kernel/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
  89 static struct __btrfs_workqueue *
  90 __btrfs_alloc_workqueue(const char *name, unsigned int flags, int max_active,
  91                          int thresh)
  92 {
  93         struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
  94
  95         if (!ret)
  96                 return NULL;
  97
  98         ret->max_active = max_active;
  99         atomic_set(&ret->pending, 0);
 100         if (thresh == 0)
 101                 thresh = DFT_THRESHOLD;
 102         /* For low threshold, disabling threshold is a better choice */
 103         if (thresh < DFT_THRESHOLD) {
 104                 ret->current_max = max_active;
 105                 ret->thresh = NO_THRESHOLD;
 106         } else {
 107                 ret->current_max = 1;
 108                 ret->thresh = thresh;
 109         }
 110
 111         if (flags & WQ_HIGHPRI)
 112                 ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
 113                                                  ret->max_active,
 114                                                  "btrfs", name);
 115         else
 116                 ret->normal_wq = alloc_workqueue("%s-%s", flags,
 117                                                  ret->max_active, "btrfs",
 118                                                  name);
 119         if (!ret->normal_wq) {
 120                 kfree(ret);
 121                 return NULL;
 122         }
 123
 124         INIT_LIST_HEAD(&ret->ordered_list);
 125         spin_lock_init(&ret->list_lock);
 126         spin_lock_init(&ret->thres_lock);
 127         trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
 128         return ret;
 129 }
 130
 131 static inline void
 132 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
 133
 134 struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
 135                                               unsigned int flags,
 136                                               int max_active,
 137                                               int thresh)
 138 {
 139         struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 140
 141         if (!ret)
 142                 return NULL;
 143
 144         ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
 145                                               max_active, thresh);
 146         if (!ret->normal) {
 147                 kfree(ret);
 148                 return NULL;
 149         }
 150
 151         if (flags & WQ_HIGHPRI) {
 152                 ret->high = __btrfs_alloc_workqueue(name, flags, max_active,
 153                                                     thresh);
 154                 if (!ret->high) {
 155                         __btrfs_destroy_workqueue(ret->normal);
 156                         kfree(ret);
 157                         return NULL;
 158                 }
 159         }
 160         return ret;
 161 }
 162
 163 /*
 164  * Hook for threshold which will be called in btrfs_queue_work.
 165  * This hook WILL be called in IRQ handler context,
 166  * so workqueue_set_max_active MUST NOT be called in this hook
 167  */
 168 static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
 169 {
 170         if (wq->thresh == NO_THRESHOLD)
 171                 return;
 172         atomic_inc(&wq->pending);
 173 }
 174
 175 /*
 176  * Hook for threshold which will be called before executing the work,
 177  * This hook is called in kthread content.
 178  * So workqueue_set_max_active is called here.
 179  */
 180 static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
 181 {
 182         int new_max_active;
 183         long pending;
 184         int need_change = 0;
 185
 186         if (wq->thresh == NO_THRESHOLD)
 187                 return;
 188
 189         atomic_dec(&wq->pending);
 190         spin_lock(&wq->thres_lock);
 191         /*
 192          * Use wq->count to limit the calling frequency of
 193          * workqueue_set_max_active.
 194          */
 195         wq->count++;
 196         wq->count %= (wq->thresh / 4);
 197         if (!wq->count)
 198                 goto  out;
 199         new_max_active = wq->current_max;
 200
 201         /*
 202          * pending may be changed later, but it's OK since we really
 203          * don't need it so accurate to calculate new_max_active.
 204          */
 205         pending = atomic_read(&wq->pending);
 206         if (pending > wq->thresh)
 207                 new_max_active++;
 208         if (pending < wq->thresh / 2)
 209                 new_max_active--;
 210         new_max_active = clamp_val(new_max_active, 1, wq->max_active);
 211         if (new_max_active != wq->current_max)  {
 212                 need_change = 1;
 213                 wq->current_max = new_max_active;
 214         }
 215 out:
 216         spin_unlock(&wq->thres_lock);
 217
 218         if (need_change) {
 219                 workqueue_set_max_active(wq->normal_wq, wq->current_max);
 220         }
 221 }
 222
 223 static void run_ordered_work(struct __btrfs_workqueue *wq)
 224 {
 225         struct list_head *list = &wq->ordered_list;
 226         struct btrfs_work *work;
 227         spinlock_t *lock = &wq->list_lock;
 228         unsigned long flags;
 229
 230         while (1) {
 231                 spin_lock_irqsave(lock, flags);
 232                 if (list_empty(list))
 233                         break;
 234                 work = list_entry(list->next, struct btrfs_work,
 235                                   ordered_list);
 236                 if (!test_bit(WORK_DONE_BIT, &work->flags))
 237                         break;
 238
 239                 /*
 240                  * we are going to call the ordered done function, but
 241                  * we leave the work item on the list as a barrier so
 242                  * that later work items that are done don't have their
 243                  * functions called before this one returns
 244                  */
 245                 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
 246                         break;
 247                 trace_btrfs_ordered_sched(work);
 248                 spin_unlock_irqrestore(lock, flags);
 249                 work->ordered_func(work);
 250
 251                 /* now take the lock again and drop our item from the list */
 252                 spin_lock_irqsave(lock, flags);
 253                 list_del(&work->ordered_list);
 254                 spin_unlock_irqrestore(lock, flags);
 255
 256                 /*
 257                  * we don't want to call the ordered free functions
 258                  * with the lock held though
 259                  */
 260                 work->ordered_free(work);
 261                 trace_btrfs_all_work_done(work);
 262         }
 263         spin_unlock_irqrestore(lock, flags);
 264 }
 265
 266 static void normal_work_helper(struct btrfs_work *work)
 267 {
 268         struct __btrfs_workqueue *wq;
 269         int need_order = 0;
 270
 271         /*
 272          * We should not touch things inside work in the following cases:
 273          * 1) after work->func() if it has no ordered_free
 274          *    Since the struct is freed in work->func().
 275          * 2) after setting WORK_DONE_BIT
 276          *    The work may be freed in other threads almost instantly.
 277          * So we save the needed things here.
 278          */
 279         if (work->ordered_func)
 280                 need_order = 1;
 281         wq = work->wq;
 282
 283         trace_btrfs_work_sched(work);
 284         thresh_exec_hook(wq);
 285         work->func(work);
 286         if (need_order) {
 287                 set_bit(WORK_DONE_BIT, &work->flags);
 288                 run_ordered_work(wq);
 289         }
 290         if (!need_order)
 291                 trace_btrfs_all_work_done(work);
 292 }
 293
 294 void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
 295                      btrfs_func_t func,
 296                      btrfs_func_t ordered_func,
 297                      btrfs_func_t ordered_free)
 298 {
 299         work->func = func;
 300         work->ordered_func = ordered_func;
 301         work->ordered_free = ordered_free;
 302         INIT_WORK(&work->normal_work, uniq_func);
 303         INIT_LIST_HEAD(&work->ordered_list);
 304         work->flags = 0;
 305 }
 306
 307 static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
 308                                       struct btrfs_work *work)
 309 {
 310         unsigned long flags;
 311
 312         work->wq = wq;
 313         thresh_queue_hook(wq);
 314         if (work->ordered_func) {
 315                 spin_lock_irqsave(&wq->list_lock, flags);
 316                 list_add_tail(&work->ordered_list, &wq->ordered_list);
 317                 spin_unlock_irqrestore(&wq->list_lock, flags);
 318         }
 319         queue_work(wq->normal_wq, &work->normal_work);
 320         trace_btrfs_work_queued(work);
 321 }
 322
 323 void btrfs_queue_work(struct btrfs_workqueue *wq,
 324                       struct btrfs_work *work)
 325 {
 326         struct __btrfs_workqueue *dest_wq;
 327
 328         if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
 329                 dest_wq = wq->high;
 330         else
 331                 dest_wq = wq->normal;
 332         __btrfs_queue_work(dest_wq, work);
 333 }
 334
 335 static inline void
 336 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
 337 {
 338         destroy_workqueue(wq->normal_wq);
 339         trace_btrfs_workqueue_destroy(wq);
 340         kfree(wq);
 341 }
 342
 343 void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
 344 {
 345         if (!wq)
 346                 return;
 347         if (wq->high)
 348                 __btrfs_destroy_workqueue(wq->high);
 349         __btrfs_destroy_workqueue(wq->normal);
 350         kfree(wq);
 351 }
 352
 353 void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max)
 354 {
 355         if (!wq)
 356                 return;
 357         wq->normal->max_active = max;
 358         if (wq->high)
 359                 wq->high->max_active = max;
 360 }
 361
 362 void btrfs_set_work_high_priority(struct btrfs_work *work)
 363 {
 364         set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
 365 }