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