linux/fs/ocfs2/dlmfs/dlmfs.c
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * dlmfs.c
   5 *
   6 * Code which implements the kernel side of a minimal userspace
   7 * interface to our DLM. This file handles the virtual file system
   8 * used for communication with userspace. Credit should go to ramfs,
   9 * which was a template for the fs side of this module.
  10 *
  11 * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  12 *
  13 * This program is free software; you can redistribute it and/or
  14 * modify it under the terms of the GNU General Public
  15 * License as published by the Free Software Foundation; either
  16 * version 2 of the License, or (at your option) any later version.
  17 *
  18 * This program is distributed in the hope that it will be useful,
  19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21 * General Public License for more details.
  22 *
  23 * You should have received a copy of the GNU General Public
  24 * License along with this program; if not, write to the
  25 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  26 * Boston, MA 021110-1307, USA.
  27 */
  28
  29/* Simple VFS hooks based on: */
  30/*
  31 * Resizable simple ram filesystem for Linux.
  32 *
  33 * Copyright (C) 2000 Linus Torvalds.
  34 *               2000 Transmeta Corp.
  35 */
  36
  37#include <linux/module.h>
  38#include <linux/fs.h>
  39#include <linux/pagemap.h>
  40#include <linux/types.h>
  41#include <linux/slab.h>
  42#include <linux/highmem.h>
  43#include <linux/init.h>
  44#include <linux/string.h>
  45#include <linux/backing-dev.h>
  46#include <linux/poll.h>
  47
  48#include <linux/uaccess.h>
  49
  50#include "stackglue.h"
  51#include "userdlm.h"
  52
  53#define MLOG_MASK_PREFIX ML_DLMFS
  54#include "cluster/masklog.h"
  55
  56
  57static const struct super_operations dlmfs_ops;
  58static const struct file_operations dlmfs_file_operations;
  59static const struct inode_operations dlmfs_dir_inode_operations;
  60static const struct inode_operations dlmfs_root_inode_operations;
  61static const struct inode_operations dlmfs_file_inode_operations;
  62static struct kmem_cache *dlmfs_inode_cache;
  63
  64struct workqueue_struct *user_dlm_worker;
  65
  66
  67
  68/*
  69 * These are the ABI capabilities of dlmfs.
  70 *
  71 * Over time, dlmfs has added some features that were not part of the
  72 * initial ABI.  Unfortunately, some of these features are not detectable
  73 * via standard usage.  For example, Linux's default poll always returns
  74 * POLLIN, so there is no way for a caller of poll(2) to know when dlmfs
  75 * added poll support.  Instead, we provide this list of new capabilities.
  76 *
  77 * Capabilities is a read-only attribute.  We do it as a module parameter
  78 * so we can discover it whether dlmfs is built in, loaded, or even not
  79 * loaded.
  80 *
  81 * The ABI features are local to this machine's dlmfs mount.  This is
  82 * distinct from the locking protocol, which is concerned with inter-node
  83 * interaction.
  84 *
  85 * Capabilities:
  86 * - bast       : POLLIN against the file descriptor of a held lock
  87 *                signifies a bast fired on the lock.
  88 */
  89#define DLMFS_CAPABILITIES "bast stackglue"
  90static int param_set_dlmfs_capabilities(const char *val,
  91                                        struct kernel_param *kp)
  92{
  93        printk(KERN_ERR "%s: readonly parameter\n", kp->name);
  94        return -EINVAL;
  95}
  96static int param_get_dlmfs_capabilities(char *buffer,
  97                                        struct kernel_param *kp)
  98{
  99        return strlcpy(buffer, DLMFS_CAPABILITIES,
 100                       strlen(DLMFS_CAPABILITIES) + 1);
 101}
 102module_param_call(capabilities, param_set_dlmfs_capabilities,
 103                  param_get_dlmfs_capabilities, NULL, 0444);
 104MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
 105
 106
 107/*
 108 * decodes a set of open flags into a valid lock level and a set of flags.
 109 * returns < 0 if we have invalid flags
 110 * flags which mean something to us:
 111 * O_RDONLY -> PRMODE level
 112 * O_WRONLY -> EXMODE level
 113 *
 114 * O_NONBLOCK -> NOQUEUE
 115 */
 116static int dlmfs_decode_open_flags(int open_flags,
 117                                   int *level,
 118                                   int *flags)
 119{
 120        if (open_flags & (O_WRONLY|O_RDWR))
 121                *level = DLM_LOCK_EX;
 122        else
 123                *level = DLM_LOCK_PR;
 124
 125        *flags = 0;
 126        if (open_flags & O_NONBLOCK)
 127                *flags |= DLM_LKF_NOQUEUE;
 128
 129        return 0;
 130}
 131
 132static int dlmfs_file_open(struct inode *inode,
 133                           struct file *file)
 134{
 135        int status, level, flags;
 136        struct dlmfs_filp_private *fp = NULL;
 137        struct dlmfs_inode_private *ip;
 138
 139        if (S_ISDIR(inode->i_mode))
 140                BUG();
 141
 142        mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
 143                file->f_flags);
 144
 145        status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
 146        if (status < 0)
 147                goto bail;
 148
 149        /* We don't want to honor O_APPEND at read/write time as it
 150         * doesn't make sense for LVB writes. */
 151        file->f_flags &= ~O_APPEND;
 152
 153        fp = kmalloc(sizeof(*fp), GFP_NOFS);
 154        if (!fp) {
 155                status = -ENOMEM;
 156                goto bail;
 157        }
 158        fp->fp_lock_level = level;
 159
 160        ip = DLMFS_I(inode);
 161
 162        status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
 163        if (status < 0) {
 164                /* this is a strange error to return here but I want
 165                 * to be able userspace to be able to distinguish a
 166                 * valid lock request from one that simply couldn't be
 167                 * granted. */
 168                if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
 169                        status = -ETXTBSY;
 170                kfree(fp);
 171                goto bail;
 172        }
 173
 174        file->private_data = fp;
 175bail:
 176        return status;
 177}
 178
 179static int dlmfs_file_release(struct inode *inode,
 180                              struct file *file)
 181{
 182        int level, status;
 183        struct dlmfs_inode_private *ip = DLMFS_I(inode);
 184        struct dlmfs_filp_private *fp = file->private_data;
 185
 186        if (S_ISDIR(inode->i_mode))
 187                BUG();
 188
 189        mlog(0, "close called on inode %lu\n", inode->i_ino);
 190
 191        status = 0;
 192        if (fp) {
 193                level = fp->fp_lock_level;
 194                if (level != DLM_LOCK_IV)
 195                        user_dlm_cluster_unlock(&ip->ip_lockres, level);
 196
 197                kfree(fp);
 198                file->private_data = NULL;
 199        }
 200
 201        return 0;
 202}
 203
 204/*
 205 * We do ->setattr() just to override size changes.  Our size is the size
 206 * of the LVB and nothing else.
 207 */
 208static int dlmfs_file_setattr(struct dentry *dentry, struct iattr *attr)
 209{
 210        int error;
 211        struct inode *inode = d_inode(dentry);
 212
 213        attr->ia_valid &= ~ATTR_SIZE;
 214        error = setattr_prepare(dentry, attr);
 215        if (error)
 216                return error;
 217
 218        setattr_copy(inode, attr);
 219        mark_inode_dirty(inode);
 220        return 0;
 221}
 222
 223static unsigned int dlmfs_file_poll(struct file *file, poll_table *wait)
 224{
 225        int event = 0;
 226        struct inode *inode = file_inode(file);
 227        struct dlmfs_inode_private *ip = DLMFS_I(inode);
 228
 229        poll_wait(file, &ip->ip_lockres.l_event, wait);
 230
 231        spin_lock(&ip->ip_lockres.l_lock);
 232        if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
 233                event = POLLIN | POLLRDNORM;
 234        spin_unlock(&ip->ip_lockres.l_lock);
 235
 236        return event;
 237}
 238
 239static ssize_t dlmfs_file_read(struct file *filp,
 240                               char __user *buf,
 241                               size_t count,
 242                               loff_t *ppos)
 243{
 244        int bytes_left;
 245        ssize_t readlen, got;
 246        char *lvb_buf;
 247        struct inode *inode = file_inode(filp);
 248
 249        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
 250                inode->i_ino, count, *ppos);
 251
 252        if (*ppos >= i_size_read(inode))
 253                return 0;
 254
 255        if (!count)
 256                return 0;
 257
 258        if (!access_ok(VERIFY_WRITE, buf, count))
 259                return -EFAULT;
 260
 261        /* don't read past the lvb */
 262        if ((count + *ppos) > i_size_read(inode))
 263                readlen = i_size_read(inode) - *ppos;
 264        else
 265                readlen = count;
 266
 267        lvb_buf = kmalloc(readlen, GFP_NOFS);
 268        if (!lvb_buf)
 269                return -ENOMEM;
 270
 271        got = user_dlm_read_lvb(inode, lvb_buf, readlen);
 272        if (got) {
 273                BUG_ON(got != readlen);
 274                bytes_left = __copy_to_user(buf, lvb_buf, readlen);
 275                readlen -= bytes_left;
 276        } else
 277                readlen = 0;
 278
 279        kfree(lvb_buf);
 280
 281        *ppos = *ppos + readlen;
 282
 283        mlog(0, "read %zd bytes\n", readlen);
 284        return readlen;
 285}
 286
 287static ssize_t dlmfs_file_write(struct file *filp,
 288                                const char __user *buf,
 289                                size_t count,
 290                                loff_t *ppos)
 291{
 292        int bytes_left;
 293        ssize_t writelen;
 294        char *lvb_buf;
 295        struct inode *inode = file_inode(filp);
 296
 297        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
 298                inode->i_ino, count, *ppos);
 299
 300        if (*ppos >= i_size_read(inode))
 301                return -ENOSPC;
 302
 303        if (!count)
 304                return 0;
 305
 306        if (!access_ok(VERIFY_READ, buf, count))
 307                return -EFAULT;
 308
 309        /* don't write past the lvb */
 310        if ((count + *ppos) > i_size_read(inode))
 311                writelen = i_size_read(inode) - *ppos;
 312        else
 313                writelen = count - *ppos;
 314
 315        lvb_buf = kmalloc(writelen, GFP_NOFS);
 316        if (!lvb_buf)
 317                return -ENOMEM;
 318
 319        bytes_left = copy_from_user(lvb_buf, buf, writelen);
 320        writelen -= bytes_left;
 321        if (writelen)
 322                user_dlm_write_lvb(inode, lvb_buf, writelen);
 323
 324        kfree(lvb_buf);
 325
 326        *ppos = *ppos + writelen;
 327        mlog(0, "wrote %zd bytes\n", writelen);
 328        return writelen;
 329}
 330
 331static void dlmfs_init_once(void *foo)
 332{
 333        struct dlmfs_inode_private *ip =
 334                (struct dlmfs_inode_private *) foo;
 335
 336        ip->ip_conn = NULL;
 337        ip->ip_parent = NULL;
 338
 339        inode_init_once(&ip->ip_vfs_inode);
 340}
 341
 342static struct inode *dlmfs_alloc_inode(struct super_block *sb)
 343{
 344        struct dlmfs_inode_private *ip;
 345
 346        ip = kmem_cache_alloc(dlmfs_inode_cache, GFP_NOFS);
 347        if (!ip)
 348                return NULL;
 349
 350        return &ip->ip_vfs_inode;
 351}
 352
 353static void dlmfs_i_callback(struct rcu_head *head)
 354{
 355        struct inode *inode = container_of(head, struct inode, i_rcu);
 356        kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
 357}
 358
 359static void dlmfs_destroy_inode(struct inode *inode)
 360{
 361        call_rcu(&inode->i_rcu, dlmfs_i_callback);
 362}
 363
 364static void dlmfs_evict_inode(struct inode *inode)
 365{
 366        int status;
 367        struct dlmfs_inode_private *ip;
 368
 369        clear_inode(inode);
 370
 371        mlog(0, "inode %lu\n", inode->i_ino);
 372
 373        ip = DLMFS_I(inode);
 374
 375        if (S_ISREG(inode->i_mode)) {
 376                status = user_dlm_destroy_lock(&ip->ip_lockres);
 377                if (status < 0)
 378                        mlog_errno(status);
 379                iput(ip->ip_parent);
 380                goto clear_fields;
 381        }
 382
 383        mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
 384        /* we must be a directory. If required, lets unregister the
 385         * dlm context now. */
 386        if (ip->ip_conn)
 387                user_dlm_unregister(ip->ip_conn);
 388clear_fields:
 389        ip->ip_parent = NULL;
 390        ip->ip_conn = NULL;
 391}
 392
 393static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 394{
 395        struct inode *inode = new_inode(sb);
 396        umode_t mode = S_IFDIR | 0755;
 397
 398        if (inode) {
 399                inode->i_ino = get_next_ino();
 400                inode_init_owner(inode, NULL, mode);
 401                inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 402                inc_nlink(inode);
 403
 404                inode->i_fop = &simple_dir_operations;
 405                inode->i_op = &dlmfs_root_inode_operations;
 406        }
 407
 408        return inode;
 409}
 410
 411static struct inode *dlmfs_get_inode(struct inode *parent,
 412                                     struct dentry *dentry,
 413                                     umode_t mode)
 414{
 415        struct super_block *sb = parent->i_sb;
 416        struct inode * inode = new_inode(sb);
 417        struct dlmfs_inode_private *ip;
 418
 419        if (!inode)
 420                return NULL;
 421
 422        inode->i_ino = get_next_ino();
 423        inode_init_owner(inode, parent, mode);
 424        inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 425
 426        ip = DLMFS_I(inode);
 427        ip->ip_conn = DLMFS_I(parent)->ip_conn;
 428
 429        switch (mode & S_IFMT) {
 430        default:
 431                /* for now we don't support anything other than
 432                 * directories and regular files. */
 433                BUG();
 434                break;
 435        case S_IFREG:
 436                inode->i_op = &dlmfs_file_inode_operations;
 437                inode->i_fop = &dlmfs_file_operations;
 438
 439                i_size_write(inode,  DLM_LVB_LEN);
 440
 441                user_dlm_lock_res_init(&ip->ip_lockres, dentry);
 442
 443                /* released at clear_inode time, this insures that we
 444                 * get to drop the dlm reference on each lock *before*
 445                 * we call the unregister code for releasing parent
 446                 * directories. */
 447                ip->ip_parent = igrab(parent);
 448                BUG_ON(!ip->ip_parent);
 449                break;
 450        case S_IFDIR:
 451                inode->i_op = &dlmfs_dir_inode_operations;
 452                inode->i_fop = &simple_dir_operations;
 453
 454                /* directory inodes start off with i_nlink ==
 455                 * 2 (for "." entry) */
 456                inc_nlink(inode);
 457                break;
 458        }
 459        return inode;
 460}
 461
 462/*
 463 * File creation. Allocate an inode, and we're done..
 464 */
 465/* SMP-safe */
 466static int dlmfs_mkdir(struct inode * dir,
 467                       struct dentry * dentry,
 468                       umode_t mode)
 469{
 470        int status;
 471        struct inode *inode = NULL;
 472        const struct qstr *domain = &dentry->d_name;
 473        struct dlmfs_inode_private *ip;
 474        struct ocfs2_cluster_connection *conn;
 475
 476        mlog(0, "mkdir %.*s\n", domain->len, domain->name);
 477
 478        /* verify that we have a proper domain */
 479        if (domain->len >= GROUP_NAME_MAX) {
 480                status = -EINVAL;
 481                mlog(ML_ERROR, "invalid domain name for directory.\n");
 482                goto bail;
 483        }
 484
 485        inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
 486        if (!inode) {
 487                status = -ENOMEM;
 488                mlog_errno(status);
 489                goto bail;
 490        }
 491
 492        ip = DLMFS_I(inode);
 493
 494        conn = user_dlm_register(domain);
 495        if (IS_ERR(conn)) {
 496                status = PTR_ERR(conn);
 497                mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
 498                     status, domain->len, domain->name);
 499                goto bail;
 500        }
 501        ip->ip_conn = conn;
 502
 503        inc_nlink(dir);
 504        d_instantiate(dentry, inode);
 505        dget(dentry);   /* Extra count - pin the dentry in core */
 506
 507        status = 0;
 508bail:
 509        if (status < 0)
 510                iput(inode);
 511        return status;
 512}
 513
 514static int dlmfs_create(struct inode *dir,
 515                        struct dentry *dentry,
 516                        umode_t mode,
 517                        bool excl)
 518{
 519        int status = 0;
 520        struct inode *inode;
 521        const struct qstr *name = &dentry->d_name;
 522
 523        mlog(0, "create %.*s\n", name->len, name->name);
 524
 525        /* verify name is valid and doesn't contain any dlm reserved
 526         * characters */
 527        if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
 528            name->name[0] == '$') {
 529                status = -EINVAL;
 530                mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
 531                     name->name);
 532                goto bail;
 533        }
 534
 535        inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
 536        if (!inode) {
 537                status = -ENOMEM;
 538                mlog_errno(status);
 539                goto bail;
 540        }
 541
 542        d_instantiate(dentry, inode);
 543        dget(dentry);   /* Extra count - pin the dentry in core */
 544bail:
 545        return status;
 546}
 547
 548static int dlmfs_unlink(struct inode *dir,
 549                        struct dentry *dentry)
 550{
 551        int status;
 552        struct inode *inode = d_inode(dentry);
 553
 554        mlog(0, "unlink inode %lu\n", inode->i_ino);
 555
 556        /* if there are no current holders, or none that are waiting
 557         * to acquire a lock, this basically destroys our lockres. */
 558        status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
 559        if (status < 0) {
 560                mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
 561                     dentry, status);
 562                goto bail;
 563        }
 564        status = simple_unlink(dir, dentry);
 565bail:
 566        return status;
 567}
 568
 569static int dlmfs_fill_super(struct super_block * sb,
 570                            void * data,
 571                            int silent)
 572{
 573        sb->s_maxbytes = MAX_LFS_FILESIZE;
 574        sb->s_blocksize = PAGE_SIZE;
 575        sb->s_blocksize_bits = PAGE_SHIFT;
 576        sb->s_magic = DLMFS_MAGIC;
 577        sb->s_op = &dlmfs_ops;
 578        sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
 579        if (!sb->s_root)
 580                return -ENOMEM;
 581        return 0;
 582}
 583
 584static const struct file_operations dlmfs_file_operations = {
 585        .open           = dlmfs_file_open,
 586        .release        = dlmfs_file_release,
 587        .poll           = dlmfs_file_poll,
 588        .read           = dlmfs_file_read,
 589        .write          = dlmfs_file_write,
 590        .llseek         = default_llseek,
 591};
 592
 593static const struct inode_operations dlmfs_dir_inode_operations = {
 594        .create         = dlmfs_create,
 595        .lookup         = simple_lookup,
 596        .unlink         = dlmfs_unlink,
 597};
 598
 599/* this way we can restrict mkdir to only the toplevel of the fs. */
 600static const struct inode_operations dlmfs_root_inode_operations = {
 601        .lookup         = simple_lookup,
 602        .mkdir          = dlmfs_mkdir,
 603        .rmdir          = simple_rmdir,
 604};
 605
 606static const struct super_operations dlmfs_ops = {
 607        .statfs         = simple_statfs,
 608        .alloc_inode    = dlmfs_alloc_inode,
 609        .destroy_inode  = dlmfs_destroy_inode,
 610        .evict_inode    = dlmfs_evict_inode,
 611        .drop_inode     = generic_delete_inode,
 612};
 613
 614static const struct inode_operations dlmfs_file_inode_operations = {
 615        .getattr        = simple_getattr,
 616        .setattr        = dlmfs_file_setattr,
 617};
 618
 619static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
 620        int flags, const char *dev_name, void *data)
 621{
 622        return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
 623}
 624
 625static struct file_system_type dlmfs_fs_type = {
 626        .owner          = THIS_MODULE,
 627        .name           = "ocfs2_dlmfs",
 628        .mount          = dlmfs_mount,
 629        .kill_sb        = kill_litter_super,
 630};
 631MODULE_ALIAS_FS("ocfs2_dlmfs");
 632
 633static int __init init_dlmfs_fs(void)
 634{
 635        int status;
 636        int cleanup_inode = 0, cleanup_worker = 0;
 637
 638        dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
 639                                sizeof(struct dlmfs_inode_private),
 640                                0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 641                                        SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 642                                dlmfs_init_once);
 643        if (!dlmfs_inode_cache) {
 644                status = -ENOMEM;
 645                goto bail;
 646        }
 647        cleanup_inode = 1;
 648
 649        user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0);
 650        if (!user_dlm_worker) {
 651                status = -ENOMEM;
 652                goto bail;
 653        }
 654        cleanup_worker = 1;
 655
 656        user_dlm_set_locking_protocol();
 657        status = register_filesystem(&dlmfs_fs_type);
 658bail:
 659        if (status) {
 660                if (cleanup_inode)
 661                        kmem_cache_destroy(dlmfs_inode_cache);
 662                if (cleanup_worker)
 663                        destroy_workqueue(user_dlm_worker);
 664        } else
 665                printk("OCFS2 User DLM kernel interface loaded\n");
 666        return status;
 667}
 668
 669static void __exit exit_dlmfs_fs(void)
 670{
 671        unregister_filesystem(&dlmfs_fs_type);
 672
 673        flush_workqueue(user_dlm_worker);
 674        destroy_workqueue(user_dlm_worker);
 675
 676        /*
 677         * Make sure all delayed rcu free inodes are flushed before we
 678         * destroy cache.
 679         */
 680        rcu_barrier();
 681        kmem_cache_destroy(dlmfs_inode_cache);
 682
 683}
 684
 685MODULE_AUTHOR("Oracle");
 686MODULE_LICENSE("GPL");
 687MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
 688
 689module_init(init_dlmfs_fs)
 690module_exit(exit_dlmfs_fs)
 691