4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2011, 2017, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
33 * Lustre Lite I/O page cache routines shared by different kernel revs
36 #include <linux/kernel.h>
38 #include <linux/string.h>
39 #include <linux/stat.h>
40 #include <linux/errno.h>
41 #include <linux/unistd.h>
42 #include <linux/writeback.h>
43 #include <asm/uaccess.h>
46 #include <linux/file.h>
47 #include <linux/stat.h>
48 #include <asm/uaccess.h>
50 #include <linux/pagemap.h>
51 /* current_is_kswapd() */
52 #include <linux/swap.h>
53 #include <linux/task_io_accounting_ops.h>
55 #define DEBUG_SUBSYSTEM S_LLITE
57 #include <obd_cksum.h>
58 #include "llite_internal.h"
59 #include <lustre_compat.h>
61 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which);
64 * Get readahead pages from the filesystem readahead pool of the client for a
67 * /param sbi superblock for filesystem readahead state ll_ra_info
68 * /param ria per-thread readahead state
69 * /param pages number of pages requested for readahead for the thread.
71 * WARNING: This algorithm is used to reduce contention on sbi->ll_lock.
72 * It should work well if the ra_max_pages is much greater than the single
73 * file's read-ahead window, and not too many threads contending for
74 * these readahead pages.
76 * TODO: There may be a 'global sync problem' if many threads are trying
77 * to get an ra budget that is larger than the remaining readahead pages
78 * and reach here at exactly the same time. They will compute /a ret to
79 * consume the remaining pages, but will fail at atomic_add_return() and
80 * get a zero ra window, although there is still ra space remaining. - Jay */
82 static unsigned long ll_ra_count_get(struct ll_sb_info *sbi,
83 struct ra_io_arg *ria,
85 unsigned long pages_min)
87 struct ll_ra_info *ra = &sbi->ll_ra_info;
92 WARN_ON_ONCE(pages_min > pages);
94 * Don't try readahead aggresively if we are limited
95 * LRU pages, otherwise, it could cause deadlock.
97 pages = min(sbi->ll_cache->ccc_lru_max >> 2, pages);
99 * if this happen, we reserve more pages than needed,
100 * this will make us leak @ra_cur_pages, because
101 * ll_ra_count_put() acutally freed @pages.
103 if (unlikely(pages_min > pages))
107 * If read-ahead pages left are less than 1M, do not do read-ahead,
108 * otherwise it will form small read RPC(< 1M), which hurt server
111 ret = min(ra->ra_max_pages - atomic_read(&ra->ra_cur_pages),
113 if (ret < 0 || ret < min_t(long, PTLRPC_MAX_BRW_PAGES, pages))
116 if (atomic_add_return(ret, &ra->ra_cur_pages) > ra->ra_max_pages) {
117 atomic_sub(ret, &ra->ra_cur_pages);
122 if (ret < pages_min) {
123 /* override ra limit for maximum performance */
124 atomic_add(pages_min - ret, &ra->ra_cur_pages);
130 void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long pages)
132 struct ll_ra_info *ra = &sbi->ll_ra_info;
133 atomic_sub(pages, &ra->ra_cur_pages);
136 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which)
138 LASSERTF(which < _NR_RA_STAT, "which: %u\n", which);
139 lprocfs_counter_incr(sbi->ll_ra_stats, which);
142 static inline bool ll_readahead_enabled(struct ll_sb_info *sbi)
144 return sbi->ll_ra_info.ra_max_pages_per_file > 0 &&
145 sbi->ll_ra_info.ra_max_pages > 0;
148 void ll_ra_stats_inc(struct inode *inode, enum ra_stat which)
150 struct ll_sb_info *sbi = ll_i2sbi(inode);
152 ll_ra_stats_inc_sbi(sbi, which);
155 static void ll_ra_stats_add(struct inode *inode, enum ra_stat which, long count)
157 struct ll_sb_info *sbi = ll_i2sbi(inode);
159 LASSERTF(which < _NR_RA_STAT, "which: %u\n", which);
160 lprocfs_counter_add(sbi->ll_ra_stats, which, count);
163 #define RAS_CDEBUG(ras) \
165 "lre %llu cr %lu cb %llu wsi %lu wp %lu nra %lu rpc %lu " \
166 "r %lu csr %lu so %llu sb %llu sl %llu lr %lu\n", \
167 ras->ras_last_read_end_bytes, ras->ras_consecutive_requests, \
168 ras->ras_consecutive_bytes, ras->ras_window_start_idx, \
169 ras->ras_window_pages, ras->ras_next_readahead_idx, \
170 ras->ras_rpc_pages, ras->ras_requests, \
171 ras->ras_consecutive_stride_requests, ras->ras_stride_offset, \
172 ras->ras_stride_bytes, ras->ras_stride_length, \
173 ras->ras_async_last_readpage_idx)
175 static bool pos_in_window(loff_t pos, loff_t point,
176 unsigned long before, unsigned long after)
178 loff_t start = point - before;
179 loff_t end = point + after;
186 return start <= pos && pos <= end;
189 enum ll_ra_page_hint {
190 MAYNEED = 0, /* this page possibly accessed soon */
191 WILLNEED /* this page is gurateed to be needed */
195 * Initiates read-ahead of a page with given index.
197 * \retval +ve: page was already uptodate so it will be skipped
199 * \retval -ve: page wasn't added to \a queue for error;
200 * \retval 0: page was added into \a queue for read ahead.
202 static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
203 struct cl_page_list *queue, pgoff_t index,
204 enum ll_ra_page_hint hint)
206 struct cl_object *clob = io->ci_obj;
207 struct inode *inode = vvp_object_inode(clob);
208 struct page *vmpage = NULL;
210 enum ra_stat which = _NR_RA_STAT; /* keep gcc happy */
212 const char *msg = NULL;
219 * We need __GFP_NORETRY here for read-ahead page, otherwise
220 * the process will fail with OOM killed due to memcg limit.
221 * See @readahead_gfp_mask for an example.
223 vmpage = pagecache_get_page(inode->i_mapping, index,
224 FGP_LOCK | FGP_CREAT |
225 FGP_NOFS | FGP_NOWAIT,
226 mapping_gfp_mask(inode->i_mapping) |
227 __GFP_NORETRY | __GFP_NOWARN);
228 if (vmpage == NULL) {
229 which = RA_STAT_FAILED_GRAB_PAGE;
230 msg = "g_c_p_n failed";
231 GOTO(out, rc = -EBUSY);
235 vmpage = find_or_create_page(inode->i_mapping, index,
238 GOTO(out, rc = -ENOMEM);
241 /* should not come here */
242 GOTO(out, rc = -EINVAL);
245 /* Check if vmpage was truncated or reclaimed */
246 if (vmpage->mapping != inode->i_mapping) {
247 which = RA_STAT_WRONG_GRAB_PAGE;
248 msg = "g_c_p_n returned invalid page";
249 GOTO(out, rc = -EBUSY);
252 cp = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
254 which = RA_STAT_FAILED_GRAB_PAGE;
255 msg = "cl_page_find failed";
256 GOTO(out, rc = PTR_ERR(cp));
259 lu_ref_add(&cp->cp_reference, "ra", current);
260 cl_page_assume(env, io, cp);
262 if (!cp->cp_defer_uptodate && !PageUptodate(vmpage)) {
263 if (hint == MAYNEED) {
264 cp->cp_defer_uptodate = 1;
268 cl_page_list_add(queue, cp, true);
270 /* skip completed pages */
271 cl_page_unassume(env, io, cp);
272 /* This page is already uptodate, returning a positive number
273 * to tell the callers about this */
277 lu_ref_del(&cp->cp_reference, "ra", current);
278 cl_page_put(env, cp);
281 if (vmpage != NULL) {
286 if (msg != NULL && hint == MAYNEED) {
287 ll_ra_stats_inc(inode, which);
288 CDEBUG(D_READA, "%s\n", msg);
295 #define RIA_DEBUG(ria) \
296 CDEBUG(D_READA, "rs %lu re %lu ro %llu rl %llu rb %llu\n", \
297 ria->ria_start_idx, ria->ria_end_idx, ria->ria_stoff, \
298 ria->ria_length, ria->ria_bytes)
300 static inline int stride_io_mode(struct ll_readahead_state *ras)
302 return ras->ras_consecutive_stride_requests > 1;
305 /* The function calculates how many bytes will be read in
306 * [off, off + length], in such stride IO area,
307 * stride_offset = st_off, stride_lengh = st_len,
308 * stride_bytes = st_bytes
310 * |------------------|*****|------------------|*****|------------|*****|....
313 * |----- st_len -----|
315 * How many bytes it should read in such pattern
316 * |-------------------------------------------------------------|
318 * |<------ length ------->|
320 * = |<----->| + |-------------------------------------| + |---|
321 * start_left st_bytes * i end_left
323 static loff_t stride_byte_count(loff_t st_off, loff_t st_len, loff_t st_bytes,
324 loff_t off, loff_t length)
326 u64 start = off > st_off ? off - st_off : 0;
327 u64 end = off + length > st_off ? off + length - st_off : 0;
332 if (st_len == 0 || length == 0 || end == 0)
335 start = div64_u64_rem(start, st_len, &start_left);
336 if (start_left < st_bytes)
337 start_left = st_bytes - start_left;
341 end = div64_u64_rem(end, st_len, &end_left);
342 if (end_left > st_bytes)
345 CDEBUG(D_READA, "start %llu, end %llu start_left %llu end_left %llu\n",
346 start, end, start_left, end_left);
349 bytes_count = end_left - (st_bytes - start_left);
351 bytes_count = start_left +
352 st_bytes * (end - start - 1) + end_left;
355 "st_off %llu, st_len %llu st_bytes %llu off %llu length %llu bytescount %llu\n",
356 st_off, st_len, st_bytes, off, length, bytes_count);
361 static unsigned long ria_page_count(struct ra_io_arg *ria)
363 loff_t length_bytes = ria->ria_end_idx >= ria->ria_start_idx ?
364 (loff_t)(ria->ria_end_idx -
365 ria->ria_start_idx + 1) << PAGE_SHIFT : 0;
368 if (ria->ria_length > ria->ria_bytes && ria->ria_bytes &&
369 (ria->ria_length & ~PAGE_MASK || ria->ria_bytes & ~PAGE_MASK ||
370 ria->ria_stoff & ~PAGE_MASK)) {
371 /* Over-estimate un-aligned page stride read */
372 unsigned long pg_count = ((ria->ria_bytes +
373 PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
374 pg_count *= length_bytes / ria->ria_length + 1;
378 bytes_count = stride_byte_count(ria->ria_stoff, ria->ria_length,
380 (loff_t)ria->ria_start_idx<<PAGE_SHIFT,
382 return (bytes_count + PAGE_SIZE - 1) >> PAGE_SHIFT;
385 static pgoff_t ras_align(struct ll_readahead_state *ras, pgoff_t index)
387 unsigned opt_size = min(ras->ras_window_pages, ras->ras_rpc_pages);
391 return index - (index % opt_size);
394 /* Check whether the index is in the defined ra-window */
395 static bool ras_inside_ra_window(pgoff_t idx, struct ra_io_arg *ria)
397 loff_t pos = (loff_t)idx << PAGE_SHIFT;
399 /* If ria_length == ria_bytes, it means non-stride I/O mode,
400 * idx should always inside read-ahead window in this case
401 * For stride I/O mode, just check whether the idx is inside
404 if (ria->ria_length == 0 || ria->ria_length == ria->ria_bytes)
407 if (pos >= ria->ria_stoff) {
410 div64_u64_rem(pos - ria->ria_stoff, ria->ria_length, &offset);
412 if (offset < ria->ria_bytes ||
413 (ria->ria_length - offset) < PAGE_SIZE)
415 } else if (pos + PAGE_SIZE > ria->ria_stoff) {
423 ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
424 struct cl_page_list *queue, struct ll_readahead_state *ras,
425 struct ra_io_arg *ria, pgoff_t *ra_end, pgoff_t skip_index)
427 struct cl_read_ahead ra = { 0 };
428 /* busy page count is per stride */
429 int rc = 0, count = 0, busy_page_count = 0;
432 LASSERT(ria != NULL);
435 for (page_idx = ria->ria_start_idx;
436 page_idx <= ria->ria_end_idx && ria->ria_reserved > 0;
438 if (skip_index && page_idx == skip_index)
440 if (ras_inside_ra_window(page_idx, ria)) {
441 if (ra.cra_end_idx == 0 || ra.cra_end_idx < page_idx) {
445 * Do not shrink ria_end_idx at any case until
446 * the minimum end of current read is covered.
448 * Do not extend read lock accross stripe if
449 * lock contention detected.
451 if (ra.cra_contention &&
452 page_idx > ria->ria_end_idx_min) {
453 ria->ria_end_idx = *ra_end;
457 cl_read_ahead_release(env, &ra);
459 rc = cl_io_read_ahead(env, io, page_idx, &ra);
464 * Only shrink ria_end_idx if the matched
465 * LDLM lock doesn't cover more.
467 if (page_idx > ra.cra_end_idx) {
468 ria->ria_end_idx = ra.cra_end_idx;
472 CDEBUG(D_READA, "idx: %lu, ra: %lu, rpc: %lu\n",
473 page_idx, ra.cra_end_idx,
475 LASSERTF(ra.cra_end_idx >= page_idx,
476 "object: %px, indcies %lu / %lu\n",
477 io->ci_obj, ra.cra_end_idx, page_idx);
478 /* update read ahead RPC size.
479 * NB: it's racy but doesn't matter */
480 if (ras->ras_rpc_pages != ra.cra_rpc_pages &&
481 ra.cra_rpc_pages > 0)
482 ras->ras_rpc_pages = ra.cra_rpc_pages;
484 /* trim it to align with optimal RPC size */
485 end_idx = ras_align(ras, ria->ria_end_idx + 1);
486 if (end_idx > 0 && !ria->ria_eof)
487 ria->ria_end_idx = end_idx - 1;
489 if (ria->ria_end_idx < ria->ria_end_idx_min)
490 ria->ria_end_idx = ria->ria_end_idx_min;
492 if (page_idx > ria->ria_end_idx)
495 /* If the page is inside the read-ahead window */
496 rc = ll_read_ahead_page(env, io, queue, page_idx,
498 if (rc < 0 && rc != -EBUSY)
503 "skip busy page: %lu\n", page_idx);
504 /* For page unaligned readahead the first
505 * last pages of each region can be read by
506 * another reader on the same node, and so
507 * may be busy. So only stop for > 2 busy
509 if (busy_page_count > 2)
514 /* Only subtract from reserve & count the page if we
515 * really did readahead on that page. */
520 } else if (stride_io_mode(ras)) {
521 /* If it is not in the read-ahead window, and it is
522 * read-ahead mode, then check whether it should skip
525 loff_t pos = (loff_t)page_idx << PAGE_SHIFT;
528 div64_u64_rem(pos - ria->ria_stoff, ria->ria_length,
530 if (offset >= ria->ria_bytes) {
531 pos += (ria->ria_length - offset);
532 if ((pos >> PAGE_SHIFT) >= page_idx + 1)
533 page_idx = (pos >> PAGE_SHIFT) - 1;
536 "Stride: jump %llu pages to %lu\n",
537 ria->ria_length - offset, page_idx);
543 cl_read_ahead_release(env, &ra);
546 ll_ra_stats_add(vvp_object_inode(io->ci_obj),
547 RA_STAT_READAHEAD_PAGES, count);
552 static void ll_readahead_work_free(struct ll_readahead_work *work)
554 fput(work->lrw_file);
558 static void ll_readahead_handle_work(struct work_struct *wq);
559 static void ll_readahead_work_add(struct inode *inode,
560 struct ll_readahead_work *work)
562 INIT_WORK(&work->lrw_readahead_work, ll_readahead_handle_work);
563 queue_work(ll_i2sbi(inode)->ll_ra_info.ll_readahead_wq,
564 &work->lrw_readahead_work);
567 static int ll_readahead_file_kms(const struct lu_env *env,
568 struct cl_io *io, __u64 *kms)
570 struct cl_object *clob;
572 struct cl_attr *attr = vvp_env_thread_attr(env);
576 inode = vvp_object_inode(clob);
578 cl_object_attr_lock(clob);
579 ret = cl_object_attr_get(env, clob, attr);
580 cl_object_attr_unlock(clob);
585 *kms = attr->cat_kms;
589 static void ll_readahead_handle_work(struct work_struct *wq)
591 struct ll_readahead_work *work;
594 struct ra_io_arg *ria;
596 struct ll_file_data *fd;
597 struct ll_readahead_state *ras;
599 struct cl_2queue *queue;
600 pgoff_t ra_end_idx = 0;
601 unsigned long pages, pages_min = 0;
606 struct ll_sb_info *sbi;
608 work = container_of(wq, struct ll_readahead_work,
610 fd = work->lrw_file->private_data;
612 file = work->lrw_file;
613 inode = file_inode(file);
614 sbi = ll_i2sbi(inode);
616 CDEBUG(D_READA|D_IOTRACE,
617 "%s:"DFID": async ra from %lu to %lu triggered by user pid %d\n",
618 file_dentry(file)->d_name.name, PFID(ll_inode2fid(inode)),
619 work->lrw_start_idx, work->lrw_end_idx, work->lrw_user_pid);
621 env = cl_env_alloc(&refcheck, LCT_NOREF);
623 GOTO(out_free_work, rc = PTR_ERR(env));
625 io = vvp_env_thread_io(env);
626 ll_io_init(io, file, CIT_READ, NULL);
628 rc = ll_readahead_file_kms(env, io, &kms);
630 GOTO(out_put_env, rc);
633 ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
634 GOTO(out_put_env, rc = 0);
637 ria = &ll_env_info(env)->lti_ria;
638 memset(ria, 0, sizeof(*ria));
640 ria->ria_start_idx = work->lrw_start_idx;
641 /* Truncate RA window to end of file */
642 eof_index = (pgoff_t)(kms - 1) >> PAGE_SHIFT;
643 if (eof_index <= work->lrw_end_idx) {
644 work->lrw_end_idx = eof_index;
647 if (work->lrw_end_idx <= work->lrw_start_idx)
648 GOTO(out_put_env, rc = 0);
650 ria->ria_end_idx = work->lrw_end_idx;
651 pages = ria->ria_end_idx - ria->ria_start_idx + 1;
652 ria->ria_reserved = ll_ra_count_get(sbi, ria,
653 ria_page_count(ria), pages_min);
656 "async reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
657 ria->ria_reserved, pages, pages_min,
658 atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
659 ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
661 if (ria->ria_reserved < pages) {
662 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
663 if (PAGES_TO_MiB(ria->ria_reserved) < 1) {
664 ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
665 GOTO(out_put_env, rc = 0);
669 rc = cl_io_rw_init(env, io, CIT_READ, ria->ria_start_idx, pages);
671 GOTO(out_put_env, rc);
673 /* overwrite jobid inited in vvp_io_init() */
674 if (strncmp(ll_i2info(inode)->lli_jobid, work->lrw_jobid,
675 sizeof(work->lrw_jobid)))
676 memcpy(ll_i2info(inode)->lli_jobid, work->lrw_jobid,
677 sizeof(work->lrw_jobid));
679 vvp_env_io(env)->vui_fd = fd;
680 io->ci_state = CIS_LOCKED;
681 io->ci_async_readahead = true;
682 rc = cl_io_start(env, io);
684 GOTO(out_io_fini, rc);
686 queue = &io->ci_queue;
687 cl_2queue_init(queue);
689 rc = ll_read_ahead_pages(env, io, &queue->c2_qin, ras, ria,
691 if (ria->ria_reserved != 0)
692 ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
693 if (queue->c2_qin.pl_nr > 0) {
694 int count = queue->c2_qin.pl_nr;
696 rc = cl_io_submit_rw(env, io, CRT_READ, queue);
698 task_io_account_read(PAGE_SIZE * count);
700 if (ria->ria_end_idx == ra_end_idx && ra_end_idx == (kms >> PAGE_SHIFT))
701 ll_ra_stats_inc(inode, RA_STAT_EOF);
703 if (ra_end_idx != ria->ria_end_idx)
704 ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
706 /* TODO: discard all pages until page reinit route is implemented */
707 cl_page_list_discard(env, io, &queue->c2_qin);
709 /* Unlock unsent read pages in case of error. */
710 cl_page_list_disown(env, &queue->c2_qin);
712 cl_2queue_fini(env, queue);
717 cl_env_put(env, &refcheck);
720 ll_ra_stats_inc_sbi(ll_i2sbi(inode), RA_STAT_ASYNC);
721 atomic_dec(&sbi->ll_ra_info.ra_async_inflight);
722 ll_readahead_work_free(work);
725 static int ll_readahead(const struct lu_env *env, struct cl_io *io,
726 struct cl_page_list *queue,
727 struct ll_readahead_state *ras, bool hit,
728 struct file *file, pgoff_t skip_index,
731 struct vvp_io *vio = vvp_env_io(env);
732 struct ll_thread_info *lti = ll_env_info(env);
733 unsigned long pages, pages_min = 0;
734 pgoff_t ra_end_idx = 0, end_idx = 0;
736 struct ra_io_arg *ria = <i->lti_ria;
737 struct cl_object *clob;
740 struct ll_sb_info *sbi;
741 struct ll_ra_info *ra;
746 inode = vvp_object_inode(clob);
747 sbi = ll_i2sbi(inode);
748 ra = &sbi->ll_ra_info;
751 * In case we have a limited max_cached_mb, readahead
752 * should be stopped if it have run out of all LRU slots.
754 if (atomic_read(&ra->ra_cur_pages) >= sbi->ll_cache->ccc_lru_max) {
755 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
759 memset(ria, 0, sizeof(*ria));
760 ret = ll_readahead_file_kms(env, io, &kms);
765 ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
769 spin_lock(&ras->ras_lock);
772 * Note: other thread might rollback the ras_next_readahead_idx,
773 * if it can not get the full size of prepared pages, see the
774 * end of this function. For stride read ahead, it needs to
775 * make sure the offset is no less than ras_stride_offset,
776 * so that stride read ahead can work correctly.
778 if (stride_io_mode(ras))
779 *start_idx = max_t(pgoff_t, ras->ras_next_readahead_idx,
780 ras->ras_stride_offset >> PAGE_SHIFT);
782 *start_idx = ras->ras_next_readahead_idx;
784 if (ras->ras_window_pages > 0)
785 end_idx = ras->ras_window_start_idx + ras->ras_window_pages - 1;
788 end_idx = *start_idx + ras->ras_window_pages - 1;
790 /* Enlarge the RA window to encompass the full read */
791 if (vio->vui_ra_valid &&
792 end_idx < vio->vui_ra_start_idx + vio->vui_ra_pages - 1)
793 end_idx = vio->vui_ra_start_idx + vio->vui_ra_pages - 1;
798 /* Truncate RA window to end of file */
799 eof_index = (pgoff_t)((kms - 1) >> PAGE_SHIFT);
800 if (eof_index <= end_idx) {
805 ria->ria_start_idx = *start_idx;
806 ria->ria_end_idx = end_idx;
807 /* If stride I/O mode is detected, get stride window*/
808 if (stride_io_mode(ras)) {
809 ria->ria_stoff = ras->ras_stride_offset;
810 ria->ria_length = ras->ras_stride_length;
811 ria->ria_bytes = ras->ras_stride_bytes;
813 spin_unlock(&ras->ras_lock);
815 pages = ria_page_count(ria);
819 DFID": ria: %lu/%lu, bead: %lu/%lu, pages %lu, hit: %d\n",
820 PFID(lu_object_fid(&clob->co_lu)),
821 ria->ria_start_idx, ria->ria_end_idx,
822 vio->vui_ra_valid ? vio->vui_ra_start_idx : 0,
823 vio->vui_ra_valid ? vio->vui_ra_pages : 0,
827 ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
831 ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
835 /* at least to extend the readahead window to cover current read */
836 if (!hit && vio->vui_ra_valid &&
837 vio->vui_ra_start_idx + vio->vui_ra_pages > ria->ria_start_idx) {
838 ria->ria_end_idx_min =
839 vio->vui_ra_start_idx + vio->vui_ra_pages - 1;
840 pages_min = vio->vui_ra_start_idx + vio->vui_ra_pages -
843 * For performance reason, exceeding @ra_max_pages
844 * are allowed, but this should be limited with RPC
845 * size in case a large block size read issued. Trim
848 pages_min = min(pages_min, ras->ras_rpc_pages -
849 (ria->ria_start_idx % ras->ras_rpc_pages));
852 /* don't over reserved for mmap range read */
855 if (pages_min > pages)
857 ria->ria_reserved = ll_ra_count_get(ll_i2sbi(inode), ria, pages,
859 if (ria->ria_reserved < pages)
860 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
862 CDEBUG(D_READA, "reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
863 ria->ria_reserved, pages, pages_min,
864 atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
865 ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
867 ret = ll_read_ahead_pages(env, io, queue, ras, ria, &ra_end_idx,
869 if (ria->ria_reserved != 0)
870 ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
872 if (ra_end_idx == end_idx && ra_end_idx == (kms >> PAGE_SHIFT))
873 ll_ra_stats_inc(inode, RA_STAT_EOF);
876 "ra_end_idx = %lu end_idx = %lu stride end = %lu pages = %d\n",
877 ra_end_idx, end_idx, ria->ria_end_idx, ret);
879 if (ra_end_idx != end_idx)
880 ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
881 if (ra_end_idx > 0) {
882 /* update the ras so that the next read-ahead tries from
883 * where we left off. */
884 spin_lock(&ras->ras_lock);
885 ras->ras_next_readahead_idx = ra_end_idx + 1;
886 spin_unlock(&ras->ras_lock);
893 static int ll_readpages(const struct lu_env *env, struct cl_io *io,
894 struct cl_page_list *queue,
895 pgoff_t start, pgoff_t end)
904 ret = ll_readahead_file_kms(env, io, &kms);
912 unsigned long end_index;
914 end_index = (unsigned long)((kms - 1) >> PAGE_SHIFT);
915 if (end_index <= end)
919 for (page_idx = start; page_idx <= end; page_idx++) {
920 ret= ll_read_ahead_page(env, io, queue, page_idx,
924 else if (ret == 0) /* ret 1 is already uptodate */
928 RETURN(count > 0 ? count : ret);
931 /* called with the ras_lock held or from places where it doesn't matter */
932 static void ras_reset(struct ll_readahead_state *ras, pgoff_t index)
934 ras->ras_consecutive_requests = 0;
935 ras->ras_consecutive_bytes = 0;
936 ras->ras_window_pages = 0;
937 ras->ras_window_start_idx = ras_align(ras, index);
938 ras->ras_next_readahead_idx = max(ras->ras_window_start_idx, index + 1);
943 /* called with the ras_lock held or from places where it doesn't matter */
944 static void ras_stride_reset(struct ll_readahead_state *ras)
946 ras->ras_consecutive_stride_requests = 0;
947 ras->ras_stride_length = 0;
948 ras->ras_stride_bytes = 0;
952 void ll_readahead_init(struct inode *inode, struct ll_readahead_state *ras)
954 spin_lock_init(&ras->ras_lock);
955 ras->ras_rpc_pages = PTLRPC_MAX_BRW_PAGES;
957 ras->ras_last_read_end_bytes = 0;
958 ras->ras_requests = 0;
959 ras->ras_range_min_start_idx = 0;
960 ras->ras_range_max_end_idx = 0;
961 ras->ras_range_requests = 0;
962 ras->ras_last_range_pages = 0;
966 * Check whether the read request is in the stride window.
967 * If it is in the stride window, return true, otherwise return false.
969 static bool read_in_stride_window(struct ll_readahead_state *ras,
970 loff_t pos, loff_t bytes)
974 if (ras->ras_stride_length == 0 || ras->ras_stride_bytes == 0 ||
975 ras->ras_stride_bytes == ras->ras_stride_length)
978 stride_gap = pos - ras->ras_last_read_end_bytes - 1;
980 /* If it is contiguous read */
982 return ras->ras_consecutive_bytes + bytes <=
983 ras->ras_stride_bytes;
985 /* Otherwise check the stride by itself */
986 return (ras->ras_stride_length - ras->ras_stride_bytes) == stride_gap &&
987 ras->ras_consecutive_bytes == ras->ras_stride_bytes &&
988 bytes <= ras->ras_stride_bytes;
991 static void ras_init_stride_detector(struct ll_readahead_state *ras,
992 loff_t pos, loff_t bytes)
994 loff_t stride_gap = pos - ras->ras_last_read_end_bytes - 1;
996 LASSERT(ras->ras_consecutive_stride_requests == 0);
998 if (pos <= ras->ras_last_read_end_bytes) {
999 /* Reset stride window for forward read */
1000 ras_stride_reset(ras);
1004 ras->ras_stride_bytes = ras->ras_consecutive_bytes;
1005 ras->ras_stride_length = stride_gap + ras->ras_consecutive_bytes;
1006 ras->ras_consecutive_stride_requests++;
1007 ras->ras_stride_offset = pos;
1012 static unsigned long
1013 stride_page_count(struct ll_readahead_state *ras, loff_t len)
1015 loff_t bytes_count =
1016 stride_byte_count(ras->ras_stride_offset,
1017 ras->ras_stride_length, ras->ras_stride_bytes,
1018 ras->ras_window_start_idx << PAGE_SHIFT, len);
1020 return (bytes_count + PAGE_SIZE - 1) >> PAGE_SHIFT;
1023 /* Stride Read-ahead window will be increased inc_len according to
1024 * stride I/O pattern */
1025 static void ras_stride_increase_window(struct ll_readahead_state *ras,
1026 struct ll_ra_info *ra, loff_t inc_bytes)
1028 loff_t window_bytes, stride_bytes;
1033 /* temporarily store in page units to reduce LASSERT() cost below */
1034 end = ras->ras_window_start_idx + ras->ras_window_pages;
1036 LASSERT(ras->ras_stride_length > 0);
1037 LASSERTF(end >= (ras->ras_stride_offset >> PAGE_SHIFT),
1038 "window_start_idx %lu, window_pages %lu stride_offset %llu\n",
1039 ras->ras_window_start_idx, ras->ras_window_pages,
1040 ras->ras_stride_offset);
1043 if (end <= ras->ras_stride_offset)
1046 stride_bytes = end - ras->ras_stride_offset;
1048 div64_u64_rem(stride_bytes, ras->ras_stride_length, &left_bytes);
1049 window_bytes = (ras->ras_window_pages << PAGE_SHIFT);
1050 if (left_bytes < ras->ras_stride_bytes) {
1051 if (ras->ras_stride_bytes - left_bytes >= inc_bytes) {
1052 window_bytes += inc_bytes;
1055 window_bytes += (ras->ras_stride_bytes - left_bytes);
1056 inc_bytes -= (ras->ras_stride_bytes - left_bytes);
1059 window_bytes += (ras->ras_stride_length - left_bytes);
1062 LASSERT(ras->ras_stride_bytes != 0);
1064 step = div64_u64_rem(inc_bytes, ras->ras_stride_bytes, &left_bytes);
1066 window_bytes += step * ras->ras_stride_length + left_bytes;
1067 LASSERT(window_bytes > 0);
1070 if (stride_page_count(ras, window_bytes) <=
1071 ra->ra_max_pages_per_file || ras->ras_window_pages == 0)
1072 ras->ras_window_pages = (window_bytes >> PAGE_SHIFT);
1074 LASSERT(ras->ras_window_pages > 0);
1079 static void ras_increase_window(struct inode *inode,
1080 struct ll_readahead_state *ras,
1081 struct ll_ra_info *ra)
1083 /* The stretch of ra-window should be aligned with max rpc_size
1084 * but current clio architecture does not support retrieve such
1085 * information from lower layer. FIXME later
1087 if (stride_io_mode(ras)) {
1088 ras_stride_increase_window(ras, ra,
1089 (loff_t)ras->ras_rpc_pages << PAGE_SHIFT);
1091 pgoff_t window_pages;
1093 window_pages = min(ras->ras_window_pages + ras->ras_rpc_pages,
1094 ra->ra_max_pages_per_file);
1095 if (window_pages < ras->ras_rpc_pages)
1096 ras->ras_window_pages = window_pages;
1098 ras->ras_window_pages = ras_align(ras, window_pages);
1103 * Seek within 8 pages are considered as sequential read for now.
1105 static inline bool is_loose_seq_read(struct ll_readahead_state *ras, loff_t pos)
1107 return pos_in_window(pos, ras->ras_last_read_end_bytes,
1108 8UL << PAGE_SHIFT, 8UL << PAGE_SHIFT);
1111 static inline bool is_loose_mmap_read(struct ll_sb_info *sbi,
1112 struct ll_readahead_state *ras,
1115 unsigned long range_pages = sbi->ll_ra_info.ra_range_pages;
1117 return pos_in_window(pos, ras->ras_last_read_end_bytes,
1118 range_pages << PAGE_SHIFT,
1119 range_pages << PAGE_SHIFT);
1123 * We have observed slow mmap read performances for some
1124 * applications. The problem is if access pattern is neither
1125 * sequential nor stride, but could be still adjacent in a
1126 * small range and then seek a random position.
1128 * So the pattern could be something like this:
1130 * [1M data] [hole] [0.5M data] [hole] [0.7M data] [1M data]
1133 * Every time an application reads mmap data, it may not only
1134 * read a single 4KB page, but aslo a cluster of nearby pages in
1135 * a range(e.g. 1MB) of the first page after a cache miss.
1137 * The readahead engine is modified to track the range size of
1138 * a cluster of mmap reads, so that after a seek and/or cache miss,
1139 * the range size is used to efficiently prefetch multiple pages
1140 * in a single RPC rather than many small RPCs.
1142 static void ras_detect_cluster_range(struct ll_readahead_state *ras,
1143 struct ll_sb_info *sbi,
1144 unsigned long pos, unsigned long count)
1146 pgoff_t last_pages, pages;
1147 pgoff_t end_idx = (pos + count - 1) >> PAGE_SHIFT;
1149 last_pages = ras->ras_range_max_end_idx -
1150 ras->ras_range_min_start_idx + 1;
1151 /* First time come here */
1152 if (!ras->ras_range_max_end_idx)
1155 /* Random or Stride read */
1156 if (!is_loose_mmap_read(sbi, ras, pos))
1159 ras->ras_range_requests++;
1160 if (ras->ras_range_max_end_idx < end_idx)
1161 ras->ras_range_max_end_idx = end_idx;
1163 if (ras->ras_range_min_start_idx > (pos >> PAGE_SHIFT))
1164 ras->ras_range_min_start_idx = pos >> PAGE_SHIFT;
1166 /* Out of range, consider it as random or stride */
1167 pages = ras->ras_range_max_end_idx -
1168 ras->ras_range_min_start_idx + 1;
1169 if (pages <= sbi->ll_ra_info.ra_range_pages)
1172 ras->ras_last_range_pages = last_pages;
1173 ras->ras_range_requests = 0;
1174 ras->ras_range_min_start_idx = pos >> PAGE_SHIFT;
1175 ras->ras_range_max_end_idx = end_idx;
1178 static void ras_detect_read_pattern(struct ll_readahead_state *ras,
1179 struct ll_sb_info *sbi,
1180 loff_t pos, size_t bytes, bool mmap)
1182 bool stride_detect = false;
1183 pgoff_t index = pos >> PAGE_SHIFT;
1187 * Reset the read-ahead window in two cases. First when the app seeks
1188 * or reads to some other part of the file. Secondly if we get a
1189 * read-ahead miss that we think we've previously issued. This can
1190 * be a symptom of there being so many read-ahead pages that the VM
1191 * is reclaiming it before we get to it.
1193 if (!is_loose_seq_read(ras, pos)) {
1194 /* Check whether it is in stride I/O mode */
1195 if (!read_in_stride_window(ras, pos, bytes)) {
1196 if (ras->ras_consecutive_stride_requests == 0)
1197 ras_init_stride_detector(ras, pos, bytes);
1199 ras_stride_reset(ras);
1200 ras->ras_consecutive_bytes = 0;
1201 ras_reset(ras, index);
1203 ras->ras_consecutive_bytes = 0;
1204 ras->ras_consecutive_requests = 0;
1205 if (++ras->ras_consecutive_stride_requests > 1)
1206 stride_detect = true;
1209 ll_ra_stats_inc_sbi(sbi, RA_STAT_DISTANT_READPAGE);
1210 } else if (stride_io_mode(ras)) {
1212 * If this is contiguous read but in stride I/O mode
1213 * currently, check whether stride step still is valid,
1214 * if invalid, it will reset the stride ra window to
1217 if (!read_in_stride_window(ras, pos, bytes)) {
1218 ras_stride_reset(ras);
1219 ras->ras_window_pages = 0;
1220 ras->ras_next_readahead_idx = index;
1224 ras->ras_consecutive_bytes += bytes;
1226 pgoff_t idx = ras->ras_consecutive_bytes >> PAGE_SHIFT;
1227 unsigned long ra_range_pages =
1228 max_t(unsigned long, RA_MIN_MMAP_RANGE_PAGES,
1229 sbi->ll_ra_info.ra_range_pages);
1231 if ((idx >= ra_range_pages &&
1232 idx % ra_range_pages == 0) || stride_detect)
1233 ras->ras_need_increase_window = true;
1234 } else if ((ras->ras_consecutive_requests > 1 || stride_detect)) {
1235 ras->ras_need_increase_window = true;
1238 ras->ras_last_read_end_bytes = pos + bytes - 1;
1242 void ll_ras_enter(struct file *f, loff_t pos, size_t bytes)
1244 struct ll_file_data *fd = f->private_data;
1245 struct ll_readahead_state *ras = &fd->fd_ras;
1246 struct inode *inode = file_inode(f);
1247 struct ll_sb_info *sbi = ll_i2sbi(inode);
1249 spin_lock(&ras->ras_lock);
1250 ras->ras_requests++;
1251 ras->ras_consecutive_requests++;
1252 ras->ras_need_increase_window = false;
1253 ras->ras_whole_file_read = false;
1255 * On the second access to a file smaller than the tunable
1256 * ra_max_read_ahead_whole_pages trigger RA on all pages in the
1257 * file up to ra_max_pages_per_file. This is simply a best effort
1258 * and only occurs once per open file. Normal RA behavior is reverted
1259 * to for subsequent IO.
1261 if (ras->ras_requests >= 2) {
1263 struct ll_ra_info *ra = &sbi->ll_ra_info;
1265 kms_pages = (i_size_read(inode) + PAGE_SIZE - 1) >>
1268 CDEBUG(D_READA, "kmsp %llu mwp %lu mp %lu\n", kms_pages,
1269 ra->ra_max_read_ahead_whole_pages,
1270 ra->ra_max_pages_per_file);
1273 kms_pages <= ra->ra_max_read_ahead_whole_pages) {
1274 ras->ras_whole_file_read = true;
1275 ras->ras_window_start_idx = 0;
1276 ras->ras_next_readahead_idx = 0;
1277 ras->ras_window_pages = min(ra->ra_max_pages_per_file,
1278 ra->ra_max_read_ahead_whole_pages);
1279 GOTO(out_unlock, 0);
1282 ras_detect_read_pattern(ras, sbi, pos, bytes, false);
1284 spin_unlock(&ras->ras_lock);
1287 static bool index_in_stride_window(struct ll_readahead_state *ras,
1290 loff_t pos = (loff_t)index << PAGE_SHIFT;
1292 if (ras->ras_stride_length == 0 || ras->ras_stride_bytes == 0 ||
1293 ras->ras_stride_bytes == ras->ras_stride_length)
1296 if (pos >= ras->ras_stride_offset) {
1299 div64_u64_rem(pos - ras->ras_stride_offset,
1300 ras->ras_stride_length, &offset);
1301 if (offset < ras->ras_stride_bytes ||
1302 ras->ras_stride_length - offset < PAGE_SIZE)
1304 } else if (ras->ras_stride_offset - pos < PAGE_SIZE) {
1312 * ll_ras_enter() is used to detect read pattern according to pos and count.
1314 * ras_update() is used to detect cache miss and
1315 * reset window or increase window accordingly
1317 static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
1318 struct ll_readahead_state *ras, pgoff_t index,
1319 enum ras_update_flags flags, struct cl_io *io)
1321 struct ll_ra_info *ra = &sbi->ll_ra_info;
1322 bool hit = flags & LL_RAS_HIT;
1325 spin_lock(&ras->ras_lock);
1330 CDEBUG(D_READA|D_IOTRACE, DFID " pages at %lu miss.\n",
1331 PFID(ll_inode2fid(inode)), index);
1332 ll_ra_stats_inc_sbi(sbi, hit ? RA_STAT_HIT : RA_STAT_MISS);
1335 * The readahead window has been expanded to cover whole
1336 * file size, we don't care whether ra miss happen or not.
1337 * Because we will read whole file to page cache even if
1338 * some pages missed.
1340 if (ras->ras_whole_file_read)
1341 GOTO(out_unlock, 0);
1343 if (io && io->ci_rand_read)
1344 GOTO(out_unlock, 0);
1346 if (io && io->ci_seq_read) {
1348 /* to avoid many small read RPC here */
1349 ras->ras_window_pages = sbi->ll_ra_info.ra_range_pages;
1350 ll_ra_stats_inc_sbi(sbi, RA_STAT_MMAP_RANGE_READ);
1352 goto skip_miss_checking;
1355 if (flags & LL_RAS_MMAP) {
1356 unsigned long ra_pages;
1358 ras_detect_cluster_range(ras, sbi, index << PAGE_SHIFT,
1360 ras_detect_read_pattern(ras, sbi, (loff_t)index << PAGE_SHIFT,
1363 /* we did not detect anything but we could prefetch */
1364 if (!ras->ras_need_increase_window &&
1365 ras->ras_window_pages <= sbi->ll_ra_info.ra_range_pages &&
1366 ras->ras_range_requests >= 2) {
1368 ra_pages = max_t(unsigned long,
1369 RA_MIN_MMAP_RANGE_PAGES,
1370 ras->ras_last_range_pages);
1371 if (index < ra_pages / 2)
1374 index -= ra_pages / 2;
1375 ras->ras_window_pages = ra_pages;
1376 ll_ra_stats_inc_sbi(sbi,
1377 RA_STAT_MMAP_RANGE_READ);
1379 ras->ras_window_pages = 0;
1381 goto skip_miss_checking;
1385 if (!hit && ras->ras_window_pages &&
1386 index < ras->ras_next_readahead_idx &&
1387 pos_in_window(index, ras->ras_window_start_idx, 0,
1388 ras->ras_window_pages)) {
1389 ll_ra_stats_inc_sbi(sbi, RA_STAT_MISS_IN_WINDOW);
1390 ras->ras_need_increase_window = false;
1392 if (index_in_stride_window(ras, index) &&
1393 stride_io_mode(ras)) {
1395 * if (index != ras->ras_last_readpage + 1)
1396 * ras->ras_consecutive_pages = 0;
1398 ras_reset(ras, index);
1401 * If stride-RA hit cache miss, the stride
1402 * detector will not be reset to avoid the
1403 * overhead of redetecting read-ahead mode,
1404 * but on the condition that the stride window
1405 * is still intersect with normal sequential
1406 * read-ahead window.
1408 if (ras->ras_window_start_idx < ras->ras_stride_offset)
1409 ras_stride_reset(ras);
1413 * Reset both stride window and normal RA
1416 ras_reset(ras, index);
1417 /* ras->ras_consecutive_pages++; */
1418 ras->ras_consecutive_bytes = 0;
1419 ras_stride_reset(ras);
1420 GOTO(out_unlock, 0);
1425 ras->ras_window_start_idx = ras_align(ras, index);
1427 if (stride_io_mode(ras)) {
1428 /* Since stride readahead is sentivite to the offset
1429 * of read-ahead, so we use original offset here,
1430 * instead of ras_window_start_idx, which is RPC aligned.
1432 ras->ras_next_readahead_idx = max(index + 1,
1433 ras->ras_next_readahead_idx);
1434 ras->ras_window_start_idx =
1435 max_t(pgoff_t, ras->ras_window_start_idx,
1436 ras->ras_stride_offset >> PAGE_SHIFT);
1438 if (ras->ras_next_readahead_idx < ras->ras_window_start_idx)
1439 ras->ras_next_readahead_idx = ras->ras_window_start_idx;
1441 ras->ras_next_readahead_idx = index + 1;
1444 if (ras->ras_need_increase_window) {
1445 ras_increase_window(inode, ras, ra);
1446 ras->ras_need_increase_window = false;
1452 spin_unlock(&ras->ras_lock);
1455 int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
1457 struct inode *inode = vmpage->mapping->host;
1458 struct ll_inode_info *lli = ll_i2info(inode);
1461 struct cl_page *page;
1462 struct cl_object *clob;
1463 bool redirtied = false;
1464 bool unlocked = false;
1469 LASSERT(PageLocked(vmpage));
1470 LASSERT(!PageWriteback(vmpage));
1472 LASSERT(ll_i2dtexp(inode) != NULL);
1474 env = cl_env_get(&refcheck);
1476 GOTO(out, result = PTR_ERR(env));
1478 clob = ll_i2info(inode)->lli_clob;
1479 LASSERT(clob != NULL);
1481 io = vvp_env_thread_io(env);
1483 io->ci_ignore_layout = 1;
1484 result = cl_io_init(env, io, CIT_MISC, clob);
1486 page = cl_page_find(env, clob, vmpage->index,
1487 vmpage, CPT_CACHEABLE);
1488 if (!IS_ERR(page)) {
1489 lu_ref_add(&page->cp_reference, "writepage",
1491 cl_page_assume(env, io, page);
1492 result = cl_page_flush(env, io, page);
1495 * Re-dirty page on error so it retries write,
1496 * but not in case when IO has actually
1497 * occurred and completed with an error.
1499 if (!PageError(vmpage)) {
1500 redirty_page_for_writepage(wbc, vmpage);
1505 cl_page_disown(env, io, page);
1507 lu_ref_del(&page->cp_reference,
1508 "writepage", current);
1509 cl_page_put(env, page);
1511 result = PTR_ERR(page);
1514 cl_io_fini(env, io);
1516 if (redirtied && wbc->sync_mode == WB_SYNC_ALL) {
1517 loff_t offset = vmpage->index << PAGE_SHIFT;
1519 /* Flush page failed because the extent is being written out.
1520 * Wait for the write of extent to be finished to avoid
1521 * breaking kernel which assumes ->writepage should mark
1522 * PageWriteback or clean the page. */
1523 result = cl_sync_file_range(inode, offset,
1524 offset + PAGE_SIZE - 1,
1527 /* actually we may have written more than one page.
1528 * decreasing this page because the caller will count
1530 wbc->nr_to_write -= result - 1;
1535 cl_env_put(env, &refcheck);
1540 if (!lli->lli_async_rc)
1541 lli->lli_async_rc = result;
1542 SetPageError(vmpage);
1544 unlock_page(vmpage);
1549 int ll_writepages(struct address_space *mapping, struct writeback_control *wbc)
1551 struct inode *inode = mapping->host;
1554 enum cl_fsync_mode mode;
1555 int range_whole = 0;
1560 if (wbc->range_cyclic) {
1561 start = (loff_t)mapping->writeback_index << PAGE_SHIFT;
1562 end = OBD_OBJECT_EOF;
1564 start = wbc->range_start;
1565 end = wbc->range_end;
1566 if (end == LLONG_MAX) {
1567 end = OBD_OBJECT_EOF;
1568 range_whole = start == 0;
1572 mode = CL_FSYNC_NONE;
1573 if (wbc->sync_mode == WB_SYNC_ALL)
1574 mode = CL_FSYNC_LOCAL;
1576 if (wbc->sync_mode == WB_SYNC_NONE) {
1577 #ifdef SB_I_CGROUPWB
1578 struct bdi_writeback *wb;
1581 * As it may break full stripe writes on the inode,
1582 * disable periodic kupdate writeback (@wbc->for_kupdate)?
1586 * The system is under memory pressure and it is now reclaiming
1589 wb = inode_to_wb(inode);
1590 if (wbc->for_background ||
1591 (wb->start_all_reason == WB_REASON_VMSCAN &&
1592 test_bit(WB_start_all, &wb->state)))
1593 mode = CL_FSYNC_RECLAIM;
1596 * We have no idea about writeback reason for memory reclaim
1597 * WB_REASON_TRY_TO_FREE_PAGES in the old kernel such as rhel7
1598 * (WB_REASON_VMSCAN in the newer kernel) ...
1599 * Here set mode with CL_FSYNC_RECLAIM forcely on the old
1602 if (!wbc->for_kupdate)
1603 mode = CL_FSYNC_RECLAIM;
1607 if (ll_i2info(inode)->lli_clob == NULL || (inode->i_state & I_FREEING))
1610 /* for directio, it would call writepages() to evict cached pages
1611 * inside the IO context of write, which will cause deadlock at
1612 * layout_conf since it waits for active IOs to complete. */
1613 result = cl_sync_file_range(inode, start, end, mode, 1);
1615 wbc->nr_to_write -= result;
1619 if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) {
1620 if (end == OBD_OBJECT_EOF)
1621 mapping->writeback_index = 0;
1623 mapping->writeback_index = (end >> PAGE_SHIFT) + 1;
1628 struct ll_cl_context *ll_cl_find(struct inode *inode)
1630 struct ll_inode_info *lli = ll_i2info(inode);
1631 struct ll_cl_context *lcc;
1632 struct ll_cl_context *found = NULL;
1634 read_lock(&lli->lli_lock);
1635 list_for_each_entry(lcc, &lli->lli_lccs, lcc_list) {
1636 if (lcc->lcc_cookie == current) {
1641 read_unlock(&lli->lli_lock);
1646 void ll_cl_add(struct inode *inode, const struct lu_env *env, struct cl_io *io,
1649 struct ll_inode_info *lli = ll_i2info(inode);
1650 struct ll_cl_context *lcc = &ll_env_info(env)->lti_io_ctx;
1652 memset(lcc, 0, sizeof(*lcc));
1653 INIT_LIST_HEAD(&lcc->lcc_list);
1654 lcc->lcc_cookie = current;
1657 lcc->lcc_type = type;
1659 write_lock(&lli->lli_lock);
1660 list_add(&lcc->lcc_list, &lli->lli_lccs);
1661 write_unlock(&lli->lli_lock);
1664 void ll_cl_remove(struct inode *inode, const struct lu_env *env)
1666 struct ll_inode_info *lli = ll_i2info(inode);
1667 struct ll_cl_context *lcc = &ll_env_info(env)->lti_io_ctx;
1669 write_lock(&lli->lli_lock);
1670 list_del_init(&lcc->lcc_list);
1671 write_unlock(&lli->lli_lock);
1674 int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
1675 struct cl_page *page, struct file *file)
1677 struct inode *inode = vvp_object_inode(page->cp_obj);
1678 struct ll_sb_info *sbi = ll_i2sbi(inode);
1679 struct ll_file_data *fd = NULL;
1680 struct ll_readahead_state *ras = NULL;
1681 struct cl_2queue *queue = &io->ci_queue;
1682 struct cl_sync_io *anchor = NULL;
1683 int rc = 0, rc2 = 0;
1685 struct vvp_io *vio = vvp_env_io(env);
1686 bool mmap = !vio->vui_ra_valid;
1687 pgoff_t ra_start_index = 0;
1688 pgoff_t io_start_index;
1689 pgoff_t io_end_index;
1690 bool unlockpage = true;
1694 fd = file->private_data;
1698 /* PagePrivate2 is set in ll_io_zero_page() to tell us the vmpage
1699 * must not be unlocked after processing.
1701 if (page->cp_vmpage && PagePrivate2(page->cp_vmpage))
1704 uptodate = page->cp_defer_uptodate;
1706 if (ll_readahead_enabled(sbi) && !page->cp_ra_updated && ras) {
1707 enum ras_update_flags flags = 0;
1710 flags |= LL_RAS_HIT;
1712 flags |= LL_RAS_MMAP;
1713 ras_update(sbi, inode, ras, cl_page_index(page), flags, io);
1716 cl_2queue_init(queue);
1718 page->cp_ra_used = 1;
1719 SetPageUptodate(page->cp_vmpage);
1720 cl_page_disown(env, io, page);
1722 anchor = &vvp_env_info(env)->vti_anchor;
1723 cl_sync_io_init(anchor, 1);
1724 page->cp_sync_io = anchor;
1726 cl_page_list_add(&queue->c2_qin, page, true);
1729 /* mmap does not set the ci_rw fields */
1731 io_start_index = io->u.ci_rw.crw_pos >> PAGE_SHIFT;
1732 io_end_index = (io->u.ci_rw.crw_pos +
1733 io->u.ci_rw.crw_bytes - 1) >> PAGE_SHIFT;
1735 io_start_index = cl_page_index(page);
1736 io_end_index = cl_page_index(page);
1739 if (ll_readahead_enabled(sbi) && ras && !io->ci_rand_read) {
1740 pgoff_t skip_index = 0;
1742 if (ras->ras_next_readahead_idx < cl_page_index(page))
1743 skip_index = cl_page_index(page);
1744 rc2 = ll_readahead(env, io, &queue->c2_qin, ras,
1745 uptodate, file, skip_index,
1747 /* to keep iotrace clean, we only print here if we actually
1750 CDEBUG(D_READA | (rc2 ? D_IOTRACE : 0),
1751 DFID " %d pages read ahead at %lu, triggered by user read at %lu, stride offset %lld, stride length %lld, stride bytes %lld\n",
1752 PFID(ll_inode2fid(inode)), rc2, ra_start_index,
1753 cl_page_index(page), ras->ras_stride_offset,
1754 ras->ras_stride_length, ras->ras_stride_bytes);
1756 } else if (cl_page_index(page) == io_start_index &&
1757 io_end_index - io_start_index > 0) {
1758 rc2 = ll_readpages(env, io, &queue->c2_qin, io_start_index + 1,
1760 CDEBUG(D_READA, DFID " %d pages read at %lu\n",
1761 PFID(ll_inode2fid(inode)), rc2, cl_page_index(page));
1764 if (queue->c2_qin.pl_nr > 0) {
1765 int count = queue->c2_qin.pl_nr;
1766 rc = cl_io_submit_rw(env, io, CRT_READ, queue);
1768 task_io_account_read(PAGE_SIZE * count);
1772 if (anchor != NULL && !cl_page_is_owned(page, io)) { /* have sent */
1773 rc = cl_sync_io_wait(env, anchor, 0);
1775 cl_page_assume(env, io, page);
1776 cl_page_list_del(env, &queue->c2_qout, page, true);
1778 if (!PageUptodate(cl_page_vmpage(page))) {
1779 /* Failed to read a mirror, discard this page so that
1780 * new page can be created with new mirror.
1782 * TODO: this is not needed after page reinit
1783 * route is implemented */
1784 cl_page_discard(env, io, page);
1787 cl_page_disown(env, io, page);
1790 /* TODO: discard all pages until page reinit route is implemented */
1791 cl_page_list_discard(env, io, &queue->c2_qin);
1793 /* Unlock unsent read pages in case of error. */
1794 cl_page_list_disown(env, &queue->c2_qin);
1796 cl_2queue_fini(env, queue);
1802 * Possible return value:
1803 * 0 no async readahead triggered and fast read could not be used.
1804 * 1 no async readahead, but fast read could be used.
1805 * 2 async readahead triggered and fast read could be used too.
1808 static int kickoff_async_readahead(struct file *file, unsigned long pages)
1810 struct ll_readahead_work *lrw;
1811 struct inode *inode = file_inode(file);
1812 struct ll_sb_info *sbi = ll_i2sbi(inode);
1813 struct ll_file_data *fd = file->private_data;
1814 struct ll_readahead_state *ras = &fd->fd_ras;
1815 struct ll_ra_info *ra = &sbi->ll_ra_info;
1816 unsigned long throttle;
1817 pgoff_t start_idx = ras_align(ras, ras->ras_next_readahead_idx);
1818 pgoff_t end_idx = start_idx + pages - 1;
1821 * In case we have a limited max_cached_mb, readahead
1822 * should be stopped if it have run out of all LRU slots.
1824 if (atomic_read(&ra->ra_cur_pages) >= sbi->ll_cache->ccc_lru_max) {
1825 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
1829 throttle = min(ra->ra_async_pages_per_file_threshold,
1830 ra->ra_max_pages_per_file);
1832 * If this is strided i/o or the window is smaller than the
1833 * throttle limit, we do not do async readahead. Otherwise,
1834 * we do async readahead, allowing the user thread to do fast i/o.
1836 if (stride_io_mode(ras) || !throttle ||
1837 ras->ras_window_pages < throttle ||
1838 atomic_read(&ra->ra_async_inflight) > ra->ra_async_max_active)
1841 if ((atomic_read(&ra->ra_cur_pages) + pages) > ra->ra_max_pages)
1844 if (ras->ras_async_last_readpage_idx == start_idx)
1847 /* ll_readahead_work_free() free it */
1850 atomic_inc(&sbi->ll_ra_info.ra_async_inflight);
1851 lrw->lrw_file = get_file(file);
1852 lrw->lrw_start_idx = start_idx;
1853 lrw->lrw_end_idx = end_idx;
1854 lrw->lrw_user_pid = current->pid;
1855 spin_lock(&ras->ras_lock);
1856 ras->ras_next_readahead_idx = end_idx + 1;
1857 ras->ras_async_last_readpage_idx = start_idx;
1858 spin_unlock(&ras->ras_lock);
1859 memcpy(lrw->lrw_jobid, ll_i2info(inode)->lli_jobid,
1860 sizeof(lrw->lrw_jobid));
1861 ll_readahead_work_add(inode, lrw);
1870 * Check if we can issue a readahead RPC, if that is
1871 * the case, we can't do fast IO because we will need
1872 * a cl_io to issue the RPC.
1874 static bool ll_use_fast_io(struct file *file,
1875 struct ll_readahead_state *ras, pgoff_t index)
1877 unsigned long fast_read_pages =
1878 max(RA_REMAIN_WINDOW_MIN, ras->ras_rpc_pages);
1880 loff_t stride_bytes = ras->ras_stride_bytes;
1884 if (stride_io_mode(ras) && stride_bytes) {
1885 skip_pages = (ras->ras_stride_length +
1886 ras->ras_stride_bytes - 1) / stride_bytes;
1887 skip_pages *= fast_read_pages;
1889 skip_pages = fast_read_pages;
1894 if (ras->ras_whole_file_read ||
1895 ras->ras_window_start_idx + ras->ras_window_pages <
1896 ras->ras_next_readahead_idx + skip_pages ||
1897 kickoff_async_readahead(file, fast_read_pages) > 0) {
1904 int ll_readpage(struct file *file, struct page *vmpage)
1906 struct inode *inode = file_inode(file);
1907 struct cl_object *clob = ll_i2info(inode)->lli_clob;
1908 struct ll_sb_info *sbi = ll_i2sbi(inode);
1909 const struct lu_env *env = NULL;
1910 struct cl_read_ahead ra = { 0 };
1911 struct ll_cl_context *lcc;
1912 struct cl_io *io = NULL;
1913 struct cl_page *page;
1920 if (CFS_FAIL_PRECHECK(OBD_FAIL_LLITE_READPAGE_PAUSE)) {
1921 unlock_page(vmpage);
1922 CFS_FAIL_TIMEOUT(OBD_FAIL_LLITE_READPAGE_PAUSE, cfs_fail_val);
1927 * The @vmpage got truncated.
1928 * This is a kernel bug introduced since kernel 5.12:
1929 * comment: cbd59c48ae2bcadc4a7599c29cf32fd3f9b78251
1930 * ("mm/filemap: use head pages in generic_file_buffered_read")
1932 * The page end offset calculation in filemap_get_read_batch() was off
1933 * by one. When a read is submitted with end offset 1048575, then it
1934 * calculates the end page for read of 256 where it should be 255. This
1935 * results in the readpage() for the page with index 256 is over stripe
1936 * boundary and may not covered by a DLM extent lock.
1938 * This happens in a corner race case: filemap_get_read_batch() adds
1939 * the page with index 256 for read which is not in the current read
1940 * I/O context, and this page is being invalidated and will be removed
1941 * from page cache due to the lock protected it being revoken. This
1942 * results in this page in the read path not covered by any DLM lock.
1944 * The solution is simple. Check whether the page was truncated in
1945 * ->readpage(). If so, just return AOP_TRUNCATED_PAGE to the upper
1946 * caller. Then the kernel will retry to batch pages, and it will not
1947 * add the truncated page into batches as it was removed from page
1948 * cache of the file.
1950 if (vmpage->mapping != inode->i_mapping) {
1951 unlock_page(vmpage);
1952 RETURN(AOP_TRUNCATED_PAGE);
1955 lcc = ll_cl_find(inode);
1961 if (io == NULL) { /* fast read */
1962 struct inode *inode = file_inode(file);
1963 struct ll_file_data *fd = file->private_data;
1964 struct ll_readahead_state *ras = &fd->fd_ras;
1965 struct lu_env *local_env = NULL;
1967 CDEBUG(D_VFSTRACE, "fast read pgno: %ld\n", vmpage->index);
1971 /* TODO: need to verify the layout version to make sure
1972 * the page is not invalid due to layout change. */
1973 page = cl_vmpage_page(vmpage, clob);
1975 unlock_page(vmpage);
1976 CDEBUG(D_READA, "fast read: failed to find page %ld\n",
1978 ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
1982 if (page->cp_defer_uptodate) {
1983 enum ras_update_flags flags = LL_RAS_HIT;
1985 if (lcc && lcc->lcc_type == LCC_MMAP)
1986 flags |= LL_RAS_MMAP;
1988 /* For fast read, it updates read ahead state only
1989 * if the page is hit in cache because non cache page
1990 * case will be handled by slow read later. */
1991 ras_update(sbi, inode, ras, cl_page_index(page), flags, io);
1992 /* avoid duplicate ras_update() call */
1993 page->cp_ra_updated = 1;
1995 if (ll_use_fast_io(file, ras, cl_page_index(page)))
2000 local_env = cl_env_percpu_get();
2004 /* export the page and skip io stack */
2006 page->cp_ra_used = 1;
2007 SetPageUptodate(vmpage);
2009 ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
2012 /* release page refcount before unlocking the page to ensure
2013 * the object won't be destroyed in the calling path of
2014 * cl_page_put(). Please see comment in ll_releasepage(). */
2015 cl_page_put(env, page);
2016 unlock_page(vmpage);
2018 cl_env_percpu_put(local_env);
2023 if (lcc && lcc->lcc_type != LCC_MMAP) {
2025 * This handles a kernel bug introduced in kernel 5.12:
2026 * comment: cbd59c48ae2bcadc4a7599c29cf32fd3f9b78251
2027 * ("mm/filemap: use head pages in generic_file_buffered_read")
2029 * See above in this function for a full description of the
2030 * bug. Briefly, the kernel will try to read 1 more page than
2031 * was actually requested *if that page is already in cache*.
2033 * Because this page is beyond the boundary of the requested
2034 * read, Lustre does not lock it as part of the read. This
2035 * means we must check if there is a valid dlmlock on this
2036 * this page and reference it before we attempt to read in the
2037 * page. If there is not a valid dlmlock, then we are racing
2038 * with dlmlock cancellation and the page is being removed
2041 * That means we should return AOP_TRUNCATED_PAGE, which will
2042 * cause the kernel to retry the read, which should allow the
2043 * page to be removed from cache as the lock is cancelled.
2045 * This should never occur except in kernels with the bug
2048 if (vmpage->index >= lcc->lcc_end_index) {
2050 "pgno:%ld, beyond read end_index:%ld\n",
2051 vmpage->index, lcc->lcc_end_index);
2053 result = cl_io_read_ahead(env, io, vmpage->index, &ra);
2054 if (result < 0 || vmpage->index > ra.cra_end_idx) {
2055 cl_read_ahead_release(env, &ra);
2056 unlock_page(vmpage);
2057 RETURN(AOP_TRUNCATED_PAGE);
2062 vio = vvp_env_io(env);
2064 * Direct read can fall back to buffered read, but DIO is done
2065 * with lockless i/o, and buffered requires LDLM locking, so in
2066 * this case we must restart without lockless.
2068 flags = iocb_ki_flags_get(file, vio->vui_iocb);
2069 if (iocb_ki_flags_check(flags, DIRECT) &&
2070 lcc && lcc->lcc_type == LCC_RW &&
2072 unlock_page(vmpage);
2073 io->ci_dio_lock = 1;
2074 io->ci_need_restart = 1;
2075 GOTO(out, result = -ENOLCK);
2078 LASSERT(io->ci_state == CIS_IO_GOING);
2079 page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
2080 if (!IS_ERR(page)) {
2081 LASSERT(page->cp_type == CPT_CACHEABLE);
2082 if (likely(!PageUptodate(vmpage))) {
2083 cl_page_assume(env, io, page);
2085 result = ll_io_read_page(env, io, page, file);
2087 /* Page from a non-object file. */
2088 unlock_page(vmpage);
2091 cl_page_put(env, page);
2093 unlock_page(vmpage);
2094 result = PTR_ERR(page);
2098 if (ra.cra_release != NULL)
2099 cl_read_ahead_release(env, &ra);
2101 /* this delay gives time for the actual read of the page to finish and
2102 * unlock the page in vvp_page_completion_read before we return to our
2103 * caller and the caller tries to use the page, allowing us to test
2104 * races with the page being unlocked after readpage() but before it's
2105 * used by the caller
2107 CFS_FAIL_TIMEOUT(OBD_FAIL_LLITE_READPAGE_PAUSE2, cfs_fail_val);
2112 #ifdef HAVE_AOPS_READ_FOLIO
2113 int ll_read_folio(struct file *file, struct folio *folio)
2115 return ll_readpage(file, folio_page(folio, 0));