tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/* Extended attribute handling for AFS. We use xattrs to get and set metadata
2 * instead of providing pioctl().
3 *
4 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public Licence
9 * as published by the Free Software Foundation; either version
10 * 2 of the Licence, or (at your option) any later version.
11 */
12
13#include <linux/slab.h>
14#include <linux/fs.h>
15#include <linux/xattr.h>
16#include "internal.h"
17
18static const char afs_xattr_list[] =
19 "afs.cell\0"
20 "afs.fid\0"
21 "afs.volume";
22
23/*
24 * Retrieve a list of the supported xattrs.
25 */
26ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
27{
28 if (size == 0)
29 return sizeof(afs_xattr_list);
30 if (size < sizeof(afs_xattr_list))
31 return -ERANGE;
32 memcpy(buffer, afs_xattr_list, sizeof(afs_xattr_list));
33 return sizeof(afs_xattr_list);
34}
35
36/*
37 * Get the name of the cell on which a file resides.
38 */
39static int afs_xattr_get_cell(const struct xattr_handler *handler,
40 struct dentry *dentry,
41 struct inode *inode, const char *name,
42 void *buffer, size_t size)
43{
44 struct afs_vnode *vnode = AFS_FS_I(inode);
45 struct afs_cell *cell = vnode->volume->cell;
46 size_t namelen;
47
48 namelen = cell->name_len;
49 if (size == 0)
50 return namelen;
51 if (namelen > size)
52 return -ERANGE;
53 memcpy(buffer, cell->name, size);
54 return namelen;
55}
56
57static const struct xattr_handler afs_xattr_afs_cell_handler = {
58 .name = "afs.cell",
59 .get = afs_xattr_get_cell,
60};
61
62/*
63 * Get the volume ID, vnode ID and vnode uniquifier of a file as a sequence of
64 * hex numbers separated by colons.
65 */
66static int afs_xattr_get_fid(const struct xattr_handler *handler,
67 struct dentry *dentry,
68 struct inode *inode, const char *name,
69 void *buffer, size_t size)
70{
71 struct afs_vnode *vnode = AFS_FS_I(inode);
72 char text[8 + 1 + 8 + 1 + 8 + 1];
73 size_t len;
74
75 len = sprintf(text, "%x:%x:%x",
76 vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
77 if (size == 0)
78 return len;
79 if (len > size)
80 return -ERANGE;
81 memcpy(buffer, text, len);
82 return len;
83}
84
85static const struct xattr_handler afs_xattr_afs_fid_handler = {
86 .name = "afs.fid",
87 .get = afs_xattr_get_fid,
88};
89
90/*
91 * Get the name of the volume on which a file resides.
92 */
93static int afs_xattr_get_volume(const struct xattr_handler *handler,
94 struct dentry *dentry,
95 struct inode *inode, const char *name,
96 void *buffer, size_t size)
97{
98 struct afs_vnode *vnode = AFS_FS_I(inode);
99 const char *volname = vnode->volume->name;
100 size_t namelen;
101
102 namelen = strlen(volname);
103 if (size == 0)
104 return namelen;
105 if (namelen > size)
106 return -ERANGE;
107 memcpy(buffer, volname, size);
108 return namelen;
109}
110
111static const struct xattr_handler afs_xattr_afs_volume_handler = {
112 .name = "afs.volume",
113 .get = afs_xattr_get_volume,
114};
115
116const struct xattr_handler *afs_xattr_handlers[] = {
117 &afs_xattr_afs_cell_handler,
118 &afs_xattr_afs_fid_handler,
119 &afs_xattr_afs_volume_handler,
120 NULL
121};