fs/afs/fs_operation.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Fileserver-directed operation handling.
   3  *
   4  * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/slab.h>
  10 #include <linux/fs.h>
  11 #include "internal.h"
  12
  13 static atomic_t afs_operation_debug_counter;
  14
  15 /*
  16  * Create an operation against a volume.
  17  */
  18 struct afs_operation *afs_alloc_operation(struct key *key, struct afs_volume *volume)
  19 {
  20         struct afs_operation *op;
  21
  22         _enter("");
  23
  24         op = kzalloc(sizeof(*op), GFP_KERNEL);
  25         if (!op)
  26                 return ERR_PTR(-ENOMEM);
  27
  28         if (!key) {
  29                 key = afs_request_key(volume->cell);
  30                 if (IS_ERR(key)) {
  31                         kfree(op);
  32                         return ERR_CAST(key);
  33                 }
  34         } else {
  35                 key_get(key);
  36         }
  37
  38         op->key                 = key;
  39         op->volume              = afs_get_volume(volume, afs_volume_trace_get_new_op);
  40         op->net                 = volume->cell->net;
  41         op->cb_v_break          = atomic_read(&volume->cb_v_break);
  42         op->pre_volsync.creation = volume->creation_time;
  43         op->pre_volsync.update  = volume->update_time;
  44         op->debug_id            = atomic_inc_return(&afs_operation_debug_counter);
  45         op->nr_iterations       = -1;
  46         afs_op_set_error(op, -EDESTADDRREQ);
  47
  48         _leave(" = [op=%08x]", op->debug_id);
  49         return op;
  50 }
  51
  52 struct afs_io_locker {
  53         struct list_head        link;
  54         struct task_struct      *task;
  55         unsigned long           have_lock;
  56 };
  57
  58 /*
  59  * Unlock the I/O lock on a vnode.
  60  */
  61 static void afs_unlock_for_io(struct afs_vnode *vnode)
  62 {
  63         struct afs_io_locker *locker;
  64
  65         spin_lock(&vnode->lock);
  66         locker = list_first_entry_or_null(&vnode->io_lock_waiters,
  67                                           struct afs_io_locker, link);
  68         if (locker) {
  69                 list_del(&locker->link);
  70                 smp_store_release(&locker->have_lock, 1); /* The unlock barrier. */
  71                 smp_mb__after_atomic(); /* Store have_lock before task state */
  72                 wake_up_process(locker->task);
  73         } else {
  74                 clear_bit(AFS_VNODE_IO_LOCK, &vnode->flags);
  75         }
  76         spin_unlock(&vnode->lock);
  77 }
  78
  79 /*
  80  * Lock the I/O lock on a vnode uninterruptibly.  We can't use an ordinary
  81  * mutex as lockdep will complain if we unlock it in the wrong thread.
  82  */
  83 static void afs_lock_for_io(struct afs_vnode *vnode)
  84 {
  85         struct afs_io_locker myself = { .task = current, };
  86
  87         spin_lock(&vnode->lock);
  88
  89         if (!test_and_set_bit(AFS_VNODE_IO_LOCK, &vnode->flags)) {
  90                 spin_unlock(&vnode->lock);
  91                 return;
  92         }
  93
  94         list_add_tail(&myself.link, &vnode->io_lock_waiters);
  95         spin_unlock(&vnode->lock);
  96
  97         for (;;) {
  98                 set_current_state(TASK_UNINTERRUPTIBLE);
  99                 if (smp_load_acquire(&myself.have_lock)) /* The lock barrier */
 100                         break;
 101                 schedule();
 102         }
 103         __set_current_state(TASK_RUNNING);
 104 }
 105
 106 /*
 107  * Lock the I/O lock on a vnode interruptibly.  We can't use an ordinary mutex
 108  * as lockdep will complain if we unlock it in the wrong thread.
 109  */
 110 static int afs_lock_for_io_interruptible(struct afs_vnode *vnode)
 111 {
 112         struct afs_io_locker myself = { .task = current, };
 113         int ret = 0;
 114
 115         spin_lock(&vnode->lock);
 116
 117         if (!test_and_set_bit(AFS_VNODE_IO_LOCK, &vnode->flags)) {
 118                 spin_unlock(&vnode->lock);
 119                 return 0;
 120         }
 121
 122         list_add_tail(&myself.link, &vnode->io_lock_waiters);
 123         spin_unlock(&vnode->lock);
 124
 125         for (;;) {
 126                 set_current_state(TASK_INTERRUPTIBLE);
 127                 if (smp_load_acquire(&myself.have_lock) || /* The lock barrier */
 128                     signal_pending(current))
 129                         break;
 130                 schedule();
 131         }
 132         __set_current_state(TASK_RUNNING);
 133
 134         /* If we got a signal, try to transfer the lock onto the next
 135          * waiter.
 136          */
 137         if (unlikely(signal_pending(current))) {
 138                 spin_lock(&vnode->lock);
 139                 if (myself.have_lock) {
 140                         spin_unlock(&vnode->lock);
 141                         afs_unlock_for_io(vnode);
 142                 } else {
 143                         list_del(&myself.link);
 144                         spin_unlock(&vnode->lock);
 145                 }
 146                 ret = -ERESTARTSYS;
 147         }
 148         return ret;
 149 }
 150
 151 /*
 152  * Lock the vnode(s) being operated upon.
 153  */
 154 static bool afs_get_io_locks(struct afs_operation *op)
 155 {
 156         struct afs_vnode *vnode = op->file[0].vnode;
 157         struct afs_vnode *vnode2 = op->file[1].vnode;
 158
 159         _enter("");
 160
 161         if (op->flags & AFS_OPERATION_UNINTR) {
 162                 afs_lock_for_io(vnode);
 163                 op->flags |= AFS_OPERATION_LOCK_0;
 164                 _leave(" = t [1]");
 165                 return true;
 166         }
 167
 168         if (!vnode2 || !op->file[1].need_io_lock || vnode == vnode2)
 169                 vnode2 = NULL;
 170
 171         if (vnode2 > vnode)
 172                 swap(vnode, vnode2);
 173
 174         if (afs_lock_for_io_interruptible(vnode) < 0) {
 175                 afs_op_set_error(op, -ERESTARTSYS);
 176                 op->flags |= AFS_OPERATION_STOP;
 177                 _leave(" = f [I 0]");
 178                 return false;
 179         }
 180         op->flags |= AFS_OPERATION_LOCK_0;
 181
 182         if (vnode2) {
 183                 if (afs_lock_for_io_interruptible(vnode2) < 0) {
 184                         afs_op_set_error(op, -ERESTARTSYS);
 185                         op->flags |= AFS_OPERATION_STOP;
 186                         afs_unlock_for_io(vnode);
 187                         op->flags &= ~AFS_OPERATION_LOCK_0;
 188                         _leave(" = f [I 1]");
 189                         return false;
 190                 }
 191                 op->flags |= AFS_OPERATION_LOCK_1;
 192         }
 193
 194         _leave(" = t [2]");
 195         return true;
 196 }
 197
 198 static void afs_drop_io_locks(struct afs_operation *op)
 199 {
 200         struct afs_vnode *vnode = op->file[0].vnode;
 201         struct afs_vnode *vnode2 = op->file[1].vnode;
 202
 203         _enter("");
 204
 205         if (op->flags & AFS_OPERATION_LOCK_1)
 206                 afs_unlock_for_io(vnode2);
 207         if (op->flags & AFS_OPERATION_LOCK_0)
 208                 afs_unlock_for_io(vnode);
 209 }
 210
 211 static void afs_prepare_vnode(struct afs_operation *op, struct afs_vnode_param *vp,
 212                               unsigned int index)
 213 {
 214         struct afs_vnode *vnode = vp->vnode;
 215
 216         if (vnode) {
 217                 vp->fid                 = vnode->fid;
 218                 vp->dv_before           = vnode->status.data_version;
 219                 vp->cb_break_before     = afs_calc_vnode_cb_break(vnode);
 220                 if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
 221                         op->flags       |= AFS_OPERATION_CUR_ONLY;
 222                 if (vp->modification)
 223                         set_bit(AFS_VNODE_MODIFYING, &vnode->flags);
 224         }
 225
 226         if (vp->fid.vnode)
 227                 _debug("PREP[%u] {%llx:%llu.%u}",
 228                        index, vp->fid.vid, vp->fid.vnode, vp->fid.unique);
 229 }
 230
 231 /*
 232  * Begin an operation on the fileserver.
 233  *
 234  * Fileserver operations are serialised on the server by vnode, so we serialise
 235  * them here also using the io_lock.
 236  */
 237 bool afs_begin_vnode_operation(struct afs_operation *op)
 238 {
 239         struct afs_vnode *vnode = op->file[0].vnode;
 240
 241         ASSERT(vnode);
 242
 243         _enter("");
 244
 245         if (op->file[0].need_io_lock)
 246                 if (!afs_get_io_locks(op))
 247                         return false;
 248
 249         afs_prepare_vnode(op, &op->file[0], 0);
 250         afs_prepare_vnode(op, &op->file[1], 1);
 251         op->cb_v_break = atomic_read(&op->volume->cb_v_break);
 252         _leave(" = true");
 253         return true;
 254 }
 255
 256 /*
 257  * Tidy up a filesystem cursor and unlock the vnode.
 258  */
 259 void afs_end_vnode_operation(struct afs_operation *op)
 260 {
 261         _enter("");
 262
 263         switch (afs_op_error(op)) {
 264         case -EDESTADDRREQ:
 265         case -EADDRNOTAVAIL:
 266         case -ENETUNREACH:
 267         case -EHOSTUNREACH:
 268                 afs_dump_edestaddrreq(op);
 269                 break;
 270         }
 271
 272         afs_drop_io_locks(op);
 273 }
 274
 275 /*
 276  * Wait for an in-progress operation to complete.
 277  */
 278 void afs_wait_for_operation(struct afs_operation *op)
 279 {
 280         _enter("");
 281
 282         while (afs_select_fileserver(op)) {
 283                 op->call_responded = false;
 284                 op->call_error = 0;
 285                 op->call_abort_code = 0;
 286                 if (test_bit(AFS_SERVER_FL_IS_YFS, &op->server->flags) &&
 287                     op->ops->issue_yfs_rpc)
 288                         op->ops->issue_yfs_rpc(op);
 289                 else if (op->ops->issue_afs_rpc)
 290                         op->ops->issue_afs_rpc(op);
 291                 else
 292                         op->call_error = -ENOTSUPP;
 293
 294                 if (op->call) {
 295                         afs_wait_for_call_to_complete(op->call);
 296                         op->call_abort_code = op->call->abort_code;
 297                         op->call_error = op->call->error;
 298                         op->call_responded = op->call->responded;
 299                         afs_put_call(op->call);
 300                 }
 301         }
 302
 303         if (op->call_responded && op->server)
 304                 set_bit(AFS_SERVER_FL_RESPONDING, &op->server->flags);
 305
 306         if (!afs_op_error(op)) {
 307                 _debug("success");
 308                 op->ops->success(op);
 309         } else if (op->cumul_error.aborted) {
 310                 if (op->ops->aborted)
 311                         op->ops->aborted(op);
 312         } else {
 313                 if (op->ops->failed)
 314                         op->ops->failed(op);
 315         }
 316
 317         afs_end_vnode_operation(op);
 318
 319         if (!afs_op_error(op) && op->ops->edit_dir) {
 320                 _debug("edit_dir");
 321                 op->ops->edit_dir(op);
 322         }
 323         _leave("");
 324 }
 325
 326 /*
 327  * Dispose of an operation.
 328  */
 329 int afs_put_operation(struct afs_operation *op)
 330 {
 331         struct afs_addr_list *alist;
 332         int i, ret = afs_op_error(op);
 333
 334         _enter("op=%08x,%d", op->debug_id, ret);
 335
 336         if (op->ops && op->ops->put)
 337                 op->ops->put(op);
 338         if (op->file[0].modification)
 339                 clear_bit(AFS_VNODE_MODIFYING, &op->file[0].vnode->flags);
 340         if (op->file[1].modification && op->file[1].vnode != op->file[0].vnode)
 341                 clear_bit(AFS_VNODE_MODIFYING, &op->file[1].vnode->flags);
 342         if (op->file[0].put_vnode)
 343                 iput(&op->file[0].vnode->netfs.inode);
 344         if (op->file[1].put_vnode)
 345                 iput(&op->file[1].vnode->netfs.inode);
 346
 347         if (op->more_files) {
 348                 for (i = 0; i < op->nr_files - 2; i++)
 349                         if (op->more_files[i].put_vnode)
 350                                 iput(&op->more_files[i].vnode->netfs.inode);
 351                 kfree(op->more_files);
 352         }
 353
 354         if (op->estate) {
 355                 alist = op->estate->addresses;
 356                 if (alist) {
 357                         if (op->call_responded &&
 358                             op->addr_index != alist->preferred &&
 359                             test_bit(alist->preferred, &op->addr_tried))
 360                                 WRITE_ONCE(alist->preferred, op->addr_index);
 361                 }
 362         }
 363
 364         afs_clear_server_states(op);
 365         afs_put_serverlist(op->net, op->server_list);
 366         afs_put_volume(op->volume, afs_volume_trace_put_put_op);
 367         key_put(op->key);
 368         kfree(op);
 369         return ret;
 370 }
 371
 372 int afs_do_sync_operation(struct afs_operation *op)
 373 {
 374         afs_begin_vnode_operation(op);
 375         afs_wait_for_operation(op);
 376         return afs_put_operation(op);
 377 }