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
  46         /* Up limit of concurrency workers */
  47         int limit_active;
  48
  49         /* Current number of concurrency workers */
  50         int current_active;
  51
  52         /* Threshold to change current_active */
  53         int thresh;
  54         unsigned int count;
  55         spinlock_t thres_lock;
  56 };
  57
  58 struct btrfs_workqueue {
  59         struct __btrfs_workqueue *normal;
  60         struct __btrfs_workqueue *high;
  61 };
  62
  63 static void normal_work_helper(struct btrfs_work *work);
  64
  65 #define BTRFS_WORK_HELPER(name)                                 \
  66 void btrfs_##name(struct work_struct *arg)                              \
  67 {                                                                       \
  68         struct btrfs_work *work = container_of(arg, struct btrfs_work,  \
  69                                                normal_work);            \
  70         normal_work_helper(work);                                       \
  71 }
  72
  73 BTRFS_WORK_HELPER(worker_helper);
  74 BTRFS_WORK_HELPER(delalloc_helper);
  75 BTRFS_WORK_HELPER(flush_delalloc_helper);
  76 BTRFS_WORK_HELPER(cache_helper);
  77 BTRFS_WORK_HELPER(submit_helper);
  78 BTRFS_WORK_HELPER(fixup_helper);
  79 BTRFS_WORK_HELPER(endio_helper);
  80 BTRFS_WORK_HELPER(endio_meta_helper);
  81 BTRFS_WORK_HELPER(endio_meta_write_helper);
  82 BTRFS_WORK_HELPER(endio_raid56_helper);
  83 BTRFS_WORK_HELPER(endio_repair_helper);
  84 BTRFS_WORK_HELPER(rmw_helper);
  85 BTRFS_WORK_HELPER(endio_write_helper);
  86 BTRFS_WORK_HELPER(freespace_write_helper);
  87 BTRFS_WORK_HELPER(delayed_meta_helper);
  88 BTRFS_WORK_HELPER(readahead_helper);
  89 BTRFS_WORK_HELPER(qgroup_rescan_helper);
  90 BTRFS_WORK_HELPER(extent_refs_helper);
  91 BTRFS_WORK_HELPER(scrub_helper);
  92 BTRFS_WORK_HELPER(scrubwrc_helper);
  93 BTRFS_WORK_HELPER(scrubnc_helper);
  94 BTRFS_WORK_HELPER(scrubparity_helper);
  95
  96 static struct __btrfs_workqueue *
  97 __btrfs_alloc_workqueue(const char *name, unsigned int flags, int limit_active,
  98                          int thresh)
  99 {
 100         struct __btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 101
 102         if (!ret)
 103                 return NULL;
 104
 105         ret->limit_active = limit_active;
 106         atomic_set(&ret->pending, 0);
 107         if (thresh == 0)
 108                 thresh = DFT_THRESHOLD;
 109         /* For low threshold, disabling threshold is a better choice */
 110         if (thresh < DFT_THRESHOLD) {
 111                 ret->current_active = limit_active;
 112                 ret->thresh = NO_THRESHOLD;
 113         } else {
 114                 /*
 115                  * For threshold-able wq, let its concurrency grow on demand.
 116                  * Use minimal max_active at alloc time to reduce resource
 117                  * usage.
 118                  */
 119                 ret->current_active = 1;
 120                 ret->thresh = thresh;
 121         }
 122
 123         if (flags & WQ_HIGHPRI)
 124                 ret->normal_wq = alloc_workqueue("%s-%s-high", flags,
 125                                                  ret->current_active, "btrfs",
 126                                                  name);
 127         else
 128                 ret->normal_wq = alloc_workqueue("%s-%s", flags,
 129                                                  ret->current_active, "btrfs",
 130                                                  name);
 131         if (!ret->normal_wq) {
 132                 kfree(ret);
 133                 return NULL;
 134         }
 135
 136         INIT_LIST_HEAD(&ret->ordered_list);
 137         spin_lock_init(&ret->list_lock);
 138         spin_lock_init(&ret->thres_lock);
 139         trace_btrfs_workqueue_alloc(ret, name, flags & WQ_HIGHPRI);
 140         return ret;
 141 }
 142
 143 static inline void
 144 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq);
 145
 146 struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
 147                                               unsigned int flags,
 148                                               int limit_active,
 149                                               int thresh)
 150 {
 151         struct btrfs_workqueue *ret = kzalloc(sizeof(*ret), GFP_NOFS);
 152
 153         if (!ret)
 154                 return NULL;
 155
 156         ret->normal = __btrfs_alloc_workqueue(name, flags & ~WQ_HIGHPRI,
 157                                               limit_active, thresh);
 158         if (!ret->normal) {
 159                 kfree(ret);
 160                 return NULL;
 161         }
 162
 163         if (flags & WQ_HIGHPRI) {
 164                 ret->high = __btrfs_alloc_workqueue(name, flags, limit_active,
 165                                                     thresh);
 166                 if (!ret->high) {
 167                         __btrfs_destroy_workqueue(ret->normal);
 168                         kfree(ret);
 169                         return NULL;
 170                 }
 171         }
 172         return ret;
 173 }
 174
 175 /*
 176  * Hook for threshold which will be called in btrfs_queue_work.
 177  * This hook WILL be called in IRQ handler context,
 178  * so workqueue_set_max_active MUST NOT be called in this hook
 179  */
 180 static inline void thresh_queue_hook(struct __btrfs_workqueue *wq)
 181 {
 182         if (wq->thresh == NO_THRESHOLD)
 183                 return;
 184         atomic_inc(&wq->pending);
 185 }
 186
 187 /*
 188  * Hook for threshold which will be called before executing the work,
 189  * This hook is called in kthread content.
 190  * So workqueue_set_max_active is called here.
 191  */
 192 static inline void thresh_exec_hook(struct __btrfs_workqueue *wq)
 193 {
 194         int new_current_active;
 195         long pending;
 196         int need_change = 0;
 197
 198         if (wq->thresh == NO_THRESHOLD)
 199                 return;
 200
 201         atomic_dec(&wq->pending);
 202         spin_lock(&wq->thres_lock);
 203         /*
 204          * Use wq->count to limit the calling frequency of
 205          * workqueue_set_max_active.
 206          */
 207         wq->count++;
 208         wq->count %= (wq->thresh / 4);
 209         if (!wq->count)
 210                 goto  out;
 211         new_current_active = wq->current_active;
 212
 213         /*
 214          * pending may be changed later, but it's OK since we really
 215          * don't need it so accurate to calculate new_max_active.
 216          */
 217         pending = atomic_read(&wq->pending);
 218         if (pending > wq->thresh)
 219                 new_current_active++;
 220         if (pending < wq->thresh / 2)
 221                 new_current_active--;
 222         new_current_active = clamp_val(new_current_active, 1, wq->limit_active);
 223         if (new_current_active != wq->current_active)  {
 224                 need_change = 1;
 225                 wq->current_active = new_current_active;
 226         }
 227 out:
 228         spin_unlock(&wq->thres_lock);
 229
 230         if (need_change) {
 231                 workqueue_set_max_active(wq->normal_wq, wq->current_active);
 232         }
 233 }
 234
 235 static void run_ordered_work(struct __btrfs_workqueue *wq)
 236 {
 237         struct list_head *list = &wq->ordered_list;
 238         struct btrfs_work *work;
 239         spinlock_t *lock = &wq->list_lock;
 240         unsigned long flags;
 241
 242         while (1) {
 243                 spin_lock_irqsave(lock, flags);
 244                 if (list_empty(list))
 245                         break;
 246                 work = list_entry(list->next, struct btrfs_work,
 247                                   ordered_list);
 248                 if (!test_bit(WORK_DONE_BIT, &work->flags))
 249                         break;
 250
 251                 /*
 252                  * we are going to call the ordered done function, but
 253                  * we leave the work item on the list as a barrier so
 254                  * that later work items that are done don't have their
 255                  * functions called before this one returns
 256                  */
 257                 if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags))
 258                         break;
 259                 trace_btrfs_ordered_sched(work);
 260                 spin_unlock_irqrestore(lock, flags);
 261                 work->ordered_func(work);
 262
 263                 /* now take the lock again and drop our item from the list */
 264                 spin_lock_irqsave(lock, flags);
 265                 list_del(&work->ordered_list);
 266                 spin_unlock_irqrestore(lock, flags);
 267
 268                 /*
 269                  * we don't want to call the ordered free functions
 270                  * with the lock held though
 271                  */
 272                 work->ordered_free(work);
 273                 trace_btrfs_all_work_done(work);
 274         }
 275         spin_unlock_irqrestore(lock, flags);
 276 }
 277
 278 static void normal_work_helper(struct btrfs_work *work)
 279 {
 280         struct __btrfs_workqueue *wq;
 281         int need_order = 0;
 282
 283         /*
 284          * We should not touch things inside work in the following cases:
 285          * 1) after work->func() if it has no ordered_free
 286          *    Since the struct is freed in work->func().
 287          * 2) after setting WORK_DONE_BIT
 288          *    The work may be freed in other threads almost instantly.
 289          * So we save the needed things here.
 290          */
 291         if (work->ordered_func)
 292                 need_order = 1;
 293         wq = work->wq;
 294
 295         trace_btrfs_work_sched(work);
 296         thresh_exec_hook(wq);
 297         work->func(work);
 298         if (need_order) {
 299                 set_bit(WORK_DONE_BIT, &work->flags);
 300                 run_ordered_work(wq);
 301         }
 302         if (!need_order)
 303                 trace_btrfs_all_work_done(work);
 304 }
 305
 306 void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func,
 307                      btrfs_func_t func,
 308                      btrfs_func_t ordered_func,
 309                      btrfs_func_t ordered_free)
 310 {
 311         work->func = func;
 312         work->ordered_func = ordered_func;
 313         work->ordered_free = ordered_free;
 314         INIT_WORK(&work->normal_work, uniq_func);
 315         INIT_LIST_HEAD(&work->ordered_list);
 316         work->flags = 0;
 317 }
 318
 319 static inline void __btrfs_queue_work(struct __btrfs_workqueue *wq,
 320                                       struct btrfs_work *work)
 321 {
 322         unsigned long flags;
 323
 324         work->wq = wq;
 325         thresh_queue_hook(wq);
 326         if (work->ordered_func) {
 327                 spin_lock_irqsave(&wq->list_lock, flags);
 328                 list_add_tail(&work->ordered_list, &wq->ordered_list);
 329                 spin_unlock_irqrestore(&wq->list_lock, flags);
 330         }
 331         trace_btrfs_work_queued(work);
 332         queue_work(wq->normal_wq, &work->normal_work);
 333 }
 334
 335 void btrfs_queue_work(struct btrfs_workqueue *wq,
 336                       struct btrfs_work *work)
 337 {
 338         struct __btrfs_workqueue *dest_wq;
 339
 340         if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags) && wq->high)
 341                 dest_wq = wq->high;
 342         else
 343                 dest_wq = wq->normal;
 344         __btrfs_queue_work(dest_wq, work);
 345 }
 346
 347 static inline void
 348 __btrfs_destroy_workqueue(struct __btrfs_workqueue *wq)
 349 {
 350         destroy_workqueue(wq->normal_wq);
 351         trace_btrfs_workqueue_destroy(wq);
 352         kfree(wq);
 353 }
 354
 355 void btrfs_destroy_workqueue(struct btrfs_workqueue *wq)
 356 {
 357         if (!wq)
 358                 return;
 359         if (wq->high)
 360                 __btrfs_destroy_workqueue(wq->high);
 361         __btrfs_destroy_workqueue(wq->normal);
 362         kfree(wq);
 363 }
 364
 365 void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int limit_active)
 366 {
 367         if (!wq)
 368                 return;
 369         wq->normal->limit_active = limit_active;
 370         if (wq->high)
 371                 wq->high->limit_active = limit_active;
 372 }
 373
 374 void btrfs_set_work_high_priority(struct btrfs_work *work)
 375 {
 376         set_bit(WORK_HIGH_PRIO_BIT, &work->flags);
 377 }