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 | ||
f41c5934 | 42 | 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 | ||
0c23b225 TH |
51 | /** |
52 | * kernfs_root_from_sb - determine kernfs_root associated with a super_block | |
53 | * @sb: the super_block in question | |
54 | * | |
55 | * Return the kernfs_root associated with @sb. If @sb is not a kernfs one, | |
56 | * %NULL is returned. | |
57 | */ | |
58 | struct kernfs_root *kernfs_root_from_sb(struct super_block *sb) | |
59 | { | |
60 | if (sb->s_op == &kernfs_sops) | |
61 | return kernfs_info(sb)->root; | |
62 | return NULL; | |
63 | } | |
64 | ||
c637b8ac | 65 | static int kernfs_fill_super(struct super_block *sb) |
fa736a95 | 66 | { |
c525aadd | 67 | struct kernfs_super_info *info = kernfs_info(sb); |
fa736a95 TH |
68 | struct inode *inode; |
69 | struct dentry *root; | |
70 | ||
7d568a83 | 71 | info->sb = sb; |
fa736a95 TH |
72 | sb->s_blocksize = PAGE_CACHE_SIZE; |
73 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
74 | sb->s_magic = SYSFS_MAGIC; | |
a797bfc3 | 75 | sb->s_op = &kernfs_sops; |
fa736a95 TH |
76 | sb->s_time_gran = 1; |
77 | ||
78 | /* get root inode, initialize and unlock it */ | |
a797bfc3 | 79 | mutex_lock(&kernfs_mutex); |
c637b8ac | 80 | inode = kernfs_get_inode(sb, info->root->kn); |
a797bfc3 | 81 | mutex_unlock(&kernfs_mutex); |
fa736a95 | 82 | if (!inode) { |
c637b8ac | 83 | pr_debug("kernfs: could not get root inode\n"); |
fa736a95 TH |
84 | return -ENOMEM; |
85 | } | |
86 | ||
87 | /* instantiate and link root dentry */ | |
88 | root = d_make_root(inode); | |
89 | if (!root) { | |
90 | pr_debug("%s: could not get root dentry!\n", __func__); | |
91 | return -ENOMEM; | |
92 | } | |
324a56e1 TH |
93 | kernfs_get(info->root->kn); |
94 | root->d_fsdata = info->root->kn; | |
fa736a95 | 95 | sb->s_root = root; |
a797bfc3 | 96 | sb->s_d_op = &kernfs_dops; |
fa736a95 TH |
97 | return 0; |
98 | } | |
99 | ||
c637b8ac | 100 | static int kernfs_test_super(struct super_block *sb, void *data) |
fa736a95 | 101 | { |
c525aadd TH |
102 | struct kernfs_super_info *sb_info = kernfs_info(sb); |
103 | struct kernfs_super_info *info = data; | |
fa736a95 TH |
104 | |
105 | return sb_info->root == info->root && sb_info->ns == info->ns; | |
106 | } | |
107 | ||
c637b8ac | 108 | static int kernfs_set_super(struct super_block *sb, void *data) |
fa736a95 TH |
109 | { |
110 | int error; | |
111 | error = set_anon_super(sb, data); | |
112 | if (!error) | |
113 | sb->s_fs_info = data; | |
114 | return error; | |
115 | } | |
116 | ||
117 | /** | |
118 | * kernfs_super_ns - determine the namespace tag of a kernfs super_block | |
119 | * @sb: super_block of interest | |
120 | * | |
121 | * Return the namespace tag associated with kernfs super_block @sb. | |
122 | */ | |
123 | const void *kernfs_super_ns(struct super_block *sb) | |
124 | { | |
c525aadd | 125 | struct kernfs_super_info *info = kernfs_info(sb); |
fa736a95 TH |
126 | |
127 | return info->ns; | |
128 | } | |
129 | ||
130 | /** | |
131 | * kernfs_mount_ns - kernfs mount helper | |
132 | * @fs_type: file_system_type of the fs being mounted | |
133 | * @flags: mount flags specified for the mount | |
134 | * @root: kernfs_root of the hierarchy being mounted | |
fed95bab | 135 | * @new_sb_created: tell the caller if we allocated a new superblock |
fa736a95 TH |
136 | * @ns: optional namespace tag of the mount |
137 | * | |
138 | * This is to be called from each kernfs user's file_system_type->mount() | |
139 | * implementation, which should pass through the specified @fs_type and | |
140 | * @flags, and specify the hierarchy and namespace tag to mount via @root | |
141 | * and @ns, respectively. | |
142 | * | |
143 | * The return value can be passed to the vfs layer verbatim. | |
144 | */ | |
145 | struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, | |
fed95bab LZ |
146 | struct kernfs_root *root, bool *new_sb_created, |
147 | const void *ns) | |
fa736a95 TH |
148 | { |
149 | struct super_block *sb; | |
c525aadd | 150 | struct kernfs_super_info *info; |
fa736a95 TH |
151 | int error; |
152 | ||
153 | info = kzalloc(sizeof(*info), GFP_KERNEL); | |
154 | if (!info) | |
155 | return ERR_PTR(-ENOMEM); | |
156 | ||
157 | info->root = root; | |
158 | info->ns = ns; | |
159 | ||
c637b8ac | 160 | sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info); |
fa736a95 TH |
161 | if (IS_ERR(sb) || sb->s_fs_info != info) |
162 | kfree(info); | |
163 | if (IS_ERR(sb)) | |
164 | return ERR_CAST(sb); | |
fed95bab LZ |
165 | |
166 | if (new_sb_created) | |
167 | *new_sb_created = !sb->s_root; | |
168 | ||
fa736a95 | 169 | if (!sb->s_root) { |
7d568a83 TH |
170 | struct kernfs_super_info *info = kernfs_info(sb); |
171 | ||
c637b8ac | 172 | error = kernfs_fill_super(sb); |
fa736a95 TH |
173 | if (error) { |
174 | deactivate_locked_super(sb); | |
175 | return ERR_PTR(error); | |
176 | } | |
177 | sb->s_flags |= MS_ACTIVE; | |
7d568a83 TH |
178 | |
179 | mutex_lock(&kernfs_mutex); | |
180 | list_add(&info->node, &root->supers); | |
181 | mutex_unlock(&kernfs_mutex); | |
fa736a95 TH |
182 | } |
183 | ||
184 | return dget(sb->s_root); | |
185 | } | |
186 | ||
187 | /** | |
188 | * kernfs_kill_sb - kill_sb for kernfs | |
189 | * @sb: super_block being killed | |
190 | * | |
191 | * This can be used directly for file_system_type->kill_sb(). If a kernfs | |
192 | * user needs extra cleanup, it can implement its own kill_sb() and call | |
193 | * this function at the end. | |
194 | */ | |
195 | void kernfs_kill_sb(struct super_block *sb) | |
196 | { | |
c525aadd | 197 | struct kernfs_super_info *info = kernfs_info(sb); |
324a56e1 | 198 | struct kernfs_node *root_kn = sb->s_root->d_fsdata; |
fa736a95 | 199 | |
7d568a83 TH |
200 | mutex_lock(&kernfs_mutex); |
201 | list_del(&info->node); | |
202 | mutex_unlock(&kernfs_mutex); | |
203 | ||
fa736a95 TH |
204 | /* |
205 | * Remove the superblock from fs_supers/s_instances | |
c525aadd | 206 | * so we can't find it, before freeing kernfs_super_info. |
fa736a95 TH |
207 | */ |
208 | kill_anon_super(sb); | |
209 | kfree(info); | |
324a56e1 | 210 | kernfs_put(root_kn); |
fa736a95 TH |
211 | } |
212 | ||
213 | void __init kernfs_init(void) | |
214 | { | |
a797bfc3 | 215 | kernfs_node_cache = kmem_cache_create("kernfs_node_cache", |
324a56e1 | 216 | sizeof(struct kernfs_node), |
fa736a95 | 217 | 0, SLAB_PANIC, NULL); |
c637b8ac | 218 | kernfs_inode_init(); |
fa736a95 | 219 | } |