Tejun Heo | b8441ed | 2013-11-24 09:54:58 -0500 | [diff] [blame] | 1 | /* |
| 2 | * fs/kernfs/file.c - kernfs file 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 | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 10 | |
| 11 | #include <linux/fs.h> |
| 12 | #include <linux/seq_file.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/poll.h> |
| 15 | #include <linux/pagemap.h> |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 16 | #include <linux/sched.h> |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 17 | #include <linux/fsnotify.h> |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 18 | |
| 19 | #include "kernfs-internal.h" |
| 20 | |
| 21 | /* |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 22 | * There's one kernfs_open_file for each open file and one kernfs_open_node |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 23 | * for each kernfs_node with one or more open files. |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 24 | * |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 25 | * kernfs_node->attr.open points to kernfs_open_node. attr.open is |
| 26 | * protected by kernfs_open_node_lock. |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 27 | * |
| 28 | * filp->private_data points to seq_file whose ->private points to |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 29 | * kernfs_open_file. kernfs_open_files are chained at |
| 30 | * kernfs_open_node->files, which is protected by kernfs_open_file_mutex. |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 31 | */ |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 32 | static DEFINE_SPINLOCK(kernfs_open_node_lock); |
| 33 | static DEFINE_MUTEX(kernfs_open_file_mutex); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 34 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 35 | struct kernfs_open_node { |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 36 | atomic_t refcnt; |
| 37 | atomic_t event; |
| 38 | wait_queue_head_t poll; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 39 | struct list_head files; /* goes through kernfs_open_file.list */ |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 40 | }; |
| 41 | |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 42 | /* |
| 43 | * kernfs_notify() may be called from any context and bounces notifications |
| 44 | * through a work item. To minimize space overhead in kernfs_node, the |
| 45 | * pending queue is implemented as a singly linked list of kernfs_nodes. |
| 46 | * The list is terminated with the self pointer so that whether a |
| 47 | * kernfs_node is on the list or not can be determined by testing the next |
| 48 | * pointer for NULL. |
| 49 | */ |
| 50 | #define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list) |
| 51 | |
| 52 | static DEFINE_SPINLOCK(kernfs_notify_lock); |
| 53 | static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL; |
| 54 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 55 | static struct kernfs_open_file *kernfs_of(struct file *file) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 56 | { |
| 57 | return ((struct seq_file *)file->private_data)->private; |
| 58 | } |
| 59 | |
| 60 | /* |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 61 | * Determine the kernfs_ops for the given kernfs_node. This function must |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 62 | * be called while holding an active reference. |
| 63 | */ |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 64 | static const struct kernfs_ops *kernfs_ops(struct kernfs_node *kn) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 65 | { |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 66 | if (kn->flags & KERNFS_LOCKDEP) |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 67 | lockdep_assert_held(kn); |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 68 | return kn->attr.ops; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 69 | } |
| 70 | |
Tejun Heo | bb30594 | 2014-01-14 09:52:01 -0500 | [diff] [blame] | 71 | /* |
| 72 | * As kernfs_seq_stop() is also called after kernfs_seq_start() or |
| 73 | * kernfs_seq_next() failure, it needs to distinguish whether it's stopping |
| 74 | * a seq_file iteration which is fully initialized with an active reference |
| 75 | * or an aborted kernfs_seq_start() due to get_active failure. The |
| 76 | * position pointer is the only context for each seq_file iteration and |
| 77 | * thus the stop condition should be encoded in it. As the return value is |
| 78 | * directly visible to userland, ERR_PTR(-ENODEV) is the only acceptable |
| 79 | * choice to indicate get_active failure. |
| 80 | * |
| 81 | * Unfortunately, this is complicated due to the optional custom seq_file |
| 82 | * operations which may return ERR_PTR(-ENODEV) too. kernfs_seq_stop() |
| 83 | * can't distinguish whether ERR_PTR(-ENODEV) is from get_active failure or |
| 84 | * custom seq_file operations and thus can't decide whether put_active |
| 85 | * should be performed or not only on ERR_PTR(-ENODEV). |
| 86 | * |
| 87 | * This is worked around by factoring out the custom seq_stop() and |
| 88 | * put_active part into kernfs_seq_stop_active(), skipping it from |
| 89 | * kernfs_seq_stop() if ERR_PTR(-ENODEV) while invoking it directly after |
| 90 | * custom seq_file operations fail with ERR_PTR(-ENODEV) - this ensures |
| 91 | * that kernfs_seq_stop_active() is skipped only after get_active failure. |
| 92 | */ |
| 93 | static void kernfs_seq_stop_active(struct seq_file *sf, void *v) |
| 94 | { |
| 95 | struct kernfs_open_file *of = sf->private; |
| 96 | const struct kernfs_ops *ops = kernfs_ops(of->kn); |
| 97 | |
| 98 | if (ops->seq_stop) |
| 99 | ops->seq_stop(sf, v); |
| 100 | kernfs_put_active(of->kn); |
| 101 | } |
| 102 | |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 103 | static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos) |
| 104 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 105 | struct kernfs_open_file *of = sf->private; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 106 | const struct kernfs_ops *ops; |
| 107 | |
| 108 | /* |
| 109 | * @of->mutex nests outside active ref and is just to ensure that |
| 110 | * the ops aren't called concurrently for the same open file. |
| 111 | */ |
| 112 | mutex_lock(&of->mutex); |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 113 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 114 | return ERR_PTR(-ENODEV); |
| 115 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 116 | ops = kernfs_ops(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 117 | if (ops->seq_start) { |
Tejun Heo | bb30594 | 2014-01-14 09:52:01 -0500 | [diff] [blame] | 118 | void *next = ops->seq_start(sf, ppos); |
| 119 | /* see the comment above kernfs_seq_stop_active() */ |
| 120 | if (next == ERR_PTR(-ENODEV)) |
| 121 | kernfs_seq_stop_active(sf, next); |
| 122 | return next; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 123 | } else { |
| 124 | /* |
| 125 | * The same behavior and code as single_open(). Returns |
| 126 | * !NULL if pos is at the beginning; otherwise, NULL. |
| 127 | */ |
| 128 | return NULL + !*ppos; |
| 129 | } |
| 130 | } |
| 131 | |
| 132 | static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos) |
| 133 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 134 | struct kernfs_open_file *of = sf->private; |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 135 | const struct kernfs_ops *ops = kernfs_ops(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 136 | |
| 137 | if (ops->seq_next) { |
Tejun Heo | bb30594 | 2014-01-14 09:52:01 -0500 | [diff] [blame] | 138 | void *next = ops->seq_next(sf, v, ppos); |
| 139 | /* see the comment above kernfs_seq_stop_active() */ |
| 140 | if (next == ERR_PTR(-ENODEV)) |
| 141 | kernfs_seq_stop_active(sf, next); |
| 142 | return next; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 143 | } else { |
| 144 | /* |
| 145 | * The same behavior and code as single_open(), always |
| 146 | * terminate after the initial read. |
| 147 | */ |
| 148 | ++*ppos; |
| 149 | return NULL; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | static void kernfs_seq_stop(struct seq_file *sf, void *v) |
| 154 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 155 | struct kernfs_open_file *of = sf->private; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 156 | |
Tejun Heo | bb30594 | 2014-01-14 09:52:01 -0500 | [diff] [blame] | 157 | if (v != ERR_PTR(-ENODEV)) |
| 158 | kernfs_seq_stop_active(sf, v); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 159 | mutex_unlock(&of->mutex); |
| 160 | } |
| 161 | |
| 162 | static int kernfs_seq_show(struct seq_file *sf, void *v) |
| 163 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 164 | struct kernfs_open_file *of = sf->private; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 165 | |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 166 | of->event = atomic_read(&of->kn->attr.open->event); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 167 | |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 168 | return of->kn->attr.ops->seq_show(sf, v); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 169 | } |
| 170 | |
| 171 | static const struct seq_operations kernfs_seq_ops = { |
| 172 | .start = kernfs_seq_start, |
| 173 | .next = kernfs_seq_next, |
| 174 | .stop = kernfs_seq_stop, |
| 175 | .show = kernfs_seq_show, |
| 176 | }; |
| 177 | |
| 178 | /* |
| 179 | * As reading a bin file can have side-effects, the exact offset and bytes |
| 180 | * specified in read(2) call should be passed to the read callback making |
| 181 | * it difficult to use seq_file. Implement simplistic custom buffering for |
| 182 | * bin files. |
| 183 | */ |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 184 | static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 185 | char __user *user_buf, size_t count, |
| 186 | loff_t *ppos) |
| 187 | { |
| 188 | ssize_t len = min_t(size_t, count, PAGE_SIZE); |
| 189 | const struct kernfs_ops *ops; |
| 190 | char *buf; |
| 191 | |
| 192 | buf = kmalloc(len, GFP_KERNEL); |
| 193 | if (!buf) |
| 194 | return -ENOMEM; |
| 195 | |
| 196 | /* |
| 197 | * @of->mutex nests outside active ref and is just to ensure that |
| 198 | * the ops aren't called concurrently for the same open file. |
| 199 | */ |
| 200 | mutex_lock(&of->mutex); |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 201 | if (!kernfs_get_active(of->kn)) { |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 202 | len = -ENODEV; |
| 203 | mutex_unlock(&of->mutex); |
| 204 | goto out_free; |
| 205 | } |
| 206 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 207 | ops = kernfs_ops(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 208 | if (ops->read) |
| 209 | len = ops->read(of, buf, len, *ppos); |
| 210 | else |
| 211 | len = -EINVAL; |
| 212 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 213 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 214 | mutex_unlock(&of->mutex); |
| 215 | |
| 216 | if (len < 0) |
| 217 | goto out_free; |
| 218 | |
| 219 | if (copy_to_user(user_buf, buf, len)) { |
| 220 | len = -EFAULT; |
| 221 | goto out_free; |
| 222 | } |
| 223 | |
| 224 | *ppos += len; |
| 225 | |
| 226 | out_free: |
| 227 | kfree(buf); |
| 228 | return len; |
| 229 | } |
| 230 | |
| 231 | /** |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 232 | * kernfs_fop_read - kernfs vfs read callback |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 233 | * @file: file pointer |
| 234 | * @user_buf: data to write |
| 235 | * @count: number of bytes |
| 236 | * @ppos: starting offset |
| 237 | */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 238 | static ssize_t kernfs_fop_read(struct file *file, char __user *user_buf, |
| 239 | size_t count, loff_t *ppos) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 240 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 241 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 242 | |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 243 | if (of->kn->flags & KERNFS_HAS_SEQ_SHOW) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 244 | return seq_read(file, user_buf, count, ppos); |
| 245 | else |
| 246 | return kernfs_file_direct_read(of, user_buf, count, ppos); |
| 247 | } |
| 248 | |
| 249 | /** |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 250 | * kernfs_fop_write - kernfs vfs write callback |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 251 | * @file: file pointer |
| 252 | * @user_buf: data to write |
| 253 | * @count: number of bytes |
| 254 | * @ppos: starting offset |
| 255 | * |
| 256 | * Copy data in from userland and pass it to the matching kernfs write |
| 257 | * operation. |
| 258 | * |
| 259 | * There is no easy way for us to know if userspace is only doing a partial |
| 260 | * write, so we don't support them. We expect the entire buffer to come on |
| 261 | * the first write. Hint: if you're writing a value, first read the file, |
| 262 | * modify only the the value you're changing, then write entire buffer |
| 263 | * back. |
| 264 | */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 265 | static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf, |
| 266 | size_t count, loff_t *ppos) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 267 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 268 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 269 | const struct kernfs_ops *ops; |
Tejun Heo | b7ce40c | 2014-03-04 15:38:46 -0500 | [diff] [blame] | 270 | size_t len; |
| 271 | char *buf; |
| 272 | |
| 273 | if (of->atomic_write_len) { |
| 274 | len = count; |
| 275 | if (len > of->atomic_write_len) |
| 276 | return -E2BIG; |
| 277 | } else { |
| 278 | len = min_t(size_t, count, PAGE_SIZE); |
| 279 | } |
| 280 | |
| 281 | buf = kmalloc(len + 1, GFP_KERNEL); |
| 282 | if (!buf) |
| 283 | return -ENOMEM; |
| 284 | |
| 285 | if (copy_from_user(buf, user_buf, len)) { |
| 286 | len = -EFAULT; |
| 287 | goto out_free; |
| 288 | } |
| 289 | buf[len] = '\0'; /* guarantee string termination */ |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 290 | |
| 291 | /* |
| 292 | * @of->mutex nests outside active ref and is just to ensure that |
| 293 | * the ops aren't called concurrently for the same open file. |
| 294 | */ |
| 295 | mutex_lock(&of->mutex); |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 296 | if (!kernfs_get_active(of->kn)) { |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 297 | mutex_unlock(&of->mutex); |
Tejun Heo | b7ce40c | 2014-03-04 15:38:46 -0500 | [diff] [blame] | 298 | len = -ENODEV; |
| 299 | goto out_free; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 300 | } |
| 301 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 302 | ops = kernfs_ops(of->kn); |
Tejun Heo | b7ce40c | 2014-03-04 15:38:46 -0500 | [diff] [blame] | 303 | if (ops->write) |
| 304 | len = ops->write(of, buf, len, *ppos); |
| 305 | else |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 306 | len = -EINVAL; |
| 307 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 308 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 309 | mutex_unlock(&of->mutex); |
| 310 | |
| 311 | if (len > 0) |
| 312 | *ppos += len; |
Tejun Heo | b7ce40c | 2014-03-04 15:38:46 -0500 | [diff] [blame] | 313 | out_free: |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 314 | kfree(buf); |
| 315 | return len; |
| 316 | } |
| 317 | |
| 318 | static void kernfs_vma_open(struct vm_area_struct *vma) |
| 319 | { |
| 320 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 321 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 322 | |
| 323 | if (!of->vm_ops) |
| 324 | return; |
| 325 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 326 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 327 | return; |
| 328 | |
| 329 | if (of->vm_ops->open) |
| 330 | of->vm_ops->open(vma); |
| 331 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 332 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 333 | } |
| 334 | |
| 335 | static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
| 336 | { |
| 337 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 338 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 339 | int ret; |
| 340 | |
| 341 | if (!of->vm_ops) |
| 342 | return VM_FAULT_SIGBUS; |
| 343 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 344 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 345 | return VM_FAULT_SIGBUS; |
| 346 | |
| 347 | ret = VM_FAULT_SIGBUS; |
| 348 | if (of->vm_ops->fault) |
| 349 | ret = of->vm_ops->fault(vma, vmf); |
| 350 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 351 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 352 | return ret; |
| 353 | } |
| 354 | |
| 355 | static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma, |
| 356 | struct vm_fault *vmf) |
| 357 | { |
| 358 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 359 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 360 | int ret; |
| 361 | |
| 362 | if (!of->vm_ops) |
| 363 | return VM_FAULT_SIGBUS; |
| 364 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 365 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 366 | return VM_FAULT_SIGBUS; |
| 367 | |
| 368 | ret = 0; |
| 369 | if (of->vm_ops->page_mkwrite) |
| 370 | ret = of->vm_ops->page_mkwrite(vma, vmf); |
| 371 | else |
| 372 | file_update_time(file); |
| 373 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 374 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 375 | return ret; |
| 376 | } |
| 377 | |
| 378 | static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr, |
| 379 | void *buf, int len, int write) |
| 380 | { |
| 381 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 382 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 383 | int ret; |
| 384 | |
| 385 | if (!of->vm_ops) |
| 386 | return -EINVAL; |
| 387 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 388 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 389 | return -EINVAL; |
| 390 | |
| 391 | ret = -EINVAL; |
| 392 | if (of->vm_ops->access) |
| 393 | ret = of->vm_ops->access(vma, addr, buf, len, write); |
| 394 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 395 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 396 | return ret; |
| 397 | } |
| 398 | |
| 399 | #ifdef CONFIG_NUMA |
| 400 | static int kernfs_vma_set_policy(struct vm_area_struct *vma, |
| 401 | struct mempolicy *new) |
| 402 | { |
| 403 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 404 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 405 | int ret; |
| 406 | |
| 407 | if (!of->vm_ops) |
| 408 | return 0; |
| 409 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 410 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 411 | return -EINVAL; |
| 412 | |
| 413 | ret = 0; |
| 414 | if (of->vm_ops->set_policy) |
| 415 | ret = of->vm_ops->set_policy(vma, new); |
| 416 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 417 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 418 | return ret; |
| 419 | } |
| 420 | |
| 421 | static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma, |
| 422 | unsigned long addr) |
| 423 | { |
| 424 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 425 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 426 | struct mempolicy *pol; |
| 427 | |
| 428 | if (!of->vm_ops) |
| 429 | return vma->vm_policy; |
| 430 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 431 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 432 | return vma->vm_policy; |
| 433 | |
| 434 | pol = vma->vm_policy; |
| 435 | if (of->vm_ops->get_policy) |
| 436 | pol = of->vm_ops->get_policy(vma, addr); |
| 437 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 438 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 439 | return pol; |
| 440 | } |
| 441 | |
| 442 | static int kernfs_vma_migrate(struct vm_area_struct *vma, |
| 443 | const nodemask_t *from, const nodemask_t *to, |
| 444 | unsigned long flags) |
| 445 | { |
| 446 | struct file *file = vma->vm_file; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 447 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 448 | int ret; |
| 449 | |
| 450 | if (!of->vm_ops) |
| 451 | return 0; |
| 452 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 453 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 454 | return 0; |
| 455 | |
| 456 | ret = 0; |
| 457 | if (of->vm_ops->migrate) |
| 458 | ret = of->vm_ops->migrate(vma, from, to, flags); |
| 459 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 460 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 461 | return ret; |
| 462 | } |
| 463 | #endif |
| 464 | |
| 465 | static const struct vm_operations_struct kernfs_vm_ops = { |
| 466 | .open = kernfs_vma_open, |
| 467 | .fault = kernfs_vma_fault, |
| 468 | .page_mkwrite = kernfs_vma_page_mkwrite, |
| 469 | .access = kernfs_vma_access, |
| 470 | #ifdef CONFIG_NUMA |
| 471 | .set_policy = kernfs_vma_set_policy, |
| 472 | .get_policy = kernfs_vma_get_policy, |
| 473 | .migrate = kernfs_vma_migrate, |
| 474 | #endif |
| 475 | }; |
| 476 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 477 | static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 478 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 479 | struct kernfs_open_file *of = kernfs_of(file); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 480 | const struct kernfs_ops *ops; |
| 481 | int rc; |
| 482 | |
Tejun Heo | 9b2db6e | 2013-12-10 09:29:17 -0500 | [diff] [blame] | 483 | /* |
| 484 | * mmap path and of->mutex are prone to triggering spurious lockdep |
| 485 | * warnings and we don't want to add spurious locking dependency |
| 486 | * between the two. Check whether mmap is actually implemented |
| 487 | * without grabbing @of->mutex by testing HAS_MMAP flag. See the |
| 488 | * comment in kernfs_file_open() for more details. |
| 489 | */ |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 490 | if (!(of->kn->flags & KERNFS_HAS_MMAP)) |
Tejun Heo | 9b2db6e | 2013-12-10 09:29:17 -0500 | [diff] [blame] | 491 | return -ENODEV; |
| 492 | |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 493 | mutex_lock(&of->mutex); |
| 494 | |
| 495 | rc = -ENODEV; |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 496 | if (!kernfs_get_active(of->kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 497 | goto out_unlock; |
| 498 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 499 | ops = kernfs_ops(of->kn); |
Tejun Heo | 9b2db6e | 2013-12-10 09:29:17 -0500 | [diff] [blame] | 500 | rc = ops->mmap(of, vma); |
Tejun Heo | b44b214 | 2014-04-20 08:29:21 -0400 | [diff] [blame] | 501 | if (rc) |
| 502 | goto out_put; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 503 | |
| 504 | /* |
| 505 | * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup() |
| 506 | * to satisfy versions of X which crash if the mmap fails: that |
| 507 | * substitutes a new vm_file, and we don't then want bin_vm_ops. |
| 508 | */ |
| 509 | if (vma->vm_file != file) |
| 510 | goto out_put; |
| 511 | |
| 512 | rc = -EINVAL; |
| 513 | if (of->mmapped && of->vm_ops != vma->vm_ops) |
| 514 | goto out_put; |
| 515 | |
| 516 | /* |
| 517 | * It is not possible to successfully wrap close. |
| 518 | * So error if someone is trying to use close. |
| 519 | */ |
| 520 | rc = -EINVAL; |
| 521 | if (vma->vm_ops && vma->vm_ops->close) |
| 522 | goto out_put; |
| 523 | |
| 524 | rc = 0; |
| 525 | of->mmapped = 1; |
| 526 | of->vm_ops = vma->vm_ops; |
| 527 | vma->vm_ops = &kernfs_vm_ops; |
| 528 | out_put: |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 529 | kernfs_put_active(of->kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 530 | out_unlock: |
| 531 | mutex_unlock(&of->mutex); |
| 532 | |
| 533 | return rc; |
| 534 | } |
| 535 | |
| 536 | /** |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 537 | * kernfs_get_open_node - get or create kernfs_open_node |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 538 | * @kn: target kernfs_node |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 539 | * @of: kernfs_open_file for this instance of open |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 540 | * |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 541 | * If @kn->attr.open exists, increment its reference count; otherwise, |
| 542 | * create one. @of is chained to the files list. |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 543 | * |
| 544 | * LOCKING: |
| 545 | * Kernel thread context (may sleep). |
| 546 | * |
| 547 | * RETURNS: |
| 548 | * 0 on success, -errno on failure. |
| 549 | */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 550 | static int kernfs_get_open_node(struct kernfs_node *kn, |
| 551 | struct kernfs_open_file *of) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 552 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 553 | struct kernfs_open_node *on, *new_on = NULL; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 554 | |
| 555 | retry: |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 556 | mutex_lock(&kernfs_open_file_mutex); |
| 557 | spin_lock_irq(&kernfs_open_node_lock); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 558 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 559 | if (!kn->attr.open && new_on) { |
| 560 | kn->attr.open = new_on; |
| 561 | new_on = NULL; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 562 | } |
| 563 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 564 | on = kn->attr.open; |
| 565 | if (on) { |
| 566 | atomic_inc(&on->refcnt); |
| 567 | list_add_tail(&of->list, &on->files); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 568 | } |
| 569 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 570 | spin_unlock_irq(&kernfs_open_node_lock); |
| 571 | mutex_unlock(&kernfs_open_file_mutex); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 572 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 573 | if (on) { |
| 574 | kfree(new_on); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 575 | return 0; |
| 576 | } |
| 577 | |
| 578 | /* not there, initialize a new one and retry */ |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 579 | new_on = kmalloc(sizeof(*new_on), GFP_KERNEL); |
| 580 | if (!new_on) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 581 | return -ENOMEM; |
| 582 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 583 | atomic_set(&new_on->refcnt, 0); |
| 584 | atomic_set(&new_on->event, 1); |
| 585 | init_waitqueue_head(&new_on->poll); |
| 586 | INIT_LIST_HEAD(&new_on->files); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 587 | goto retry; |
| 588 | } |
| 589 | |
| 590 | /** |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 591 | * kernfs_put_open_node - put kernfs_open_node |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 592 | * @kn: target kernfs_nodet |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 593 | * @of: associated kernfs_open_file |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 594 | * |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 595 | * Put @kn->attr.open and unlink @of from the files list. If |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 596 | * reference count reaches zero, disassociate and free it. |
| 597 | * |
| 598 | * LOCKING: |
| 599 | * None. |
| 600 | */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 601 | static void kernfs_put_open_node(struct kernfs_node *kn, |
| 602 | struct kernfs_open_file *of) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 603 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 604 | struct kernfs_open_node *on = kn->attr.open; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 605 | unsigned long flags; |
| 606 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 607 | mutex_lock(&kernfs_open_file_mutex); |
| 608 | spin_lock_irqsave(&kernfs_open_node_lock, flags); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 609 | |
| 610 | if (of) |
| 611 | list_del(&of->list); |
| 612 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 613 | if (atomic_dec_and_test(&on->refcnt)) |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 614 | kn->attr.open = NULL; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 615 | else |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 616 | on = NULL; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 617 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 618 | spin_unlock_irqrestore(&kernfs_open_node_lock, flags); |
| 619 | mutex_unlock(&kernfs_open_file_mutex); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 620 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 621 | kfree(on); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 622 | } |
| 623 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 624 | static int kernfs_fop_open(struct inode *inode, struct file *file) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 625 | { |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 626 | struct kernfs_node *kn = file->f_path.dentry->d_fsdata; |
Tejun Heo | 555724a | 2014-05-12 13:56:27 -0400 | [diff] [blame] | 627 | struct kernfs_root *root = kernfs_root(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 628 | const struct kernfs_ops *ops; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 629 | struct kernfs_open_file *of; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 630 | bool has_read, has_write, has_mmap; |
| 631 | int error = -EACCES; |
| 632 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 633 | if (!kernfs_get_active(kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 634 | return -ENODEV; |
| 635 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 636 | ops = kernfs_ops(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 637 | |
| 638 | has_read = ops->seq_show || ops->read || ops->mmap; |
| 639 | has_write = ops->write || ops->mmap; |
| 640 | has_mmap = ops->mmap; |
| 641 | |
Tejun Heo | 555724a | 2014-05-12 13:56:27 -0400 | [diff] [blame] | 642 | /* see the flag definition for details */ |
| 643 | if (root->flags & KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK) { |
| 644 | if ((file->f_mode & FMODE_WRITE) && |
| 645 | (!(inode->i_mode & S_IWUGO) || !has_write)) |
| 646 | goto err_out; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 647 | |
Tejun Heo | 555724a | 2014-05-12 13:56:27 -0400 | [diff] [blame] | 648 | if ((file->f_mode & FMODE_READ) && |
| 649 | (!(inode->i_mode & S_IRUGO) || !has_read)) |
| 650 | goto err_out; |
| 651 | } |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 652 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 653 | /* allocate a kernfs_open_file for the file */ |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 654 | error = -ENOMEM; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 655 | of = kzalloc(sizeof(struct kernfs_open_file), GFP_KERNEL); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 656 | if (!of) |
| 657 | goto err_out; |
| 658 | |
| 659 | /* |
| 660 | * The following is done to give a different lockdep key to |
| 661 | * @of->mutex for files which implement mmap. This is a rather |
| 662 | * crude way to avoid false positive lockdep warning around |
| 663 | * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and |
| 664 | * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under |
| 665 | * which mm->mmap_sem nests, while holding @of->mutex. As each |
| 666 | * open file has a separate mutex, it's okay as long as those don't |
| 667 | * happen on the same file. At this point, we can't easily give |
| 668 | * each file a separate locking class. Let's differentiate on |
| 669 | * whether the file has mmap or not for now. |
Tejun Heo | 9b2db6e | 2013-12-10 09:29:17 -0500 | [diff] [blame] | 670 | * |
| 671 | * Both paths of the branch look the same. They're supposed to |
| 672 | * look that way and give @of->mutex different static lockdep keys. |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 673 | */ |
| 674 | if (has_mmap) |
| 675 | mutex_init(&of->mutex); |
| 676 | else |
| 677 | mutex_init(&of->mutex); |
| 678 | |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 679 | of->kn = kn; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 680 | of->file = file; |
| 681 | |
| 682 | /* |
Tejun Heo | b7ce40c | 2014-03-04 15:38:46 -0500 | [diff] [blame] | 683 | * Write path needs to atomic_write_len outside active reference. |
| 684 | * Cache it in open_file. See kernfs_fop_write() for details. |
| 685 | */ |
| 686 | of->atomic_write_len = ops->atomic_write_len; |
| 687 | |
| 688 | /* |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 689 | * Always instantiate seq_file even if read access doesn't use |
| 690 | * seq_file or is not requested. This unifies private data access |
| 691 | * and readable regular files are the vast majority anyway. |
| 692 | */ |
| 693 | if (ops->seq_show) |
| 694 | error = seq_open(file, &kernfs_seq_ops); |
| 695 | else |
| 696 | error = seq_open(file, NULL); |
| 697 | if (error) |
| 698 | goto err_free; |
| 699 | |
| 700 | ((struct seq_file *)file->private_data)->private = of; |
| 701 | |
| 702 | /* seq_file clears PWRITE unconditionally, restore it if WRITE */ |
| 703 | if (file->f_mode & FMODE_WRITE) |
| 704 | file->f_mode |= FMODE_PWRITE; |
| 705 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 706 | /* make sure we have open node struct */ |
| 707 | error = kernfs_get_open_node(kn, of); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 708 | if (error) |
| 709 | goto err_close; |
| 710 | |
| 711 | /* open succeeded, put active references */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 712 | kernfs_put_active(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 713 | return 0; |
| 714 | |
| 715 | err_close: |
| 716 | seq_release(inode, file); |
| 717 | err_free: |
| 718 | kfree(of); |
| 719 | err_out: |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 720 | kernfs_put_active(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 721 | return error; |
| 722 | } |
| 723 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 724 | static int kernfs_fop_release(struct inode *inode, struct file *filp) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 725 | { |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 726 | struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 727 | struct kernfs_open_file *of = kernfs_of(filp); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 728 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 729 | kernfs_put_open_node(kn, of); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 730 | seq_release(inode, filp); |
| 731 | kfree(of); |
| 732 | |
| 733 | return 0; |
| 734 | } |
| 735 | |
Greg Kroah-Hartman | 55f6e30 | 2014-01-13 14:27:16 -0800 | [diff] [blame] | 736 | void kernfs_unmap_bin_file(struct kernfs_node *kn) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 737 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 738 | struct kernfs_open_node *on; |
| 739 | struct kernfs_open_file *of; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 740 | |
Greg Kroah-Hartman | 55f6e30 | 2014-01-13 14:27:16 -0800 | [diff] [blame] | 741 | if (!(kn->flags & KERNFS_HAS_MMAP)) |
| 742 | return; |
| 743 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 744 | spin_lock_irq(&kernfs_open_node_lock); |
| 745 | on = kn->attr.open; |
| 746 | if (on) |
| 747 | atomic_inc(&on->refcnt); |
| 748 | spin_unlock_irq(&kernfs_open_node_lock); |
| 749 | if (!on) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 750 | return; |
| 751 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 752 | mutex_lock(&kernfs_open_file_mutex); |
| 753 | list_for_each_entry(of, &on->files, list) { |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 754 | struct inode *inode = file_inode(of->file); |
| 755 | unmap_mapping_range(inode->i_mapping, 0, 0, 1); |
| 756 | } |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 757 | mutex_unlock(&kernfs_open_file_mutex); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 758 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 759 | kernfs_put_open_node(kn, NULL); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 760 | } |
| 761 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 762 | /* |
| 763 | * Kernfs attribute files are pollable. The idea is that you read |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 764 | * the content and then you use 'poll' or 'select' to wait for |
| 765 | * the content to change. When the content changes (assuming the |
| 766 | * manager for the kobject supports notification), poll will |
| 767 | * return POLLERR|POLLPRI, and select will return the fd whether |
| 768 | * it is waiting for read, write, or exceptions. |
| 769 | * Once poll/select indicates that the value has changed, you |
| 770 | * need to close and re-open the file, or seek to 0 and read again. |
| 771 | * Reminder: this only works for attributes which actively support |
| 772 | * it, and it is not possible to test an attribute from userspace |
| 773 | * to see if it supports poll (Neither 'poll' nor 'select' return |
| 774 | * an appropriate error code). When in doubt, set a suitable timeout value. |
| 775 | */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 776 | static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 777 | { |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 778 | struct kernfs_open_file *of = kernfs_of(filp); |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 779 | struct kernfs_node *kn = filp->f_path.dentry->d_fsdata; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 780 | struct kernfs_open_node *on = kn->attr.open; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 781 | |
| 782 | /* need parent for the kobj, grab both */ |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 783 | if (!kernfs_get_active(kn)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 784 | goto trigger; |
| 785 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 786 | poll_wait(filp, &on->poll, wait); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 787 | |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 788 | kernfs_put_active(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 789 | |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 790 | if (of->event != atomic_read(&on->event)) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 791 | goto trigger; |
| 792 | |
| 793 | return DEFAULT_POLLMASK; |
| 794 | |
| 795 | trigger: |
| 796 | return DEFAULT_POLLMASK|POLLERR|POLLPRI; |
| 797 | } |
| 798 | |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 799 | static void kernfs_notify_workfn(struct work_struct *work) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 800 | { |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 801 | struct kernfs_node *kn; |
Tejun Heo | c525aad | 2013-12-11 14:11:55 -0500 | [diff] [blame] | 802 | struct kernfs_open_node *on; |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 803 | struct kernfs_super_info *info; |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 804 | repeat: |
| 805 | /* pop one off the notify_list */ |
| 806 | spin_lock_irq(&kernfs_notify_lock); |
| 807 | kn = kernfs_notify_list; |
| 808 | if (kn == KERNFS_NOTIFY_EOL) { |
| 809 | spin_unlock_irq(&kernfs_notify_lock); |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 810 | return; |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 811 | } |
| 812 | kernfs_notify_list = kn->attr.notify_next; |
| 813 | kn->attr.notify_next = NULL; |
| 814 | spin_unlock_irq(&kernfs_notify_lock); |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 815 | |
| 816 | /* kick poll */ |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 817 | spin_lock_irq(&kernfs_open_node_lock); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 818 | |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 819 | on = kn->attr.open; |
| 820 | if (on) { |
| 821 | atomic_inc(&on->event); |
| 822 | wake_up_interruptible(&on->poll); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 823 | } |
| 824 | |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 825 | spin_unlock_irq(&kernfs_open_node_lock); |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 826 | |
| 827 | /* kick fsnotify */ |
| 828 | mutex_lock(&kernfs_mutex); |
| 829 | |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 830 | list_for_each_entry(info, &kernfs_root(kn)->supers, node) { |
Tejun Heo | d911d98 | 2014-04-09 11:07:31 -0400 | [diff] [blame] | 831 | struct inode *inode; |
| 832 | struct dentry *dentry; |
| 833 | |
| 834 | inode = ilookup(info->sb, kn->ino); |
| 835 | if (!inode) |
| 836 | continue; |
| 837 | |
| 838 | dentry = d_find_any_alias(inode); |
| 839 | if (dentry) { |
| 840 | fsnotify_parent(NULL, dentry, FS_MODIFY); |
| 841 | fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE, |
| 842 | NULL, 0); |
| 843 | dput(dentry); |
| 844 | } |
| 845 | |
| 846 | iput(inode); |
| 847 | } |
| 848 | |
| 849 | mutex_unlock(&kernfs_mutex); |
Tejun Heo | ecca47c | 2014-07-01 16:41:03 -0400 | [diff] [blame^] | 850 | kernfs_put(kn); |
| 851 | goto repeat; |
| 852 | } |
| 853 | |
| 854 | /** |
| 855 | * kernfs_notify - notify a kernfs file |
| 856 | * @kn: file to notify |
| 857 | * |
| 858 | * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any |
| 859 | * context. |
| 860 | */ |
| 861 | void kernfs_notify(struct kernfs_node *kn) |
| 862 | { |
| 863 | static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn); |
| 864 | unsigned long flags; |
| 865 | |
| 866 | if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) |
| 867 | return; |
| 868 | |
| 869 | spin_lock_irqsave(&kernfs_notify_lock, flags); |
| 870 | if (!kn->attr.notify_next) { |
| 871 | kernfs_get(kn); |
| 872 | kn->attr.notify_next = kernfs_notify_list; |
| 873 | kernfs_notify_list = kn; |
| 874 | schedule_work(&kernfs_notify_work); |
| 875 | } |
| 876 | spin_unlock_irqrestore(&kernfs_notify_lock, flags); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 877 | } |
| 878 | EXPORT_SYMBOL_GPL(kernfs_notify); |
| 879 | |
Tejun Heo | a797bfc | 2013-12-11 14:11:57 -0500 | [diff] [blame] | 880 | const struct file_operations kernfs_file_fops = { |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 881 | .read = kernfs_fop_read, |
| 882 | .write = kernfs_fop_write, |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 883 | .llseek = generic_file_llseek, |
Tejun Heo | c637b8a | 2013-12-11 14:11:58 -0500 | [diff] [blame] | 884 | .mmap = kernfs_fop_mmap, |
| 885 | .open = kernfs_fop_open, |
| 886 | .release = kernfs_fop_release, |
| 887 | .poll = kernfs_fop_poll, |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 888 | }; |
| 889 | |
| 890 | /** |
Tejun Heo | 2063d60 | 2013-12-11 16:02:57 -0500 | [diff] [blame] | 891 | * __kernfs_create_file - kernfs internal function to create a file |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 892 | * @parent: directory to create the file in |
| 893 | * @name: name of the file |
| 894 | * @mode: mode of the file |
| 895 | * @size: size of the file |
| 896 | * @ops: kernfs operations for the file |
| 897 | * @priv: private data for the file |
| 898 | * @ns: optional namespace tag of the file |
Tejun Heo | 2063d60 | 2013-12-11 16:02:57 -0500 | [diff] [blame] | 899 | * @static_name: don't copy file name |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 900 | * @key: lockdep key for the file's active_ref, %NULL to disable lockdep |
| 901 | * |
| 902 | * Returns the created node on success, ERR_PTR() value on error. |
| 903 | */ |
Tejun Heo | 2063d60 | 2013-12-11 16:02:57 -0500 | [diff] [blame] | 904 | struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, |
| 905 | const char *name, |
| 906 | umode_t mode, loff_t size, |
| 907 | const struct kernfs_ops *ops, |
| 908 | void *priv, const void *ns, |
| 909 | bool name_is_static, |
| 910 | struct lock_class_key *key) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 911 | { |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 912 | struct kernfs_node *kn; |
Tejun Heo | 2063d60 | 2013-12-11 16:02:57 -0500 | [diff] [blame] | 913 | unsigned flags; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 914 | int rc; |
| 915 | |
Tejun Heo | 2063d60 | 2013-12-11 16:02:57 -0500 | [diff] [blame] | 916 | flags = KERNFS_FILE; |
| 917 | if (name_is_static) |
| 918 | flags |= KERNFS_STATIC_NAME; |
| 919 | |
Tejun Heo | db4aad2 | 2014-01-17 09:58:25 -0500 | [diff] [blame] | 920 | kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG, flags); |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 921 | if (!kn) |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 922 | return ERR_PTR(-ENOMEM); |
| 923 | |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 924 | kn->attr.ops = ops; |
| 925 | kn->attr.size = size; |
| 926 | kn->ns = ns; |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 927 | kn->priv = priv; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 928 | |
| 929 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 930 | if (key) { |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 931 | lockdep_init_map(&kn->dep_map, "s_active", key, 0); |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 932 | kn->flags |= KERNFS_LOCKDEP; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 933 | } |
| 934 | #endif |
| 935 | |
| 936 | /* |
Tejun Heo | adc5e8b | 2013-12-11 14:11:54 -0500 | [diff] [blame] | 937 | * kn->attr.ops is accesible only while holding active ref. We |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 938 | * need to know whether some ops are implemented outside active |
| 939 | * ref. Cache their existence in flags. |
| 940 | */ |
| 941 | if (ops->seq_show) |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 942 | kn->flags |= KERNFS_HAS_SEQ_SHOW; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 943 | if (ops->mmap) |
Tejun Heo | df23fc3 | 2013-12-11 14:11:56 -0500 | [diff] [blame] | 944 | kn->flags |= KERNFS_HAS_MMAP; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 945 | |
Tejun Heo | 988cd7a | 2014-02-03 14:02:58 -0500 | [diff] [blame] | 946 | rc = kernfs_add_one(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 947 | if (rc) { |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 948 | kernfs_put(kn); |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 949 | return ERR_PTR(rc); |
| 950 | } |
Tejun Heo | 324a56e | 2013-12-11 14:11:53 -0500 | [diff] [blame] | 951 | return kn; |
Tejun Heo | 414985a | 2013-11-28 14:54:34 -0500 | [diff] [blame] | 952 | } |