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(rmw_helper);
  78 BTRFS_WORK_HELPER(endio_write_helper);
  79 BTRFS_WORK_HELPER(freespace_write_helper);
  80 BTRFS_WORK_HELPER(delayed_meta_helper);
  81 BTRFS_WORK_HELPER(readahead_helper);
  82 BTRFS_WORK_HELPER(qgroup_rescan_helper);
  83 BTRFS_WORK_HELPER(extent_refs_helper);
  84 BTRFS_WORK_HELPER(scrub_helper);
  85 BTRFS_WORK_HELPER(scrubwrc_helper);
  86 BTRFS_WORK_HELPER(scrubnc_helper);
  87
  88 static struct __btrfs_workqueue *
  89 __btrfs_alloc_workqueue(const char *name, int flags, int max_active,
  90                          int thresh)
  91 {
  92         struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
  93
  94         if (unlikely(!ret))
  95                 return NULL;
  96
  97         ret->max_active = max_active;
  98         atomic_set(&ret->pending, 0);
  99         if (thresh == 0)
 100                 thresh = DFT_THRESHOLD;
 101         /* For low threshold, disabling threshold is a better choice */
 102         if (thresh < DFT_THRESHOLD) {
 103                 ret->current_max = max_active;
 104                 ret->thresh = NO_THRESHOLD;
 105         } else {
 106                 ret->current_max = 1;
 107                 ret->thresh = thresh;
 108         }
 109
 110         if (flags & WQ_HIGHPRI)
 111                 ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
 112                                                  ret->max_active,
 113                                                  "btrfs", name);
 114         else
 115                 ret->normal_wq = alloc_workqueue("%s-%s", flags,
 116                                                  ret->max_active, "btrfs",
 117                                                  name);
 118         if (unlikely(!ret->normal_wq)) {
 119                 kfree(ret);
 120                 return NULL;
 121         }
 122
 123         INIT_LIST_HEAD(&ret->ordered_list);
 124         spin_lock_init(&ret->list_lock);
 125         spin_lock_init(&ret->thres_lock);
 126         trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
 127         return ret;
 128 }
 129
 130 static inline void
 131 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
 132
 133 struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
 134                                               int flags,
 135                                               int max_active,
 136                                               int thresh)
 137 {
 138         struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 139
 140         if (unlikely(!ret))
 141                 return NULL;
 142
 143         ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
 144                                               max_active, thresh);
 145         if (unlikely(!ret->normal)) {
 146                 kfree(ret);
 147                 return NULL;
 148         }
 149
 150         if (flags & WQ_HIGHPRI) {
 151                 ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
 152                                                     thresh);
 153                 if (unlikely(!ret->high)) {
 154                         __btrfs_destroy_workqueue(ret->normal);
 155                         kfree(ret);
 156                         return NULL;
 157                 }
 158         }
 159         return ret;
 160 }
 161
 162 /*
 163  * Hook for threshold which will be called in btrfs_queue_work.
 164  * This hook WILL be called in IRQ handler context,
 165  * so workqueue_set_max_active MUST NOT be called in this hook
 166  */
 167 static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
 168 {
 169         if (wq->thresh == NO_THRESHOLD)
 170                 return;
 171         atomic_inc(&wq->pending);
 172 }
 173
 174 /*
 175  * Hook for threshold which will be called before executing the work,
 176  * This hook is called in kthread content.
 177  * So workqueue_set_max_active is called here.
 178  */
 179 static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
 180 {
 181         int new_max_active;
 182         long pending;
 183         int need_change = 0;
 184
 185         if (wq->thresh == NO_THRESHOLD)
 186                 return;
 187
 188         atomic_dec(&wq->pending);
 189         spin_lock(&wq->thres_lock);
 190         /*
 191          * Use wq->count to limit the calling frequency of
 192          * workqueue_set_max_active.
 193          */
 194         wq->count++;
 195         wq->count %= (wq->thresh / 4);
 196         if (!wq->count)
 197                 goto  out;
 198         new_max_active = wq->current_max;
 199
 200         /*
 201          * pending may be changed later, but it's OK since we really
 202          * don't need it so accurate to calculate new_max_active.
 203          */
 204         pending = atomic_read(&wq->pending);
 205         if (pending > wq->thresh)
 206                 new_max_active++;
 207         if (pending < wq->thresh / 2)
 208                 new_max_active--;
 209         new_max_active = clamp_val(new_max_active, 1, wq->max_active);
 210         if (new_max_active != wq->current_max)  {
 211                 need_change = 1;
 212                 wq->current_max = new_max_active;
 213         }
 214 out:
 215         spin_unlock(&wq->thres_lock);
 216
 217         if (need_change) {
 218                 workqueue_set_max_active(wq->normal_wq, wq->current_max);
 219         }
 220 }
 221
 222 static void run_ordered_work(struct __btrfs_workqueue *wq)
 223 {
 224         struct list_head *list = &wq->ordered_list;
 225         struct btrfs_work *work;
 226         spinlock_t *lock = &wq->list_lock;
 227         unsigned long flags;
 228
 229         while (1) {
 230                 spin_lock_irqsave(lock, flags);
 231                 if (list_empty(list))
 232                         break;
 233                 work = list_entry(list->next, struct btrfs_work,
 234                                   ordered_list);
 235                 if (!test_bit(WORK_DONE_BIT, &work->flags))
 236                         break;
 237
 238                 /*
 239                  * we are going to call the ordered done function, but
 240                  * we leave the work item on the list as a barrier so
 241                  * that later work items that are done don't have their
 242                  * functions called before this one returns
 243                  */
 244                 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
 245                         break;
 246                 trace_btrfs_ordered_sched(work);
 247                 spin_unlock_irqrestore(lock, flags);
 248                 work->ordered_func(work);
 249
 250                 /* now take the lock again and drop our item from the list */
 251                 spin_lock_irqsave(lock, flags);
 252                 list_del(&work->ordered_list);
 253                 spin_unlock_irqrestore(lock, flags);
 254
 255                 /*
 256                  * we don't want to call the ordered free functions
 257                  * with the lock held though
 258                  */
 259                 work->ordered_free(work);
 260                 trace_btrfs_all_work_done(work);
 261         }
 262         spin_unlock_irqrestore(lock, flags);
 263 }
 264
 265 static void normal_work_helper(struct btrfs_work *work)
 266 {
 267         struct __btrfs_workqueue *wq;
 268         int need_order = 0;
 269
 270         /*
 271          * We should not touch things inside work in the following cases:
 272          * 1) after work->func() if it has no ordered_free
 273          *    Since the struct is freed in work->func().
 274          * 2) after setting WORK_DONE_BIT
 275          *    The work may be freed in other threads almost instantly.
 276          * So we save the needed things here.
 277          */
 278         if (work->ordered_func)
 279                 need_order = 1;
 280         wq = work->wq;
 281
 282         trace_btrfs_work_sched(work);
 283         thresh_exec_hook(wq);
 284         work->func(work);
 285         if (need_order) {
 286                 set_bit(WORK_DONE_BIT, &work->flags);
 287                 run_ordered_work(wq);
 288         }
 289         if (!need_order)
 290                 trace_btrfs_all_work_done(work);
 291 }
 292
 293 void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
 294                      btrfs_func_t func,
 295                      btrfs_func_t ordered_func,
 296                      btrfs_func_t ordered_free)
 297 {
 298         work->func = func;
 299         work->ordered_func = ordered_func;
 300         work->ordered_free = ordered_free;
 301         INIT_WORK(&work->normal_work, uniq_func);
 302         INIT_LIST_HEAD(&work->ordered_list);
 303         work->flags = 0;
 304 }
 305
 306 static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
 307                                       struct btrfs_work *work)
 308 {
 309         unsigned long flags;
 310
 311         work->wq = wq;
 312         thresh_queue_hook(wq);
 313         if (work->ordered_func) {
 314                 spin_lock_irqsave(&wq->list_lock, flags);
 315                 list_add_tail(&work->ordered_list, &wq->ordered_list);
 316                 spin_unlock_irqrestore(&wq->list_lock, flags);
 317         }
 318         queue_work(wq->normal_wq, &work->normal_work);
 319         trace_btrfs_work_queued(work);
 320 }
 321
 322 void btrfs_queue_work(struct btrfs_workqueue *wq,
 323                       struct btrfs_work *work)
 324 {
 325         struct __btrfs_workqueue *dest_wq;
 326
 327         if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
 328                 dest_wq = wq->high;
 329         else
 330                 dest_wq = wq->normal;
 331         __btrfs_queue_work(dest_wq, work);
 332 }
 333
 334 static inline void
 335 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
 336 {
 337         destroy_workqueue(wq->normal_wq);
 338         trace_btrfs_workqueue_destroy(wq);
 339         kfree(wq);
 340 }
 341
 342 void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
 343 {
 344         if (!wq)
 345                 return;
 346         if (wq->high)
 347                 __btrfs_destroy_workqueue(wq->high);
 348         __btrfs_destroy_workqueue(wq->normal);
 349         kfree(wq);
 350 }
 351
 352 void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
 353 {
 354         if (!wq)
 355                 return;
 356         wq->normal->max_active = max;
 357         if (wq->high)
 358                 wq->high->max_active = max;
 359 }
 360
 361 void btrfs_set_work_high_priority(struct btrfs_work *work)
 362 {
 363         set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
 364 }