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 * Remove an object from the object list.
  75 */
  76void fscache_objlist_remove(struct fscache_object *obj)
  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 *buf = data->buf, *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->def->type) {
 253                case 0:
 254                        type = "IX";
 255                        break;
 256                case 1:
 257                        type = "DT";
 258                        break;
 259                default:
 260                        sprintf(_type, "%02u", cookie->def->type);
 261                        type = _type;
 262                        break;
 263                }
 264
 265                seq_printf(m, "%-16s %s %2lx %16p",
 266                           cookie->def->name,
 267                           type,
 268                           cookie->flags,
 269                           cookie->netfs_data);
 270
 271                if (cookie->def->get_key &&
 272                    config & FSCACHE_OBJLIST_CONFIG_KEY)
 273                        keylen = cookie->def->get_key(cookie->netfs_data,
 274                                                      buf, 400);
 275
 276                if (cookie->def->get_aux &&
 277                    config & FSCACHE_OBJLIST_CONFIG_AUX)
 278                        auxlen = cookie->def->get_aux(cookie->netfs_data,
 279                                                      buf + keylen, 512 - keylen);
 280                fscache_unuse_cookie(obj);
 281
 282                if (keylen > 0 || auxlen > 0) {
 283                        seq_printf(m, " ");
 284                        for (p = buf; keylen > 0; keylen--)
 285                                seq_printf(m, "%02x", *p++);
 286                        if (auxlen > 0) {
 287                                if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 288                                        seq_printf(m, ", ");
 289                                for (; auxlen > 0; auxlen--)
 290                                        seq_printf(m, "%02x", *p++);
 291                        }
 292                }
 293
 294                seq_printf(m, "\n");
 295        } else {
 296                seq_printf(m, "<no_netfs>\n");
 297        }
 298        return 0;
 299}
 300
 301static const struct seq_operations fscache_objlist_ops = {
 302        .start          = fscache_objlist_start,
 303        .stop           = fscache_objlist_stop,
 304        .next           = fscache_objlist_next,
 305        .show           = fscache_objlist_show,
 306};
 307
 308/*
 309 * get the configuration for filtering the list
 310 */
 311static void fscache_objlist_config(struct fscache_objlist_data *data)
 312{
 313#ifdef CONFIG_KEYS
 314        struct user_key_payload *confkey;
 315        unsigned long config;
 316        struct key *key;
 317        const char *buf;
 318        int len;
 319
 320        key = request_key(&key_type_user, "fscache:objlist", NULL);
 321        if (IS_ERR(key))
 322                goto no_config;
 323
 324        config = 0;
 325        rcu_read_lock();
 326
 327        confkey = key->payload.data;
 328        buf = confkey->data;
 329
 330        for (len = confkey->datalen - 1; len >= 0; len--) {
 331                switch (buf[len]) {
 332                case 'K': config |= FSCACHE_OBJLIST_CONFIG_KEY;         break;
 333                case 'A': config |= FSCACHE_OBJLIST_CONFIG_AUX;         break;
 334                case 'C': config |= FSCACHE_OBJLIST_CONFIG_COOKIE;      break;
 335                case 'c': config |= FSCACHE_OBJLIST_CONFIG_NOCOOKIE;    break;
 336                case 'B': config |= FSCACHE_OBJLIST_CONFIG_BUSY;        break;
 337                case 'b': config |= FSCACHE_OBJLIST_CONFIG_IDLE;        break;
 338                case 'W': config |= FSCACHE_OBJLIST_CONFIG_PENDWR;      break;
 339                case 'w': config |= FSCACHE_OBJLIST_CONFIG_NOPENDWR;    break;
 340                case 'R': config |= FSCACHE_OBJLIST_CONFIG_READS;       break;
 341                case 'r': config |= FSCACHE_OBJLIST_CONFIG_NOREADS;     break;
 342                case 'S': config |= FSCACHE_OBJLIST_CONFIG_WORK;        break;
 343                case 's': config |= FSCACHE_OBJLIST_CONFIG_NOWORK;      break;
 344                }
 345        }
 346
 347        rcu_read_unlock();
 348        key_put(key);
 349
 350        if (!(config & (FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE)))
 351            config   |= FSCACHE_OBJLIST_CONFIG_COOKIE | FSCACHE_OBJLIST_CONFIG_NOCOOKIE;
 352        if (!(config & (FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE)))
 353            config   |= FSCACHE_OBJLIST_CONFIG_BUSY | FSCACHE_OBJLIST_CONFIG_IDLE;
 354        if (!(config & (FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR)))
 355            config   |= FSCACHE_OBJLIST_CONFIG_PENDWR | FSCACHE_OBJLIST_CONFIG_NOPENDWR;
 356        if (!(config & (FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS)))
 357            config   |= FSCACHE_OBJLIST_CONFIG_READS | FSCACHE_OBJLIST_CONFIG_NOREADS;
 358        if (!(config & (FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS)))
 359            config   |= FSCACHE_OBJLIST_CONFIG_EVENTS | FSCACHE_OBJLIST_CONFIG_NOEVENTS;
 360        if (!(config & (FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK)))
 361            config   |= FSCACHE_OBJLIST_CONFIG_WORK | FSCACHE_OBJLIST_CONFIG_NOWORK;
 362
 363        data->config = config;
 364        return;
 365
 366no_config:
 367#endif
 368        data->config = ULONG_MAX;
 369}
 370
 371/*
 372 * open "/proc/fs/fscache/objects" to provide a list of active objects
 373 * - can be configured by a user-defined key added to the caller's keyrings
 374 */
 375static int fscache_objlist_open(struct inode *inode, struct file *file)
 376{
 377        struct fscache_objlist_data *data;
 378        struct seq_file *m;
 379        int ret;
 380
 381        ret = seq_open(file, &fscache_objlist_ops);
 382        if (ret < 0)
 383                return ret;
 384
 385        m = file->private_data;
 386
 387        /* buffer for key extraction */
 388        data = kmalloc(sizeof(struct fscache_objlist_data), GFP_KERNEL);
 389        if (!data) {
 390                seq_release(inode, file);
 391                return -ENOMEM;
 392        }
 393
 394        /* get the configuration key */
 395        fscache_objlist_config(data);
 396
 397        m->private = data;
 398        return 0;
 399}
 400
 401/*
 402 * clean up on close
 403 */
 404static int fscache_objlist_release(struct inode *inode, struct file *file)
 405{
 406        struct seq_file *m = file->private_data;
 407
 408        kfree(m->private);
 409        m->private = NULL;
 410        return seq_release(inode, file);
 411}
 412
 413const struct file_operations fscache_objlist_fops = {
 414        .owner          = THIS_MODULE,
 415        .open           = fscache_objlist_open,
 416        .read           = seq_read,
 417        .llseek         = seq_lseek,
 418        .release        = fscache_objlist_release,
 419};
 420