned, KnownLayout, Immutable)]
9#[repr(C, packed)]
10pub struct InodeItem {
11    // FIXME: add documentation!
12    pub generation: U64LE,
13
14    // FIXME: add documentation!
15    pub transid: U64LE,
16
17    /// The size of a file, in bytes.
18    pub size: U64LE,
19
20    /// The size allocated to the file, in bytes.
21    ///
22    /// This is equal to the sum of all of the extent data for the inode.
23    /// This is 0 for directories.
24    pub nbytes: U64LE,
25
26    /// This contains the byte offset of a block group when structure is a free space inode.
27    ///
28    /// This value is unused for normal inodes.
29    pub block_group: U64LE,
30
31    /// Count of inode references for the inode.
32    ///
33    /// When used outside of a file tree, this value is 1.
34    pub nlink: U32LE,
35
36    /// The user ID of the owner in Unix.
37    pub uid: U32LE,
38
39    /// The group ID of the group owner in Unix.
40    pub gid: U32LE,
41
42    /// The Unix protection mode.
43    pub mode: U32LE,
44
45    /// The device identifier (if a special file).
46    pub rdev: U64LE,
47
48    /// Flags for the inode. See [InodeFlags] for values.
49    pub flags: U64LE,
50
51    /// A sequence number used for compatibility with NFS.
52    ///
53    /// This value is initialized to 0 and incremented each time [mtime] is updated.
54    ///
55    /// [mtime]: InodeItem::mtime
56    pub sequence: U64LE,
57
58    pub _unused: [u64; 4],
59
60    /// Timestamp of the last access to the inode.
61    pub atime: Time,
62
63    /// Timestamp of the last change to the inode's properties.
64    pub ctime: Time,
65
66    /// Timestamp of the last change to the inode's contents.
67    pub mtime: Time,
68
69    /// Timestamp of the creation of the inode.
70    pub otime: Time,
71}
72const_assert_eq!(core::mem::size_of::<InodeItem>(), 160);
73
74bitflags! {
75    pub struct InodeFlags: u64 {
76        /// Do not perform checksum operations.
77        const NO_DATA_SUM = 0x1;
78
79        /// Do not perform copy-on-write for data extents when the reference count is 1.
80        const NO_DATA_COW = 0x2;
81
82        /// The inode is read-only, regardless of permissions or ownership.
83        const READ_ONLY = 0x4;
84
85        /// Do not perform compression.
86        const NO_COMPRESS = 0x8;
87
88        /// Denotes preallocated extents are present. Hints that filesystem should avoid CoWing
89        /// those extents.
90        const PREALLOC = 0x10;
91
92        /// Operations on this inode should be performed synchronously.
93        const SYNC = 0x20;
94
95        /// The inode is read-only; regardless of permissions or ownership.
96        const IMMUTABLE = 0x40;
97
98        /// The inode is append-only.
99        const APPEND = 0x80;
100
101        /// Do not consider the inode for dumping when using the Unix program `dump`.
102        const NO_DUMP = 0x100;
103
104        /// Do not update [`atime`](InodeItem::atime).
105        const NO_ATIME = 0x200;
106
107        /// Operations on directory should be performed synchronously.
108        const DIR_SYNC = 0x400;
109
110        /// Perform compression for the inode.
111        const COMPRESS = 0x800;
112    }
113}
btrfs_diskformat/core/inode_item.rs

btrfs_diskformat/core/
inode_item.rs
