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         dout("ceph_lock, fl_owner: %p\n", fl->fl_owner);
 245
 246         /* set wait bit as appropriate, then make command as Ceph expects it*/
 247         if (IS_GETLK(cmd))
 248                 op = CEPH_MDS_OP_GETFILELOCK;
 249         else if (IS_SETLKW(cmd))
 250                 wait = 1;
 251
 252         spin_lock(&ci->i_ceph_lock);
 253         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 254                 err = -EIO;
 255         }
 256         spin_unlock(&ci->i_ceph_lock);
 257         if (err < 0) {
 258                 if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type)
 259                         posix_lock_file(file, fl, NULL);
 260                 return err;
 261         }
 262
 263         if (F_RDLCK == fl->fl_type)
 264                 lock_cmd = CEPH_LOCK_SHARED;
 265         else if (F_WRLCK == fl->fl_type)
 266                 lock_cmd = CEPH_LOCK_EXCL;
 267         else
 268                 lock_cmd = CEPH_LOCK_UNLOCK;
 269
 270         if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
 271                 err = try_unlock_file(file, fl);
 272                 if (err <= 0)
 273                         return err;
 274         }
 275
 276         err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
 277         if (!err) {
 278                 if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->fl_type) {
 279                         dout("mds locked, locking locally\n");
 280                         err = posix_lock_file(file, fl, NULL);
 281                         if (err) {
 282                                 /* undo! This should only happen if
 283                                  * the kernel detects local
 284                                  * deadlock. */
 285                                 ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
 286                                                   CEPH_LOCK_UNLOCK, 0, fl);
 287                                 dout("got %d on posix_lock_file, undid lock\n",
 288                                      err);
 289                         }
 290                 }
 291         }
 292         return err;
 293 }
 294
 295 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 296 {
 297         struct inode *inode = file_inode(file);
 298         struct ceph_inode_info *ci = ceph_inode(inode);
 299         int err = 0;
 300         u8 wait = 0;
 301         u8 lock_cmd;
 302
 303         if (!(fl->fl_flags & FL_FLOCK))
 304                 return -ENOLCK;
 305
 306         dout("ceph_flock, fl_file: %p\n", fl->fl_file);
 307
 308         spin_lock(&ci->i_ceph_lock);
 309         if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 310                 err = -EIO;
 311         }
 312         spin_unlock(&ci->i_ceph_lock);
 313         if (err < 0) {
 314                 if (F_UNLCK == fl->fl_type)
 315                         locks_lock_file_wait(file, fl);
 316                 return err;
 317         }
 318
 319         if (IS_SETLKW(cmd))
 320                 wait = 1;
 321
 322         if (F_RDLCK == fl->fl_type)
 323                 lock_cmd = CEPH_LOCK_SHARED;
 324         else if (F_WRLCK == fl->fl_type)
 325                 lock_cmd = CEPH_LOCK_EXCL;
 326         else
 327                 lock_cmd = CEPH_LOCK_UNLOCK;
 328
 329         if (F_UNLCK == fl->fl_type) {
 330                 err = try_unlock_file(file, fl);
 331                 if (err <= 0)
 332                         return err;
 333         }
 334
 335         err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 336                                 inode, lock_cmd, wait, fl);
 337         if (!err && F_UNLCK != fl->fl_type) {
 338                 err = locks_lock_file_wait(file, fl);
 339                 if (err) {
 340                         ceph_lock_message(CEPH_LOCK_FLOCK,
 341                                           CEPH_MDS_OP_SETFILELOCK,
 342                                           inode, CEPH_LOCK_UNLOCK, 0, fl);
 343                         dout("got %d on locks_lock_file_wait, undid lock\n", err);
 344                 }
 345         }
 346         return err;
 347 }
 348
 349 /*
 350  * Fills in the passed counter variables, so you can prepare pagelist metadata
 351  * before calling ceph_encode_locks.
 352  */
 353 void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
 354 {
 355         struct file_lock *lock;
 356         struct file_lock_context *ctx;
 357
 358         *fcntl_count = 0;
 359         *flock_count = 0;
 360
 361         ctx = inode->i_flctx;
 362         if (ctx) {
 363                 spin_lock(&ctx->flc_lock);
 364                 list_for_each_entry(lock, &ctx->flc_posix, fl_list)
 365                         ++(*fcntl_count);
 366                 list_for_each_entry(lock, &ctx->flc_flock, fl_list)
 367                         ++(*flock_count);
 368                 spin_unlock(&ctx->flc_lock);
 369         }
 370         dout("counted %d flock locks and %d fcntl locks\n",
 371              *flock_count, *fcntl_count);
 372 }
 373
 374 /*
 375  * Given a pointer to a lock, convert it to a ceph filelock
 376  */
 377 static int lock_to_ceph_filelock(struct file_lock *lock,
 378                                  struct ceph_filelock *cephlock)
 379 {
 380         int err = 0;
 381         cephlock->start = cpu_to_le64(lock->fl_start);
 382         cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
 383         cephlock->client = cpu_to_le64(0);
 384         cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
 385         cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));
 386
 387         switch (lock->fl_type) {
 388         case F_RDLCK:
 389                 cephlock->type = CEPH_LOCK_SHARED;
 390                 break;
 391         case F_WRLCK:
 392                 cephlock->type = CEPH_LOCK_EXCL;
 393                 break;
 394         case F_UNLCK:
 395                 cephlock->type = CEPH_LOCK_UNLOCK;
 396                 break;
 397         default:
 398                 dout("Have unknown lock type %d\n", lock->fl_type);
 399                 err = -EINVAL;
 400         }
 401
 402         return err;
 403 }
 404
 405 /*
 406  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 407  * array. Must be called with inode->i_lock already held.
 408  * If we encounter more of a specific lock type than expected, return -ENOSPC.
 409  */
 410 int ceph_encode_locks_to_buffer(struct inode *inode,
 411                                 struct ceph_filelock *flocks,
 412                                 int num_fcntl_locks, int num_flock_locks)
 413 {
 414         struct file_lock *lock;
 415         struct file_lock_context *ctx = inode->i_flctx;
 416         int err = 0;
 417         int seen_fcntl = 0;
 418         int seen_flock = 0;
 419         int l = 0;
 420
 421         dout("encoding %d flock and %d fcntl locks\n", num_flock_locks,
 422              num_fcntl_locks);
 423
 424         if (!ctx)
 425                 return 0;
 426
 427         spin_lock(&ctx->flc_lock);
 428         list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
 429                 ++seen_fcntl;
 430                 if (seen_fcntl > num_fcntl_locks) {
 431                         err = -ENOSPC;
 432                         goto fail;
 433                 }
 434                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 435                 if (err)
 436                         goto fail;
 437                 ++l;
 438         }
 439         list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
 440                 ++seen_flock;
 441                 if (seen_flock > num_flock_locks) {
 442                         err = -ENOSPC;
 443                         goto fail;
 444                 }
 445                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 446                 if (err)
 447                         goto fail;
 448                 ++l;
 449         }
 450 fail:
 451         spin_unlock(&ctx->flc_lock);
 452         return err;
 453 }
 454
 455 /*
 456  * Copy the encoded flock and fcntl locks into the pagelist.
 457  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 458  * sequential flock locks.
 459  * Returns zero on success.
 460  */
 461 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
 462                            struct ceph_pagelist *pagelist,
 463                            int num_fcntl_locks, int num_flock_locks)
 464 {
 465         int err = 0;
 466         __le32 nlocks;
 467
 468         nlocks = cpu_to_le32(num_fcntl_locks);
 469         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 470         if (err)
 471                 goto out_fail;
 472
 473         if (num_fcntl_locks > 0) {
 474                 err = ceph_pagelist_append(pagelist, flocks,
 475                                            num_fcntl_locks * sizeof(*flocks));
 476                 if (err)
 477                         goto out_fail;
 478         }
 479
 480         nlocks = cpu_to_le32(num_flock_locks);
 481         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 482         if (err)
 483                 goto out_fail;
 484
 485         if (num_flock_locks > 0) {
 486                 err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
 487                                            num_flock_locks * sizeof(*flocks));
 488         }
 489 out_fail:
 490         return err;
 491 }