fs/ceph/locks.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/ceph/ceph_debug.h>
   3
   4 #include <linux/file.h>
   5 #include <linux/namei.h>
   6 #include <linux/random.h>
   7
   8 #include "super.h"
   9 #include "mds_client.h"
  10 #include <linux/filelock.h>
  11 #include <linux/ceph/pagelist.h>
  12
  13 static u64 lock_secret;
  14 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
  15                                          struct ceph_mds_request *req);
  16
  17 static inline u64 secure_addr(void *addr)
  18 {
  19         u64 v = lock_secret ^ (u64)(unsigned long)addr;
  20         /*
  21          * Set the most significant bit, so that MDS knows the 'owner'
  22          * is sufficient to identify the owner of lock. (old code uses
  23          * both 'owner' and 'pid')
  24          */
  25         v |= (1ULL << 63);
  26         return v;
  27 }
  28
  29 void __init ceph_flock_init(void)
  30 {
  31         get_random_bytes(&lock_secret, sizeof(lock_secret));
  32 }
  33
  34 static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
  35 {
  36         struct inode *inode = file_inode(dst->fl_file);
  37         atomic_inc(&ceph_inode(inode)->i_filelock_ref);
  38         dst->fl_u.ceph.inode = igrab(inode);
  39 }
  40
  41 /*
  42  * Do not use the 'fl->fl_file' in release function, which
  43  * is possibly already released by another thread.
  44  */
  45 static void ceph_fl_release_lock(struct file_lock *fl)
  46 {
  47         struct inode *inode = fl->fl_u.ceph.inode;
  48         struct ceph_inode_info *ci;
  49
  50         /*
  51          * If inode is NULL it should be a request file_lock,
  52          * nothing we can do.
  53          */
  54         if (!inode)
  55                 return;
  56
  57         ci = ceph_inode(inode);
  58         if (atomic_dec_and_test(&ci->i_filelock_ref)) {
  59                 /* clear error when all locks are released */
  60                 spin_lock(&ci->i_ceph_lock);
  61                 ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
  62                 spin_unlock(&ci->i_ceph_lock);
  63         }
  64         fl->fl_u.ceph.inode = NULL;
  65         iput(inode);
  66 }
  67
  68 static const struct file_lock_operations ceph_fl_lock_ops = {
  69         .fl_copy_lock = ceph_fl_copy_lock,
  70         .fl_release_private = ceph_fl_release_lock,
  71 };
  72
  73 /*
  74  * Implement fcntl and flock locking functions.
  75  */
  76 static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
  77                              int cmd, u8 wait, struct file_lock *fl)
  78 {
  79         struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
  80         struct ceph_mds_request *req;
  81         int err;
  82         u64 length = 0;
  83         u64 owner;
  84
  85         if (operation == CEPH_MDS_OP_SETFILELOCK) {
  86                 /*
  87                  * increasing i_filelock_ref closes race window between
  88                  * handling request reply and adding file_lock struct to
  89                  * inode. Otherwise, auth caps may get trimmed in the
  90                  * window. Caller function will decrease the counter.
  91                  */
  92                 fl->fl_ops = &ceph_fl_lock_ops;
  93                 fl->fl_ops->fl_copy_lock(fl, NULL);
  94         }
  95
  96         if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
  97                 wait = 0;
  98
  99         req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
 100         if (IS_ERR(req))
 101                 return PTR_ERR(req);
 102         req->r_inode = inode;
 103         ihold(inode);
 104         req->r_num_caps = 1;
 105
 106         /* mds requires start and length rather than start and end */
 107         if (LLONG_MAX == fl->fl_end)
 108                 length = 0;
 109         else
 110                 length = fl->fl_end - fl->fl_start + 1;
 111
 112         owner = secure_addr(fl->fl_owner);
 113
 114         dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
 115              "start: %llu, length: %llu, wait: %d, type: %d\n", (int)lock_type,
 116              (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
 117              wait, fl->fl_type);
 118
 119         req->r_args.filelock_change.rule = lock_type;
 120         req->r_args.filelock_change.type = cmd;
 121         req->r_args.filelock_change.owner = cpu_to_le64(owner);
 122         req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
 123         req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
 124         req->r_args.filelock_change.length = cpu_to_le64(length);
 125         req->r_args.filelock_change.wait = wait;
 126
 127         err = ceph_mdsc_submit_request(mdsc, inode, req);
 128         if (!err)
 129                 err = ceph_mdsc_wait_request(mdsc, req, wait ?
 130                                         ceph_lock_wait_for_completion : NULL);
 131         if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
 132                 fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
 133                 if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
 134                         fl->fl_type = F_RDLCK;
 135                 else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
 136                         fl->fl_type = F_WRLCK;
 137                 else
 138                         fl->fl_type = F_UNLCK;
 139
 140                 fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
 141                 length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
 142                                                  le64_to_cpu(req->r_reply_info.filelock_reply->length);
 143                 if (length >= 1)
 144                         fl->fl_end = length -1;
 145                 else
 146                         fl->fl_end = 0;
 147
 148         }
 149         ceph_mdsc_put_request(req);
 150         dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
 151              "length: %llu, wait: %d, type: %d, err code %d\n", (int)lock_type,
 152              (int)operation, (u64)fl->fl_pid, fl->fl_start,
 153              length, wait, fl->fl_type, err);
 154         return err;
 155 }
 156
 157 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
 158                                          struct ceph_mds_request *req)
 159 {
 160         struct ceph_mds_request *intr_req;
 161         struct inode *inode = req->r_inode;
 162         int err, lock_type;
 163
 164         BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
 165         if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
 166                 lock_type = CEPH_LOCK_FCNTL_INTR;
 167         else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
 168                 lock_type = CEPH_LOCK_FLOCK_INTR;
 169         else
 170                 BUG_ON(1);
 171         BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);
 172
 173         err = wait_for_completion_interruptible(&req->r_completion);
 174         if (!err)
 175                 return 0;
 176
 177         dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
 178              req->r_tid);
 179
 180         mutex_lock(&mdsc->mutex);
 181         if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
 182                 err = 0;
 183         } else {
 184                 /*
 185                  * ensure we aren't running concurrently with
 186                  * ceph_fill_trace or ceph_readdir_prepopulate, which
 187                  * rely on locks (dir mutex) held by our caller.
 188                  */
 189                 mutex_lock(&req->r_fill_mutex);
 190                 req->r_err = err;
 191                 set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
 192                 mutex_unlock(&req->r_fill_mutex);
 193
 194                 if (!req->r_session) {
 195                         // haven't sent the request
 196                         err = 0;
 197                 }
 198         }
 199         mutex_unlock(&mdsc->mutex);
 200         if (!err)
 201                 return 0;
 202
 203         intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
 204                                             USE_AUTH_MDS);
 205         if (IS_ERR(intr_req))
 206                 return PTR_ERR(intr_req);
 207
 208         intr_req->r_inode = inode;
 209         ihold(inode);
 210         intr_req->r_num_caps = 1;
 211
 212         intr_req->r_args.filelock_change = req->r_args.filelock_change;
 213         intr_req->r_args.filelock_change.rule = lock_type;
 214         intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;
 215
 216         err = ceph_mdsc_do_request(mdsc, inode, intr_req);
 217         ceph_mdsc_put_request(intr_req);
 218
 219         if (err && err != -ERESTARTSYS)
 220                 return err;
 221
 222         wait_for_completion_killable(&req->r_safe_completion);
 223         return 0;
 224 }
 225
 226 static int try_unlock_file(struct file *file, struct file_lock *fl)
 227 {
 228         int err;
 229         unsigned int orig_flags = fl->fl_flags;
 230         fl->fl_flags |= FL_EXISTS;
 231         err = locks_lock_file_wait(file, fl);
 232         fl->fl_flags = orig_flags;
 233         if (err == -ENOENT) {
 234                 if (!(orig_flags & FL_EXISTS))
 235                         err = 0;
 236                 return err;
 237         }
 238         return 1;
 239 }
 240
 241 /*
 242  * Attempt to set an fcntl lock.
 243  * For now, this just goes away to the server. Later it may be more awesome.
 244  */
 245 int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 246 {
 247         struct inode *inode = file_inode(file);
 248         struct ceph_inode_info *ci = ceph_inode(inode);
 249         int err = 0;
 250         u16 op = CEPH_MDS_OP_SETFILELOCK;
 251         u8 wait = 0;
 252         u8 lock_cmd;
 253
 254         if (!(fl->fl_flags & FL_POSIX))
 255                 return -ENOLCK;
 256
 257         if (ceph_inode_is_shutdown(inode))
 258                 return -ESTALE;
 259
 260         dout("ceph_lock, fl_owner: %p\n", fl->fl_owner);
 261
 262         /* set wait bit as appropriate, then make command as Ceph expects it*/
 263         if (IS_GETLK(cmd))
 264                 op = CEPH_MDS_OP_GETFILELOCK;
 265         else if (IS_SETLKW(cmd))
 266                 wait = 1;
 267
 268         spin_lock(&ci->i_ceph_lock);
 269         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 270                 err = -EIO;
 271         }
 272         spin_unlock(&ci->i_ceph_lock);
 273         if (err < 0) {
 274                 if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type)
 275                         posix_lock_file(file, fl, NULL);
 276                 return err;
 277         }
 278
 279         if (F_RDLCK == fl->fl_type)
 280                 lock_cmd = CEPH_LOCK_SHARED;
 281         else if (F_WRLCK == fl->fl_type)
 282                 lock_cmd = CEPH_LOCK_EXCL;
 283         else
 284                 lock_cmd = CEPH_LOCK_UNLOCK;
 285
 286         if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
 287                 err = try_unlock_file(file, fl);
 288                 if (err <= 0)
 289                         return err;
 290         }
 291
 292         err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
 293         if (!err) {
 294                 if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->fl_type) {
 295                         dout("mds locked, locking locally\n");
 296                         err = posix_lock_file(file, fl, NULL);
 297                         if (err) {
 298                                 /* undo! This should only happen if
 299                                  * the kernel detects local
 300                                  * deadlock. */
 301                                 ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
 302                                                   CEPH_LOCK_UNLOCK, 0, fl);
 303                                 dout("got %d on posix_lock_file, undid lock\n",
 304                                      err);
 305                         }
 306                 }
 307         }
 308         return err;
 309 }
 310
 311 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 312 {
 313         struct inode *inode = file_inode(file);
 314         struct ceph_inode_info *ci = ceph_inode(inode);
 315         int err = 0;
 316         u8 wait = 0;
 317         u8 lock_cmd;
 318
 319         if (!(fl->fl_flags & FL_FLOCK))
 320                 return -ENOLCK;
 321
 322         if (ceph_inode_is_shutdown(inode))
 323                 return -ESTALE;
 324
 325         dout("ceph_flock, fl_file: %p\n", fl->fl_file);
 326
 327         spin_lock(&ci->i_ceph_lock);
 328         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 329                 err = -EIO;
 330         }
 331         spin_unlock(&ci->i_ceph_lock);
 332         if (err < 0) {
 333                 if (F_UNLCK == fl->fl_type)
 334                         locks_lock_file_wait(file, fl);
 335                 return err;
 336         }
 337
 338         if (IS_SETLKW(cmd))
 339                 wait = 1;
 340
 341         if (F_RDLCK == fl->fl_type)
 342                 lock_cmd = CEPH_LOCK_SHARED;
 343         else if (F_WRLCK == fl->fl_type)
 344                 lock_cmd = CEPH_LOCK_EXCL;
 345         else
 346                 lock_cmd = CEPH_LOCK_UNLOCK;
 347
 348         if (F_UNLCK == fl->fl_type) {
 349                 err = try_unlock_file(file, fl);
 350                 if (err <= 0)
 351                         return err;
 352         }
 353
 354         err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 355                                 inode, lock_cmd, wait, fl);
 356         if (!err && F_UNLCK != fl->fl_type) {
 357                 err = locks_lock_file_wait(file, fl);
 358                 if (err) {
 359                         ceph_lock_message(CEPH_LOCK_FLOCK,
 360                                           CEPH_MDS_OP_SETFILELOCK,
 361                                           inode, CEPH_LOCK_UNLOCK, 0, fl);
 362                         dout("got %d on locks_lock_file_wait, undid lock\n", err);
 363                 }
 364         }
 365         return err;
 366 }
 367
 368 /*
 369  * Fills in the passed counter variables, so you can prepare pagelist metadata
 370  * before calling ceph_encode_locks.
 371  */
 372 void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
 373 {
 374         struct file_lock *lock;
 375         struct file_lock_context *ctx;
 376
 377         *fcntl_count = 0;
 378         *flock_count = 0;
 379
 380         ctx = locks_inode_context(inode);
 381         if (ctx) {
 382                 spin_lock(&ctx->flc_lock);
 383                 list_for_each_entry(lock, &ctx->flc_posix, fl_list)
 384                         ++(*fcntl_count);
 385                 list_for_each_entry(lock, &ctx->flc_flock, fl_list)
 386                         ++(*flock_count);
 387                 spin_unlock(&ctx->flc_lock);
 388         }
 389         dout("counted %d flock locks and %d fcntl locks\n",
 390              *flock_count, *fcntl_count);
 391 }
 392
 393 /*
 394  * Given a pointer to a lock, convert it to a ceph filelock
 395  */
 396 static int lock_to_ceph_filelock(struct file_lock *lock,
 397                                  struct ceph_filelock *cephlock)
 398 {
 399         int err = 0;
 400         cephlock->start = cpu_to_le64(lock->fl_start);
 401         cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
 402         cephlock->client = cpu_to_le64(0);
 403         cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
 404         cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));
 405
 406         switch (lock->fl_type) {
 407         case F_RDLCK:
 408                 cephlock->type = CEPH_LOCK_SHARED;
 409                 break;
 410         case F_WRLCK:
 411                 cephlock->type = CEPH_LOCK_EXCL;
 412                 break;
 413         case F_UNLCK:
 414                 cephlock->type = CEPH_LOCK_UNLOCK;
 415                 break;
 416         default:
 417                 dout("Have unknown lock type %d\n", lock->fl_type);
 418                 err = -EINVAL;
 419         }
 420
 421         return err;
 422 }
 423
 424 /*
 425  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 426  * array. Must be called with inode->i_lock already held.
 427  * If we encounter more of a specific lock type than expected, return -ENOSPC.
 428  */
 429 int ceph_encode_locks_to_buffer(struct inode *inode,
 430                                 struct ceph_filelock *flocks,
 431                                 int num_fcntl_locks, int num_flock_locks)
 432 {
 433         struct file_lock *lock;
 434         struct file_lock_context *ctx = locks_inode_context(inode);
 435         int err = 0;
 436         int seen_fcntl = 0;
 437         int seen_flock = 0;
 438         int l = 0;
 439
 440         dout("encoding %d flock and %d fcntl locks\n", num_flock_locks,
 441              num_fcntl_locks);
 442
 443         if (!ctx)
 444                 return 0;
 445
 446         spin_lock(&ctx->flc_lock);
 447         list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
 448                 ++seen_fcntl;
 449                 if (seen_fcntl > num_fcntl_locks) {
 450                         err = -ENOSPC;
 451                         goto fail;
 452                 }
 453                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 454                 if (err)
 455                         goto fail;
 456                 ++l;
 457         }
 458         list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
 459                 ++seen_flock;
 460                 if (seen_flock > num_flock_locks) {
 461                         err = -ENOSPC;
 462                         goto fail;
 463                 }
 464                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 465                 if (err)
 466                         goto fail;
 467                 ++l;
 468         }
 469 fail:
 470         spin_unlock(&ctx->flc_lock);
 471         return err;
 472 }
 473
 474 /*
 475  * Copy the encoded flock and fcntl locks into the pagelist.
 476  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 477  * sequential flock locks.
 478  * Returns zero on success.
 479  */
 480 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
 481                            struct ceph_pagelist *pagelist,
 482                            int num_fcntl_locks, int num_flock_locks)
 483 {
 484         int err = 0;
 485         __le32 nlocks;
 486
 487         nlocks = cpu_to_le32(num_fcntl_locks);
 488         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 489         if (err)
 490                 goto out_fail;
 491
 492         if (num_fcntl_locks > 0) {
 493                 err = ceph_pagelist_append(pagelist, flocks,
 494                                            num_fcntl_locks * sizeof(*flocks));
 495                 if (err)
 496                         goto out_fail;
 497         }
 498
 499         nlocks = cpu_to_le32(num_flock_locks);
 500         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 501         if (err)
 502                 goto out_fail;
 503
 504         if (num_flock_locks > 0) {
 505                 err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
 506                                            num_flock_locks * sizeof(*flocks));
 507         }
 508 out_fail:
 509         return err;
 510 }