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->c.flc_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_client *cl = mdsc->fsc->client;
  81         struct ceph_mds_request *req;
  82         int err;
  83         u64 length = 0;
  84         u64 owner;
  85
  86         if (operation == CEPH_MDS_OP_SETFILELOCK) {
  87                 /*
  88                  * increasing i_filelock_ref closes race window between
  89                  * handling request reply and adding file_lock struct to
  90                  * inode. Otherwise, auth caps may get trimmed in the
  91                  * window. Caller function will decrease the counter.
  92                  */
  93                 fl->fl_ops = &ceph_fl_lock_ops;
  94                 fl->fl_ops->fl_copy_lock(fl, NULL);
  95         }
  96
  97         if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
  98                 wait = 0;
  99
 100         req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
 101         if (IS_ERR(req))
 102                 return PTR_ERR(req);
 103         req->r_inode = inode;
 104         ihold(inode);
 105         req->r_num_caps = 1;
 106
 107         /* mds requires start and length rather than start and end */
 108         if (LLONG_MAX == fl->fl_end)
 109                 length = 0;
 110         else
 111                 length = fl->fl_end - fl->fl_start + 1;
 112
 113         owner = secure_addr(fl->c.flc_owner);
 114
 115         doutc(cl, "rule: %d, op: %d, owner: %llx, pid: %llu, "
 116                     "start: %llu, length: %llu, wait: %d, type: %d\n",
 117                     (int)lock_type, (int)operation, owner,
 118                     (u64) fl->c.flc_pid,
 119                     fl->fl_start, length, wait, fl->c.flc_type);
 120
 121         req->r_args.filelock_change.rule = lock_type;
 122         req->r_args.filelock_change.type = cmd;
 123         req->r_args.filelock_change.owner = cpu_to_le64(owner);
 124         req->r_args.filelock_change.pid = cpu_to_le64((u64) fl->c.flc_pid);
 125         req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
 126         req->r_args.filelock_change.length = cpu_to_le64(length);
 127         req->r_args.filelock_change.wait = wait;
 128
 129         err = ceph_mdsc_submit_request(mdsc, inode, req);
 130         if (!err)
 131                 err = ceph_mdsc_wait_request(mdsc, req, wait ?
 132                                         ceph_lock_wait_for_completion : NULL);
 133         if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
 134                 fl->c.flc_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
 135                 if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
 136                         fl->c.flc_type = F_RDLCK;
 137                 else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
 138                         fl->c.flc_type = F_WRLCK;
 139                 else
 140                         fl->c.flc_type = F_UNLCK;
 141
 142                 fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
 143                 length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
 144                                                  le64_to_cpu(req->r_reply_info.filelock_reply->length);
 145                 if (length >= 1)
 146                         fl->fl_end = length -1;
 147                 else
 148                         fl->fl_end = 0;
 149
 150         }
 151         ceph_mdsc_put_request(req);
 152         doutc(cl, "rule: %d, op: %d, pid: %llu, start: %llu, "
 153               "length: %llu, wait: %d, type: %d, err code %d\n",
 154               (int)lock_type, (int)operation, (u64) fl->c.flc_pid,
 155               fl->fl_start, length, wait, fl->c.flc_type, err);
 156         return err;
 157 }
 158
 159 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
 160                                          struct ceph_mds_request *req)
 161 {
 162         struct ceph_client *cl = mdsc->fsc->client;
 163         struct ceph_mds_request *intr_req;
 164         struct inode *inode = req->r_inode;
 165         int err, lock_type;
 166
 167         BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
 168         if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
 169                 lock_type = CEPH_LOCK_FCNTL_INTR;
 170         else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
 171                 lock_type = CEPH_LOCK_FLOCK_INTR;
 172         else
 173                 BUG_ON(1);
 174         BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);
 175
 176         err = wait_for_completion_interruptible(&req->r_completion);
 177         if (!err)
 178                 return 0;
 179
 180         doutc(cl, "request %llu was interrupted\n", req->r_tid);
 181
 182         mutex_lock(&mdsc->mutex);
 183         if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
 184                 err = 0;
 185         } else {
 186                 /*
 187                  * ensure we aren't running concurrently with
 188                  * ceph_fill_trace or ceph_readdir_prepopulate, which
 189                  * rely on locks (dir mutex) held by our caller.
 190                  */
 191                 mutex_lock(&req->r_fill_mutex);
 192                 req->r_err = err;
 193                 set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
 194                 mutex_unlock(&req->r_fill_mutex);
 195
 196                 if (!req->r_session) {
 197                         // haven't sent the request
 198                         err = 0;
 199                 }
 200         }
 201         mutex_unlock(&mdsc->mutex);
 202         if (!err)
 203                 return 0;
 204
 205         intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
 206                                             USE_AUTH_MDS);
 207         if (IS_ERR(intr_req))
 208                 return PTR_ERR(intr_req);
 209
 210         intr_req->r_inode = inode;
 211         ihold(inode);
 212         intr_req->r_num_caps = 1;
 213
 214         intr_req->r_args.filelock_change = req->r_args.filelock_change;
 215         intr_req->r_args.filelock_change.rule = lock_type;
 216         intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;
 217
 218         err = ceph_mdsc_do_request(mdsc, inode, intr_req);
 219         ceph_mdsc_put_request(intr_req);
 220
 221         if (err && err != -ERESTARTSYS)
 222                 return err;
 223
 224         wait_for_completion_killable(&req->r_safe_completion);
 225         return 0;
 226 }
 227
 228 static int try_unlock_file(struct file *file, struct file_lock *fl)
 229 {
 230         int err;
 231         unsigned int orig_flags = fl->c.flc_flags;
 232         fl->c.flc_flags |= FL_EXISTS;
 233         err = locks_lock_file_wait(file, fl);
 234         fl->c.flc_flags = orig_flags;
 235         if (err == -ENOENT) {
 236                 if (!(orig_flags & FL_EXISTS))
 237                         err = 0;
 238                 return err;
 239         }
 240         return 1;
 241 }
 242
 243 /*
 244  * Attempt to set an fcntl lock.
 245  * For now, this just goes away to the server. Later it may be more awesome.
 246  */
 247 int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 248 {
 249         struct inode *inode = file_inode(file);
 250         struct ceph_inode_info *ci = ceph_inode(inode);
 251         struct ceph_client *cl = ceph_inode_to_client(inode);
 252         int err = 0;
 253         u16 op = CEPH_MDS_OP_SETFILELOCK;
 254         u8 wait = 0;
 255         u8 lock_cmd;
 256
 257         if (!(fl->c.flc_flags & FL_POSIX))
 258                 return -ENOLCK;
 259
 260         if (ceph_inode_is_shutdown(inode))
 261                 return -ESTALE;
 262
 263         doutc(cl, "fl_owner: %p\n", fl->c.flc_owner);
 264
 265         /* set wait bit as appropriate, then make command as Ceph expects it*/
 266         if (IS_GETLK(cmd))
 267                 op = CEPH_MDS_OP_GETFILELOCK;
 268         else if (IS_SETLKW(cmd))
 269                 wait = 1;
 270
 271         spin_lock(&ci->i_ceph_lock);
 272         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 273                 err = -EIO;
 274         }
 275         spin_unlock(&ci->i_ceph_lock);
 276         if (err < 0) {
 277                 if (op == CEPH_MDS_OP_SETFILELOCK && lock_is_unlock(fl))
 278                         posix_lock_file(file, fl, NULL);
 279                 return err;
 280         }
 281
 282         if (lock_is_read(fl))
 283                 lock_cmd = CEPH_LOCK_SHARED;
 284         else if (lock_is_write(fl))
 285                 lock_cmd = CEPH_LOCK_EXCL;
 286         else
 287                 lock_cmd = CEPH_LOCK_UNLOCK;
 288
 289         if (op == CEPH_MDS_OP_SETFILELOCK && lock_is_unlock(fl)) {
 290                 err = try_unlock_file(file, fl);
 291                 if (err <= 0)
 292                         return err;
 293         }
 294
 295         err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
 296         if (!err) {
 297                 if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->c.flc_type) {
 298                         doutc(cl, "locking locally\n");
 299                         err = posix_lock_file(file, fl, NULL);
 300                         if (err) {
 301                                 /* undo! This should only happen if
 302                                  * the kernel detects local
 303                                  * deadlock. */
 304                                 ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
 305                                                   CEPH_LOCK_UNLOCK, 0, fl);
 306                                 doutc(cl, "got %d on posix_lock_file, undid lock\n",
 307                                       err);
 308                         }
 309                 }
 310         }
 311         return err;
 312 }
 313
 314 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 315 {
 316         struct inode *inode = file_inode(file);
 317         struct ceph_inode_info *ci = ceph_inode(inode);
 318         struct ceph_client *cl = ceph_inode_to_client(inode);
 319         int err = 0;
 320         u8 wait = 0;
 321         u8 lock_cmd;
 322
 323         if (!(fl->c.flc_flags & FL_FLOCK))
 324                 return -ENOLCK;
 325
 326         if (ceph_inode_is_shutdown(inode))
 327                 return -ESTALE;
 328
 329         doutc(cl, "fl_file: %p\n", fl->c.flc_file);
 330
 331         spin_lock(&ci->i_ceph_lock);
 332         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 333                 err = -EIO;
 334         }
 335         spin_unlock(&ci->i_ceph_lock);
 336         if (err < 0) {
 337                 if (lock_is_unlock(fl))
 338                         locks_lock_file_wait(file, fl);
 339                 return err;
 340         }
 341
 342         if (IS_SETLKW(cmd))
 343                 wait = 1;
 344
 345         if (lock_is_read(fl))
 346                 lock_cmd = CEPH_LOCK_SHARED;
 347         else if (lock_is_write(fl))
 348                 lock_cmd = CEPH_LOCK_EXCL;
 349         else
 350                 lock_cmd = CEPH_LOCK_UNLOCK;
 351
 352         if (lock_is_unlock(fl)) {
 353                 err = try_unlock_file(file, fl);
 354                 if (err <= 0)
 355                         return err;
 356         }
 357
 358         err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 359                                 inode, lock_cmd, wait, fl);
 360         if (!err && F_UNLCK != fl->c.flc_type) {
 361                 err = locks_lock_file_wait(file, fl);
 362                 if (err) {
 363                         ceph_lock_message(CEPH_LOCK_FLOCK,
 364                                           CEPH_MDS_OP_SETFILELOCK,
 365                                           inode, CEPH_LOCK_UNLOCK, 0, fl);
 366                         doutc(cl, "got %d on locks_lock_file_wait, undid lock\n",
 367                               err);
 368                 }
 369         }
 370         return err;
 371 }
 372
 373 /*
 374  * Fills in the passed counter variables, so you can prepare pagelist metadata
 375  * before calling ceph_encode_locks.
 376  */
 377 void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
 378 {
 379         struct ceph_client *cl = ceph_inode_to_client(inode);
 380         struct file_lock *lock;
 381         struct file_lock_context *ctx;
 382
 383         *fcntl_count = 0;
 384         *flock_count = 0;
 385
 386         ctx = locks_inode_context(inode);
 387         if (ctx) {
 388                 spin_lock(&ctx->flc_lock);
 389                 for_each_file_lock(lock, &ctx->flc_posix)
 390                         ++(*fcntl_count);
 391                 for_each_file_lock(lock, &ctx->flc_flock)
 392                         ++(*flock_count);
 393                 spin_unlock(&ctx->flc_lock);
 394         }
 395         doutc(cl, "counted %d flock locks and %d fcntl locks\n",
 396               *flock_count, *fcntl_count);
 397 }
 398
 399 /*
 400  * Given a pointer to a lock, convert it to a ceph filelock
 401  */
 402 static int lock_to_ceph_filelock(struct inode *inode,
 403                                  struct file_lock *lock,
 404                                  struct ceph_filelock *cephlock)
 405 {
 406         struct ceph_client *cl = ceph_inode_to_client(inode);
 407         int err = 0;
 408
 409         cephlock->start = cpu_to_le64(lock->fl_start);
 410         cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
 411         cephlock->client = cpu_to_le64(0);
 412         cephlock->pid = cpu_to_le64((u64) lock->c.flc_pid);
 413         cephlock->owner = cpu_to_le64(secure_addr(lock->c.flc_owner));
 414
 415         switch (lock->c.flc_type) {
 416         case F_RDLCK:
 417                 cephlock->type = CEPH_LOCK_SHARED;
 418                 break;
 419         case F_WRLCK:
 420                 cephlock->type = CEPH_LOCK_EXCL;
 421                 break;
 422         case F_UNLCK:
 423                 cephlock->type = CEPH_LOCK_UNLOCK;
 424                 break;
 425         default:
 426                 doutc(cl, "Have unknown lock type %d\n",
 427                       lock->c.flc_type);
 428                 err = -EINVAL;
 429         }
 430
 431         return err;
 432 }
 433
 434 /*
 435  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 436  * array. Must be called with inode->i_lock already held.
 437  * If we encounter more of a specific lock type than expected, return -ENOSPC.
 438  */
 439 int ceph_encode_locks_to_buffer(struct inode *inode,
 440                                 struct ceph_filelock *flocks,
 441                                 int num_fcntl_locks, int num_flock_locks)
 442 {
 443         struct file_lock *lock;
 444         struct file_lock_context *ctx = locks_inode_context(inode);
 445         struct ceph_client *cl = ceph_inode_to_client(inode);
 446         int err = 0;
 447         int seen_fcntl = 0;
 448         int seen_flock = 0;
 449         int l = 0;
 450
 451         doutc(cl, "encoding %d flock and %d fcntl locks\n", num_flock_locks,
 452               num_fcntl_locks);
 453
 454         if (!ctx)
 455                 return 0;
 456
 457         spin_lock(&ctx->flc_lock);
 458         for_each_file_lock(lock, &ctx->flc_posix) {
 459                 ++seen_fcntl;
 460                 if (seen_fcntl > num_fcntl_locks) {
 461                         err = -ENOSPC;
 462                         goto fail;
 463                 }
 464                 err = lock_to_ceph_filelock(inode, lock, &flocks[l]);
 465                 if (err)
 466                         goto fail;
 467                 ++l;
 468         }
 469         for_each_file_lock(lock, &ctx->flc_flock) {
 470                 ++seen_flock;
 471                 if (seen_flock > num_flock_locks) {
 472                         err = -ENOSPC;
 473                         goto fail;
 474                 }
 475                 err = lock_to_ceph_filelock(inode, lock, &flocks[l]);
 476                 if (err)
 477                         goto fail;
 478                 ++l;
 479         }
 480 fail:
 481         spin_unlock(&ctx->flc_lock);
 482         return err;
 483 }
 484
 485 /*
 486  * Copy the encoded flock and fcntl locks into the pagelist.
 487  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 488  * sequential flock locks.
 489  * Returns zero on success.
 490  */
 491 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
 492                            struct ceph_pagelist *pagelist,
 493                            int num_fcntl_locks, int num_flock_locks)
 494 {
 495         int err = 0;
 496         __le32 nlocks;
 497
 498         nlocks = cpu_to_le32(num_fcntl_locks);
 499         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 500         if (err)
 501                 goto out_fail;
 502
 503         if (num_fcntl_locks > 0) {
 504                 err = ceph_pagelist_append(pagelist, flocks,
 505                                            num_fcntl_locks * sizeof(*flocks));
 506                 if (err)
 507                         goto out_fail;
 508         }
 509
 510         nlocks = cpu_to_le32(num_flock_locks);
 511         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 512         if (err)
 513                 goto out_fail;
 514
 515         if (num_flock_locks > 0) {
 516                 err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
 517                                            num_flock_locks * sizeof(*flocks));
 518         }
 519 out_fail:
 520         return err;
 521 }