Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * symlink.c - operations for sysfs symlinks. |
| 3 | */ |
| 4 | |
| 5 | #include <linux/fs.h> |
Greg Kroah-Hartman | ceeee1f | 2002-04-09 12:14:34 -0700 | [diff] [blame] | 6 | #include <linux/mount.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include <linux/module.h> |
| 8 | #include <linux/kobject.h> |
| 9 | #include <linux/namei.h> |
Dave Young | 869512a | 2007-07-26 14:53:53 +0000 | [diff] [blame] | 10 | #include <linux/mutex.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | |
| 12 | #include "sysfs.h" |
| 13 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 14 | static int object_depth(struct sysfs_dirent *sd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | int depth = 0; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 17 | |
| 18 | for (; sd->s_parent; sd = sd->s_parent) |
| 19 | depth++; |
| 20 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | return depth; |
| 22 | } |
| 23 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 24 | static int object_path_length(struct sysfs_dirent * sd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 25 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | int length = 1; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 27 | |
| 28 | for (; sd->s_parent; sd = sd->s_parent) |
| 29 | length += strlen(sd->s_name) + 1; |
| 30 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | return length; |
| 32 | } |
| 33 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 34 | static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | --length; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 37 | for (; sd->s_parent; sd = sd->s_parent) { |
| 38 | int cur = strlen(sd->s_name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | |
| 40 | /* back up enough to print this bus id with '/' */ |
| 41 | length -= cur; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 42 | strncpy(buffer + length, sd->s_name, cur); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | *(buffer + --length) = '/'; |
| 44 | } |
| 45 | } |
| 46 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | /** |
| 48 | * sysfs_create_link - create symlink between two objects. |
| 49 | * @kobj: object whose directory we're creating the link in. |
| 50 | * @target: object we're pointing to. |
| 51 | * @name: name of the symlink. |
| 52 | */ |
Dmitry Torokhov | e3a15db | 2005-04-26 02:31:08 -0500 | [diff] [blame] | 53 | int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | { |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 55 | struct sysfs_dirent *parent_sd = NULL; |
| 56 | struct sysfs_dirent *target_sd = NULL; |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 57 | struct sysfs_dirent *sd = NULL; |
Tejun Heo | fb6896d | 2007-06-14 04:27:24 +0900 | [diff] [blame] | 58 | struct sysfs_addrm_cxt acxt; |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 59 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | |
Greg Kroah-Hartman | ceeee1f | 2002-04-09 12:14:34 -0700 | [diff] [blame] | 61 | BUG_ON(!name); |
| 62 | |
| 63 | if (!kobj) { |
| 64 | if (sysfs_mount && sysfs_mount->mnt_sb) |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 65 | parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata; |
Greg Kroah-Hartman | ceeee1f | 2002-04-09 12:14:34 -0700 | [diff] [blame] | 66 | } else |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 67 | parent_sd = kobj->sd; |
Greg Kroah-Hartman | ceeee1f | 2002-04-09 12:14:34 -0700 | [diff] [blame] | 68 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 69 | error = -EFAULT; |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 70 | if (!parent_sd) |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 71 | goto out_put; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 72 | |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 73 | /* target->sd can go away beneath us but is protected with |
Tejun Heo | 5f99532 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 74 | * sysfs_assoc_lock. Fetch target_sd from it. |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 75 | */ |
Tejun Heo | 5f99532 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 76 | spin_lock(&sysfs_assoc_lock); |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 77 | if (target->sd) |
| 78 | target_sd = sysfs_get(target->sd); |
Tejun Heo | 5f99532 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 79 | spin_unlock(&sysfs_assoc_lock); |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 80 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 81 | error = -ENOENT; |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 82 | if (!target_sd) |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 83 | goto out_put; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 85 | error = -ENOMEM; |
| 86 | sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK); |
| 87 | if (!sd) |
| 88 | goto out_put; |
Tejun Heo | a1da4df | 2007-07-18 16:14:45 +0900 | [diff] [blame] | 89 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 90 | sd->s_elem.symlink.target_sd = target_sd; |
Tejun Heo | a1da4df | 2007-07-18 16:14:45 +0900 | [diff] [blame] | 91 | target_sd = NULL; /* reference is now owned by the symlink */ |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 92 | |
Tejun Heo | fb6896d | 2007-06-14 04:27:24 +0900 | [diff] [blame] | 93 | sysfs_addrm_start(&acxt, parent_sd); |
| 94 | |
Tejun Heo | 41fc1c2 | 2007-08-02 21:38:03 +0900 | [diff] [blame^] | 95 | if (!sysfs_find_dirent(parent_sd, name)) |
Tejun Heo | fb6896d | 2007-06-14 04:27:24 +0900 | [diff] [blame] | 96 | sysfs_add_one(&acxt, sd); |
Tejun Heo | fb6896d | 2007-06-14 04:27:24 +0900 | [diff] [blame] | 97 | |
Tejun Heo | 967e35d | 2007-07-18 16:38:11 +0900 | [diff] [blame] | 98 | if (!sysfs_addrm_finish(&acxt)) { |
| 99 | error = -EEXIST; |
| 100 | goto out_put; |
| 101 | } |
Tejun Heo | fb6896d | 2007-06-14 04:27:24 +0900 | [diff] [blame] | 102 | |
Tejun Heo | 967e35d | 2007-07-18 16:38:11 +0900 | [diff] [blame] | 103 | return 0; |
| 104 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 105 | out_put: |
| 106 | sysfs_put(target_sd); |
| 107 | sysfs_put(sd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | return error; |
| 109 | } |
| 110 | |
| 111 | |
| 112 | /** |
| 113 | * sysfs_remove_link - remove symlink in object's directory. |
| 114 | * @kobj: object we're acting for. |
| 115 | * @name: name of the symlink to remove. |
| 116 | */ |
| 117 | |
Dmitry Torokhov | e3a15db | 2005-04-26 02:31:08 -0500 | [diff] [blame] | 118 | void sysfs_remove_link(struct kobject * kobj, const char * name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | { |
Tejun Heo | 608e266 | 2007-06-14 04:27:22 +0900 | [diff] [blame] | 120 | sysfs_hash_and_remove(kobj->sd, name); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | } |
| 122 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 123 | static int sysfs_get_target_path(struct sysfs_dirent * parent_sd, |
| 124 | struct sysfs_dirent * target_sd, char *path) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | { |
| 126 | char * s; |
| 127 | int depth, size; |
| 128 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 129 | depth = object_depth(parent_sd); |
| 130 | size = object_path_length(target_sd) + depth * 3 - 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | if (size > PATH_MAX) |
| 132 | return -ENAMETOOLONG; |
| 133 | |
| 134 | pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size); |
| 135 | |
| 136 | for (s = path; depth--; s += 3) |
| 137 | strcpy(s,"../"); |
| 138 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 139 | fill_object_path(target_sd, path, size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | pr_debug("%s: path = '%s'\n", __FUNCTION__, path); |
| 141 | |
| 142 | return 0; |
| 143 | } |
| 144 | |
| 145 | static int sysfs_getlink(struct dentry *dentry, char * path) |
| 146 | { |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 147 | struct sysfs_dirent *sd = dentry->d_fsdata; |
| 148 | struct sysfs_dirent *parent_sd = sd->s_parent; |
| 149 | struct sysfs_dirent *target_sd = sd->s_elem.symlink.target_sd; |
| 150 | int error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 152 | mutex_lock(&sysfs_mutex); |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 153 | error = sysfs_get_target_path(parent_sd, target_sd, path); |
Tejun Heo | 3007e99 | 2007-06-14 04:27:23 +0900 | [diff] [blame] | 154 | mutex_unlock(&sysfs_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | |
Tejun Heo | 2b29ac2 | 2007-06-14 03:45:15 +0900 | [diff] [blame] | 156 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 157 | } |
| 158 | |
Linus Torvalds | cc314ee | 2005-08-19 18:02:56 -0700 | [diff] [blame] | 159 | static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 160 | { |
| 161 | int error = -ENOMEM; |
| 162 | unsigned long page = get_zeroed_page(GFP_KERNEL); |
| 163 | if (page) |
| 164 | error = sysfs_getlink(dentry, (char *) page); |
| 165 | nd_set_link(nd, error ? ERR_PTR(error) : (char *)page); |
Linus Torvalds | cc314ee | 2005-08-19 18:02:56 -0700 | [diff] [blame] | 166 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | } |
| 168 | |
Linus Torvalds | cc314ee | 2005-08-19 18:02:56 -0700 | [diff] [blame] | 169 | static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | { |
| 171 | char *page = nd_get_link(nd); |
| 172 | if (!IS_ERR(page)) |
| 173 | free_page((unsigned long)page); |
| 174 | } |
| 175 | |
Arjan van de Ven | c5ef1c4 | 2007-02-12 00:55:40 -0800 | [diff] [blame] | 176 | const struct inode_operations sysfs_symlink_inode_operations = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 177 | .readlink = generic_readlink, |
| 178 | .follow_link = sysfs_follow_link, |
| 179 | .put_link = sysfs_put_link, |
| 180 | }; |
| 181 | |
| 182 | |
| 183 | EXPORT_SYMBOL_GPL(sysfs_create_link); |
| 184 | EXPORT_SYMBOL_GPL(sysfs_remove_link); |