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 /**
  34  * Implement fcntl and flock locking functions.
  35  */
  36 static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
  37                              int cmd, u8 wait, struct file_lock *fl)
  38 {
  39         struct inode *inode = file_inode(file);
  40         struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
  41         struct ceph_mds_request *req;
  42         int err;
  43         u64 length = 0;
  44         u64 owner;
  45
  46         if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
  47                 wait = 0;
  48
  49         req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
  50         if (IS_ERR(req))
  51                 return PTR_ERR(req);
  52         req->r_inode = inode;
  53         ihold(inode);
  54         req->r_num_caps = 1;
  55
  56         /* mds requires start and length rather than start and end */
  57         if (LLONG_MAX == fl->fl_end)
  58                 length = 0;
  59         else
  60                 length = fl->fl_end - fl->fl_start + 1;
  61
  62         owner = secure_addr(fl->fl_owner);
  63
  64         dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
  65              "start: %llu, length: %llu, wait: %d, type: %d", (int)lock_type,
  66              (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
  67              wait, fl->fl_type);
  68
  69         req->r_args.filelock_change.rule = lock_type;
  70         req->r_args.filelock_change.type = cmd;
  71         req->r_args.filelock_change.owner = cpu_to_le64(owner);
  72         req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
  73         req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
  74         req->r_args.filelock_change.length = cpu_to_le64(length);
  75         req->r_args.filelock_change.wait = wait;
  76
  77         if (wait)
  78                 req->r_wait_for_completion = ceph_lock_wait_for_completion;
  79
  80         err = ceph_mdsc_do_request(mdsc, inode, req);
  81
  82         if (operation == CEPH_MDS_OP_GETFILELOCK) {
  83                 fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
  84                 if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
  85                         fl->fl_type = F_RDLCK;
  86                 else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
  87                         fl->fl_type = F_WRLCK;
  88                 else
  89                         fl->fl_type = F_UNLCK;
  90
  91                 fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
  92                 length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
  93                                                  le64_to_cpu(req->r_reply_info.filelock_reply->length);
  94                 if (length >= 1)
  95                         fl->fl_end = length -1;
  96                 else
  97                         fl->fl_end = 0;
  98
  99         }
 100         ceph_mdsc_put_request(req);
 101         dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
 102              "length: %llu, wait: %d, type: %d, err code %d", (int)lock_type,
 103              (int)operation, (u64)fl->fl_pid, fl->fl_start,
 104              length, wait, fl->fl_type, err);
 105         return err;
 106 }
 107
 108 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
 109                                          struct ceph_mds_request *req)
 110 {
 111         struct ceph_mds_request *intr_req;
 112         struct inode *inode = req->r_inode;
 113         int err, lock_type;
 114
 115         BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
 116         if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
 117                 lock_type = CEPH_LOCK_FCNTL_INTR;
 118         else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
 119                 lock_type = CEPH_LOCK_FLOCK_INTR;
 120         else
 121                 BUG_ON(1);
 122         BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);
 123
 124         err = wait_for_completion_interruptible(&req->r_completion);
 125         if (!err)
 126                 return 0;
 127
 128         dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
 129              req->r_tid);
 130
 131         mutex_lock(&mdsc->mutex);
 132         if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
 133                 err = 0;
 134         } else {
 135                 /*
 136                  * ensure we aren't running concurrently with
 137                  * ceph_fill_trace or ceph_readdir_prepopulate, which
 138                  * rely on locks (dir mutex) held by our caller.
 139                  */
 140                 mutex_lock(&req->r_fill_mutex);
 141                 req->r_err = err;
 142                 set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
 143                 mutex_unlock(&req->r_fill_mutex);
 144
 145                 if (!req->r_session) {
 146                         // haven't sent the request
 147                         err = 0;
 148                 }
 149         }
 150         mutex_unlock(&mdsc->mutex);
 151         if (!err)
 152                 return 0;
 153
 154         intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
 155                                             USE_AUTH_MDS);
 156         if (IS_ERR(intr_req))
 157                 return PTR_ERR(intr_req);
 158
 159         intr_req->r_inode = inode;
 160         ihold(inode);
 161         intr_req->r_num_caps = 1;
 162
 163         intr_req->r_args.filelock_change = req->r_args.filelock_change;
 164         intr_req->r_args.filelock_change.rule = lock_type;
 165         intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;
 166
 167         err = ceph_mdsc_do_request(mdsc, inode, intr_req);
 168         ceph_mdsc_put_request(intr_req);
 169
 170         if (err && err != -ERESTARTSYS)
 171                 return err;
 172
 173         wait_for_completion_killable(&req->r_safe_completion);
 174         return 0;
 175 }
 176
 177 /**
 178  * Attempt to set an fcntl lock.
 179  * For now, this just goes away to the server. Later it may be more awesome.
 180  */
 181 int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 182 {
 183         u8 lock_cmd;
 184         int err;
 185         u8 wait = 0;
 186         u16 op = CEPH_MDS_OP_SETFILELOCK;
 187
 188         if (!(fl->fl_flags & FL_POSIX))
 189                 return -ENOLCK;
 190         /* No mandatory locks */
 191         if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
 192                 return -ENOLCK;
 193
 194         dout("ceph_lock, fl_owner: %p", fl->fl_owner);
 195
 196         /* set wait bit as appropriate, then make command as Ceph expects it*/
 197         if (IS_GETLK(cmd))
 198                 op = CEPH_MDS_OP_GETFILELOCK;
 199         else if (IS_SETLKW(cmd))
 200                 wait = 1;
 201
 202         if (F_RDLCK == fl->fl_type)
 203                 lock_cmd = CEPH_LOCK_SHARED;
 204         else if (F_WRLCK == fl->fl_type)
 205                 lock_cmd = CEPH_LOCK_EXCL;
 206         else
 207                 lock_cmd = CEPH_LOCK_UNLOCK;
 208
 209         err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file, lock_cmd, wait, fl);
 210         if (!err) {
 211                 if (op != CEPH_MDS_OP_GETFILELOCK) {
 212                         dout("mds locked, locking locally");
 213                         err = posix_lock_file(file, fl, NULL);
 214                         if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
 215                                 /* undo! This should only happen if
 216                                  * the kernel detects local
 217                                  * deadlock. */
 218                                 ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
 219                                                   CEPH_LOCK_UNLOCK, 0, fl);
 220                                 dout("got %d on posix_lock_file, undid lock",
 221                                      err);
 222                         }
 223                 }
 224         }
 225         return err;
 226 }
 227
 228 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 229 {
 230         u8 lock_cmd;
 231         int err;
 232         u8 wait = 0;
 233
 234         if (!(fl->fl_flags & FL_FLOCK))
 235                 return -ENOLCK;
 236         /* No mandatory locks */
 237         if (fl->fl_type & LOCK_MAND)
 238                 return -EOPNOTSUPP;
 239
 240         dout("ceph_flock, fl_file: %p", fl->fl_file);
 241
 242         if (IS_SETLKW(cmd))
 243                 wait = 1;
 244
 245         if (F_RDLCK == fl->fl_type)
 246                 lock_cmd = CEPH_LOCK_SHARED;
 247         else if (F_WRLCK == fl->fl_type)
 248                 lock_cmd = CEPH_LOCK_EXCL;
 249         else
 250                 lock_cmd = CEPH_LOCK_UNLOCK;
 251
 252         err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 253                                 file, lock_cmd, wait, fl);
 254         if (!err) {
 255                 err = locks_lock_file_wait(file, fl);
 256                 if (err) {
 257                         ceph_lock_message(CEPH_LOCK_FLOCK,
 258                                           CEPH_MDS_OP_SETFILELOCK,
 259                                           file, CEPH_LOCK_UNLOCK, 0, fl);
 260                         dout("got %d on locks_lock_file_wait, undid lock", err);
 261                 }
 262         }
 263         return err;
 264 }
 265
 266 /*
 267  * Fills in the passed counter variables, so you can prepare pagelist metadata
 268  * before calling ceph_encode_locks.
 269  */
 270 void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
 271 {
 272         struct file_lock *lock;
 273         struct file_lock_context *ctx;
 274
 275         *fcntl_count = 0;
 276         *flock_count = 0;
 277
 278         ctx = inode->i_flctx;
 279         if (ctx) {
 280                 spin_lock(&ctx->flc_lock);
 281                 list_for_each_entry(lock, &ctx->flc_posix, fl_list)
 282                         ++(*fcntl_count);
 283                 list_for_each_entry(lock, &ctx->flc_flock, fl_list)
 284                         ++(*flock_count);
 285                 spin_unlock(&ctx->flc_lock);
 286         }
 287         dout("counted %d flock locks and %d fcntl locks",
 288              *flock_count, *fcntl_count);
 289 }
 290
 291 /**
 292  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
 293  * array. Must be called with inode->i_lock already held.
 294  * If we encounter more of a specific lock type than expected, return -ENOSPC.
 295  */
 296 int ceph_encode_locks_to_buffer(struct inode *inode,
 297                                 struct ceph_filelock *flocks,
 298                                 int num_fcntl_locks, int num_flock_locks)
 299 {
 300         struct file_lock *lock;
 301         struct file_lock_context *ctx = inode->i_flctx;
 302         int err = 0;
 303         int seen_fcntl = 0;
 304         int seen_flock = 0;
 305         int l = 0;
 306
 307         dout("encoding %d flock and %d fcntl locks", num_flock_locks,
 308              num_fcntl_locks);
 309
 310         if (!ctx)
 311                 return 0;
 312
 313         spin_lock(&ctx->flc_lock);
 314         list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
 315                 ++seen_fcntl;
 316                 if (seen_fcntl > num_fcntl_locks) {
 317                         err = -ENOSPC;
 318                         goto fail;
 319                 }
 320                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 321                 if (err)
 322                         goto fail;
 323                 ++l;
 324         }
 325         list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
 326                 ++seen_flock;
 327                 if (seen_flock > num_flock_locks) {
 328                         err = -ENOSPC;
 329                         goto fail;
 330                 }
 331                 err = lock_to_ceph_filelock(lock, &flocks[l]);
 332                 if (err)
 333                         goto fail;
 334                 ++l;
 335         }
 336 fail:
 337         spin_unlock(&ctx->flc_lock);
 338         return err;
 339 }
 340
 341 /**
 342  * Copy the encoded flock and fcntl locks into the pagelist.
 343  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
 344  * sequential flock locks.
 345  * Returns zero on success.
 346  */
 347 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
 348                            struct ceph_pagelist *pagelist,
 349                            int num_fcntl_locks, int num_flock_locks)
 350 {
 351         int err = 0;
 352         __le32 nlocks;
 353
 354         nlocks = cpu_to_le32(num_fcntl_locks);
 355         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 356         if (err)
 357                 goto out_fail;
 358
 359         err = ceph_pagelist_append(pagelist, flocks,
 360                                    num_fcntl_locks * sizeof(*flocks));
 361         if (err)
 362                 goto out_fail;
 363
 364         nlocks = cpu_to_le32(num_flock_locks);
 365         err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 366         if (err)
 367                 goto out_fail;
 368
 369         err = ceph_pagelist_append(pagelist,
 370                                    &flocks[num_fcntl_locks],
 371                                    num_flock_locks * sizeof(*flocks));
 372 out_fail:
 373         return err;
 374 }
 375
 376 /*
 377  * Given a pointer to a lock, convert it to a ceph filelock
 378  */
 379 int lock_to_ceph_filelock(struct file_lock *lock,
 380                           struct ceph_filelock *cephlock)
 381 {
 382         int err = 0;
 383         cephlock->start = cpu_to_le64(lock->fl_start);
 384         cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
 385         cephlock->client = cpu_to_le64(0);
 386         cephlock->pid = cpu_to_le64((u64)lock->fl_pid);
 387         cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));
 388
 389         switch (lock->fl_type) {
 390         case F_RDLCK:
 391                 cephlock->type = CEPH_LOCK_SHARED;
 392                 break;
 393         case F_WRLCK:
 394                 cephlock->type = CEPH_LOCK_EXCL;
 395                 break;
 396         case F_UNLCK:
 397                 cephlock->type = CEPH_LOCK_UNLOCK;
 398                 break;
 399         default:
 400                 dout("Have unknown lock type %d", lock->fl_type);
 401                 err = -EINVAL;
 402         }
 403
 404         return err;
 405 }