Commit | Line | Data |
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b8441ed2 TH |
1 | /* |
2 | * fs/kernfs/mount.c - kernfs mount implementation | |
3 | * | |
4 | * Copyright (c) 2001-3 Patrick Mochel | |
5 | * Copyright (c) 2007 SUSE Linux Products GmbH | |
6 | * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> | |
7 | * | |
8 | * This file is released under the GPLv2. | |
9 | */ | |
fa736a95 TH |
10 | |
11 | #include <linux/fs.h> | |
12 | #include <linux/mount.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/magic.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/pagemap.h> | |
17 | ||
18 | #include "kernfs-internal.h" | |
19 | ||
a797bfc3 | 20 | struct kmem_cache *kernfs_node_cache; |
fa736a95 | 21 | |
6a7fed4e TH |
22 | static int kernfs_sop_remount_fs(struct super_block *sb, int *flags, char *data) |
23 | { | |
24 | struct kernfs_root *root = kernfs_info(sb)->root; | |
25 | struct kernfs_syscall_ops *scops = root->syscall_ops; | |
26 | ||
27 | if (scops && scops->remount_fs) | |
28 | return scops->remount_fs(root, flags, data); | |
29 | return 0; | |
30 | } | |
31 | ||
32 | static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry) | |
33 | { | |
34 | struct kernfs_root *root = kernfs_root(dentry->d_fsdata); | |
35 | struct kernfs_syscall_ops *scops = root->syscall_ops; | |
36 | ||
37 | if (scops && scops->show_options) | |
38 | return scops->show_options(sf, root); | |
39 | return 0; | |
40 | } | |
41 | ||
a797bfc3 | 42 | static const struct super_operations kernfs_sops = { |
fa736a95 TH |
43 | .statfs = simple_statfs, |
44 | .drop_inode = generic_delete_inode, | |
c637b8ac | 45 | .evict_inode = kernfs_evict_inode, |
6a7fed4e TH |
46 | |
47 | .remount_fs = kernfs_sop_remount_fs, | |
48 | .show_options = kernfs_sop_show_options, | |
fa736a95 TH |
49 | }; |
50 | ||
c637b8ac | 51 | static int kernfs_fill_super(struct super_block *sb) |
fa736a95 | 52 | { |
c525aadd | 53 | struct kernfs_super_info *info = kernfs_info(sb); |
fa736a95 TH |
54 | struct inode *inode; |
55 | struct dentry *root; | |
56 | ||
57 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
58 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
59 | sb->s_magic = SYSFS_MAGIC; | |
a797bfc3 | 60 | sb->s_op = &kernfs_sops; |
fa736a95 TH |
61 | sb->s_time_gran = 1; |
62 | ||
63 | /* get root inode, initialize and unlock it */ | |
a797bfc3 | 64 | mutex_lock(&kernfs_mutex); |
c637b8ac | 65 | inode = kernfs_get_inode(sb, info->root->kn); |
a797bfc3 | 66 | mutex_unlock(&kernfs_mutex); |
fa736a95 | 67 | if (!inode) { |
c637b8ac | 68 | pr_debug("kernfs: could not get root inode\n"); |
fa736a95 TH |
69 | return -ENOMEM; |
70 | } | |
71 | ||
72 | /* instantiate and link root dentry */ | |
73 | root = d_make_root(inode); | |
74 | if (!root) { | |
75 | pr_debug("%s: could not get root dentry!\n", __func__); | |
76 | return -ENOMEM; | |
77 | } | |
324a56e1 TH |
78 | kernfs_get(info->root->kn); |
79 | root->d_fsdata = info->root->kn; | |
fa736a95 | 80 | sb->s_root = root; |
a797bfc3 | 81 | sb->s_d_op = &kernfs_dops; |
fa736a95 TH |
82 | return 0; |
83 | } | |
84 | ||
c637b8ac | 85 | static int kernfs_test_super(struct super_block *sb, void *data) |
fa736a95 | 86 | { |
c525aadd TH |
87 | struct kernfs_super_info *sb_info = kernfs_info(sb); |
88 | struct kernfs_super_info *info = data; | |
fa736a95 TH |
89 | |
90 | return sb_info->root == info->root && sb_info->ns == info->ns; | |
91 | } | |
92 | ||
c637b8ac | 93 | static int kernfs_set_super(struct super_block *sb, void *data) |
fa736a95 TH |
94 | { |
95 | int error; | |
96 | error = set_anon_super(sb, data); | |
97 | if (!error) | |
98 | sb->s_fs_info = data; | |
99 | return error; | |
100 | } | |
101 | ||
102 | /** | |
103 | * kernfs_super_ns - determine the namespace tag of a kernfs super_block | |
104 | * @sb: super_block of interest | |
105 | * | |
106 | * Return the namespace tag associated with kernfs super_block @sb. | |
107 | */ | |
108 | const void *kernfs_super_ns(struct super_block *sb) | |
109 | { | |
c525aadd | 110 | struct kernfs_super_info *info = kernfs_info(sb); |
fa736a95 TH |
111 | |
112 | return info->ns; | |
113 | } | |
114 | ||
115 | /** | |
116 | * kernfs_mount_ns - kernfs mount helper | |
117 | * @fs_type: file_system_type of the fs being mounted | |
118 | * @flags: mount flags specified for the mount | |
119 | * @root: kernfs_root of the hierarchy being mounted | |
120 | * @ns: optional namespace tag of the mount | |
121 | * | |
122 | * This is to be called from each kernfs user's file_system_type->mount() | |
123 | * implementation, which should pass through the specified @fs_type and | |
124 | * @flags, and specify the hierarchy and namespace tag to mount via @root | |
125 | * and @ns, respectively. | |
126 | * | |
127 | * The return value can be passed to the vfs layer verbatim. | |
128 | */ | |
129 | struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, | |
130 | struct kernfs_root *root, const void *ns) | |
131 | { | |
132 | struct super_block *sb; | |
c525aadd | 133 | struct kernfs_super_info *info; |
fa736a95 TH |
134 | int error; |
135 | ||
136 | info = kzalloc(sizeof(*info), GFP_KERNEL); | |
137 | if (!info) | |
138 | return ERR_PTR(-ENOMEM); | |
139 | ||
140 | info->root = root; | |
141 | info->ns = ns; | |
142 | ||
c637b8ac | 143 | sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info); |
fa736a95 TH |
144 | if (IS_ERR(sb) || sb->s_fs_info != info) |
145 | kfree(info); | |
146 | if (IS_ERR(sb)) | |
147 | return ERR_CAST(sb); | |
148 | if (!sb->s_root) { | |
c637b8ac | 149 | error = kernfs_fill_super(sb); |
fa736a95 TH |
150 | if (error) { |
151 | deactivate_locked_super(sb); | |
152 | return ERR_PTR(error); | |
153 | } | |
154 | sb->s_flags |= MS_ACTIVE; | |
155 | } | |
156 | ||
157 | return dget(sb->s_root); | |
158 | } | |
159 | ||
160 | /** | |
161 | * kernfs_kill_sb - kill_sb for kernfs | |
162 | * @sb: super_block being killed | |
163 | * | |
164 | * This can be used directly for file_system_type->kill_sb(). If a kernfs | |
165 | * user needs extra cleanup, it can implement its own kill_sb() and call | |
166 | * this function at the end. | |
167 | */ | |
168 | void kernfs_kill_sb(struct super_block *sb) | |
169 | { | |
c525aadd | 170 | struct kernfs_super_info *info = kernfs_info(sb); |
324a56e1 | 171 | struct kernfs_node *root_kn = sb->s_root->d_fsdata; |
fa736a95 TH |
172 | |
173 | /* | |
174 | * Remove the superblock from fs_supers/s_instances | |
c525aadd | 175 | * so we can't find it, before freeing kernfs_super_info. |
fa736a95 TH |
176 | */ |
177 | kill_anon_super(sb); | |
178 | kfree(info); | |
324a56e1 | 179 | kernfs_put(root_kn); |
fa736a95 TH |
180 | } |
181 | ||
182 | void __init kernfs_init(void) | |
183 | { | |
a797bfc3 | 184 | kernfs_node_cache = kmem_cache_create("kernfs_node_cache", |
324a56e1 | 185 | sizeof(struct kernfs_node), |
fa736a95 | 186 | 0, SLAB_PANIC, NULL); |
c637b8ac | 187 | kernfs_inode_init(); |
fa736a95 | 188 | } |