linux/fs/fscache/object-list.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* Global fscache object list maintainer and viewer
   3 *
   4 * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
   5 * Written by David Howells (dhowells@redhat.com)
   6 */
   7
   8#define FSCACHE_DEBUG_LEVEL COOKIE
   9#include <linux/module.h>
  10#include <linux/proc_fs.h>
  11#include <linux/seq_file.h>
  12#include <linux/slab.h>
  13#include <linux/key.h>
  14#include <keys/user-type.h>
  15#include "internal.h"
  16
  17static struct rb_root fscache_object_list;
  18static DEFINE_RWLOCK(fscache_object_list_lock);
  19
  20struct fscache_objlist_data {
  21        unsigned long   config;         /* display configuration */
  22#define FSCACHE_OBJLIST_CONFIG_KEY      0x00000001      /* show object keys */
  23#define FSCACHE_OBJLIST_CONFIG_AUX      0x00000002      /* show object auxdata */
  24#define FSCACHE_OBJLIST_CONFIG_COOKIE   0x00000004      /* show objects with cookies */
  25#define FSCACHE_OBJLIST_CONFIG_NOCOOKIE 0x00000008      /* show objects without cookies */
  26#define FSCACHE_OBJLIST_CONFIG_BUSY     0x00000010      /* show busy objects */
  27#define FSCACHE_OBJLIST_CONFIG_IDLE     0x00000020      /* show idle objects */
  28#define FSCACHE_OBJLIST_CONFIG_PENDWR   0x00000040      /* show objects with pending writes */
  29#define FSCACHE_OBJLIST_CONFIG_NOPENDWR 0x00000080      /* show objects without pending writes */
  30#define FSCACHE_OBJLIST_CONFIG_READS    0x00000100      /* show objects with active reads */
  31#define FSCACHE_OBJLIST_CONFIG_NOREADS  0x00000200      /* show objects without active reads */
  32#define FSCACHE_OBJLIST_CONFIG_EVENTS   0x00000400      /* show objects with events */
  33#define FSCACHE_OBJLIST_CONFIG_NOEVENTS 0x00000800      /* show objects without no events */
  34#define FSCACHE_OBJLIST_CONFIG_WORK     0x00001000      /* show objects with work */
  35#define FSCACHE_OBJLIST_CONFIG_NOWORK   0x00002000      /* show objects without work */
  36};
  37
  38/*
  39 * Add an object to the object list
  40 * - we use the address of the fscache_object structure as the key into the
  41 *   tree
  42 */
  43void fscache_objlist_add(struct fscache_object *obj)
  44{
  45        struct fscache_object *xobj;
  46        struct rb_node **p = &fscache_object_list.rb_node, *parent = NULL;
  47
  48        ASSERT(RB_EMPTY_NODE(&obj->objlist_link));
  49
  50        write_lock(&fscache_object_list_lock);
  51
  52        while (*p) {
  53                parent = *p;
  54                xobj = rb_entry(parent, struct fscache_object, objlist_link);
  55
  56                if (obj < xobj)
  57                        p = &(*p)->rb_left;
  58                else if (obj > xobj)
  59                        p = &(*p)->rb_right;
  60                else
  61                        BUG();
  62        }
  63
  64        rb_link_node(&obj->objlist_link, parent, p);
  65        rb_insert_color(&obj->objlist_link, &fscache_object_list);
  66
  67        write_unlock(&fscache_object_list_lock);
  68}
  69
  70/*
  71 * Remove an object from the object list.
  72 */
  73void fscache_objlist_remove(struct fscache_object *obj)
  74{
  75        if (RB_EMPTY_NODE(&obj->objlist_link))
  76                return;
  77
  78        write_lock(&fscache_object_list_lock);
  79
  80        BUG_ON(RB_EMPTY_ROOT(&fscache_object_list));
  81        rb_erase(&obj->objlist_link, &fscache_object_list);
  82
  83        write_unlock(&fscache_object_list_lock);
  84}
  85
  86/*
  87 * find the object in the tree on or after the specified index
  88 */
  89static struct fscache_object *fscache_objlist_lookup(loff_t *_pos)
  90{
  91        struct fscache_object *pobj, *obj = NULL, *minobj = NULL;
  92        struct rb_node *p;
  93        unsigned long pos;
  94
  95        if (*_pos >= (unsigned long) ERR_PTR(-ENOENT))
  96                return NULL;
  97        pos = *_pos;
  98
  99        /* banners (can't represent line 0 by pos 0 as that would involve
 100         * returning a NULL pointer) */
 101        if (pos == 0)
 102                return (struct fscache_object *)(long)++(*_pos);
 103        if (pos < 3)
 104                return (struct fscache_object *)pos;
 105
 106        pobj = (struct fscache_object *)pos;
 107        p = fscache_object_list.rb_node;
 108        while (p) {
 109                obj = rb_entry(p, struct fscache_object, objlist_link);
 110                if (pobj < obj) {
 111                        if (!minobj || minobj > obj)
 112                                minobj = obj;
 113                        p = p->rb_left;
 114                } else if (pobj > obj) {
 115                        p = p->rb_right;
 116                } else {
 117                        minobj = obj;
 118                        break;
 119                }
 120                obj = NULL;
 121        }
 122
 123        if (!minobj)
 124                *_pos = (unsigned long) ERR_PTR(-ENOENT);
 125        else if (minobj != obj)
 126                *_pos = (unsigned long) minobj;
 127        return minobj;
 128}
 129
 130/*
 131 * set up the iterator to start reading from the first line
 132 */
 133static void *fscache_objlist_start(struct seq_file *m, loff_t *_pos)
 134        __acquires(&fscache_object_list_lock)
 135{
 136        read_lock(&fscache_object_list_lock);
 137        return fscache_objlist_lookup(_pos);
 138}
 139
 140/*
 141 * move to the next line
 142 */
 143static void *fscache_objlist_next(struct seq_file *m, void *v, loff_t *_pos)
 144{
 145        (*_pos)++;
 146        return fscache_objlist_lookup(_pos);
 147}
 148
 149/*
 150 * clean up after reading
 151 */
 152static void fscache_objlist_stop(struct seq_file *m, void *v)
 153        __releases(&fscache_object_list_lock)
 154{
 155        read_unlock(&fscache_object_list_lock);
 156}
 157
 158/*
 159 * display an object
 160 */
 161static int fscache_objlist_show(struct seq_file *m, void *v)
 162{
 163        struct fscache_objlist_data *data = m->private;
 164        struct fscache_object *obj = v;
 165        struct fscache_cookie *cookie;
 166        unsigned long config = data->config;
 167        char _type[3], *type;
 168        u8 *p;
 169
 170        if ((unsigned long) v == 1) {
 171                seq_puts(m, "OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS"
 172                         " EM EV FL S"
 173                         " | NETFS_COOKIE_DEF TY FL NETFS_DATA");
 174                if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 175                              FSCACHE_OBJLIST_CONFIG_AUX))
 176                        seq_puts(m, "       ");
 177                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 178                        seq_puts(m, "OBJECT_KEY");
 179                if ((config & (FSCACHE_OBJLIST_CONFIG_KEY |
 180                               FSCACHE_OBJLIST_CONFIG_AUX)) ==
 181                    (FSCACHE_OBJLIST_CONFIG_KEY | FSCACHE_OBJLIST_CONFIG_AUX))
 182                        seq_puts(m, ", ");
 183                if (config & FSCACHE_OBJLIST_CONFIG_AUX)
 184                        seq_puts(m, "AUX_DATA");
 185                seq_puts(m, "\n");
 186                return 0;
 187        }
 188
 189        if ((unsigned long) v == 2) {
 190                seq_puts(m, "======== ======== ==== ===== === === === == ====="
 191                         " == == == ="
 192                         " | ================ == == ================");
 193                if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 194                              FSCACHE_OBJLIST_CONFIG_AUX))
 195                        seq_puts(m, " ================");
 196                seq_puts(m, "\n");
 197                return 0;
 198        }
 199
 200        /* filter out any unwanted objects */
 201#define FILTER(criterion, _yes, _no)                                    \
 202        do {                                                            \
 203                unsigned long yes = FSCACHE_OBJLIST_CONFIG_##_yes;      \
 204                unsigned long no = FSCACHE_OBJLIST_CONFIG_##_no;        \
 205                if (criterion) {                                        \
 206                        if (!(config & yes))                            \
 207                                return 0;                               \
 208                } else {                                                \
 209                        if (!(config & no))                             \
 210                                return 0;                               \
 211                }                                                       \
 212        } while(0)
 213
 214        cookie = obj->cookie;
 215        if (~config) {
 216                FILTER(cookie->def,
 217                       COOKIE, NOCOOKIE);
 218                FILTER(fscache_object_is_active(obj) ||
 219                       obj->n_ops != 0 ||
 220                       obj->n_obj_ops != 0 ||
 221                       obj->flags ||
 222                       !list_empty(&obj->dependents),
 223                       BUSY, IDLE);
 224                FILTER(test_bit(FSCACHE_OBJECT_PENDING_WRITE, &obj->flags),
 225                       PENDWR, NOPENDWR);
 226                FILTER(atomic_read(&obj->n_reads),
 227                       READS, NOREADS);
 228                FILTER(obj->events & obj->event_mask,
 229                       EVENTS, NOEVENTS);
 230                FILTER(work_busy(&obj->work), WORK, NOWORK);
 231        }
 232
 233        seq_printf(m,
 234                   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %2lx %1x | ",
 235                   obj->debug_id,
 236                   obj->parent ? obj->parent->debug_id : -1,
 237                   obj->state->short_name,
 238                   obj->n_children,
 239                   obj->n_ops,
 240                   obj->n_obj_ops,
 241                   obj->n_in_progress,
 242                   obj->n_exclusive,
 243                   atomic_read(&obj->n_reads),
 244                   obj->event_mask,
 245                   obj->events,
 246                   obj->flags,
 247                   work_busy(&obj->work));
 248
 249        if (fscache_use_cookie(obj)) {
 250                uint16_t keylen = 0, auxlen = 0;
 251
 252                switch (cookie->type) {
 253                case 0:
 254                        type = "IX";
 255                        break;
 256                case 1:
 257                        type = "DT";
 258                        break;
 259                default:
 260                        snprintf(_type, sizeof(_type), "%02u",
 261                                 cookie->type);
 262                        type = _type;
 263                        break;
 264                }
 265
 266                seq_printf(m, "%-16s %s %2lx %16p",
 267                           cookie->def->name,
 268                           type,
 269                           cookie->flags,
 270                           cookie->netfs_data);
 271
 272                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 273                        keylen = cookie->key_len;
 274
 275                if (config & FSCACHE_OBJLIST_CONFIG_AUX)
 276                        auxlen = cookie->aux_len;
 277
 278                if (keylen > 0 || auxlen > 0) {
 279                        seq_puts(m, " ");
 280                        p = keylen <= sizeof(cookie->inline_key) ?
 281                                cookie->inline_key : cookie->key;
 282                        for (; keylen > 0; keylen--)
 283                                seq_printf(m, "%02x", *p++);
 284                        if (auxlen > 0) {
 285                                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 286                                        seq_puts(m, ", ");
 287                                p = auxlen <= sizeof(cookie->inline_aux) ?
 288                                        cookie->inline_aux : cookie->aux;
 289                                for (; auxlen > 0; auxlen--)
 290                                        seq_printf(m, "%02x", *p++);
 291                        }
 292                }
 293
 294                seq_puts(m, "\n");
 295                fscache_unuse_cookie(obj);
 296        } else {
 297                seq_puts(m, "<no_netfs>\n");
 298        }
 299        return 0;
 300}
 301
 302static const struct seq_operations fscache_objlist_ops = {
 303        .start          = fscache_objlist_start,
 304        .stop           = fscache_objlist_stop,
 305        .next           = fscache_objlist_next,
 306        .show           = fscache_objlist_show,
 307};
 308
 309/*
 310 * get the configuration for filtering the list
 311 */
 312static void fscache_objlist_config(struct fscache_objlist_data *data)
 313{
 314#ifdef CONFIG_KEYS
 315        const struct user_key_payload *confkey;
 316        unsigned long config;
 317        struct key *key;
 318        const char *buf;
 319        int len;
 320
 321        key = request_key(&key_type_user, "fscache:objlist", NULL);
 322        if (IS_ERR(key))
 323                goto no_config;
 324
 325        config = 0;
 326        rcu_read_lock();
 327
 328        confkey = user_key_payload_rcu(key);
 329        if (!confkey) {
 330                /* key was revoked */
 331                rcu_read_unlock();
 332                key_put(key);
 333                goto no_config;
 334        }
 335
 336        buf = confkey->data;
 337
 338        for (len = confkey->datalen - 1; len >= 0; len--) {
 339                switch (buf[len]) {
 340                case 'K': config |= FSCACHE_OBJLIST_CONFIG_KEY;         break;
 341                case 'A': config |= FSCACHE_OBJLIST_CONFIG_AUX;         break;
 342                case 'C': config |= FSCACHE_OBJLIST_CONFIG_COOKIE;      break;
 343                case 'c': config |= FSCACHE_OBJLIST_CONFIG_NOCOOKIE;    break;
 344                case 'B': config |= FSCACHE_OBJLIST_CONFIG_BUSY;        break;
 345                case 'b': config |= FSCACHE_OBJLIST_CONFIG_IDLE;        break;
 346                case 'W': config |= FSCACHE_OBJLIST_CONFIG_PENDWR;      break;
 347                case 'w': config |= FSCACHE_OBJLIST_CONFIG_NOPENDWR;    break;
 348                case 'R': config |= FSCACHE_OBJLIST_CONFIG_READS;       break;
 349                case 'r': config |= FSCACHE_OBJLIST_CONFIG_NOREADS;     break;
 350                case 'S': config |= FSCACHE_OBJLIST_CONFIG_WORK;        break;
 351                case 's': config |= FSCACHE_OBJLIST_CONFIG_NOWORK;      break;
 352                }
 353        }
 354
 355        rcu_read_unlock();
 356        key_put(key);
 357
 358        if (!(config & (FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE)))
 359            config   |= FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE;
 360        if (!(config & (FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE)))
 361            config   |= FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE;
 362        if (!(config & (FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR)))
 363            config   |= FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR;
 364        if (!(config & (FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS)))
 365            config   |= FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS;
 366        if (!(config & (FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS)))
 367            config   |= FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS;
 368        if (!(config & (FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK)))
 369            config   |= FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK;
 370
 371        data->config = config;
 372        return;
 373
 374no_config:
 375#endif
 376        data->config = ULONG_MAX;
 377}
 378
 379/*
 380 * open "/proc/fs/fscache/objects" to provide a list of active objects
 381 * - can be configured by a user-defined key added to the caller's keyrings
 382 */
 383static int fscache_objlist_open(struct inode *inode, struct file *file)
 384{
 385        struct fscache_objlist_data *data;
 386
 387        data = __seq_open_private(file, &fscache_objlist_ops, sizeof(*data));
 388        if (!data)
 389                return -ENOMEM;
 390
 391        /* get the configuration key */
 392        fscache_objlist_config(data);
 393
 394        return 0;
 395}
 396
 397/*
 398 * clean up on close
 399 */
 400static int fscache_objlist_release(struct inode *inode, struct file *file)
 401{
 402        struct seq_file *m = file->private_data;
 403
 404        kfree(m->private);
 405        m->private = NULL;
 406        return seq_release(inode, file);
 407}
 408
 409const struct proc_ops fscache_objlist_proc_ops = {
 410        .proc_open      = fscache_objlist_open,
 411        .proc_read      = seq_read,
 412        .proc_lseek     = seq_lseek,
 413        .proc_release   = fscache_objlist_release,
 414};
 415