root/fs/ocfs2/dlmfs/dlmfs.c

DEFINITIONS

1. param_set_dlmfs_capabilities
2. param_get_dlmfs_capabilities
3. dlmfs_decode_open_flags
4. dlmfs_file_open
5. dlmfs_file_release
6. dlmfs_file_setattr
7. dlmfs_file_poll
8. dlmfs_file_read
9. dlmfs_file_write
10. dlmfs_init_once
11. dlmfs_alloc_inode
12. dlmfs_free_inode
13. dlmfs_evict_inode
14. dlmfs_get_root_inode
15. dlmfs_get_inode
16. dlmfs_mkdir
17. dlmfs_create
18. dlmfs_unlink
19. dlmfs_fill_super
20. dlmfs_mount
21. init_dlmfs_fs
22. exit_dlmfs_fs

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* -*- mode: c; c-basic-offset: 8; -*-
   3  * vim: noexpandtab sw=8 ts=8 sts=0:
   4  *
   5  * dlmfs.c
   6  *
   7  * Code which implements the kernel side of a minimal userspace
   8  * interface to our DLM. This file handles the virtual file system
   9  * used for communication with userspace. Credit should go to ramfs,
  10  * which was a template for the fs side of this module.
  11  *
  12  * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
  13  */
  14 
  15 /* Simple VFS hooks based on: */
  16 /*
  17  * Resizable simple ram filesystem for Linux.
  18  *
  19  * Copyright (C) 2000 Linus Torvalds.
  20  *               2000 Transmeta Corp.
  21  */
  22 
  23 #include <linux/module.h>
  24 #include <linux/fs.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/types.h>
  27 #include <linux/slab.h>
  28 #include <linux/highmem.h>
  29 #include <linux/init.h>
  30 #include <linux/string.h>
  31 #include <linux/backing-dev.h>
  32 #include <linux/poll.h>
  33 
  34 #include <linux/uaccess.h>
  35 
  36 #include "../stackglue.h"
  37 #include "userdlm.h"
  38 
  39 #define MLOG_MASK_PREFIX ML_DLMFS
  40 #include "../cluster/masklog.h"
  41 
  42 
  43 static const struct super_operations dlmfs_ops;
  44 static const struct file_operations dlmfs_file_operations;
  45 static const struct inode_operations dlmfs_dir_inode_operations;
  46 static const struct inode_operations dlmfs_root_inode_operations;
  47 static const struct inode_operations dlmfs_file_inode_operations;
  48 static struct kmem_cache *dlmfs_inode_cache;
  49 
  50 struct workqueue_struct *user_dlm_worker;
  51 
  52 
  53 
  54 /*
  55  * These are the ABI capabilities of dlmfs.
  56  *
  57  * Over time, dlmfs has added some features that were not part of the
  58  * initial ABI.  Unfortunately, some of these features are not detectable
  59  * via standard usage.  For example, Linux's default poll always returns
  60  * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs
  61  * added poll support.  Instead, we provide this list of new capabilities.
  62  *
  63  * Capabilities is a read-only attribute.  We do it as a module parameter
  64  * so we can discover it whether dlmfs is built in, loaded, or even not
  65  * loaded.
  66  *
  67  * The ABI features are local to this machine's dlmfs mount.  This is
  68  * distinct from the locking protocol, which is concerned with inter-node
  69  * interaction.
  70  *
  71  * Capabilities:
  72  * - bast       : EPOLLIN against the file descriptor of a held lock
  73  *                signifies a bast fired on the lock.
  74  */
  75 #define DLMFS_CAPABILITIES "bast stackglue"
  76 static int param_set_dlmfs_capabilities(const char *val,
  77                                         const struct kernel_param *kp)
  78 {
  79         printk(KERN_ERR "%s: readonly parameter\n", kp->name);
  80         return -EINVAL;
  81 }
  82 static int param_get_dlmfs_capabilities(char *buffer,
  83                                         const struct kernel_param *kp)
  84 {
  85         return strlcpy(buffer, DLMFS_CAPABILITIES,
  86                        strlen(DLMFS_CAPABILITIES) + 1);
  87 }
  88 module_param_call(capabilities, param_set_dlmfs_capabilities,
  89                   param_get_dlmfs_capabilities, NULL, 0444);
  90 MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
  91 
  92 
  93 /*
  94  * decodes a set of open flags into a valid lock level and a set of flags.
  95  * returns < 0 if we have invalid flags
  96  * flags which mean something to us:
  97  * O_RDONLY -> PRMODE level
  98  * O_WRONLY -> EXMODE level
  99  *
 100  * O_NONBLOCK -> NOQUEUE
 101  */
 102 static int dlmfs_decode_open_flags(int open_flags,
 103                                    int *level,
 104                                    int *flags)
 105 {
 106         if (open_flags & (O_WRONLY|O_RDWR))
 107                 *level = DLM_LOCK_EX;
 108         else
 109                 *level = DLM_LOCK_PR;
 110 
 111         *flags = 0;
 112         if (open_flags & O_NONBLOCK)
 113                 *flags |= DLM_LKF_NOQUEUE;
 114 
 115         return 0;
 116 }
 117 
 118 static int dlmfs_file_open(struct inode *inode,
 119                            struct file *file)
 120 {
 121         int status, level, flags;
 122         struct dlmfs_filp_private *fp = NULL;
 123         struct dlmfs_inode_private *ip;
 124 
 125         if (S_ISDIR(inode->i_mode))
 126                 BUG();
 127 
 128         mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
 129                 file->f_flags);
 130 
 131         status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
 132         if (status < 0)
 133                 goto bail;
 134 
 135         /* We don't want to honor O_APPEND at read/write time as it
 136          * doesn't make sense for LVB writes. */
 137         file->f_flags &= ~O_APPEND;
 138 
 139         fp = kmalloc(sizeof(*fp), GFP_NOFS);
 140         if (!fp) {
 141                 status = -ENOMEM;
 142                 goto bail;
 143         }
 144         fp->fp_lock_level = level;
 145 
 146         ip = DLMFS_I(inode);
 147 
 148         status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
 149         if (status < 0) {
 150                 /* this is a strange error to return here but I want
 151                  * to be able userspace to be able to distinguish a
 152                  * valid lock request from one that simply couldn't be
 153                  * granted. */
 154                 if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
 155                         status = -ETXTBSY;
 156                 kfree(fp);
 157                 goto bail;
 158         }
 159 
 160         file->private_data = fp;
 161 bail:
 162         return status;
 163 }
 164 
 165 static int dlmfs_file_release(struct inode *inode,
 166                               struct file *file)
 167 {
 168         int level;
 169         struct dlmfs_inode_private *ip = DLMFS_I(inode);
 170         struct dlmfs_filp_private *fp = file->private_data;
 171 
 172         if (S_ISDIR(inode->i_mode))
 173                 BUG();
 174 
 175         mlog(0, "close called on inode %lu\n", inode->i_ino);
 176 
 177         if (fp) {
 178                 level = fp->fp_lock_level;
 179                 if (level != DLM_LOCK_IV)
 180                         user_dlm_cluster_unlock(&ip->ip_lockres, level);
 181 
 182                 kfree(fp);
 183                 file->private_data = NULL;
 184         }
 185 
 186         return 0;
 187 }
 188 
 189 /*
 190  * We do ->setattr() just to override size changes.  Our size is the size
 191  * of the LVB and nothing else.
 192  */
 193 static int dlmfs_file_setattr(struct dentry *dentry, struct iattr *attr)
 194 {
 195         int error;
 196         struct inode *inode = d_inode(dentry);
 197 
 198         attr->ia_valid &= ~ATTR_SIZE;
 199         error = setattr_prepare(dentry, attr);
 200         if (error)
 201                 return error;
 202 
 203         setattr_copy(inode, attr);
 204         mark_inode_dirty(inode);
 205         return 0;
 206 }
 207 
 208 static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait)
 209 {
 210         __poll_t event = 0;
 211         struct inode *inode = file_inode(file);
 212         struct dlmfs_inode_private *ip = DLMFS_I(inode);
 213 
 214         poll_wait(file, &ip->ip_lockres.l_event, wait);
 215 
 216         spin_lock(&ip->ip_lockres.l_lock);
 217         if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
 218                 event = EPOLLIN | EPOLLRDNORM;
 219         spin_unlock(&ip->ip_lockres.l_lock);
 220 
 221         return event;
 222 }
 223 
 224 static ssize_t dlmfs_file_read(struct file *filp,
 225                                char __user *buf,
 226                                size_t count,
 227                                loff_t *ppos)
 228 {
 229         int bytes_left;
 230         ssize_t readlen, got;
 231         char *lvb_buf;
 232         struct inode *inode = file_inode(filp);
 233 
 234         mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
 235                 inode->i_ino, count, *ppos);
 236 
 237         if (*ppos >= i_size_read(inode))
 238                 return 0;
 239 
 240         if (!count)
 241                 return 0;
 242 
 243         if (!access_ok(buf, count))
 244                 return -EFAULT;
 245 
 246         /* don't read past the lvb */
 247         if ((count + *ppos) > i_size_read(inode))
 248                 readlen = i_size_read(inode) - *ppos;
 249         else
 250                 readlen = count;
 251 
 252         lvb_buf = kmalloc(readlen, GFP_NOFS);
 253         if (!lvb_buf)
 254                 return -ENOMEM;
 255 
 256         got = user_dlm_read_lvb(inode, lvb_buf, readlen);
 257         if (got) {
 258                 BUG_ON(got != readlen);
 259                 bytes_left = __copy_to_user(buf, lvb_buf, readlen);
 260                 readlen -= bytes_left;
 261         } else
 262                 readlen = 0;
 263 
 264         kfree(lvb_buf);
 265 
 266         *ppos = *ppos + readlen;
 267 
 268         mlog(0, "read %zd bytes\n", readlen);
 269         return readlen;
 270 }
 271 
 272 static ssize_t dlmfs_file_write(struct file *filp,
 273                                 const char __user *buf,
 274                                 size_t count,
 275                                 loff_t *ppos)
 276 {
 277         int bytes_left;
 278         char *lvb_buf;
 279         struct inode *inode = file_inode(filp);
 280 
 281         mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
 282                 inode->i_ino, count, *ppos);
 283 
 284         if (*ppos >= i_size_read(inode))
 285                 return -ENOSPC;
 286 
 287         /* don't write past the lvb */
 288         if (count > i_size_read(inode) - *ppos)
 289                 count = i_size_read(inode) - *ppos;
 290 
 291         if (!count)
 292                 return 0;
 293 
 294         if (!access_ok(buf, count))
 295                 return -EFAULT;
 296 
 297         lvb_buf = kmalloc(count, GFP_NOFS);
 298         if (!lvb_buf)
 299                 return -ENOMEM;
 300 
 301         bytes_left = copy_from_user(lvb_buf, buf, count);
 302         count -= bytes_left;
 303         if (count)
 304                 user_dlm_write_lvb(inode, lvb_buf, count);
 305 
 306         kfree(lvb_buf);
 307 
 308         *ppos = *ppos + count;
 309         mlog(0, "wrote %zu bytes\n", count);
 310         return count;
 311 }
 312 
 313 static void dlmfs_init_once(void *foo)
 314 {
 315         struct dlmfs_inode_private *ip =
 316                 (struct dlmfs_inode_private *) foo;
 317 
 318         ip->ip_conn = NULL;
 319         ip->ip_parent = NULL;
 320 
 321         inode_init_once(&ip->ip_vfs_inode);
 322 }
 323 
 324 static struct inode *dlmfs_alloc_inode(struct super_block *sb)
 325 {
 326         struct dlmfs_inode_private *ip;
 327 
 328         ip = kmem_cache_alloc(dlmfs_inode_cache, GFP_NOFS);
 329         if (!ip)
 330                 return NULL;
 331 
 332         return &ip->ip_vfs_inode;
 333 }
 334 
 335 static void dlmfs_free_inode(struct inode *inode)
 336 {
 337         kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
 338 }
 339 
 340 static void dlmfs_evict_inode(struct inode *inode)
 341 {
 342         int status;
 343         struct dlmfs_inode_private *ip;
 344 
 345         clear_inode(inode);
 346 
 347         mlog(0, "inode %lu\n", inode->i_ino);
 348 
 349         ip = DLMFS_I(inode);
 350 
 351         if (S_ISREG(inode->i_mode)) {
 352                 status = user_dlm_destroy_lock(&ip->ip_lockres);
 353                 if (status < 0)
 354                         mlog_errno(status);
 355                 iput(ip->ip_parent);
 356                 goto clear_fields;
 357         }
 358 
 359         mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
 360         /* we must be a directory. If required, lets unregister the
 361          * dlm context now. */
 362         if (ip->ip_conn)
 363                 user_dlm_unregister(ip->ip_conn);
 364 clear_fields:
 365         ip->ip_parent = NULL;
 366         ip->ip_conn = NULL;
 367 }
 368 
 369 static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 370 {
 371         struct inode *inode = new_inode(sb);
 372         umode_t mode = S_IFDIR | 0755;
 373 
 374         if (inode) {
 375                 inode->i_ino = get_next_ino();
 376                 inode_init_owner(inode, NULL, mode);
 377                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 378                 inc_nlink(inode);
 379 
 380                 inode->i_fop = &simple_dir_operations;
 381                 inode->i_op = &dlmfs_root_inode_operations;
 382         }
 383 
 384         return inode;
 385 }
 386 
 387 static struct inode *dlmfs_get_inode(struct inode *parent,
 388                                      struct dentry *dentry,
 389                                      umode_t mode)
 390 {
 391         struct super_block *sb = parent->i_sb;
 392         struct inode * inode = new_inode(sb);
 393         struct dlmfs_inode_private *ip;
 394 
 395         if (!inode)
 396                 return NULL;
 397 
 398         inode->i_ino = get_next_ino();
 399         inode_init_owner(inode, parent, mode);
 400         inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 401 
 402         ip = DLMFS_I(inode);
 403         ip->ip_conn = DLMFS_I(parent)->ip_conn;
 404 
 405         switch (mode & S_IFMT) {
 406         default:
 407                 /* for now we don't support anything other than
 408                  * directories and regular files. */
 409                 BUG();
 410                 break;
 411         case S_IFREG:
 412                 inode->i_op = &dlmfs_file_inode_operations;
 413                 inode->i_fop = &dlmfs_file_operations;
 414 
 415                 i_size_write(inode,  DLM_LVB_LEN);
 416 
 417                 user_dlm_lock_res_init(&ip->ip_lockres, dentry);
 418 
 419                 /* released at clear_inode time, this insures that we
 420                  * get to drop the dlm reference on each lock *before*
 421                  * we call the unregister code for releasing parent
 422                  * directories. */
 423                 ip->ip_parent = igrab(parent);
 424                 BUG_ON(!ip->ip_parent);
 425                 break;
 426         case S_IFDIR:
 427                 inode->i_op = &dlmfs_dir_inode_operations;
 428                 inode->i_fop = &simple_dir_operations;
 429 
 430                 /* directory inodes start off with i_nlink ==
 431                  * 2 (for "." entry) */
 432                 inc_nlink(inode);
 433                 break;
 434         }
 435         return inode;
 436 }
 437 
 438 /*
 439  * File creation. Allocate an inode, and we're done..
 440  */
 441 /* SMP-safe */
 442 static int dlmfs_mkdir(struct inode * dir,
 443                        struct dentry * dentry,
 444                        umode_t mode)
 445 {
 446         int status;
 447         struct inode *inode = NULL;
 448         const struct qstr *domain = &dentry->d_name;
 449         struct dlmfs_inode_private *ip;
 450         struct ocfs2_cluster_connection *conn;
 451 
 452         mlog(0, "mkdir %.*s\n", domain->len, domain->name);
 453 
 454         /* verify that we have a proper domain */
 455         if (domain->len >= GROUP_NAME_MAX) {
 456                 status = -EINVAL;
 457                 mlog(ML_ERROR, "invalid domain name for directory.\n");
 458                 goto bail;
 459         }
 460 
 461         inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
 462         if (!inode) {
 463                 status = -ENOMEM;
 464                 mlog_errno(status);
 465                 goto bail;
 466         }
 467 
 468         ip = DLMFS_I(inode);
 469 
 470         conn = user_dlm_register(domain);
 471         if (IS_ERR(conn)) {
 472                 status = PTR_ERR(conn);
 473                 mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
 474                      status, domain->len, domain->name);
 475                 goto bail;
 476         }
 477         ip->ip_conn = conn;
 478 
 479         inc_nlink(dir);
 480         d_instantiate(dentry, inode);
 481         dget(dentry);   /* Extra count - pin the dentry in core */
 482 
 483         status = 0;
 484 bail:
 485         if (status < 0)
 486                 iput(inode);
 487         return status;
 488 }
 489 
 490 static int dlmfs_create(struct inode *dir,
 491                         struct dentry *dentry,
 492                         umode_t mode,
 493                         bool excl)
 494 {
 495         int status = 0;
 496         struct inode *inode;
 497         const struct qstr *name = &dentry->d_name;
 498 
 499         mlog(0, "create %.*s\n", name->len, name->name);
 500 
 501         /* verify name is valid and doesn't contain any dlm reserved
 502          * characters */
 503         if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
 504             name->name[0] == '$') {
 505                 status = -EINVAL;
 506                 mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
 507                      name->name);
 508                 goto bail;
 509         }
 510 
 511         inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
 512         if (!inode) {
 513                 status = -ENOMEM;
 514                 mlog_errno(status);
 515                 goto bail;
 516         }
 517 
 518         d_instantiate(dentry, inode);
 519         dget(dentry);   /* Extra count - pin the dentry in core */
 520 bail:
 521         return status;
 522 }
 523 
 524 static int dlmfs_unlink(struct inode *dir,
 525                         struct dentry *dentry)
 526 {
 527         int status;
 528         struct inode *inode = d_inode(dentry);
 529 
 530         mlog(0, "unlink inode %lu\n", inode->i_ino);
 531 
 532         /* if there are no current holders, or none that are waiting
 533          * to acquire a lock, this basically destroys our lockres. */
 534         status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
 535         if (status < 0) {
 536                 mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
 537                      dentry, status);
 538                 goto bail;
 539         }
 540         status = simple_unlink(dir, dentry);
 541 bail:
 542         return status;
 543 }
 544 
 545 static int dlmfs_fill_super(struct super_block * sb,
 546                             void * data,
 547                             int silent)
 548 {
 549         sb->s_maxbytes = MAX_LFS_FILESIZE;
 550         sb->s_blocksize = PAGE_SIZE;
 551         sb->s_blocksize_bits = PAGE_SHIFT;
 552         sb->s_magic = DLMFS_MAGIC;
 553         sb->s_op = &dlmfs_ops;
 554         sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
 555         if (!sb->s_root)
 556                 return -ENOMEM;
 557         return 0;
 558 }
 559 
 560 static const struct file_operations dlmfs_file_operations = {
 561         .open           = dlmfs_file_open,
 562         .release        = dlmfs_file_release,
 563         .poll           = dlmfs_file_poll,
 564         .read           = dlmfs_file_read,
 565         .write          = dlmfs_file_write,
 566         .llseek         = default_llseek,
 567 };
 568 
 569 static const struct inode_operations dlmfs_dir_inode_operations = {
 570         .create         = dlmfs_create,
 571         .lookup         = simple_lookup,
 572         .unlink         = dlmfs_unlink,
 573 };
 574 
 575 /* this way we can restrict mkdir to only the toplevel of the fs. */
 576 static const struct inode_operations dlmfs_root_inode_operations = {
 577         .lookup         = simple_lookup,
 578         .mkdir          = dlmfs_mkdir,
 579         .rmdir          = simple_rmdir,
 580 };
 581 
 582 static const struct super_operations dlmfs_ops = {
 583         .statfs         = simple_statfs,
 584         .alloc_inode    = dlmfs_alloc_inode,
 585         .free_inode     = dlmfs_free_inode,
 586         .evict_inode    = dlmfs_evict_inode,
 587         .drop_inode     = generic_delete_inode,
 588 };
 589 
 590 static const struct inode_operations dlmfs_file_inode_operations = {
 591         .getattr        = simple_getattr,
 592         .setattr        = dlmfs_file_setattr,
 593 };
 594 
 595 static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
 596         int flags, const char *dev_name, void *data)
 597 {
 598         return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
 599 }
 600 
 601 static struct file_system_type dlmfs_fs_type = {
 602         .owner          = THIS_MODULE,
 603         .name           = "ocfs2_dlmfs",
 604         .mount          = dlmfs_mount,
 605         .kill_sb        = kill_litter_super,
 606 };
 607 MODULE_ALIAS_FS("ocfs2_dlmfs");
 608 
 609 static int __init init_dlmfs_fs(void)
 610 {
 611         int status;
 612         int cleanup_inode = 0, cleanup_worker = 0;
 613 
 614         dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
 615                                 sizeof(struct dlmfs_inode_private),
 616                                 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 617                                         SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 618                                 dlmfs_init_once);
 619         if (!dlmfs_inode_cache) {
 620                 status = -ENOMEM;
 621                 goto bail;
 622         }
 623         cleanup_inode = 1;
 624 
 625         user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0);
 626         if (!user_dlm_worker) {
 627                 status = -ENOMEM;
 628                 goto bail;
 629         }
 630         cleanup_worker = 1;
 631 
 632         user_dlm_set_locking_protocol();
 633         status = register_filesystem(&dlmfs_fs_type);
 634 bail:
 635         if (status) {
 636                 if (cleanup_inode)
 637                         kmem_cache_destroy(dlmfs_inode_cache);
 638                 if (cleanup_worker)
 639                         destroy_workqueue(user_dlm_worker);
 640         } else
 641                 printk("OCFS2 User DLM kernel interface loaded\n");
 642         return status;
 643 }
 644 
 645 static void __exit exit_dlmfs_fs(void)
 646 {
 647         unregister_filesystem(&dlmfs_fs_type);
 648 
 649         destroy_workqueue(user_dlm_worker);
 650 
 651         /*
 652          * Make sure all delayed rcu free inodes are flushed before we
 653          * destroy cache.
 654          */
 655         rcu_barrier();
 656         kmem_cache_destroy(dlmfs_inode_cache);
 657 
 658 }
 659 
 660 MODULE_AUTHOR("Oracle");
 661 MODULE_LICENSE("GPL");
 662 MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
 663 
 664 module_init(init_dlmfs_fs)
 665 module_exit(exit_dlmfs_fs)