linux/fs/fscache/object-list.c
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   1/* Global fscache object list maintainer and viewer
   2 *
   3 * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11
  12#define FSCACHE_DEBUG_LEVEL COOKIE
  13#include <linux/module.h>
  14#include <linux/seq_file.h>
  15#include <linux/slab.h>
  16#include <linux/key.h>
  17#include <keys/user-type.h>
  18#include "internal.h"
  19
  20static struct rb_root fscache_object_list;
  21static DEFINE_RWLOCK(fscache_object_list_lock);
  22
  23struct fscache_objlist_data {
  24        unsigned long   config;         /* display configuration */
  25#define FSCACHE_OBJLIST_CONFIG_KEY      0x00000001      /* show object keys */
  26#define FSCACHE_OBJLIST_CONFIG_AUX      0x00000002      /* show object auxdata */
  27#define FSCACHE_OBJLIST_CONFIG_COOKIE   0x00000004      /* show objects with cookies */
  28#define FSCACHE_OBJLIST_CONFIG_NOCOOKIE 0x00000008      /* show objects without cookies */
  29#define FSCACHE_OBJLIST_CONFIG_BUSY     0x00000010      /* show busy objects */
  30#define FSCACHE_OBJLIST_CONFIG_IDLE     0x00000020      /* show idle objects */
  31#define FSCACHE_OBJLIST_CONFIG_PENDWR   0x00000040      /* show objects with pending writes */
  32#define FSCACHE_OBJLIST_CONFIG_NOPENDWR 0x00000080      /* show objects without pending writes */
  33#define FSCACHE_OBJLIST_CONFIG_READS    0x00000100      /* show objects with active reads */
  34#define FSCACHE_OBJLIST_CONFIG_NOREADS  0x00000200      /* show objects without active reads */
  35#define FSCACHE_OBJLIST_CONFIG_EVENTS   0x00000400      /* show objects with events */
  36#define FSCACHE_OBJLIST_CONFIG_NOEVENTS 0x00000800      /* show objects without no events */
  37#define FSCACHE_OBJLIST_CONFIG_WORK     0x00001000      /* show objects with work */
  38#define FSCACHE_OBJLIST_CONFIG_NOWORK   0x00002000      /* show objects without work */
  39
  40        u8              buf[512];       /* key and aux data buffer */
  41};
  42
  43/*
  44 * Add an object to the object list
  45 * - we use the address of the fscache_object structure as the key into the
  46 *   tree
  47 */
  48void fscache_objlist_add(struct fscache_object *obj)
  49{
  50        struct fscache_object *xobj;
  51        struct rb_node **p = &fscache_object_list.rb_node, *parent = NULL;
  52
  53        write_lock(&fscache_object_list_lock);
  54
  55        while (*p) {
  56                parent = *p;
  57                xobj = rb_entry(parent, struct fscache_object, objlist_link);
  58
  59                if (obj < xobj)
  60                        p = &(*p)->rb_left;
  61                else if (obj > xobj)
  62                        p = &(*p)->rb_right;
  63                else
  64                        BUG();
  65        }
  66
  67        rb_link_node(&obj->objlist_link, parent, p);
  68        rb_insert_color(&obj->objlist_link, &fscache_object_list);
  69
  70        write_unlock(&fscache_object_list_lock);
  71}
  72
  73/**
  74 * fscache_object_destroy - Note that a cache object is about to be destroyed
  75 * @object: The object to be destroyed
  76 *
  77 * Note the imminent destruction and deallocation of a cache object record.
  78 */
  79void fscache_object_destroy(struct fscache_object *obj)
  80{
  81        write_lock(&fscache_object_list_lock);
  82
  83        BUG_ON(RB_EMPTY_ROOT(&fscache_object_list));
  84        rb_erase(&obj->objlist_link, &fscache_object_list);
  85
  86        write_unlock(&fscache_object_list_lock);
  87}
  88EXPORT_SYMBOL(fscache_object_destroy);
  89
  90/*
  91 * find the object in the tree on or after the specified index
  92 */
  93static struct fscache_object *fscache_objlist_lookup(loff_t *_pos)
  94{
  95        struct fscache_object *pobj, *obj = NULL, *minobj = NULL;
  96        struct rb_node *p;
  97        unsigned long pos;
  98
  99        if (*_pos >= (unsigned long) ERR_PTR(-ENOENT))
 100                return NULL;
 101        pos = *_pos;
 102
 103        /* banners (can't represent line 0 by pos 0 as that would involve
 104         * returning a NULL pointer) */
 105        if (pos == 0)
 106                return (struct fscache_object *)(long)++(*_pos);
 107        if (pos < 3)
 108                return (struct fscache_object *)pos;
 109
 110        pobj = (struct fscache_object *)pos;
 111        p = fscache_object_list.rb_node;
 112        while (p) {
 113                obj = rb_entry(p, struct fscache_object, objlist_link);
 114                if (pobj < obj) {
 115                        if (!minobj || minobj > obj)
 116                                minobj = obj;
 117                        p = p->rb_left;
 118                } else if (pobj > obj) {
 119                        p = p->rb_right;
 120                } else {
 121                        minobj = obj;
 122                        break;
 123                }
 124                obj = NULL;
 125        }
 126
 127        if (!minobj)
 128                *_pos = (unsigned long) ERR_PTR(-ENOENT);
 129        else if (minobj != obj)
 130                *_pos = (unsigned long) minobj;
 131        return minobj;
 132}
 133
 134/*
 135 * set up the iterator to start reading from the first line
 136 */
 137static void *fscache_objlist_start(struct seq_file *m, loff_t *_pos)
 138        __acquires(&fscache_object_list_lock)
 139{
 140        read_lock(&fscache_object_list_lock);
 141        return fscache_objlist_lookup(_pos);
 142}
 143
 144/*
 145 * move to the next line
 146 */
 147static void *fscache_objlist_next(struct seq_file *m, void *v, loff_t *_pos)
 148{
 149        (*_pos)++;
 150        return fscache_objlist_lookup(_pos);
 151}
 152
 153/*
 154 * clean up after reading
 155 */
 156static void fscache_objlist_stop(struct seq_file *m, void *v)
 157        __releases(&fscache_object_list_lock)
 158{
 159        read_unlock(&fscache_object_list_lock);
 160}
 161
 162/*
 163 * display an object
 164 */
 165static int fscache_objlist_show(struct seq_file *m, void *v)
 166{
 167        struct fscache_objlist_data *data = m->private;
 168        struct fscache_object *obj = v;
 169        unsigned long config = data->config;
 170        uint16_t keylen, auxlen;
 171        char _type[3], *type;
 172        bool no_cookie;
 173        u8 *buf = data->buf, *p;
 174
 175        if ((unsigned long) v == 1) {
 176                seq_puts(m, "OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS"
 177                         " EM EV F S"
 178                         " | NETFS_COOKIE_DEF TY FL NETFS_DATA");
 179                if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 180                              FSCACHE_OBJLIST_CONFIG_AUX))
 181                        seq_puts(m, "       ");
 182                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 183                        seq_puts(m, "OBJECT_KEY");
 184                if ((config & (FSCACHE_OBJLIST_CONFIG_KEY |
 185                               FSCACHE_OBJLIST_CONFIG_AUX)) ==
 186                    (FSCACHE_OBJLIST_CONFIG_KEY | FSCACHE_OBJLIST_CONFIG_AUX))
 187                        seq_puts(m, ", ");
 188                if (config & FSCACHE_OBJLIST_CONFIG_AUX)
 189                        seq_puts(m, "AUX_DATA");
 190                seq_puts(m, "\n");
 191                return 0;
 192        }
 193
 194        if ((unsigned long) v == 2) {
 195                seq_puts(m, "======== ======== ==== ===== === === === == ====="
 196                         " == == = ="
 197                         " | ================ == == ================");
 198                if (config & (FSCACHE_OBJLIST_CONFIG_KEY |
 199                              FSCACHE_OBJLIST_CONFIG_AUX))
 200                        seq_puts(m, " ================");
 201                seq_puts(m, "\n");
 202                return 0;
 203        }
 204
 205        /* filter out any unwanted objects */
 206#define FILTER(criterion, _yes, _no)                                    \
 207        do {                                                            \
 208                unsigned long yes = FSCACHE_OBJLIST_CONFIG_##_yes;      \
 209                unsigned long no = FSCACHE_OBJLIST_CONFIG_##_no;        \
 210                if (criterion) {                                        \
 211                        if (!(config & yes))                            \
 212                                return 0;                               \
 213                } else {                                                \
 214                        if (!(config & no))                             \
 215                                return 0;                               \
 216                }                                                       \
 217        } while(0)
 218
 219        if (~config) {
 220                FILTER(obj->cookie,
 221                       COOKIE, NOCOOKIE);
 222                FILTER(obj->state != FSCACHE_OBJECT_ACTIVE ||
 223                       obj->n_ops != 0 ||
 224                       obj->n_obj_ops != 0 ||
 225                       obj->flags ||
 226                       !list_empty(&obj->dependents),
 227                       BUSY, IDLE);
 228                FILTER(test_bit(FSCACHE_OBJECT_PENDING_WRITE, &obj->flags),
 229                       PENDWR, NOPENDWR);
 230                FILTER(atomic_read(&obj->n_reads),
 231                       READS, NOREADS);
 232                FILTER(obj->events & obj->event_mask,
 233                       EVENTS, NOEVENTS);
 234                FILTER(work_busy(&obj->work), WORK, NOWORK);
 235        }
 236
 237        seq_printf(m,
 238                   "%8x %8x %s %5u %3u %3u %3u %2u %5u %2lx %2lx %1lx %1x | ",
 239                   obj->debug_id,
 240                   obj->parent ? obj->parent->debug_id : -1,
 241                   fscache_object_states_short[obj->state],
 242                   obj->n_children,
 243                   obj->n_ops,
 244                   obj->n_obj_ops,
 245                   obj->n_in_progress,
 246                   obj->n_exclusive,
 247                   atomic_read(&obj->n_reads),
 248                   obj->event_mask & FSCACHE_OBJECT_EVENTS_MASK,
 249                   obj->events,
 250                   obj->flags,
 251                   work_busy(&obj->work));
 252
 253        no_cookie = true;
 254        keylen = auxlen = 0;
 255        if (obj->cookie) {
 256                spin_lock(&obj->lock);
 257                if (obj->cookie) {
 258                        switch (obj->cookie->def->type) {
 259                        case 0:
 260                                type = "IX";
 261                                break;
 262                        case 1:
 263                                type = "DT";
 264                                break;
 265                        default:
 266                                sprintf(_type, "%02u",
 267                                        obj->cookie->def->type);
 268                                type = _type;
 269                                break;
 270                        }
 271
 272                        seq_printf(m, "%-16s %s %2lx %16p",
 273                                   obj->cookie->def->name,
 274                                   type,
 275                                   obj->cookie->flags,
 276                                   obj->cookie->netfs_data);
 277
 278                        if (obj->cookie->def->get_key &&
 279                            config & FSCACHE_OBJLIST_CONFIG_KEY)
 280                                keylen = obj->cookie->def->get_key(
 281                                        obj->cookie->netfs_data,
 282                                        buf, 400);
 283
 284                        if (obj->cookie->def->get_aux &&
 285                            config & FSCACHE_OBJLIST_CONFIG_AUX)
 286                                auxlen = obj->cookie->def->get_aux(
 287                                        obj->cookie->netfs_data,
 288                                        buf + keylen, 512 - keylen);
 289
 290                        no_cookie = false;
 291                }
 292                spin_unlock(&obj->lock);
 293
 294                if (!no_cookie && (keylen > 0 || auxlen > 0)) {
 295                        seq_printf(m, " ");
 296                        for (p = buf; keylen > 0; keylen--)
 297                                seq_printf(m, "%02x", *p++);
 298                        if (auxlen > 0) {
 299                                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 300                                        seq_printf(m, ", ");
 301                                for (; auxlen > 0; auxlen--)
 302                                        seq_printf(m, "%02x", *p++);
 303                        }
 304                }
 305        }
 306
 307        if (no_cookie)
 308                seq_printf(m, "<no_cookie>\n");
 309        else
 310                seq_printf(m, "\n");
 311        return 0;
 312}
 313
 314static const struct seq_operations fscache_objlist_ops = {
 315        .start          = fscache_objlist_start,
 316        .stop           = fscache_objlist_stop,
 317        .next           = fscache_objlist_next,
 318        .show           = fscache_objlist_show,
 319};
 320
 321/*
 322 * get the configuration for filtering the list
 323 */
 324static void fscache_objlist_config(struct fscache_objlist_data *data)
 325{
 326#ifdef CONFIG_KEYS
 327        struct user_key_payload *confkey;
 328        unsigned long config;
 329        struct key *key;
 330        const char *buf;
 331        int len;
 332
 333        key = request_key(&key_type_user, "fscache:objlist", NULL);
 334        if (IS_ERR(key))
 335                goto no_config;
 336
 337        config = 0;
 338        rcu_read_lock();
 339
 340        confkey = key->payload.data;
 341        buf = confkey->data;
 342
 343        for (len = confkey->datalen - 1; len >= 0; len--) {
 344                switch (buf[len]) {
 345                case 'K': config |= FSCACHE_OBJLIST_CONFIG_KEY;         break;
 346                case 'A': config |= FSCACHE_OBJLIST_CONFIG_AUX;         break;
 347                case 'C': config |= FSCACHE_OBJLIST_CONFIG_COOKIE;      break;
 348                case 'c': config |= FSCACHE_OBJLIST_CONFIG_NOCOOKIE;    break;
 349                case 'B': config |= FSCACHE_OBJLIST_CONFIG_BUSY;        break;
 350                case 'b': config |= FSCACHE_OBJLIST_CONFIG_IDLE;        break;
 351                case 'W': config |= FSCACHE_OBJLIST_CONFIG_PENDWR;      break;
 352                case 'w': config |= FSCACHE_OBJLIST_CONFIG_NOPENDWR;    break;
 353                case 'R': config |= FSCACHE_OBJLIST_CONFIG_READS;       break;
 354                case 'r': config |= FSCACHE_OBJLIST_CONFIG_NOREADS;     break;
 355                case 'S': config |= FSCACHE_OBJLIST_CONFIG_WORK;        break;
 356                case 's': config |= FSCACHE_OBJLIST_CONFIG_NOWORK;      break;
 357                }
 358        }
 359
 360        rcu_read_unlock();
 361        key_put(key);
 362
 363        if (!(config & (FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE)))
 364            config   |= FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE;
 365        if (!(config & (FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE)))
 366            config   |= FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE;
 367        if (!(config & (FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR)))
 368            config   |= FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR;
 369        if (!(config & (FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS)))
 370            config   |= FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS;
 371        if (!(config & (FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS)))
 372            config   |= FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS;
 373        if (!(config & (FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK)))
 374            config   |= FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK;
 375
 376        data->config = config;
 377        return;
 378
 379no_config:
 380#endif
 381        data->config = ULONG_MAX;
 382}
 383
 384/*
 385 * open "/proc/fs/fscache/objects" to provide a list of active objects
 386 * - can be configured by a user-defined key added to the caller's keyrings
 387 */
 388static int fscache_objlist_open(struct inode *inode, struct file *file)
 389{
 390        struct fscache_objlist_data *data;
 391        struct seq_file *m;
 392        int ret;
 393
 394        ret = seq_open(file, &fscache_objlist_ops);
 395        if (ret < 0)
 396                return ret;
 397
 398        m = file->private_data;
 399
 400        /* buffer for key extraction */
 401        data = kmalloc(sizeof(struct fscache_objlist_data), GFP_KERNEL);
 402        if (!data) {
 403                seq_release(inode, file);
 404                return -ENOMEM;
 405        }
 406
 407        /* get the configuration key */
 408        fscache_objlist_config(data);
 409
 410        m->private = data;
 411        return 0;
 412}
 413
 414/*
 415 * clean up on close
 416 */
 417static int fscache_objlist_release(struct inode *inode, struct file *file)
 418{
 419        struct seq_file *m = file->private_data;
 420
 421        kfree(m->private);
 422        m->private = NULL;
 423        return seq_release(inode, file);
 424}
 425
 426const struct file_operations fscache_objlist_fops = {
 427        .owner          = THIS_MODULE,
 428        .open           = fscache_objlist_open,
 429        .read           = seq_read,
 430        .llseek         = seq_lseek,
 431        .release        = fscache_objlist_release,
 432};
 433
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