fs/btrfs/async-thread.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  * Copyright (C) 2014 Fujitsu.  All rights reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public
   7  * License v2 as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public
  15  * License along with this program; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 021110-1307, USA.
  18  */
  19
  20 #include <linux/kthread.h>
  21 #include <linux/slab.h>
  22 #include <linux/list.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/freezer.h>
  25 #include "async-thread.h"
  26 #include "ctree.h"
  27
  28 #define WORK_DONE_BIT 0
  29 #define WORK_ORDER_DONE_BIT 1
  30 #define WORK_HIGH_PRIO_BIT 2
  31
  32 #define NO_THRESHOLD (-1)
  33 #define DFT_THRESHOLD (32)
  34
  35 struct __btrfs_workqueue {
  36         struct workqueue_struct *normal_wq;
  37         /* List head pointing to ordered work list */
  38         struct list_head ordered_list;
  39
  40         /* Spinlock for ordered_list */
  41         spinlock_t list_lock;
  42
  43         /* Thresholding related variants */
  44         atomic_t pending;
  45         int max_active;
  46         int current_max;
  47         int thresh;
  48         unsigned int count;
  49         spinlock_t thres_lock;
  50 };
  51
  52 struct btrfs_workqueue {
  53         struct __btrfs_workqueue *normal;
  54         struct __btrfs_workqueue *high;
  55 };
  56
  57 static void normal_work_helper(struct btrfs_work *work);
  58
  59 #define BTRFS_WORK_HELPER(name)                                 \
  60 void btrfs_##name(struct work_struct *arg)                              \
  61 {                                                                       \
  62         struct btrfs_work *work = container_of(arg, struct btrfs_work,  \
  63                                                normal_work);            \
  64         normal_work_helper(work);                                       \
  65 }
  66
  67 BTRFS_WORK_HELPER(worker_helper);
  68 BTRFS_WORK_HELPER(delalloc_helper);
  69 BTRFS_WORK_HELPER(flush_delalloc_helper);
  70 BTRFS_WORK_HELPER(cache_helper);
  71 BTRFS_WORK_HELPER(submit_helper);
  72 BTRFS_WORK_HELPER(fixup_helper);
  73 BTRFS_WORK_HELPER(endio_helper);
  74 BTRFS_WORK_HELPER(endio_meta_helper);
  75 BTRFS_WORK_HELPER(endio_meta_write_helper);
  76 BTRFS_WORK_HELPER(endio_raid56_helper);
  77 BTRFS_WORK_HELPER(endio_repair_helper);
  78 BTRFS_WORK_HELPER(rmw_helper);
  79 BTRFS_WORK_HELPER(endio_write_helper);
  80 BTRFS_WORK_HELPER(freespace_write_helper);
  81 BTRFS_WORK_HELPER(delayed_meta_helper);
  82 BTRFS_WORK_HELPER(readahead_helper);
  83 BTRFS_WORK_HELPER(qgroup_rescan_helper);
  84 BTRFS_WORK_HELPER(extent_refs_helper);
  85 BTRFS_WORK_HELPER(scrub_helper);
  86 BTRFS_WORK_HELPER(scrubwrc_helper);
  87 BTRFS_WORK_HELPER(scrubnc_helper);
  88 BTRFS_WORK_HELPER(scrubparity_helper);
  89
  90 static struct __btrfs_workqueue *
  91 __btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active,
  92                          int thresh)
  93 {
  94         struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
  95
  96         if (!ret)
  97                 return NULL;
  98
  99         ret->max_active = max_active;
 100         atomic_set(&ret->pending, 0);
 101         if (thresh == 0)
 102                 thresh = DFT_THRESHOLD;
 103         /* For low threshold, disabling threshold is a better choice */
 104         if (thresh < DFT_THRESHOLD) {
 105                 ret->current_max = max_active;
 106                 ret->thresh = NO_THRESHOLD;
 107         } else {
 108                 ret->current_max = 1;
 109                 ret->thresh = thresh;
 110         }
 111
 112         if (flags & WQ_HIGHPRI)
 113                 ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
 114                                                  ret->max_active,
 115                                                  "btrfs", name);
 116         else
 117                 ret->normal_wq = alloc_workqueue("%s-%s", flags,
 118                                                  ret->max_active, "btrfs",
 119                                                  name);
 120         if (!ret->normal_wq) {
 121                 kfree(ret);
 122                 return NULL;
 123         }
 124
 125         INIT_LIST_HEAD(&ret->ordered_list);
 126         spin_lock_init(&ret->list_lock);
 127         spin_lock_init(&ret->thres_lock);
 128         trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
 129         return ret;
 130 }
 131
 132 static inline void
 133 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
 134
 135 struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
 136                                               unsigned int flags,
 137                                               int max_active,
 138                                               int thresh)
 139 {
 140         struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 141
 142         if (!ret)
 143                 return NULL;
 144
 145         ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
 146                                               max_active, thresh);
 147         if (!ret->normal) {
 148                 kfree(ret);
 149                 return NULL;
 150         }
 151
 152         if (flags & WQ_HIGHPRI) {
 153                 ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
 154                                                     thresh);
 155                 if (!ret->high) {
 156                         __btrfs_destroy_workqueue(ret->normal);
 157                         kfree(ret);
 158                         return NULL;
 159                 }
 160         }
 161         return ret;
 162 }
 163
 164 /*
 165  * Hook for threshold which will be called in btrfs_queue_work.
 166  * This hook WILL be called in IRQ handler context,
 167  * so workqueue_set_max_active MUST NOT be called in this hook
 168  */
 169 static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
 170 {
 171         if (wq->thresh == NO_THRESHOLD)
 172                 return;
 173         atomic_inc(&wq->pending);
 174 }
 175
 176 /*
 177  * Hook for threshold which will be called before executing the work,
 178  * This hook is called in kthread content.
 179  * So workqueue_set_max_active is called here.
 180  */
 181 static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
 182 {
 183         int new_max_active;
 184         long pending;
 185         int need_change = 0;
 186
 187         if (wq->thresh == NO_THRESHOLD)
 188                 return;
 189
 190         atomic_dec(&wq->pending);
 191         spin_lock(&wq->thres_lock);
 192         /*
 193          * Use wq->count to limit the calling frequency of
 194          * workqueue_set_max_active.
 195          */
 196         wq->count++;
 197         wq->count %= (wq->thresh / 4);
 198         if (!wq->count)
 199                 goto  out;
 200         new_max_active = wq->current_max;
 201
 202         /*
 203          * pending may be changed later, but it's OK since we really
 204          * don't need it so accurate to calculate new_max_active.
 205          */
 206         pending = atomic_read(&wq->pending);
 207         if (pending > wq->thresh)
 208                 new_max_active++;
 209         if (pending < wq->thresh / 2)
 210                 new_max_active--;
 211         new_max_active = clamp_val(new_max_active, 1, wq->max_active);
 212         if (new_max_active != wq->current_max)  {
 213                 need_change = 1;
 214                 wq->current_max = new_max_active;
 215         }
 216 out:
 217         spin_unlock(&wq->thres_lock);
 218
 219         if (need_change) {
 220                 workqueue_set_max_active(wq->normal_wq, wq->current_max);
 221         }
 222 }
 223
 224 static void run_ordered_work(struct __btrfs_workqueue *wq)
 225 {
 226         struct list_head *list = &wq->ordered_list;
 227         struct btrfs_work *work;
 228         spinlock_t *lock = &wq->list_lock;
 229         unsigned long flags;
 230
 231         while (1) {
 232                 spin_lock_irqsave(lock, flags);
 233                 if (list_empty(list))
 234                         break;
 235                 work = list_entry(list->next, struct btrfs_work,
 236                                   ordered_list);
 237                 if (!test_bit(WORK_DONE_BIT, &work->flags))
 238                         break;
 239
 240                 /*
 241                  * we are going to call the ordered done function, but
 242                  * we leave the work item on the list as a barrier so
 243                  * that later work items that are done don't have their
 244                  * functions called before this one returns
 245                  */
 246                 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
 247                         break;
 248                 trace_btrfs_ordered_sched(work);
 249                 spin_unlock_irqrestore(lock, flags);
 250                 work->ordered_func(work);
 251
 252                 /* now take the lock again and drop our item from the list */
 253                 spin_lock_irqsave(lock, flags);
 254                 list_del(&work->ordered_list);
 255                 spin_unlock_irqrestore(lock, flags);
 256
 257                 /*
 258                  * we don't want to call the ordered free functions
 259                  * with the lock held though
 260                  */
 261                 work->ordered_free(work);
 262                 trace_btrfs_all_work_done(work);
 263         }
 264         spin_unlock_irqrestore(lock, flags);
 265 }
 266
 267 static void normal_work_helper(struct btrfs_work *work)
 268 {
 269         struct __btrfs_workqueue *wq;
 270         int need_order = 0;
 271
 272         /*
 273          * We should not touch things inside work in the following cases:
 274          * 1) after work->func() if it has no ordered_free
 275          *    Since the struct is freed in work->func().
 276          * 2) after setting WORK_DONE_BIT
 277          *    The work may be freed in other threads almost instantly.
 278          * So we save the needed things here.
 279          */
 280         if (work->ordered_func)
 281                 need_order = 1;
 282         wq = work->wq;
 283
 284         trace_btrfs_work_sched(work);
 285         thresh_exec_hook(wq);
 286         work->func(work);
 287         if (need_order) {
 288                 set_bit(WORK_DONE_BIT, &work->flags);
 289                 run_ordered_work(wq);
 290         }
 291         if (!need_order)
 292                 trace_btrfs_all_work_done(work);
 293 }
 294
 295 void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
 296                      btrfs_func_t func,
 297                      btrfs_func_t ordered_func,
 298                      btrfs_func_t ordered_free)
 299 {
 300         work->func = func;
 301         work->ordered_func = ordered_func;
 302         work->ordered_free = ordered_free;
 303         INIT_WORK(&work->normal_work, uniq_func);
 304         INIT_LIST_HEAD(&work->ordered_list);
 305         work->flags = 0;
 306 }
 307
 308 static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
 309                                       struct btrfs_work *work)
 310 {
 311         unsigned long flags;
 312
 313         work->wq = wq;
 314         thresh_queue_hook(wq);
 315         if (work->ordered_func) {
 316                 spin_lock_irqsave(&wq->list_lock, flags);
 317                 list_add_tail(&work->ordered_list, &wq->ordered_list);
 318                 spin_unlock_irqrestore(&wq->list_lock, flags);
 319         }
 320         queue_work(wq->normal_wq, &work->normal_work);
 321         trace_btrfs_work_queued(work);
 322 }
 323
 324 void btrfs_queue_work(struct btrfs_workqueue *wq,
 325                       struct btrfs_work *work)
 326 {
 327         struct __btrfs_workqueue *dest_wq;
 328
 329         if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
 330                 dest_wq = wq->high;
 331         else
 332                 dest_wq = wq->normal;
 333         __btrfs_queue_work(dest_wq, work);
 334 }
 335
 336 static inline void
 337 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
 338 {
 339         destroy_workqueue(wq->normal_wq);
 340         trace_btrfs_workqueue_destroy(wq);
 341         kfree(wq);
 342 }
 343
 344 void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
 345 {
 346         if (!wq)
 347                 return;
 348         if (wq->high)
 349                 __btrfs_destroy_workqueue(wq->high);
 350         __btrfs_destroy_workqueue(wq->normal);
 351         kfree(wq);
 352 }
 353
 354 void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
 355 {
 356         if (!wq)
 357                 return;
 358         wq->normal->max_active = max;
 359         if (wq->high)
 360                 wq->high->max_active = max;
 361 }
 362
 363 void btrfs_set_work_high_priority(struct btrfs_work *work)
 364 {
 365         set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
 366 }