[md PATCH 02/14] md/raid5: simplfy delaying of writes while metadata is updated.
From: NeilBrown <hidden>
Date: 2017-02-16 04:39:01
Subsystem:
software raid (multiple disks) support, the rest · Maintainers:
Song Liu, Yu Kuai, Linus Torvalds
If a device fails during a write, we must ensure the failure is
recorded in the metadata before the completion of the write is
acknowleged.
Commit c3cce6cda162 ("md/raid5: ensure device failure recorded before
write request returns.") added code for this, but it was
unnecessarily complicated. We already had similar functionality for
handling updates to the bad-block-list, thanks to Commit de393cdea66c
("md: make it easier to wait for bad blocks to be acknowledged.")
So revert most of the former commit, and instead avoid collecting
completed writes if MD_CHANGE_PENDING is set. raid5d() will then flush
the metadata and retry the stripe_head.
We check MD_CHANGE_PENDING *after* analyse_stripe() as it could be set
asynchronously. After analyse_stripe(), we have collected stable data
about the state of devices, which will be used to make decisions.
Signed-off-by: NeilBrown <redacted>
---
drivers/md/raid5.c | 27 ++++-----------------------
drivers/md/raid5.h | 3 ---
2 files changed, 4 insertions(+), 26 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 760b726943c9..154593e0afbe 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c@@ -4492,7 +4492,8 @@ static void handle_stripe(struct stripe_head *sh) if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) goto finish; - if (s.handle_bad_blocks) { + if (s.handle_bad_blocks || + test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) { set_bit(STRIPE_HANDLE, &sh->state); goto finish; }
@@ -4822,15 +4823,8 @@ static void handle_stripe(struct stripe_head *sh) md_wakeup_thread(conf->mddev->thread); } - if (!bio_list_empty(&s.return_bi)) { - if (test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) { - spin_lock_irq(&conf->device_lock); - bio_list_merge(&conf->return_bi, &s.return_bi); - spin_unlock_irq(&conf->device_lock); - md_wakeup_thread(conf->mddev->thread); - } else - return_io(&s.return_bi); - } + if (!bio_list_empty(&s.return_bi)) + return_io(&s.return_bi); clear_bit_unlock(STRIPE_ACTIVE, &sh->state); }
@@ -6055,18 +6049,6 @@ static void raid5d(struct md_thread *thread) md_check_recovery(mddev); - if (!bio_list_empty(&conf->return_bi) && - !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { - struct bio_list tmp = BIO_EMPTY_LIST; - spin_lock_irq(&conf->device_lock); - if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { - bio_list_merge(&tmp, &conf->return_bi); - bio_list_init(&conf->return_bi); - } - spin_unlock_irq(&conf->device_lock); - return_io(&tmp); - } - blk_start_plug(&plug); handled = 0; spin_lock_irq(&conf->device_lock);
@@ -6705,7 +6687,6 @@ static struct r5conf *setup_conf(struct mddev *mddev) INIT_LIST_HEAD(&conf->hold_list); INIT_LIST_HEAD(&conf->delayed_list); INIT_LIST_HEAD(&conf->bitmap_list); - bio_list_init(&conf->return_bi); init_llist_head(&conf->released_stripes); atomic_set(&conf->active_stripes, 0); atomic_set(&conf->preread_active_stripes, 0);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 1440fa26e296..1ef71273b9b2 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h@@ -621,9 +621,6 @@ struct r5conf { int skip_copy; /* Don't copy data from bio to stripe cache */ struct list_head *last_hold; /* detect hold_list promotions */ - /* bios to have bi_end_io called after metadata is synced */ - struct bio_list return_bi; - atomic_t reshape_stripes; /* stripes with pending writes for reshape */ /* unfortunately we need two cache names as we temporarily have * two caches.