blob: 0e7beea92b4cc1279def4a3c61a440ec177ef1a0 [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;
331 int nzones = 0;
332 int i;
333 unsigned long index = logical >> PAGE_CACHE_SHIFT;
Stefan Behrens8dabb742012-11-06 13:15:27 +0100334 int dev_replace_is_ongoing;
Arne Jansen7414a032011-05-23 14:33:49 +0200335
Arne Jansen7414a032011-05-23 14:33:49 +0200336 spin_lock(&fs_info->reada_lock);
337 re = radix_tree_lookup(&fs_info->reada_tree, index);
338 if (re)
Al Viro99621b42012-08-29 16:31:33 -0400339 re->refcnt++;
Arne Jansen7414a032011-05-23 14:33:49 +0200340 spin_unlock(&fs_info->reada_lock);
341
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100342 if (re)
Arne Jansen7414a032011-05-23 14:33:49 +0200343 return re;
344
345 re = kzalloc(sizeof(*re), GFP_NOFS);
346 if (!re)
347 return NULL;
348
David Sterba707e8a02014-06-04 19:22:26 +0200349 blocksize = root->nodesize;
Arne Jansen7414a032011-05-23 14:33:49 +0200350 re->logical = logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200351 re->top = *top;
352 INIT_LIST_HEAD(&re->extctl);
353 spin_lock_init(&re->lock);
Al Viro99621b42012-08-29 16:31:33 -0400354 re->refcnt = 1;
Arne Jansen7414a032011-05-23 14:33:49 +0200355
356 /*
357 * map block
358 */
359 length = blocksize;
Stefan Behrens29a8d9a2012-11-06 14:16:24 +0100360 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
361 &bbio, 0);
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400362 if (ret || !bbio || length < blocksize)
Arne Jansen7414a032011-05-23 14:33:49 +0200363 goto error;
364
Stefan Behrens94598ba2012-03-27 14:21:26 -0400365 if (bbio->num_stripes > BTRFS_MAX_MIRRORS) {
Frank Holtonefe120a2013-12-20 11:37:06 -0500366 btrfs_err(root->fs_info,
367 "readahead: more than %d copies not supported",
368 BTRFS_MAX_MIRRORS);
Arne Jansen7414a032011-05-23 14:33:49 +0200369 goto error;
370 }
371
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400372 for (nzones = 0; nzones < bbio->num_stripes; ++nzones) {
Arne Jansen7414a032011-05-23 14:33:49 +0200373 struct reada_zone *zone;
374
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400375 dev = bbio->stripes[nzones].dev;
376 zone = reada_find_zone(fs_info, dev, logical, bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200377 if (!zone)
378 break;
379
380 re->zones[nzones] = zone;
381 spin_lock(&zone->lock);
382 if (!zone->elems)
383 kref_get(&zone->refcnt);
384 ++zone->elems;
385 spin_unlock(&zone->lock);
386 spin_lock(&fs_info->reada_lock);
387 kref_put(&zone->refcnt, reada_zone_release);
388 spin_unlock(&fs_info->reada_lock);
389 }
390 re->nzones = nzones;
391 if (nzones == 0) {
392 /* not a single zone found, error and out */
393 goto error;
394 }
395
396 /* insert extent in reada_tree + all per-device trees, all or nothing */
Stefan Behrens8dabb742012-11-06 13:15:27 +0100397 btrfs_dev_replace_lock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200398 spin_lock(&fs_info->reada_lock);
399 ret = radix_tree_insert(&fs_info->reada_tree, index, re);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100400 if (ret == -EEXIST) {
401 re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
402 BUG_ON(!re_exist);
Al Viro99621b42012-08-29 16:31:33 -0400403 re_exist->refcnt++;
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100404 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100405 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100406 goto error;
407 }
Arne Jansen7414a032011-05-23 14:33:49 +0200408 if (ret) {
409 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100410 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200411 goto error;
412 }
Arne Jansen207a2322012-02-25 09:09:47 +0100413 prev_dev = NULL;
Stefan Behrens8dabb742012-11-06 13:15:27 +0100414 dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
415 &fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200416 for (i = 0; i < nzones; ++i) {
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400417 dev = bbio->stripes[i].dev;
Arne Jansen207a2322012-02-25 09:09:47 +0100418 if (dev == prev_dev) {
419 /*
420 * in case of DUP, just add the first zone. As both
421 * are on the same device, there's nothing to gain
422 * from adding both.
423 * Also, it wouldn't work, as the tree is per device
424 * and adding would fail with EEXIST
425 */
426 continue;
427 }
Stefan Behrensff023aa2012-11-06 11:43:11 +0100428 if (!dev->bdev) {
Wang Shilong5fbc7c52014-06-11 10:55:22 +0800429 /*
430 * cannot read ahead on missing device, but for RAID5/6,
431 * REQ_GET_READ_MIRRORS return 1. So don't skip missing
432 * device for such case.
433 */
434 if (nzones > 1)
435 continue;
Stefan Behrensff023aa2012-11-06 11:43:11 +0100436 }
Stefan Behrens8dabb742012-11-06 13:15:27 +0100437 if (dev_replace_is_ongoing &&
438 dev == fs_info->dev_replace.tgtdev) {
439 /*
440 * as this device is selected for reading only as
441 * a last resort, skip it for read ahead.
442 */
443 continue;
444 }
Arne Jansen207a2322012-02-25 09:09:47 +0100445 prev_dev = dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200446 ret = radix_tree_insert(&dev->reada_extents, index, re);
447 if (ret) {
448 while (--i >= 0) {
Ilya Dryomov21ca5432011-11-04 09:41:02 -0400449 dev = bbio->stripes[i].dev;
Arne Jansen7414a032011-05-23 14:33:49 +0200450 BUG_ON(dev == NULL);
Stefan Behrensff023aa2012-11-06 11:43:11 +0100451 /* ignore whether the entry was inserted */
Arne Jansen7414a032011-05-23 14:33:49 +0200452 radix_tree_delete(&dev->reada_extents, index);
453 }
454 BUG_ON(fs_info == NULL);
455 radix_tree_delete(&fs_info->reada_tree, index);
456 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100457 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200458 goto error;
459 }
460 }
461 spin_unlock(&fs_info->reada_lock);
Stefan Behrens8dabb742012-11-06 13:15:27 +0100462 btrfs_dev_replace_unlock(&fs_info->dev_replace);
Arne Jansen7414a032011-05-23 14:33:49 +0200463
Zhao Lei6e9606d2015-01-20 15:11:34 +0800464 btrfs_put_bbio(bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200465 return re;
466
467error:
468 while (nzones) {
469 struct reada_zone *zone;
470
471 --nzones;
472 zone = re->zones[nzones];
473 kref_get(&zone->refcnt);
474 spin_lock(&zone->lock);
475 --zone->elems;
476 if (zone->elems == 0) {
477 /*
478 * no fs_info->reada_lock needed, as this can't be
479 * the last ref
480 */
481 kref_put(&zone->refcnt, reada_zone_release);
482 }
483 spin_unlock(&zone->lock);
484
485 spin_lock(&fs_info->reada_lock);
486 kref_put(&zone->refcnt, reada_zone_release);
487 spin_unlock(&fs_info->reada_lock);
488 }
Zhao Lei6e9606d2015-01-20 15:11:34 +0800489 btrfs_put_bbio(bbio);
Arne Jansen7414a032011-05-23 14:33:49 +0200490 kfree(re);
Arne Jansen8c9c2bf2012-02-25 09:09:30 +0100491 return re_exist;
Arne Jansen7414a032011-05-23 14:33:49 +0200492}
493
Arne Jansen7414a032011-05-23 14:33:49 +0200494static void reada_extent_put(struct btrfs_fs_info *fs_info,
495 struct reada_extent *re)
496{
497 int i;
498 unsigned long index = re->logical >> PAGE_CACHE_SHIFT;
499
500 spin_lock(&fs_info->reada_lock);
Al Viro99621b42012-08-29 16:31:33 -0400501 if (--re->refcnt) {
Arne Jansen7414a032011-05-23 14:33:49 +0200502 spin_unlock(&fs_info->reada_lock);
503 return;
504 }
505
506 radix_tree_delete(&fs_info->reada_tree, index);
507 for (i = 0; i < re->nzones; ++i) {
508 struct reada_zone *zone = re->zones[i];
509
510 radix_tree_delete(&zone->device->reada_extents, index);
511 }
512
513 spin_unlock(&fs_info->reada_lock);
514
515 for (i = 0; i < re->nzones; ++i) {
516 struct reada_zone *zone = re->zones[i];
517
518 kref_get(&zone->refcnt);
519 spin_lock(&zone->lock);
520 --zone->elems;
521 if (zone->elems == 0) {
522 /* no fs_info->reada_lock needed, as this can't be
523 * the last ref */
524 kref_put(&zone->refcnt, reada_zone_release);
525 }
526 spin_unlock(&zone->lock);
527
528 spin_lock(&fs_info->reada_lock);
529 kref_put(&zone->refcnt, reada_zone_release);
530 spin_unlock(&fs_info->reada_lock);
531 }
532 if (re->scheduled_for)
533 atomic_dec(&re->scheduled_for->reada_in_flight);
534
535 kfree(re);
536}
537
538static void reada_zone_release(struct kref *kref)
539{
540 struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
541
542 radix_tree_delete(&zone->device->reada_zones,
543 zone->end >> PAGE_CACHE_SHIFT);
544
545 kfree(zone);
546}
547
548static void reada_control_release(struct kref *kref)
549{
550 struct reada_control *rc = container_of(kref, struct reada_control,
551 refcnt);
552
553 kfree(rc);
554}
555
556static int reada_add_block(struct reada_control *rc, u64 logical,
557 struct btrfs_key *top, int level, u64 generation)
558{
559 struct btrfs_root *root = rc->root;
560 struct reada_extent *re;
561 struct reada_extctl *rec;
562
563 re = reada_find_extent(root, logical, top, level); /* takes one ref */
564 if (!re)
565 return -1;
566
567 rec = kzalloc(sizeof(*rec), GFP_NOFS);
568 if (!rec) {
569 reada_extent_put(root->fs_info, re);
570 return -1;
571 }
572
573 rec->rc = rc;
574 rec->generation = generation;
575 atomic_inc(&rc->elems);
576
577 spin_lock(&re->lock);
578 list_add_tail(&rec->list, &re->extctl);
579 spin_unlock(&re->lock);
580
581 /* leave the ref on the extent */
582
583 return 0;
584}
585
586/*
587 * called with fs_info->reada_lock held
588 */
589static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
590{
591 int i;
592 unsigned long index = zone->end >> PAGE_CACHE_SHIFT;
593
594 for (i = 0; i < zone->ndevs; ++i) {
595 struct reada_zone *peer;
596 peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
597 if (peer && peer->device != zone->device)
598 peer->locked = lock;
599 }
600}
601
602/*
603 * called with fs_info->reada_lock held
604 */
605static int reada_pick_zone(struct btrfs_device *dev)
606{
607 struct reada_zone *top_zone = NULL;
608 struct reada_zone *top_locked_zone = NULL;
609 u64 top_elems = 0;
610 u64 top_locked_elems = 0;
611 unsigned long index = 0;
612 int ret;
613
614 if (dev->reada_curr_zone) {
615 reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
616 kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
617 dev->reada_curr_zone = NULL;
618 }
619 /* pick the zone with the most elements */
620 while (1) {
621 struct reada_zone *zone;
622
623 ret = radix_tree_gang_lookup(&dev->reada_zones,
624 (void **)&zone, index, 1);
625 if (ret == 0)
626 break;
627 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
628 if (zone->locked) {
629 if (zone->elems > top_locked_elems) {
630 top_locked_elems = zone->elems;
631 top_locked_zone = zone;
632 }
633 } else {
634 if (zone->elems > top_elems) {
635 top_elems = zone->elems;
636 top_zone = zone;
637 }
638 }
639 }
640 if (top_zone)
641 dev->reada_curr_zone = top_zone;
642 else if (top_locked_zone)
643 dev->reada_curr_zone = top_locked_zone;
644 else
645 return 0;
646
647 dev->reada_next = dev->reada_curr_zone->start;
648 kref_get(&dev->reada_curr_zone->refcnt);
649 reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
650
651 return 1;
652}
653
654static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
655 struct btrfs_device *dev)
656{
657 struct reada_extent *re = NULL;
658 int mirror_num = 0;
659 struct extent_buffer *eb = NULL;
660 u64 logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200661 int ret;
662 int i;
663 int need_kick = 0;
664
665 spin_lock(&fs_info->reada_lock);
666 if (dev->reada_curr_zone == NULL) {
667 ret = reada_pick_zone(dev);
668 if (!ret) {
669 spin_unlock(&fs_info->reada_lock);
670 return 0;
671 }
672 }
673 /*
674 * FIXME currently we issue the reads one extent at a time. If we have
675 * a contiguous block of extents, we could also coagulate them or use
676 * plugging to speed things up
677 */
678 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
679 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
680 if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
681 ret = reada_pick_zone(dev);
682 if (!ret) {
683 spin_unlock(&fs_info->reada_lock);
684 return 0;
685 }
686 re = NULL;
687 ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
688 dev->reada_next >> PAGE_CACHE_SHIFT, 1);
689 }
690 if (ret == 0) {
691 spin_unlock(&fs_info->reada_lock);
692 return 0;
693 }
David Sterbab6ae40e2014-06-15 02:18:25 +0200694 dev->reada_next = re->logical + fs_info->tree_root->nodesize;
Al Viro99621b42012-08-29 16:31:33 -0400695 re->refcnt++;
Arne Jansen7414a032011-05-23 14:33:49 +0200696
697 spin_unlock(&fs_info->reada_lock);
698
699 /*
700 * find mirror num
701 */
702 for (i = 0; i < re->nzones; ++i) {
703 if (re->zones[i]->device == dev) {
704 mirror_num = i + 1;
705 break;
706 }
707 }
708 logical = re->logical;
Arne Jansen7414a032011-05-23 14:33:49 +0200709
710 spin_lock(&re->lock);
711 if (re->scheduled_for == NULL) {
712 re->scheduled_for = dev;
713 need_kick = 1;
714 }
715 spin_unlock(&re->lock);
716
717 reada_extent_put(fs_info, re);
718
719 if (!need_kick)
720 return 0;
721
722 atomic_inc(&dev->reada_in_flight);
David Sterbab6ae40e2014-06-15 02:18:25 +0200723 ret = reada_tree_block_flagged(fs_info->extent_root, logical,
David Sterbac0dcaa42014-06-15 02:24:21 +0200724 mirror_num, &eb);
Arne Jansen7414a032011-05-23 14:33:49 +0200725 if (ret)
726 __readahead_hook(fs_info->extent_root, NULL, logical, ret);
727 else if (eb)
728 __readahead_hook(fs_info->extent_root, eb, eb->start, ret);
729
730 if (eb)
731 free_extent_buffer(eb);
732
733 return 1;
734
735}
736
Qu Wenruod458b052014-02-28 10:46:19 +0800737static void reada_start_machine_worker(struct btrfs_work *work)
Arne Jansen7414a032011-05-23 14:33:49 +0200738{
739 struct reada_machine_work *rmw;
740 struct btrfs_fs_info *fs_info;
Stefan Behrens3d136a12012-02-03 11:20:04 +0100741 int old_ioprio;
Arne Jansen7414a032011-05-23 14:33:49 +0200742
743 rmw = container_of(work, struct reada_machine_work, work);
744 fs_info = rmw->fs_info;
745
746 kfree(rmw);
747
Stefan Behrens3d136a12012-02-03 11:20:04 +0100748 old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current),
749 task_nice_ioprio(current));
750 set_task_ioprio(current, BTRFS_IOPRIO_READA);
Arne Jansen7414a032011-05-23 14:33:49 +0200751 __reada_start_machine(fs_info);
Stefan Behrens3d136a12012-02-03 11:20:04 +0100752 set_task_ioprio(current, old_ioprio);
Arne Jansen7414a032011-05-23 14:33:49 +0200753}
754
755static void __reada_start_machine(struct btrfs_fs_info *fs_info)
756{
757 struct btrfs_device *device;
758 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
759 u64 enqueued;
760 u64 total = 0;
761 int i;
762
763 do {
764 enqueued = 0;
765 list_for_each_entry(device, &fs_devices->devices, dev_list) {
766 if (atomic_read(&device->reada_in_flight) <
767 MAX_IN_FLIGHT)
768 enqueued += reada_start_machine_dev(fs_info,
769 device);
770 }
771 total += enqueued;
772 } while (enqueued && total < 10000);
773
774 if (enqueued == 0)
775 return;
776
777 /*
778 * If everything is already in the cache, this is effectively single
779 * threaded. To a) not hold the caller for too long and b) to utilize
780 * more cores, we broke the loop above after 10000 iterations and now
781 * enqueue to workers to finish it. This will distribute the load to
782 * the cores.
783 */
784 for (i = 0; i < 2; ++i)
785 reada_start_machine(fs_info);
786}
787
788static void reada_start_machine(struct btrfs_fs_info *fs_info)
789{
790 struct reada_machine_work *rmw;
791
792 rmw = kzalloc(sizeof(*rmw), GFP_NOFS);
793 if (!rmw) {
794 /* FIXME we cannot handle this properly right now */
795 BUG();
796 }
Liu Bo9e0af232014-08-15 23:36:53 +0800797 btrfs_init_work(&rmw->work, btrfs_readahead_helper,
798 reada_start_machine_worker, NULL, NULL);
Arne Jansen7414a032011-05-23 14:33:49 +0200799 rmw->fs_info = fs_info;
800
Qu Wenruo736cfa12014-02-28 10:46:13 +0800801 btrfs_queue_work(fs_info->readahead_workers, &rmw->work);
Arne Jansen7414a032011-05-23 14:33:49 +0200802}
803
804#ifdef DEBUG
805static void dump_devs(struct btrfs_fs_info *fs_info, int all)
806{
807 struct btrfs_device *device;
808 struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
809 unsigned long index;
810 int ret;
811 int i;
812 int j;
813 int cnt;
814
815 spin_lock(&fs_info->reada_lock);
816 list_for_each_entry(device, &fs_devices->devices, dev_list) {
817 printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
818 atomic_read(&device->reada_in_flight));
819 index = 0;
820 while (1) {
821 struct reada_zone *zone;
822 ret = radix_tree_gang_lookup(&device->reada_zones,
823 (void **)&zone, index, 1);
824 if (ret == 0)
825 break;
826 printk(KERN_DEBUG " zone %llu-%llu elems %llu locked "
827 "%d devs", zone->start, zone->end, zone->elems,
828 zone->locked);
829 for (j = 0; j < zone->ndevs; ++j) {
830 printk(KERN_CONT " %lld",
831 zone->devs[j]->devid);
832 }
833 if (device->reada_curr_zone == zone)
834 printk(KERN_CONT " curr off %llu",
835 device->reada_next - zone->start);
836 printk(KERN_CONT "\n");
837 index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
838 }
839 cnt = 0;
840 index = 0;
841 while (all) {
842 struct reada_extent *re = NULL;
843
844 ret = radix_tree_gang_lookup(&device->reada_extents,
845 (void **)&re, index, 1);
846 if (ret == 0)
847 break;
848 printk(KERN_DEBUG
849 " re: logical %llu size %u empty %d for %lld",
David Sterbab6ae40e2014-06-15 02:18:25 +0200850 re->logical, fs_info->tree_root->nodesize,
Arne Jansen7414a032011-05-23 14:33:49 +0200851 list_empty(&re->extctl), re->scheduled_for ?
852 re->scheduled_for->devid : -1);
853
854 for (i = 0; i < re->nzones; ++i) {
855 printk(KERN_CONT " zone %llu-%llu devs",
856 re->zones[i]->start,
857 re->zones[i]->end);
858 for (j = 0; j < re->zones[i]->ndevs; ++j) {
859 printk(KERN_CONT " %lld",
860 re->zones[i]->devs[j]->devid);
861 }
862 }
863 printk(KERN_CONT "\n");
864 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
865 if (++cnt > 15)
866 break;
867 }
868 }
869
870 index = 0;
871 cnt = 0;
872 while (all) {
873 struct reada_extent *re = NULL;
874
875 ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
876 index, 1);
877 if (ret == 0)
878 break;
879 if (!re->scheduled_for) {
880 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
881 continue;
882 }
883 printk(KERN_DEBUG
884 "re: logical %llu size %u list empty %d for %lld",
David Sterbab6ae40e2014-06-15 02:18:25 +0200885 re->logical, fs_info->tree_root->nodesize,
886 list_empty(&re->extctl),
Arne Jansen7414a032011-05-23 14:33:49 +0200887 re->scheduled_for ? re->scheduled_for->devid : -1);
888 for (i = 0; i < re->nzones; ++i) {
889 printk(KERN_CONT " zone %llu-%llu devs",
890 re->zones[i]->start,
891 re->zones[i]->end);
892 for (i = 0; i < re->nzones; ++i) {
893 printk(KERN_CONT " zone %llu-%llu devs",
894 re->zones[i]->start,
895 re->zones[i]->end);
896 for (j = 0; j < re->zones[i]->ndevs; ++j) {
897 printk(KERN_CONT " %lld",
898 re->zones[i]->devs[j]->devid);
899 }
900 }
901 }
902 printk(KERN_CONT "\n");
903 index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
904 }
905 spin_unlock(&fs_info->reada_lock);
906}
907#endif
908
909/*
910 * interface
911 */
912struct reada_control *btrfs_reada_add(struct btrfs_root *root,
913 struct btrfs_key *key_start, struct btrfs_key *key_end)
914{
915 struct reada_control *rc;
916 u64 start;
917 u64 generation;
918 int level;
919 struct extent_buffer *node;
920 static struct btrfs_key max_key = {
921 .objectid = (u64)-1,
922 .type = (u8)-1,
923 .offset = (u64)-1
924 };
925
926 rc = kzalloc(sizeof(*rc), GFP_NOFS);
927 if (!rc)
928 return ERR_PTR(-ENOMEM);
929
930 rc->root = root;
931 rc->key_start = *key_start;
932 rc->key_end = *key_end;
933 atomic_set(&rc->elems, 0);
934 init_waitqueue_head(&rc->wait);
935 kref_init(&rc->refcnt);
936 kref_get(&rc->refcnt); /* one ref for having elements */
937
938 node = btrfs_root_node(root);
939 start = node->start;
940 level = btrfs_header_level(node);
941 generation = btrfs_header_generation(node);
942 free_extent_buffer(node);
943
Stefan Behrensff023aa2012-11-06 11:43:11 +0100944 if (reada_add_block(rc, start, &max_key, level, generation)) {
945 kfree(rc);
946 return ERR_PTR(-ENOMEM);
947 }
Arne Jansen7414a032011-05-23 14:33:49 +0200948
949 reada_start_machine(root->fs_info);
950
951 return rc;
952}
953
954#ifdef DEBUG
955int btrfs_reada_wait(void *handle)
956{
957 struct reada_control *rc = handle;
958
959 while (atomic_read(&rc->elems)) {
960 wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
961 5 * HZ);
Vincent3c59ccd2013-04-16 08:15:25 +0000962 dump_devs(rc->root->fs_info,
963 atomic_read(&rc->elems) < 10 ? 1 : 0);
Arne Jansen7414a032011-05-23 14:33:49 +0200964 }
965
Vincent3c59ccd2013-04-16 08:15:25 +0000966 dump_devs(rc->root->fs_info, atomic_read(&rc->elems) < 10 ? 1 : 0);
Arne Jansen7414a032011-05-23 14:33:49 +0200967
968 kref_put(&rc->refcnt, reada_control_release);
969
970 return 0;
971}
972#else
973int btrfs_reada_wait(void *handle)
974{
975 struct reada_control *rc = handle;
976
977 while (atomic_read(&rc->elems)) {
978 wait_event(rc->wait, atomic_read(&rc->elems) == 0);
979 }
980
981 kref_put(&rc->refcnt, reada_control_release);
982
983 return 0;
984}
985#endif
986
987void btrfs_reada_detach(void *handle)
988{
989 struct reada_control *rc = handle;
990
991 kref_put(&rc->refcnt, reada_control_release);
992}