From mboxrd@z Thu Jan 1 00:00:00 1970 From: colyli@suse.de Subject: [PATCH V3 1/2] RAID1: a new I/O barrier implementation to remove resync window Date: Thu, 16 Feb 2017 00:35:22 +0800 Message-ID: <1487176523-109075-1-git-send-email-colyli@suse.de> Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Coly Li , Shaohua Li , Neil Brown , Johannes Thumshirn , Guoqing Jiang List-Id: linux-raid.ids 'Commit 79ef3a8aa1cb ("raid1: Rewrite the implementation of iobarrier.")' introduces a sliding resync window for raid1 I/O barrier, this idea limits I/O barriers to happen only inside a slidingresync window, for regular I/Os out of this resync window they don't need to wait for barrier any more. On large raid1 device, it helps a lot to improve parallel writing I/O throughput when there are background resync I/Os performing at same time. The idea of sliding resync widow is awesome, but code complexity is a challenge. Sliding resync window requires several veriables to work collectively, this is complexed and very hard to make it work correctly. Just grep "Fixes: 79ef3a8aa1" in kernel git log, there are 8 more patches to fix the original resync window patch. This is not the end, any further related modification may easily introduce more regreassion. Therefore I decide to implement a much simpler raid1 I/O barrier, by removing resync window code, I believe life will be much easier. The brief idea of the simpler barrier is, - Do not maintain a logbal unique resync window - Use multiple hash buckets to reduce I/O barrier conflictions, regular I/O only has to wait for a resync I/O when both them have same barrier bucket index, vice versa. - I/O barrier can be recuded to an acceptable number if there are enought barrier buckets Here I explain how the barrier buckets are designed, - BARRIER_UNIT_SECTOR_SIZE The whole LBA address space of a raid1 device is divided into multiple barrier units, by the size of BARRIER_UNIT_SECTOR_SIZE. Bio request won't go across border of barrier unit size, that means maximum bio size is BARRIER_UNIT_SECTOR_SIZE<<9 (64MB) in bytes. For random I/O 64MB is large enough for both read and write requests, for sequential I/O considering underlying block layer may merge them into larger requests, 64MB is still good enough. Neil also points out that for resync operation, "we want the resync to move from region to region fairly quickly so that the slowness caused by having to synchronize with the resync is averaged out over a fairly small time frame". For full speed resync, 64MB should take less then 1 second. When resync is competing with other I/O, it could take up a few minutes. Therefore 64MB size is fairly good range for resync. - BARRIER_BUCKETS_NR There are BARRIER_BUCKETS_NR buckets in total, which is defined by, #define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - 2) #define BARRIER_BUCKETS_NR (1<> BARRIER_UNIT_SECTOR_BITS, BARRIER_BUCKETS_NR_BITS); } Here sector_nr is the start sector number of a bio. - Single bio won't go across boundary of a I/O barrier unit If a request goes across boundary of barrier unit, it will be split. A bio may be split in raid1_make_request() or raid1_sync_request(), if sectors returned by align_to_barrier_unit_end() is small than original bio size. Comparing to single sliding resync window, - Currently resync I/O grows linearly, therefore regular and resync I/O will have confliction within a single barrier units. So the I/O behavior is similar to single sliding resync window. - But a barrier unit bucket is shared by all barrier units with identical barrier uinit index, the probability of confliction might be higher than single sliding resync window, in condition that writing I/Os always hit barrier units which have identical barrier bucket indexs with the resync I/Os. This is a very rare condition in real I/O work loads, I cannot imagine how it could happen in practice. - Therefore we can achieve a good enough low confliction rate with much simpler barrier algorithm and implementation. There are two changes should be noticed, - In raid1d(), I change the code to decrease conf->nr_pending[idx] into single loop, it looks like this, spin_lock_irqsave(&conf->device_lock, flags); conf->nr_queued[idx]--; spin_unlock_irqrestore(&conf->device_lock, flags); This change generates more spin lock operations, but in next patch of this patch set, it will be replaced by a single line code, atomic_dec(&conf->nr_queueud[idx]); So we don't need to worry about spin lock cost here. - Mainline raid1 code split original raid1_make_request() into raid1_read_request() and raid1_write_request(). If the original bio goes across an I/O barrier unit size, this bio will be split before calling raid1_read_request() or raid1_write_request(), this change the code logic more simple and clear. - In this patch wait_barrier() is moved from raid1_make_request() to raid1_write_request(). In raid_read_request(), original wait_barrier() is replaced by raid1_read_request(). The differnece is wait_read_barrier() only waits if array is frozen, using different barrier function in different code path makes the code more clean and easy to read. Changelog V3: - Rebase the patch against latest upstream kernel code. - Many fixes by review comments from Neil, - Back to use pointers to replace arraries in struct r1conf - Remove total_barriers from struct r1conf - Add more patch comments to explain how/why the values of BARRIER_UNIT_SECTOR_SIZE and BARRIER_BUCKETS_NR are decided. - Use get_unqueued_pending() to replace get_all_pendings() and get_all_queued() - Increase bucket number from 512 to 1024 - Change code comments format by review from Shaohua. V2: - Use bio_split() to split the orignal bio if it goes across barrier unit bounday, to make the code more simple, by suggestion from Shaohua and Neil. - Use hash_long() to replace original linear hash, to avoid a possible confilict between resync I/O and sequential write I/O, by suggestion from Shaohua. - Add conf->total_barriers to record barrier depth, which is used to control number of parallel sync I/O barriers, by suggestion from Shaohua. - In V1 patch the bellowed barrier buckets related members in r1conf are allocated in memory page. To make the code more simple, V2 patch moves the memory space into struct r1conf, like this, - int nr_pending; - int nr_waiting; - int nr_queued; - int barrier; + int nr_pending[BARRIER_BUCKETS_NR]; + int nr_waiting[BARRIER_BUCKETS_NR]; + int nr_queued[BARRIER_BUCKETS_NR]; + int barrier[BARRIER_BUCKETS_NR]; This change is by the suggestion from Shaohua. - Remove some inrelavent code comments, by suggestion from Guoqing. - Add a missing wait_barrier() before jumping to retry_write, in raid1_make_write_request(). V1: - Original RFC patch for comments Signed-off-by: Coly Li Cc: Shaohua Li Cc: Neil Brown Cc: Johannes Thumshirn Cc: Guoqing Jiang --- drivers/md/raid1.c | 447 ++++++++++++++++++++++++++++++----------------------- drivers/md/raid1.h | 42 +++-- 2 files changed, 275 insertions(+), 214 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 7b0f647..4234494 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -71,9 +71,8 @@ */ static int max_queued_requests = 1024; -static void allow_barrier(struct r1conf *conf, sector_t start_next_window, - sector_t bi_sector); -static void lower_barrier(struct r1conf *conf); +static void allow_barrier(struct r1conf *conf, sector_t sector_nr); +static void lower_barrier(struct r1conf *conf, sector_t sector_nr); #define raid1_log(md, fmt, args...) \ do { if ((md)->queue) blk_add_trace_msg((md)->queue, "raid1 " fmt, ##args); } while (0) @@ -100,7 +99,6 @@ static void r1bio_pool_free(void *r1_bio, void *data) #define RESYNC_WINDOW_SECTORS (RESYNC_WINDOW >> 9) #define CLUSTER_RESYNC_WINDOW (16 * RESYNC_WINDOW) #define CLUSTER_RESYNC_WINDOW_SECTORS (CLUSTER_RESYNC_WINDOW >> 9) -#define NEXT_NORMALIO_DISTANCE (3 * RESYNC_WINDOW_SECTORS) static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data) { @@ -215,7 +213,7 @@ static void put_buf(struct r1bio *r1_bio) mempool_free(r1_bio, conf->r1buf_pool); - lower_barrier(conf); + lower_barrier(conf, r1_bio->sector); } static void reschedule_retry(struct r1bio *r1_bio) @@ -223,10 +221,12 @@ static void reschedule_retry(struct r1bio *r1_bio) unsigned long flags; struct mddev *mddev = r1_bio->mddev; struct r1conf *conf = mddev->private; + int idx; + idx = sector_to_idx(r1_bio->sector); spin_lock_irqsave(&conf->device_lock, flags); list_add(&r1_bio->retry_list, &conf->retry_list); - conf->nr_queued ++; + conf->nr_queued[idx]++; spin_unlock_irqrestore(&conf->device_lock, flags); wake_up(&conf->wait_barrier); @@ -243,7 +243,6 @@ static void call_bio_endio(struct r1bio *r1_bio) struct bio *bio = r1_bio->master_bio; int done; struct r1conf *conf = r1_bio->mddev->private; - sector_t start_next_window = r1_bio->start_next_window; sector_t bi_sector = bio->bi_iter.bi_sector; if (bio->bi_phys_segments) { @@ -269,7 +268,7 @@ static void call_bio_endio(struct r1bio *r1_bio) * Wake up any possible resync thread that waits for the device * to go idle. */ - allow_barrier(conf, start_next_window, bi_sector); + allow_barrier(conf, bi_sector); } } @@ -517,6 +516,25 @@ static void raid1_end_write_request(struct bio *bio) bio_put(to_put); } +static sector_t align_to_barrier_unit_end(sector_t start_sector, + sector_t sectors) +{ + sector_t len; + + WARN_ON(sectors == 0); + /* + * len is the number of sectors from start_sector to end of the + * barrier unit which start_sector belongs to. + */ + len = round_up(start_sector + 1, BARRIER_UNIT_SECTOR_SIZE) - + start_sector; + + if (len > sectors) + len = sectors; + + return len; +} + /* * This routine returns the disk from which the requested read should * be done. There is a per-array 'next expected sequential IO' sector @@ -813,168 +831,168 @@ static void flush_pending_writes(struct r1conf *conf) */ static void raise_barrier(struct r1conf *conf, sector_t sector_nr) { + int idx = sector_to_idx(sector_nr); + spin_lock_irq(&conf->resync_lock); /* Wait until no block IO is waiting */ - wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting, + wait_event_lock_irq(conf->wait_barrier, !conf->nr_waiting[idx], conf->resync_lock); /* block any new IO from starting */ - conf->barrier++; - conf->next_resync = sector_nr; + conf->barrier[idx]++; /* For these conditions we must wait: * A: while the array is in frozen state - * B: while barrier >= RESYNC_DEPTH, meaning resync reach - * the max count which allowed. - * C: next_resync + RESYNC_SECTORS > start_next_window, meaning - * next resync will reach to the window which normal bios are - * handling. - * D: while there are any active requests in the current window. + * B: while conf->nr_pending[idx] is not 0, meaning regular I/O + * existing in corresponding I/O barrier bucket. + * C: while conf->barrier[idx] >= RESYNC_DEPTH, meaning reaches + * max resync count which allowed on current I/O barrier bucket. */ wait_event_lock_irq(conf->wait_barrier, !conf->array_frozen && - conf->barrier < RESYNC_DEPTH && - conf->current_window_requests == 0 && - (conf->start_next_window >= - conf->next_resync + RESYNC_SECTORS), + !conf->nr_pending[idx] && + conf->barrier[idx] < RESYNC_DEPTH, conf->resync_lock); - conf->nr_pending++; + conf->nr_pending[idx]++; spin_unlock_irq(&conf->resync_lock); } -static void lower_barrier(struct r1conf *conf) +static void lower_barrier(struct r1conf *conf, sector_t sector_nr) { unsigned long flags; - BUG_ON(conf->barrier <= 0); + int idx = sector_to_idx(sector_nr); + + BUG_ON(conf->barrier[idx] <= 0); + spin_lock_irqsave(&conf->resync_lock, flags); - conf->barrier--; - conf->nr_pending--; + conf->barrier[idx]--; + conf->nr_pending[idx]--; spin_unlock_irqrestore(&conf->resync_lock, flags); wake_up(&conf->wait_barrier); } -static bool need_to_wait_for_sync(struct r1conf *conf, struct bio *bio) +static void _wait_barrier(struct r1conf *conf, int idx) { - bool wait = false; - - if (conf->array_frozen || !bio) - wait = true; - else if (conf->barrier && bio_data_dir(bio) == WRITE) { - if ((conf->mddev->curr_resync_completed - >= bio_end_sector(bio)) || - (conf->start_next_window + NEXT_NORMALIO_DISTANCE - <= bio->bi_iter.bi_sector)) - wait = false; - else - wait = true; + spin_lock_irq(&conf->resync_lock); + if (conf->array_frozen || conf->barrier[idx]) { + conf->nr_waiting[idx]++; + /* Wait for the barrier to drop. */ + wait_event_lock_irq( + conf->wait_barrier, + !conf->array_frozen && !conf->barrier[idx], + conf->resync_lock); + conf->nr_waiting[idx]--; } - return wait; + conf->nr_pending[idx]++; + spin_unlock_irq(&conf->resync_lock); } -static sector_t wait_barrier(struct r1conf *conf, struct bio *bio) +static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) { - sector_t sector = 0; + int idx = sector_to_idx(sector_nr); spin_lock_irq(&conf->resync_lock); - if (need_to_wait_for_sync(conf, bio)) { - conf->nr_waiting++; - /* Wait for the barrier to drop. - * However if there are already pending - * requests (preventing the barrier from - * rising completely), and the - * per-process bio queue isn't empty, - * then don't wait, as we need to empty - * that queue to allow conf->start_next_window - * to increase. - */ - raid1_log(conf->mddev, "wait barrier"); - wait_event_lock_irq(conf->wait_barrier, - !conf->array_frozen && - (!conf->barrier || - ((conf->start_next_window < - conf->next_resync + RESYNC_SECTORS) && - current->bio_list && - !bio_list_empty(current->bio_list))), - conf->resync_lock); - conf->nr_waiting--; - } - - if (bio && bio_data_dir(bio) == WRITE) { - if (bio->bi_iter.bi_sector >= conf->next_resync) { - if (conf->start_next_window == MaxSector) - conf->start_next_window = - conf->next_resync + - NEXT_NORMALIO_DISTANCE; - - if ((conf->start_next_window + NEXT_NORMALIO_DISTANCE) - <= bio->bi_iter.bi_sector) - conf->next_window_requests++; - else - conf->current_window_requests++; - sector = conf->start_next_window; - } + if (conf->array_frozen) { + conf->nr_waiting[idx]++; + /* Wait for array to unfreeze */ + wait_event_lock_irq( + conf->wait_barrier, + !conf->array_frozen, + conf->resync_lock); + conf->nr_waiting[idx]--; } - conf->nr_pending++; + conf->nr_pending[idx]++; spin_unlock_irq(&conf->resync_lock); - return sector; } -static void allow_barrier(struct r1conf *conf, sector_t start_next_window, - sector_t bi_sector) +static void wait_barrier(struct r1conf *conf, sector_t sector_nr) +{ + int idx = sector_to_idx(sector_nr); + + _wait_barrier(conf, idx); +} + +static void wait_all_barriers(struct r1conf *conf) +{ + int idx; + + for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) + _wait_barrier(conf, idx); +} + +static void _allow_barrier(struct r1conf *conf, int idx) { unsigned long flags; spin_lock_irqsave(&conf->resync_lock, flags); - conf->nr_pending--; - if (start_next_window) { - if (start_next_window == conf->start_next_window) { - if (conf->start_next_window + NEXT_NORMALIO_DISTANCE - <= bi_sector) - conf->next_window_requests--; - else - conf->current_window_requests--; - } else - conf->current_window_requests--; - - if (!conf->current_window_requests) { - if (conf->next_window_requests) { - conf->current_window_requests = - conf->next_window_requests; - conf->next_window_requests = 0; - conf->start_next_window += - NEXT_NORMALIO_DISTANCE; - } else - conf->start_next_window = MaxSector; - } - } + conf->nr_pending[idx]--; spin_unlock_irqrestore(&conf->resync_lock, flags); wake_up(&conf->wait_barrier); } +static void allow_barrier(struct r1conf *conf, sector_t sector_nr) +{ + int idx = sector_to_idx(sector_nr); + + _allow_barrier(conf, idx); +} + +static void allow_all_barriers(struct r1conf *conf) +{ + int idx; + + for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) + _allow_barrier(conf, idx); +} + +/* conf->resync_lock should be held */ +static int get_unqueued_pending(struct r1conf *conf) +{ + int idx, ret; + + for (ret = 0, idx = 0; idx < BARRIER_BUCKETS_NR; idx++) + ret += conf->nr_pending[idx] - conf->nr_queued[idx]; + + return ret; +} + static void freeze_array(struct r1conf *conf, int extra) { - /* stop syncio and normal IO and wait for everything to + /* Stop sync I/O and normal I/O and wait for everything to * go quite. - * We wait until nr_pending match nr_queued+extra - * This is called in the context of one normal IO request - * that has failed. Thus any sync request that might be pending - * will be blocked by nr_pending, and we need to wait for - * pending IO requests to complete or be queued for re-try. - * Thus the number queued (nr_queued) plus this request (extra) - * must match the number of pending IOs (nr_pending) before - * we continue. + * This is called in two situations: + * 1) management command handlers (reshape, remove disk, quiesce). + * 2) one normal I/O request failed. + + * After array_frozen is set to 1, new sync IO will be blocked at + * raise_barrier(), and new normal I/O will blocked at _wait_barrier() + * or wait_read_barrier(). The flying I/Os will either complete or be + * queued. When everything goes quite, there are only queued I/Os left. + + * Every flying I/O contributes to a conf->nr_pending[idx], idx is the + * barrier bucket index which this I/O request hits. When all sync and + * normal I/O are queued, sum of all conf->nr_pending[] will match sum + * of all conf->nr_queued[]. But normal I/O failure is an exception, + * in handle_read_error(), we may call freeze_array() before trying to + * fix the read error. In this case, the error read I/O is not queued, + * so get_unqueued_pending() == 1. + * + * Therefore before this function returns, we need to wait until + * get_unqueued_pendings(conf) gets equal to extra. For + * normal I/O context, extra is 1, in rested situations extra is 0. */ spin_lock_irq(&conf->resync_lock); conf->array_frozen = 1; raid1_log(conf->mddev, "wait freeze"); - wait_event_lock_irq_cmd(conf->wait_barrier, - conf->nr_pending == conf->nr_queued+extra, - conf->resync_lock, - flush_pending_writes(conf)); + wait_event_lock_irq_cmd( + conf->wait_barrier, + get_unqueued_pending(conf) == extra, + conf->resync_lock, + flush_pending_writes(conf)); spin_unlock_irq(&conf->resync_lock); } static void unfreeze_array(struct r1conf *conf) @@ -1070,11 +1088,11 @@ static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule) kfree(plug); } -static void raid1_read_request(struct mddev *mddev, struct bio *bio, - struct r1bio *r1_bio) +static void raid1_read_request(struct mddev *mddev, struct bio *bio) { struct r1conf *conf = mddev->private; struct raid1_info *mirror; + struct r1bio *r1_bio; struct bio *read_bio; struct bitmap *bitmap = mddev->bitmap; const int op = bio_op(bio); @@ -1083,7 +1101,34 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, int max_sectors; int rdisk; - wait_barrier(conf, bio); + /* + * Still need barrier for READ in case that whole + * array is frozen. + */ + wait_read_barrier(conf, bio->bi_iter.bi_sector); + bitmap = mddev->bitmap; + + /* + * make_request() can abort the operation when read-ahead is being + * used and no empty request is available. + * + */ + r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO); + r1_bio->master_bio = bio; + r1_bio->sectors = bio_sectors(bio); + r1_bio->state = 0; + r1_bio->mddev = mddev; + r1_bio->sector = bio->bi_iter.bi_sector; + /* + * We might need to issue multiple reads to different + * devices if there are bad blocks around, so we keep + * track of the number of reads in bio->bi_phys_segments. + * If this is 0, there is only one r1_bio and no locking + * will be needed when requests complete. If it is + * non-zero, then it is the number of not-completed requests. + */ + bio->bi_phys_segments = 0; + bio_clear_flag(bio, BIO_SEG_VALID); read_again: rdisk = read_balance(conf, r1_bio, &max_sectors); @@ -1106,7 +1151,6 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, atomic_read(&bitmap->behind_writes) == 0); } r1_bio->read_disk = rdisk; - r1_bio->start_next_window = 0; read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev); bio_trim(read_bio, r1_bio->sector - bio->bi_iter.bi_sector, @@ -1163,10 +1207,10 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, generic_make_request(read_bio); } -static void raid1_write_request(struct mddev *mddev, struct bio *bio, - struct r1bio *r1_bio) +static void raid1_write_request(struct mddev *mddev, struct bio *bio) { struct r1conf *conf = mddev->private; + struct r1bio *r1_bio; int i, disks; struct bitmap *bitmap = mddev->bitmap; unsigned long flags; @@ -1180,7 +1224,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, int first_clone; int sectors_handled; int max_sectors; - sector_t start_next_window; /* * Register the new request and wait if the reconstruction @@ -1216,7 +1259,29 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, } finish_wait(&conf->wait_barrier, &w); } - start_next_window = wait_barrier(conf, bio); + wait_barrier(conf, bio->bi_iter.bi_sector); + + /* + * make_request() can abort the operation when read-ahead is being + * used and no empty request is available. + * + */ + r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO); + r1_bio->master_bio = bio; + r1_bio->sectors = bio_sectors(bio); + r1_bio->state = 0; + r1_bio->mddev = mddev; + r1_bio->sector = bio->bi_iter.bi_sector; + /* + * We might need to issue multiple writes to different + * devices if there are bad blocks around, so we keep + * track of the number of writes in bio->bi_phys_segments. + * If this is 0, there is only one r1_bio and no locking + * will be needed when requests complete. If it is + * non-zero, then it is the number of not-completed requests. + */ + bio->bi_phys_segments = 0; + bio_clear_flag(bio, BIO_SEG_VALID); if (conf->pending_count >= max_queued_requests) { md_wakeup_thread(mddev->thread); @@ -1237,7 +1302,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, disks = conf->raid_disks * 2; retry_write: - r1_bio->start_next_window = start_next_window; blocked_rdev = NULL; rcu_read_lock(); max_sectors = r1_bio->sectors; @@ -1304,25 +1368,15 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, if (unlikely(blocked_rdev)) { /* Wait for this device to become unblocked */ int j; - sector_t old = start_next_window; for (j = 0; j < i; j++) if (r1_bio->bios[j]) rdev_dec_pending(conf->mirrors[j].rdev, mddev); r1_bio->state = 0; - allow_barrier(conf, start_next_window, bio->bi_iter.bi_sector); + allow_barrier(conf, bio->bi_iter.bi_sector); raid1_log(mddev, "wait rdev %d blocked", blocked_rdev->raid_disk); md_wait_for_blocked_rdev(blocked_rdev, mddev); - start_next_window = wait_barrier(conf, bio); - /* - * We must make sure the multi r1bios of bio have - * the same value of bi_phys_segments - */ - if (bio->bi_phys_segments && old && - old != start_next_window) - /* Wait for the former r1bio(s) to complete */ - wait_event(conf->wait_barrier, - bio->bi_phys_segments == 1); + wait_barrier(conf, bio->bi_iter.bi_sector); goto retry_write; } @@ -1447,36 +1501,26 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, static void raid1_make_request(struct mddev *mddev, struct bio *bio) { - struct r1conf *conf = mddev->private; - struct r1bio *r1_bio; + void (*make_request_fn)(struct mddev *mddev, struct bio *bio); + struct bio *split; + sector_t sectors; - /* - * make_request() can abort the operation when read-ahead is being - * used and no empty request is available. - * - */ - r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO); + make_request_fn = (bio_data_dir(bio) == READ) ? + raid1_read_request : raid1_write_request; - r1_bio->master_bio = bio; - r1_bio->sectors = bio_sectors(bio); - r1_bio->state = 0; - r1_bio->mddev = mddev; - r1_bio->sector = bio->bi_iter.bi_sector; - - /* - * We might need to issue multiple reads to different devices if there - * are bad blocks around, so we keep track of the number of reads in - * bio->bi_phys_segments. If this is 0, there is only one r1_bio and - * no locking will be needed when requests complete. If it is - * non-zero, then it is the number of not-completed requests. - */ - bio->bi_phys_segments = 0; - bio_clear_flag(bio, BIO_SEG_VALID); + /* if bio exceeds barrier unit boundary, split it */ + do { + sectors = align_to_barrier_unit_end( + bio->bi_iter.bi_sector, bio_sectors(bio)); + if (sectors < bio_sectors(bio)) { + split = bio_split(bio, sectors, GFP_NOIO, fs_bio_set); + bio_chain(split, bio); + } else { + split = bio; + } - if (bio_data_dir(bio) == READ) - raid1_read_request(mddev, bio, r1_bio); - else - raid1_write_request(mddev, bio, r1_bio); + make_request_fn(mddev, split); + } while (split != bio); } static void raid1_status(struct seq_file *seq, struct mddev *mddev) @@ -1567,19 +1611,11 @@ static void print_conf(struct r1conf *conf) static void close_sync(struct r1conf *conf) { - wait_barrier(conf, NULL); - allow_barrier(conf, 0, 0); + wait_all_barriers(conf); + allow_all_barriers(conf); mempool_destroy(conf->r1buf_pool); conf->r1buf_pool = NULL; - - spin_lock_irq(&conf->resync_lock); - conf->next_resync = MaxSector - 2 * NEXT_NORMALIO_DISTANCE; - conf->start_next_window = MaxSector; - conf->current_window_requests += - conf->next_window_requests; - conf->next_window_requests = 0; - spin_unlock_irq(&conf->resync_lock); } static int raid1_spare_active(struct mddev *mddev) @@ -2326,8 +2362,9 @@ static void handle_sync_write_finished(struct r1conf *conf, struct r1bio *r1_bio static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio) { - int m; + int m, idx; bool fail = false; + for (m = 0; m < conf->raid_disks * 2 ; m++) if (r1_bio->bios[m] == IO_MADE_GOOD) { struct md_rdev *rdev = conf->mirrors[m].rdev; @@ -2353,7 +2390,8 @@ static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio) if (fail) { spin_lock_irq(&conf->device_lock); list_add(&r1_bio->retry_list, &conf->bio_end_io_list); - conf->nr_queued++; + idx = sector_to_idx(r1_bio->sector); + conf->nr_queued[idx]++; spin_unlock_irq(&conf->device_lock); md_wakeup_thread(conf->mddev->thread); } else { @@ -2475,6 +2513,7 @@ static void raid1d(struct md_thread *thread) struct r1conf *conf = mddev->private; struct list_head *head = &conf->retry_list; struct blk_plug plug; + int idx; md_check_recovery(mddev); @@ -2482,17 +2521,17 @@ static void raid1d(struct md_thread *thread) !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { LIST_HEAD(tmp); spin_lock_irqsave(&conf->device_lock, flags); - if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { - while (!list_empty(&conf->bio_end_io_list)) { - list_move(conf->bio_end_io_list.prev, &tmp); - conf->nr_queued--; - } - } + if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) + list_splice_init(&conf->bio_end_io_list, &tmp); spin_unlock_irqrestore(&conf->device_lock, flags); while (!list_empty(&tmp)) { r1_bio = list_first_entry(&tmp, struct r1bio, retry_list); list_del(&r1_bio->retry_list); + idx = sector_to_idx(r1_bio->sector); + spin_lock_irqsave(&conf->device_lock, flags); + conf->nr_queued[idx]--; + spin_unlock_irqrestore(&conf->device_lock, flags); if (mddev->degraded) set_bit(R1BIO_Degraded, &r1_bio->state); if (test_bit(R1BIO_WriteError, &r1_bio->state)) @@ -2513,7 +2552,8 @@ static void raid1d(struct md_thread *thread) } r1_bio = list_entry(head->prev, struct r1bio, retry_list); list_del(head->prev); - conf->nr_queued--; + idx = sector_to_idx(r1_bio->sector); + conf->nr_queued[idx]--; spin_unlock_irqrestore(&conf->device_lock, flags); mddev = r1_bio->mddev; @@ -2552,7 +2592,6 @@ static int init_resync(struct r1conf *conf) conf->poolinfo); if (!conf->r1buf_pool) return -ENOMEM; - conf->next_resync = 0; return 0; } @@ -2581,6 +2620,7 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr, int still_degraded = 0; int good_sectors = RESYNC_SECTORS; int min_bad = 0; /* number of sectors that are bad in all devices */ + int idx = sector_to_idx(sector_nr); if (!conf->r1buf_pool) if (init_resync(conf)) @@ -2630,7 +2670,7 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr, * If there is non-resync activity waiting for a turn, then let it * though before starting on this new sync request. */ - if (conf->nr_waiting) + if (conf->nr_waiting[idx]) schedule_timeout_uninterruptible(1); /* we are incrementing sector_nr below. To be safe, we check against @@ -2657,6 +2697,8 @@ static sector_t raid1_sync_request(struct mddev *mddev, sector_t sector_nr, r1_bio->sector = sector_nr; r1_bio->state = 0; set_bit(R1BIO_IsSync, &r1_bio->state); + /* make sure good_sectors won't go across barrier unit boundary */ + good_sectors = align_to_barrier_unit_end(sector_nr, good_sectors); for (i = 0; i < conf->raid_disks * 2; i++) { struct md_rdev *rdev; @@ -2887,6 +2929,26 @@ static struct r1conf *setup_conf(struct mddev *mddev) if (!conf) goto abort; + conf->nr_pending = kcalloc(BARRIER_BUCKETS_NR, + sizeof(int), GFP_KERNEL); + if (!conf->nr_pending) + goto abort; + + conf->nr_waiting = kcalloc(BARRIER_BUCKETS_NR, + sizeof(int), GFP_KERNEL); + if (!conf->nr_waiting) + goto abort; + + conf->nr_queued = kcalloc(BARRIER_BUCKETS_NR, + sizeof(int), GFP_KERNEL); + if (!conf->nr_queued) + goto abort; + + conf->barrier = kcalloc(BARRIER_BUCKETS_NR, + sizeof(int), GFP_KERNEL); + if (!conf->barrier) + goto abort; + conf->mirrors = kzalloc(sizeof(struct raid1_info) * mddev->raid_disks * 2, GFP_KERNEL); @@ -2942,9 +3004,6 @@ static struct r1conf *setup_conf(struct mddev *mddev) conf->pending_count = 0; conf->recovery_disabled = mddev->recovery_disabled - 1; - conf->start_next_window = MaxSector; - conf->current_window_requests = conf->next_window_requests = 0; - err = -EIO; for (i = 0; i < conf->raid_disks * 2; i++) { @@ -2987,6 +3046,10 @@ static struct r1conf *setup_conf(struct mddev *mddev) kfree(conf->mirrors); safe_put_page(conf->tmppage); kfree(conf->poolinfo); + kfree(conf->nr_pending); + kfree(conf->nr_waiting); + kfree(conf->nr_queued); + kfree(conf->barrier); kfree(conf); } return ERR_PTR(err); @@ -3088,6 +3151,10 @@ static void raid1_free(struct mddev *mddev, void *priv) kfree(conf->mirrors); safe_put_page(conf->tmppage); kfree(conf->poolinfo); + kfree(conf->nr_pending); + kfree(conf->nr_waiting); + kfree(conf->nr_queued); + kfree(conf->barrier); kfree(conf); } diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h index c52ef42..d3faf30 100644 --- a/drivers/md/raid1.h +++ b/drivers/md/raid1.h @@ -1,6 +1,14 @@ #ifndef _RAID1_H #define _RAID1_H +/* each barrier unit size is 64MB fow now + * note: it must be larger than RESYNC_DEPTH + */ +#define BARRIER_UNIT_SECTOR_BITS 17 +#define BARRIER_UNIT_SECTOR_SIZE (1<<17) +#define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - 2) +#define BARRIER_BUCKETS_NR (1<> BARRIER_UNIT_SECTOR_BITS, + BARRIER_BUCKETS_NR_BITS); +} #endif -- 2.6.6