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