Tejun Heo | b8441ed | 2013-11-24 09:54:58 -0500 | [diff] [blame] | 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 | */ |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 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 | |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 20 | struct kmem_cache *kernfs_node_cache; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 21 | |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 22 | static const struct super_operations kernfs_sops = { |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 23 | .statfs = simple_statfs, |
| 24 | .drop_inode = generic_delete_inode, |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 25 | .evict_inode = kernfs_evict_inode, |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 26 | }; |
| 27 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 28 | static int kernfs_fill_super(struct super_block *sb) |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 29 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 30 | struct kernfs_super_info *info = kernfs_info(sb); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 31 | struct inode *inode; |
| 32 | struct dentry *root; |
| 33 | |
| 34 | sb->s_blocksize = PAGE_CACHE_SIZE; |
| 35 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
| 36 | sb->s_magic = SYSFS_MAGIC; |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 37 | sb->s_op = &kernfs_sops; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 38 | sb->s_time_gran = 1; |
| 39 | |
| 40 | /* get root inode, initialize and unlock it */ |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 41 | mutex_lock(&kernfs_mutex); |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 42 | inode = kernfs_get_inode(sb, info->root->kn); |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 43 | mutex_unlock(&kernfs_mutex); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 44 | if (!inode) { |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 45 | pr_debug("kernfs: could not get root inode\n"); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 46 | return -ENOMEM; |
| 47 | } |
| 48 | |
| 49 | /* instantiate and link root dentry */ |
| 50 | root = d_make_root(inode); |
| 51 | if (!root) { |
| 52 | pr_debug("%s: could not get root dentry!\n", __func__); |
| 53 | return -ENOMEM; |
| 54 | } |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 55 | kernfs_get(info->root->kn); |
| 56 | root->d_fsdata = info->root->kn; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 57 | sb->s_root = root; |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 58 | sb->s_d_op = &kernfs_dops; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 59 | return 0; |
| 60 | } |
| 61 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 62 | static int kernfs_test_super(struct super_block *sb, void *data) |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 63 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 64 | struct kernfs_super_info *sb_info = kernfs_info(sb); |
| 65 | struct kernfs_super_info *info = data; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 66 | |
| 67 | return sb_info->root == info->root && sb_info->ns == info->ns; |
| 68 | } |
| 69 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 70 | static int kernfs_set_super(struct super_block *sb, void *data) |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 71 | { |
| 72 | int error; |
| 73 | error = set_anon_super(sb, data); |
| 74 | if (!error) |
| 75 | sb->s_fs_info = data; |
| 76 | return error; |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * kernfs_super_ns - determine the namespace tag of a kernfs super_block |
| 81 | * @sb: super_block of interest |
| 82 | * |
| 83 | * Return the namespace tag associated with kernfs super_block @sb. |
| 84 | */ |
| 85 | const void *kernfs_super_ns(struct super_block *sb) |
| 86 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 87 | struct kernfs_super_info *info = kernfs_info(sb); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 88 | |
| 89 | return info->ns; |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * kernfs_mount_ns - kernfs mount helper |
| 94 | * @fs_type: file_system_type of the fs being mounted |
| 95 | * @flags: mount flags specified for the mount |
| 96 | * @root: kernfs_root of the hierarchy being mounted |
Li Zefan | fed95ba | 2014-02-25 19:28:44 +0800 | [diff] [blame] | 97 | * @new_sb_created: tell the caller if we allocated a new superblock |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 98 | * @ns: optional namespace tag of the mount |
| 99 | * |
| 100 | * This is to be called from each kernfs user's file_system_type->mount() |
| 101 | * implementation, which should pass through the specified @fs_type and |
| 102 | * @flags, and specify the hierarchy and namespace tag to mount via @root |
| 103 | * and @ns, respectively. |
| 104 | * |
| 105 | * The return value can be passed to the vfs layer verbatim. |
| 106 | */ |
| 107 | struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags, |
Li Zefan | fed95ba | 2014-02-25 19:28:44 +0800 | [diff] [blame] | 108 | struct kernfs_root *root, bool *new_sb_created, |
| 109 | const void *ns) |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 110 | { |
| 111 | struct super_block *sb; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 112 | struct kernfs_super_info *info; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 113 | int error; |
| 114 | |
| 115 | info = kzalloc(sizeof(*info), GFP_KERNEL); |
| 116 | if (!info) |
| 117 | return ERR_PTR(-ENOMEM); |
| 118 | |
| 119 | info->root = root; |
| 120 | info->ns = ns; |
| 121 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 122 | sb = sget(fs_type, kernfs_test_super, kernfs_set_super, flags, info); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 123 | if (IS_ERR(sb) || sb->s_fs_info != info) |
| 124 | kfree(info); |
| 125 | if (IS_ERR(sb)) |
| 126 | return ERR_CAST(sb); |
Li Zefan | fed95ba | 2014-02-25 19:28:44 +0800 | [diff] [blame] | 127 | |
| 128 | if (new_sb_created) |
| 129 | *new_sb_created = !sb->s_root; |
| 130 | |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 131 | if (!sb->s_root) { |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 132 | error = kernfs_fill_super(sb); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 133 | if (error) { |
| 134 | deactivate_locked_super(sb); |
| 135 | return ERR_PTR(error); |
| 136 | } |
| 137 | sb->s_flags |= MS_ACTIVE; |
| 138 | } |
| 139 | |
| 140 | return dget(sb->s_root); |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * kernfs_kill_sb - kill_sb for kernfs |
| 145 | * @sb: super_block being killed |
| 146 | * |
| 147 | * This can be used directly for file_system_type->kill_sb(). If a kernfs |
| 148 | * user needs extra cleanup, it can implement its own kill_sb() and call |
| 149 | * this function at the end. |
| 150 | */ |
| 151 | void kernfs_kill_sb(struct super_block *sb) |
| 152 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 153 | struct kernfs_super_info *info = kernfs_info(sb); |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 154 | struct kernfs_node *root_kn = sb->s_root->d_fsdata; |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 155 | |
| 156 | /* |
| 157 | * Remove the superblock from fs_supers/s_instances |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 158 | * so we can't find it, before freeing kernfs_super_info. |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 159 | */ |
| 160 | kill_anon_super(sb); |
| 161 | kfree(info); |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 162 | kernfs_put(root_kn); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 163 | } |
| 164 | |
| 165 | void __init kernfs_init(void) |
| 166 | { |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 167 | kernfs_node_cache = kmem_cache_create("kernfs_node_cache", |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 168 | sizeof(struct kernfs_node), |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 169 | 0, SLAB_PANIC, NULL); |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 170 | kernfs_inode_init(); |
Tejun Heo | fa736a9 | 2013-11-28 14:54:44 -0500 | [diff] [blame] | 171 | } |