blob: 4645cd16d5ba22d94396eec0f00e1243371eeb7c [file] [log] [blame]
Arne Jansen7414a032011-05-23 14:33:49 +02001/*
2 * Copyright (C) 2011 STRATO. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/sched.h>
20#include <linux/pagemap.h>
21#include <linux/writeback.h>
22#include <linux/blkdev.h>
23#include <linux/rbtree.h>
24#include <linux/slab.h>
25#include <linux/workqueue.h>
26#include "ctree.h"
27#include "volumes.h"
28#include "disk-io.h"
29#include "transaction.h"
Stefan Behrens8dabb742012-11-06 13:15:27 +010030#include "dev-replace.h"
Arne Jansen7414a032011-05-23 14:33:49 +020031
32#undef DEBUG
33
34/*
35 * This is the implementation for the generic read ahead framework.
36 *
37 * To trigger a readahead, btrfs_reada_add must be called. It will start
38 * a read ahead for the given range [start, end) on tree root. The returned
39 * handle can either be used to wait on the readahead to finish
40 * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
41 *
42 * The read ahead works as follows:
43 * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
44 * reada_start_machine will then search for extents to prefetch and trigger
45 * some reads. When a read finishes for a node, all contained node/leaf
46 * pointers that lie in the given range will also be enqueued. The reads will
47 * be triggered in sequential order, thus giving a big win over a naive
48 * enumeration. It will also make use of multi-device layouts. Each disk
49 * will have its on read pointer and all disks will by utilized in parallel.
50 * Also will no two disks read both sides of a mirror simultaneously, as this
51 * would waste seeking capacity. Instead both disks will read different parts
52 * of the filesystem.
53 * Any number of readaheads can be started in parallel. The read order will be
54 * determined globally, i.e. 2 parallel readaheads will normally finish faster
55 * than the 2 started one after another.
56 */
57
Arne Jansen7414a032011-05-23 14:33:49 +020058#define MAX_IN_FLIGHT 6
59
60struct reada_extctl {
61 struct list_head list;
62 struct reada_control *rc;
63 u64 generation;
64};
65
66struct reada_extent {
67 u64 logical;
68 struct btrfs_key top;
Arne Jansen7414a032011-05-23 14:33:49 +020069 int err;
70 struct list_head extctl;
Al Viro99621b42012-08-29 16:31:33 -040071 int refcnt;
Arne Jansen7414a032011-05-23 14:33:49 +020072 spinlock_t lock;
Stefan Behrens94598ba2012-03-27 14:21:26 -040073 struct reada_zone *zones[BTRFS_MAX_MIRRORS];
Arne Jansen7414a032011-05-23 14:33:49 +020074 int nzones;
75 struct btrfs_device *scheduled_for;
76};
77
78struct reada_zone {
79 u64 start;
80 u64 end;
81 u64 elems;
82 struct list_head list;
83 spinlock_t lock;
84 int locked;
85 struct btrfs_device *device;
Stefan Behrens94598ba2012-03-27 14:21:26 -040086 struct btrfs_device *devs[BTRFS_MAX_MIRRORS]; /* full list, incl
87 * self */
Arne Jansen7414a032011-05-23 14:33:49 +020088 int ndevs;
89 struct kref refcnt;
90};
91
92struct reada_machine_work {
Qu Wenruod458b052014-02-28 10:46:19 +080093 struct btrfs_work work;
Arne Jansen7414a032011-05-23 14:33:49 +020094 struct btrfs_fs_info *fs_info;
95};
96
97static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *);
98static void reada_control_release(struct kref *kref);
99static void reada_zone_release(struct kref *kref);
100static void reada_start_machine(struct btrfs_fs_info *fs_info);
101static void __reada_start_machine(struct btrfs_fs_info *fs_info);
102
103static int reada_add_block(struct reada_control *rc, u64 logical,
104 struct btrfs_key *top, int level, u64 generation);
105
106/* recurses */
107/* in case of err, eb might be NULL */
108static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
109 u64 start, int err)
110{
111 int level = 0;
112 int nritems;
113 int i;
114 u64 bytenr;
115 u64 generation;
116 struct reada_extent *re;
117 struct btrfs_fs_info *fs_info = root->fs_info;
118 struct list_head list;
119 unsigned long index = start >> PAGE_CACHE_SHIFT;
120 struct btrfs_device *for_dev;
121
122 if (eb)
123 level = btrfs_header_level(eb);
124
125 /* find extent */
126 spin_lock(&fs_info->reada_lock);
127 re = radix_tree_lookup(&fs_info->reada_tree, index);
128 if (re)
Al Viro99621b42012-08-29 16:31:33 -0400129 re->refcnt++;
Arne Jansen7414a032011-05-23 14:33:49 +0200130 spin_unlock(&fs_info->reada_lock);
131
132 if (!re)
133 return -1;
134
135 spin_lock(&re->lock);
136 /*
137 * just take the full list from the extent. afterwards we
138 * don't need the lock anymore
139 */
140 list_replace_init(&re->extctl, &list);
141 for_dev = re->scheduled_for;
142 re->scheduled_for = NULL;
143 spin_unlock(&re->lock);
144
145 if (err == 0) {
146 nritems = level ? btrfs_header_nritems(eb) : 0;
147 generation = btrfs_header_generation(eb);
148 /*
149 * FIXME: currently we just set nritems to 0 if this is a leaf,
150 * effectively ignoring the content. In a next step we could
151 * trigger more readahead depending from the content, e.g.
152 * fetch the checksums for the extents in the leaf.
153 */
154 } else {
155 /*
156 * this is the error case, the extent buffer has not been
157 * read correctly. We won't access anything from it and
158 * just cleanup our data structures. Effectively this will
159 * cut the branch below this node from read ahead.
160 */
161 nritems = 0;
162 generation = 0;
163 }
164
165 for (i = 0; i < nritems; i++) {
166 struct reada_extctl *rec;
167 u64 n_gen;
168 struct btrfs_key key;
169 struct btrfs_key next_key;
170
171 btrfs_node_key_to_cpu(eb, &key, i);
172 if (i + 1 < nritems)
173 btrfs_node_key_to_cpu(eb, &next_key, i + 1);
174 else
175 next_key = re->top;
176 bytenr = btrfs_node_blockptr(eb, i);
177 n_gen = btrfs_node_ptr_generation(eb, i);
178
179 list_for_each_entry(rec, &list, list) {
180 struct reada_control *rc = rec->rc;
181
182 /*
183 * if the generation doesn't match, just ignore this
184 * extctl. This will probably cut off a branch from
185 * prefetch. Alternatively one could start a new (sub-)
186 * prefetch for this branch, starting again from root.
187 * FIXME: move the generation check out of this loop
188 */
189#ifdef DEBUG
190 if (rec->generation != generation) {
Frank Holtonefe120a2013-12-20 11:37:06 -0500191 btrfs_debug(root->fs_info,
192 "generation mismatch for (%llu,%d,%llu) %llu != %llu",
Arne Jansen7414a032011-05-23 14:33:49 +0200193 key.objectid, key.type, key.offset,
194 rec->generation, generation);
195 }
196#endif
197 if (rec->generation == generation &&
198 btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
199 btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
200 reada_add_block(rc, bytenr, &next_key,
201 level - 1, n_gen);
202 }
203 }
204 /*
205 * free extctl records
206 */
207 while (!list_empty(&list)) {
208 struct reada_control *rc;
209 struct reada_extctl *rec;
210
211 rec = list_first_entry(&list, struct reada_extctl, list);
212 list_del(&rec->list);
213 rc = rec->rc;
214 kfree(rec);
215
216 kref_get(&rc->refcnt);
217 if (atomic_dec_and_test(&rc->elems)) {
218 kref_put(&rc->refcnt, reada_control_release);
219 wake_up(&rc->wait);
220 }
221 kref_put(&rc->refcnt, reada_control_release);
222
223 reada_extent_put(fs_info, re); /* one ref for each entry */
224 }
225 reada_extent_put(fs_info, re); /* our ref */
226 if (for_dev)
227 atomic_dec(&for_dev->reada_in_flight);
228
229 return 0;
230}
231
232/*
233 * start is passed separately in case eb in NULL, which may be the case with
234 * failed I/O
235 */
236int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
237 u64 start, int err)
238{
239 int ret;
240
241 ret = __readahead_hook(root, eb, start, err);
242
243 reada_start_machine(root->fs_info);
244
245 return ret;
246}
247
248static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
249 struct btrfs_device *dev, u64 logical,
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400250 struct btrfs_bio *bbio)
Arne Jansen7414a032011-05-23 14:33:49 +0200251{
252 int ret;
Arne Jansen7414a032011-05-23 14:33:49 +0200253 struct reada_zone *zone;
254 struct btrfs_block_group_cache *cache = NULL;
255 u64 start;
256 u64 end;
257 int i;
258
Arne Jansen7414a032011-05-23 14:33:49 +0200259 zone = NULL;
260 spin_lock(&fs_info->reada_lock);
261 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
262 logical >> PAGE_CACHE_SHIFT, 1);
263 if (ret == 1)
264 kref_get(&zone->refcnt);
265 spin_unlock(&fs_info->reada_lock);
266
267 if (ret == 1) {
268 if (logical >= zone->start && logical < zone->end)
269 return zone;
270 spin_lock(&fs_info->reada_lock);
271 kref_put(&zone->refcnt, reada_zone_release);
272 spin_unlock(&fs_info->reada_lock);
273 }
274
Arne Jansen7414a032011-05-23 14:33:49 +0200275 cache = btrfs_lookup_block_group(fs_info, logical);
276 if (!cache)
277 return NULL;
278
279 start = cache->key.objectid;
280 end = start + cache->key.offset - 1;
281 btrfs_put_block_group(cache);
282
283 zone = kzalloc(sizeof(*zone), GFP_NOFS);
284 if (!zone)
285 return NULL;
286
287 zone->start = start;
288 zone->end = end;
289 INIT_LIST_HEAD(&zone->list);
290 spin_lock_init(&zone->lock);
291 zone->locked = 0;
292 kref_init(&zone->refcnt);
293 zone->elems = 0;
294 zone->device = dev; /* our device always sits at index 0 */
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400295 for (i = 0; i < bbio->num_stripes; ++i) {
Arne Jansen7414a032011-05-23 14:33:49 +0200296 /* bounds have already been checked */
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400297 zone->devs[i] = bbio->stripes[i].dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200298 }
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400299 zone->ndevs = bbio->num_stripes;
Arne Jansen7414a032011-05-23 14:33:49 +0200300
301 spin_lock(&fs_info->reada_lock);
302 ret = radix_tree_insert(&dev->reada_zones,
Chris Masona1754232012-02-28 12:42:44 -0500303 (unsigned long)(zone->end >> PAGE_CACHE_SHIFT),
Arne Jansen7414a032011-05-23 14:33:49 +0200304 zone);
Arne Jansen7414a032011-05-23 14:33:49 +0200305
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100306 if (ret == -EEXIST) {
Arne Jansen7414a032011-05-23 14:33:49 +0200307 kfree(zone);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100308 ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
309 logical >> PAGE_CACHE_SHIFT, 1);
310 if (ret == 1)
311 kref_get(&zone->refcnt);
Arne Jansen7414a032011-05-23 14:33:49 +0200312 }
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100313 spin_unlock(&fs_info->reada_lock);
Arne Jansen7414a032011-05-23 14:33:49 +0200314
315 return zone;
316}
317
318static struct reada_extent *reada_find_extent(struct btrfs_root *root,
319 u64 logical,
320 struct btrfs_key *top, int level)
321{
322 int ret;
Arne Jansen7414a032011-05-23 14:33:49 +0200323 struct reada_extent *re = NULL;
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100324 struct reada_extent *re_exist = NULL;
Arne Jansen7414a032011-05-23 14:33:49 +0200325 struct btrfs_fs_info *fs_info = root->fs_info;
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400326 struct btrfs_bio *bbio = NULL;
Arne Jansen7414a032011-05-23 14:33:49 +0200327 struct btrfs_device *dev;
Arne Jansen207a2322012-02-25 09:09:47 +0100328 struct btrfs_device *prev_dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200329 u32 blocksize;
330 u64 length;
Omar Sandoval7cb2c422015-06-19 11:52:49 -0700331 int real_stripes;
Arne Jansen7414a032011-05-23 14:33:49 +0200332 int nzones = 0;
333 int i;
334 unsigned long index = logical >> PAGE_CACHE_SHIFT;
Stefan Behrens8dabb742012-11-06 13:15:27 +0100335 int dev_replace_is_ongoing;
Arne Jansen7414a032011-05-23 14:33:49 +0200336
Arne Jansen7414a032011-05-23 14:33:49 +0200337 spin_lock(&fs_info->reada_lock);
338 re = radix_tree_lookup(&fs_info->reada_tree, index);
339 if (re)
Al Viro99621b42012-08-29 16:31:33 -0400340 re->refcnt++;
Arne Jansen7414a032011-05-23 14:33:49 +0200341 spin_unlock(&fs_info->reada_lock);
342
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100343 if (re)
Arne Jansen7414a032011-05-23 14:33:49 +0200344 return re;
345
346 re = kzalloc(sizeof(*re), GFP_NOFS);
347 if (!re)
348 return NULL;
349
David Sterba707e8a02014-06-04 19:22:26 +0200350 blocksize = root->nodesize;
Arne Jansen7414a032011-05-23 14:33:49 +0200351 re->logical = logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200352 re->top = *top;
353 INIT_LIST_HEAD(&re->extctl);
354 spin_lock_init(&re->lock);
Al Viro99621b42012-08-29 16:31:33 -0400355 re->refcnt = 1;
Arne Jansen7414a032011-05-23 14:33:49 +0200356
357 /*
358 * map block
359 */
360 length = blocksize;
Stefan Behrens29a8d9a2012-11-06 14:16:24 +0100361 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
362 &bbio, 0);
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400363 if (ret || !bbio || length < blocksize)
Arne Jansen7414a032011-05-23 14:33:49 +0200364 goto error;
365
Stefan Behrens94598ba2012-03-27 14:21:26 -0400366 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
Frank Holtonefe120a2013-12-20 11:37:06 -0500367 btrfs_err(root->fs_info,
368 "readahead: more than %d copies not supported",
369 BTRFS_MAX_MIRRORS);
Arne Jansen7414a032011-05-23 14:33:49 +0200370 goto error;
371 }
372
Omar Sandoval7cb2c422015-06-19 11:52:49 -0700373 real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
374 for (nzones = 0; nzones < real_stripes; ++nzones) {
Arne Jansen7414a032011-05-23 14:33:49 +0200375 struct reada_zone *zone;
376
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400377 dev = bbio->stripes[nzones].dev;
378 zone = reada_find_zone(fs_info, dev, logical, bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200379 if (!zone)
380 break;
381
382 re->zones[nzones] = zone;
383 spin_lock(&zone->lock);
384 if (!zone->elems)
385 kref_get(&zone->refcnt);
386 ++zone->elems;
387 spin_unlock(&zone->lock);
388 spin_lock(&fs_info->reada_lock);
389 kref_put(&zone->refcnt, reada_zone_release);
390 spin_unlock(&fs_info->reada_lock);
391 }
392 re->nzones = nzones;
393 if (nzones == 0) {
394 /* not a single zone found, error and out */
395 goto error;
396 }
397
398 /* insert extent in reada_tree + all per-device trees, all or nothing */
Stefan Behrens8dabb742012-11-06 13:15:27 +0100399 btrfs_dev_replace_lock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200400 spin_lock(&fs_info->reada_lock);
401 ret = radix_tree_insert(&fs_info->reada_tree, index, re);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100402 if (ret == -EEXIST) {
403 re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
404 BUG_ON(!re_exist);
Al Viro99621b42012-08-29 16:31:33 -0400405 re_exist->refcnt++;
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100406 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100407 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100408 goto error;
409 }
Arne Jansen7414a032011-05-23 14:33:49 +0200410 if (ret) {
411 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100412 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200413 goto error;
414 }
Arne Jansen207a2322012-02-25 09:09:47 +0100415 prev_dev = NULL;
Stefan Behrens8dabb742012-11-06 13:15:27 +0100416 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
417 &fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200418 for (i = 0; i < nzones; ++i) {
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400419 dev = bbio->stripes[i].dev;
Arne Jansen207a2322012-02-25 09:09:47 +0100420 if (dev == prev_dev) {
421 /*
422 * in case of DUP, just add the first zone. As both
423 * are on the same device, there's nothing to gain
424 * from adding both.
425 * Also, it wouldn't work, as the tree is per device
426 * and adding would fail with EEXIST
427 */
428 continue;
429 }
Stefan Behrensff023aa2012-11-06 11:43:11 +0100430 if (!dev->bdev) {
Wang Shilong5fbc7c52014-06-11 10:55:22 +0800431 /*
432 * cannot read ahead on missing device, but for RAID5/6,
433 * REQ_GET_READ_MIRRORS return 1. So don't skip missing
434 * device for such case.
435 */
436 if (nzones > 1)
437 continue;
Stefan Behrensff023aa2012-11-06 11:43:11 +0100438 }
Stefan Behrens8dabb742012-11-06 13:15:27 +0100439 if (dev_replace_is_ongoing &&
440 dev == fs_info->dev_replace.tgtdev) {
441 /*
442 * as this device is selected for reading only as
443 * a last resort, skip it for read ahead.
444 */
445 continue;
446 }
Arne Jansen207a2322012-02-25 09:09:47 +0100447 prev_dev = dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200448 ret = radix_tree_insert(&dev->reada_extents, index, re);
449 if (ret) {
450 while (--i >= 0) {
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400451 dev = bbio->stripes[i].dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200452 BUG_ON(dev == NULL);
Stefan Behrensff023aa2012-11-06 11:43:11 +0100453 /* ignore whether the entry was inserted */
Arne Jansen7414a032011-05-23 14:33:49 +0200454 radix_tree_delete(&dev->reada_extents, index);
455 }
456 BUG_ON(fs_info == NULL);
457 radix_tree_delete(&fs_info->reada_tree, index);
458 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100459 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200460 goto error;
461 }
462 }
463 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100464 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200465
Zhao Lei6e9606d2015-01-20 15:11:34 +0800466 btrfs_put_bbio(bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200467 return re;
468
469error:
470 while (nzones) {
471 struct reada_zone *zone;
472
473 --nzones;
474 zone = re->zones[nzones];
475 kref_get(&zone->refcnt);
476 spin_lock(&zone->lock);
477 --zone->elems;
478 if (zone->elems == 0) {
479 /*
480 * no fs_info->reada_lock needed, as this can't be
481 * the last ref
482 */
483 kref_put(&zone->refcnt, reada_zone_release);
484 }
485 spin_unlock(&zone->lock);
486
487 spin_lock(&fs_info->reada_lock);
488 kref_put(&zone->refcnt, reada_zone_release);
489 spin_unlock(&fs_info->reada_lock);
490 }
Zhao Lei6e9606d2015-01-20 15:11:34 +0800491 btrfs_put_bbio(bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200492 kfree(re);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100493 return re_exist;
Arne Jansen7414a032011-05-23 14:33:49 +0200494}
495
Arne Jansen7414a032011-05-23 14:33:49 +0200496static void reada_extent_put(struct btrfs_fs_info *fs_info,
497 struct reada_extent *re)
498{
499 int i;
500 unsigned long index = re->logical >> PAGE_CACHE_SHIFT;
501
502 spin_lock(&fs_info->reada_lock);
Al Viro99621b42012-08-29 16:31:33 -0400503 if (--re->refcnt) {
Arne Jansen7414a032011-05-23 14:33:49 +0200504 spin_unlock(&fs_info->reada_lock);
505 return;
506 }
507
508 radix_tree_delete(&fs_info->reada_tree, index);
509 for (i = 0; i < re->nzones; ++i) {
510 struct reada_zone *zone = re->zones[i];
511
512 radix_tree_delete(&zone->device->reada_extents, index);
513 }
514
515 spin_unlock(&fs_info->reada_lock);
516
517 for (i = 0; i < re->nzones; ++i) {
518 struct reada_zone *zone = re->zones[i];
519
520 kref_get(&zone->refcnt);
521 spin_lock(&zone->lock);
522 --zone->elems;
523 if (zone->elems == 0) {
524 /* no fs_info->reada_lock needed, as this can't be
525 * the last ref */
526 kref_put(&zone->refcnt, reada_zone_release);
527 }
528 spin_unlock(&zone->lock);
529
530 spin_lock(&fs_info->reada_lock);
531 kref_put(&zone->refcnt, reada_zone_release);
532 spin_unlock(&fs_info->reada_lock);
533 }
534 if (re->scheduled_for)
535 atomic_dec(&re->scheduled_for->reada_in_flight);
536
537 kfree(re);
538}
539
540static void reada_zone_release(struct kref *kref)
541{
542 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
543
544 radix_tree_delete(&zone->device->reada_zones,
545 zone->end >> PAGE_CACHE_SHIFT);
546
547 kfree(zone);
548}
549
550static void reada_control_release(struct kref *kref)
551{
552 struct reada_control *rc = container_of(kref, struct reada_control,
553 refcnt);
554
555 kfree(rc);
556}
557
558static int reada_add_block(struct reada_control *rc, u64 logical,
559 struct btrfs_key *top, int level, u64 generation)
560{
561 struct btrfs_root *root = rc->root;
562 struct reada_extent *re;
563 struct reada_extctl *rec;
564
565 re = reada_find_extent(root, logical, top, level); /* takes one ref */
566 if (!re)
567 return -1;
568
569 rec = kzalloc(sizeof(*rec), GFP_NOFS);
570 if (!rec) {
571 reada_extent_put(root->fs_info, re);
572 return -1;
573 }
574
575 rec->rc = rc;
576 rec->generation = generation;
577 atomic_inc(&rc->elems);
578
579 spin_lock(&re->lock);
580 list_add_tail(&rec->list, &re->extctl);
581 spin_unlock(&re->lock);
582
583 /* leave the ref on the extent */
584
585 return 0;
586}
587
588/*
589 * called with fs_info->reada_lock held
590 */
591static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
592{
593 int i;
594 unsigned long index = zone->end >> PAGE_CACHE_SHIFT;
595
596 for (i = 0; i < zone->ndevs; ++i) {
597 struct reada_zone *peer;
598 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
599 if (peer && peer->device != zone->device)
600 peer->locked = lock;
601 }
602}
603
604/*
605 * called with fs_info->reada_lock held
606 */
607static int reada_pick_zone(struct btrfs_device *dev)
608{
609 struct reada_zone *top_zone = NULL;
610 struct reada_zone *top_locked_zone = NULL;
611 u64 top_elems = 0;
612 u64 top_locked_elems = 0;
613 unsigned long index = 0;
614 int ret;
615
616 if (dev->reada_curr_zone) {
617 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
618 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
619 dev->reada_curr_zone = NULL;
620 }
621 /* pick the zone with the most elements */
622 while (1) {
623 struct reada_zone *zone;
624
625 ret = radix_tree_gang_lookup(&dev->reada_zones,
626 (void **)&zone, index, 1);
627 if (ret == 0)
628 break;
629 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
630 if (zone->locked) {
631 if (zone->elems > top_locked_elems) {
632 top_locked_elems = zone->elems;
633 top_locked_zone = zone;
634 }
635 } else {
636 if (zone->elems > top_elems) {
637 top_elems = zone->elems;
638 top_zone = zone;
639 }
640 }
641 }
642 if (top_zone)
643 dev->reada_curr_zone = top_zone;
644 else if (top_locked_zone)
645 dev->reada_curr_zone = top_locked_zone;
646 else
647 return 0;
648
649 dev->reada_next = dev->reada_curr_zone->start;
650 kref_get(&dev->reada_curr_zone->refcnt);
651 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
652
653 return 1;
654}
655
656static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
657 struct btrfs_device *dev)
658{
659 struct reada_extent *re = NULL;
660 int mirror_num = 0;
661 struct extent_buffer *eb = NULL;
662 u64 logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200663 int ret;
664 int i;
665 int need_kick = 0;
666
667 spin_lock(&fs_info->reada_lock);
668 if (dev->reada_curr_zone == NULL) {
669 ret = reada_pick_zone(dev);
670 if (!ret) {
671 spin_unlock(&fs_info->reada_lock);
672 return 0;
673 }
674 }
675 /*
676 * FIXME currently we issue the reads one extent at a time. If we have
677 * a contiguous block of extents, we could also coagulate them or use
678 * plugging to speed things up
679 */
680 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
681 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
682 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
683 ret = reada_pick_zone(dev);
684 if (!ret) {
685 spin_unlock(&fs_info->reada_lock);
686 return 0;
687 }
688 re = NULL;
689 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
690 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
691 }
692 if (ret == 0) {
693 spin_unlock(&fs_info->reada_lock);
694 return 0;
695 }
David Sterbab6ae40e2014-06-15 02:18:25 +0200696 dev->reada_next = re->logical + fs_info->tree_root->nodesize;
Al Viro99621b42012-08-29 16:31:33 -0400697 re->refcnt++;
Arne Jansen7414a032011-05-23 14:33:49 +0200698
699 spin_unlock(&fs_info->reada_lock);
700
701 /*
702 * find mirror num
703 */
704 for (i = 0; i < re->nzones; ++i) {
705 if (re->zones[i]->device == dev) {
706 mirror_num = i + 1;
707 break;
708 }
709 }
710 logical = re->logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200711
712 spin_lock(&re->lock);
713 if (re->scheduled_for == NULL) {
714 re->scheduled_for = dev;
715 need_kick = 1;
716 }
717 spin_unlock(&re->lock);
718
719 reada_extent_put(fs_info, re);
720
721 if (!need_kick)
722 return 0;
723
724 atomic_inc(&dev->reada_in_flight);
David Sterbab6ae40e2014-06-15 02:18:25 +0200725 ret = reada_tree_block_flagged(fs_info->extent_root, logical,
David Sterbac0dcaa42014-06-15 02:24:21 +0200726 mirror_num, &eb);
Arne Jansen7414a032011-05-23 14:33:49 +0200727 if (ret)
728 __readahead_hook(fs_info->extent_root, NULL, logical, ret);
729 else if (eb)
730 __readahead_hook(fs_info->extent_root, eb, eb->start, ret);
731
732 if (eb)
733 free_extent_buffer(eb);
734
735 return 1;
736
737}
738
Qu Wenruod458b052014-02-28 10:46:19 +0800739static void reada_start_machine_worker(struct btrfs_work *work)
Arne Jansen7414a032011-05-23 14:33:49 +0200740{
741 struct reada_machine_work *rmw;
742 struct btrfs_fs_info *fs_info;
Stefan Behrens3d136a12012-02-03 11:20:04 +0100743 int old_ioprio;
Arne Jansen7414a032011-05-23 14:33:49 +0200744
745 rmw = container_of(work, struct reada_machine_work, work);
746 fs_info = rmw->fs_info;
747
748 kfree(rmw);
749
Stefan Behrens3d136a12012-02-03 11:20:04 +0100750 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
751 task_nice_ioprio(current));
752 set_task_ioprio(current, BTRFS_IOPRIO_READA);
Arne Jansen7414a032011-05-23 14:33:49 +0200753 __reada_start_machine(fs_info);
Stefan Behrens3d136a12012-02-03 11:20:04 +0100754 set_task_ioprio(current, old_ioprio);
Arne Jansen7414a032011-05-23 14:33:49 +0200755}
756
757static void __reada_start_machine(struct btrfs_fs_info *fs_info)
758{
759 struct btrfs_device *device;
760 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
761 u64 enqueued;
762 u64 total = 0;
763 int i;
764
765 do {
766 enqueued = 0;
767 list_for_each_entry(device, &fs_devices->devices, dev_list) {
768 if (atomic_read(&device->reada_in_flight) <
769 MAX_IN_FLIGHT)
770 enqueued += reada_start_machine_dev(fs_info,
771 device);
772 }
773 total += enqueued;
774 } while (enqueued && total < 10000);
775
776 if (enqueued == 0)
777 return;
778
779 /*
780 * If everything is already in the cache, this is effectively single
781 * threaded. To a) not hold the caller for too long and b) to utilize
782 * more cores, we broke the loop above after 10000 iterations and now
783 * enqueue to workers to finish it. This will distribute the load to
784 * the cores.
785 */
786 for (i = 0; i < 2; ++i)
787 reada_start_machine(fs_info);
788}
789
790static void reada_start_machine(struct btrfs_fs_info *fs_info)
791{
792 struct reada_machine_work *rmw;
793
794 rmw = kzalloc(sizeof(*rmw), GFP_NOFS);
795 if (!rmw) {
796 /* FIXME we cannot handle this properly right now */
797 BUG();
798 }
Liu Bo9e0af232014-08-15 23:36:53 +0800799 btrfs_init_work(&rmw->work, btrfs_readahead_helper,
800 reada_start_machine_worker, NULL, NULL);
Arne Jansen7414a032011-05-23 14:33:49 +0200801 rmw->fs_info = fs_info;
802
Qu Wenruo736cfa12014-02-28 10:46:13 +0800803 btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
Arne Jansen7414a032011-05-23 14:33:49 +0200804}
805
806#ifdef DEBUG
807static void dump_devs(struct btrfs_fs_info *fs_info, int all)
808{
809 struct btrfs_device *device;
810 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
811 unsigned long index;
812 int ret;
813 int i;
814 int j;
815 int cnt;
816
817 spin_lock(&fs_info->reada_lock);
818 list_for_each_entry(device, &fs_devices->devices, dev_list) {
819 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
820 atomic_read(&device->reada_in_flight));
821 index = 0;
822 while (1) {
823 struct reada_zone *zone;
824 ret = radix_tree_gang_lookup(&device->reada_zones,
825 (void **)&zone, index, 1);
826 if (ret == 0)
827 break;
828 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked "
829 "%d devs", zone->start, zone->end, zone->elems,
830 zone->locked);
831 for (j = 0; j < zone->ndevs; ++j) {
832 printk(KERN_CONT " %lld",
833 zone->devs[j]->devid);
834 }
835 if (device->reada_curr_zone == zone)
836 printk(KERN_CONT " curr off %llu",
837 device->reada_next - zone->start);
838 printk(KERN_CONT "\n");
839 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
840 }
841 cnt = 0;
842 index = 0;
843 while (all) {
844 struct reada_extent *re = NULL;
845
846 ret = radix_tree_gang_lookup(&device->reada_extents,
847 (void **)&re, index, 1);
848 if (ret == 0)
849 break;
850 printk(KERN_DEBUG
851 " re: logical %llu size %u empty %d for %lld",
David Sterbab6ae40e2014-06-15 02:18:25 +0200852 re->logical, fs_info->tree_root->nodesize,
Arne Jansen7414a032011-05-23 14:33:49 +0200853 list_empty(&re->extctl), re->scheduled_for ?
854 re->scheduled_for->devid : -1);
855
856 for (i = 0; i < re->nzones; ++i) {
857 printk(KERN_CONT " zone %llu-%llu devs",
858 re->zones[i]->start,
859 re->zones[i]->end);
860 for (j = 0; j < re->zones[i]->ndevs; ++j) {
861 printk(KERN_CONT " %lld",
862 re->zones[i]->devs[j]->devid);
863 }
864 }
865 printk(KERN_CONT "\n");
866 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
867 if (++cnt > 15)
868 break;
869 }
870 }
871
872 index = 0;
873 cnt = 0;
874 while (all) {
875 struct reada_extent *re = NULL;
876
877 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
878 index, 1);
879 if (ret == 0)
880 break;
881 if (!re->scheduled_for) {
882 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
883 continue;
884 }
885 printk(KERN_DEBUG
886 "re: logical %llu size %u list empty %d for %lld",
David Sterbab6ae40e2014-06-15 02:18:25 +0200887 re->logical, fs_info->tree_root->nodesize,
888 list_empty(&re->extctl),
Arne Jansen7414a032011-05-23 14:33:49 +0200889 re->scheduled_for ? re->scheduled_for->devid : -1);
890 for (i = 0; i < re->nzones; ++i) {
891 printk(KERN_CONT " zone %llu-%llu devs",
892 re->zones[i]->start,
893 re->zones[i]->end);
894 for (i = 0; i < re->nzones; ++i) {
895 printk(KERN_CONT " zone %llu-%llu devs",
896 re->zones[i]->start,
897 re->zones[i]->end);
898 for (j = 0; j < re->zones[i]->ndevs; ++j) {
899 printk(KERN_CONT " %lld",
900 re->zones[i]->devs[j]->devid);
901 }
902 }
903 }
904 printk(KERN_CONT "\n");
905 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
906 }
907 spin_unlock(&fs_info->reada_lock);
908}
909#endif
910
911/*
912 * interface
913 */
914struct reada_control *btrfs_reada_add(struct btrfs_root *root,
915 struct btrfs_key *key_start, struct btrfs_key *key_end)
916{
917 struct reada_control *rc;
918 u64 start;
919 u64 generation;
920 int level;
921 struct extent_buffer *node;
922 static struct btrfs_key max_key = {
923 .objectid = (u64)-1,
924 .type = (u8)-1,
925 .offset = (u64)-1
926 };
927
928 rc = kzalloc(sizeof(*rc), GFP_NOFS);
929 if (!rc)
930 return ERR_PTR(-ENOMEM);
931
932 rc->root = root;
933 rc->key_start = *key_start;
934 rc->key_end = *key_end;
935 atomic_set(&rc->elems, 0);
936 init_waitqueue_head(&rc->wait);
937 kref_init(&rc->refcnt);
938 kref_get(&rc->refcnt); /* one ref for having elements */
939
940 node = btrfs_root_node(root);
941 start = node->start;
942 level = btrfs_header_level(node);
943 generation = btrfs_header_generation(node);
944 free_extent_buffer(node);
945
Stefan Behrensff023aa2012-11-06 11:43:11 +0100946 if (reada_add_block(rc, start, &max_key, level, generation)) {
947 kfree(rc);
948 return ERR_PTR(-ENOMEM);
949 }
Arne Jansen7414a032011-05-23 14:33:49 +0200950
951 reada_start_machine(root->fs_info);
952
953 return rc;
954}
955
956#ifdef DEBUG
957int btrfs_reada_wait(void *handle)
958{
959 struct reada_control *rc = handle;
960
961 while (atomic_read(&rc->elems)) {
962 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
963 5 * HZ);
Vincent3c59ccd2013-04-16 08:15:25 +0000964 dump_devs(rc->root->fs_info,
965 atomic_read(&rc->elems) < 10 ? 1 : 0);
Arne Jansen7414a032011-05-23 14:33:49 +0200966 }
967
Vincent3c59ccd2013-04-16 08:15:25 +0000968 dump_devs(rc->root->fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
Arne Jansen7414a032011-05-23 14:33:49 +0200969
970 kref_put(&rc->refcnt, reada_control_release);
971
972 return 0;
973}
974#else
975int btrfs_reada_wait(void *handle)
976{
977 struct reada_control *rc = handle;
978
979 while (atomic_read(&rc->elems)) {
980 wait_event(rc->wait, atomic_read(&rc->elems) == 0);
981 }
982
983 kref_put(&rc->refcnt, reada_control_release);
984
985 return 0;
986}
987#endif
988
989void btrfs_reada_detach(void *handle)
990{
991 struct reada_control *rc = handle;
992
993 kref_put(&rc->refcnt, reada_control_release);
994}