[md PATCH 03/14] md/raid5: call bio_endio() directly rather than queueing for later.

NeilBrown
2017-02-16T04:39:01Z

We currently gather bios that need to be returned into a bio_list
and call bio_endio() on them all together.
The original reason for this was to avoid making the calls while
holding a spinlock.
Locking has changed a lot since then, and that reason is no longer
valid.

So discard return_io() and various return_bi lists, and just call
bio_endio() directly as needed.

Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/md/raid5-cache.c | 13 +++++--------
drivers/md/raid5.c | 38 ++++++++++----------------------------
drivers/md/raid5.h | 3 +--
3 files changed, 16 insertions(+), 38 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 4b211f914d17..1b972a172800 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -255,8 +255,7 @@ static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
}

static void
-r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev,
- struct bio_list *return_bi)
+r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev)
{
struct bio *wbi, *wbi2;

@@ -266,23 +265,21 @@ r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev,
dev->sector + STRIPE_SECTORS) {
wbi2 = r5_next_bio(wbi, dev->sector);
md_write_end(conf->mddev);
- if (!raid5_dec_bi_active_stripes(wbi)) {
- bio_list_add(return_bi, wbi);
- }
+ if (!raid5_dec_bi_active_stripes(wbi))
+ bio_endio(wbi);
wbi = wbi2;
}
}

void r5c_handle_cached_data_endio(struct r5conf *conf,
- struct stripe_head *sh, int disks, struct bio_list *return_bi)
+ struct stripe_head *sh, int disks)
{
int i;

for (i = sh->disks; i--; ) {
if (sh->dev[i].written) {
set_bit(R5_UPTODATE, &sh->dev[i].flags);
- r5c_return_dev_pending_writes(conf, &sh->dev[i],
- return_bi);
+ r5c_return_dev_pending_writes(conf, &sh->dev[i]);
bitmap_endwrite(conf->mddev->bitmap, sh->sector,
STRIPE_SECTORS,
!test_bit(STRIPE_DEGRADED, &sh->state),
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 154593e0afbe..a6edca65b561 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -154,17 +154,6 @@ static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
return slot;
}

-static void return_io(struct bio_list *return_bi)
-{
- struct bio *bi;
- while ((bi = bio_list_pop(return_bi)) != NULL) {
- bi->bi_iter.bi_size = 0;
- trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
- bi, 0);
- bio_endio(bi);
- }
-}
-
static void print_raid5_conf (struct r5conf *conf);

static int stripe_operations_active(struct stripe_head *sh)
@@ -1175,7 +1164,6 @@ async_copy_data(int frombio, struct bio *bio, struct page **page,
static void ops_complete_biofill(void *stripe_head_ref)
{
struct stripe_head *sh = stripe_head_ref;
- struct bio_list return_bi = BIO_EMPTY_LIST;
int i;

pr_debug("%s: stripe %llu\n", __func__,
@@ -1200,15 +1188,13 @@ static void ops_complete_biofill(void *stripe_head_ref)
dev->sector + STRIPE_SECTORS) {
rbi2 = r5_next_bio(rbi, dev->sector);
if (!raid5_dec_bi_active_stripes(rbi))
- bio_list_add(&return_bi, rbi);
+ bio_endio(rbi);
rbi = rbi2;
}
}
}
clear_bit(STRIPE_BIOFILL_RUN, &sh->state);

- return_io(&return_bi);
-
set_bit(STRIPE_HANDLE, &sh->state);
raid5_release_stripe(sh);
}
@@ -3152,8 +3138,7 @@ static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,

static void
handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
- struct stripe_head_state *s, int disks,
- struct bio_list *return_bi)
+ struct stripe_head_state *s, int disks)
{
int i;
BUG_ON(sh->batch_head);
@@ -3201,7 +3186,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
bi->bi_error = -EIO;
md_write_end(conf->mddev);
if (!raid5_dec_bi_active_stripes(bi))
- bio_list_add(return_bi, bi);
+ bio_endio(bi);
bi = nextbi;
}
if (bitmap_end)
@@ -3224,7 +3209,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
bi->bi_error = -EIO;
md_write_end(conf->mddev);
if (!raid5_dec_bi_active_stripes(bi))
- bio_list_add(return_bi, bi);
+ bio_endio(bi);
bi = bi2;
}

@@ -3250,7 +3235,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,

bi->bi_error = -EIO;
if (!raid5_dec_bi_active_stripes(bi))
- bio_list_add(return_bi, bi);
+ bio_endio(bi);
bi = nextbi;
}
}
@@ -3549,7 +3534,7 @@ static void break_stripe_batch_list(struct stripe_head *head_sh,
* never LOCKED, so we don't need to test 'failed' directly.
*/
static void handle_stripe_clean_event(struct r5conf *conf,
- struct stripe_head *sh, int disks, struct bio_list *return_bi)
+ struct stripe_head *sh, int disks)
{
int i;
struct r5dev *dev;
@@ -3583,7 +3568,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
wbi2 = r5_next_bio(wbi, dev->sector);
md_write_end(conf->mddev);
if (!raid5_dec_bi_active_stripes(wbi))
- bio_list_add(return_bi, wbi);
+ bio_endio(wbi);
wbi = wbi2;
}
bitmap_endwrite(conf->mddev->bitmap, sh->sector,
@@ -4526,7 +4511,7 @@ static void handle_stripe(struct stripe_head *sh)
sh->reconstruct_state = 0;
break_stripe_batch_list(sh, 0);
if (s.to_read+s.to_write+s.written)
- handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
+ handle_failed_stripe(conf, sh, &s, disks);
if (s.syncing + s.replacing)
handle_failed_sync(conf, sh, &s);
}
@@ -4592,10 +4577,10 @@ static void handle_stripe(struct stripe_head *sh)
&& !test_bit(R5_LOCKED, &qdev->flags)
&& (test_bit(R5_UPTODATE, &qdev->flags) ||
test_bit(R5_Discard, &qdev->flags))))))
- handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
+ handle_stripe_clean_event(conf, sh, disks);

if (s.just_cached)
- r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
+ r5c_handle_cached_data_endio(conf, sh, disks);
r5l_stripe_write_finished(sh);

/* Now we might consider reading some blocks, either to check/generate
@@ -4823,9 +4808,6 @@ static void handle_stripe(struct stripe_head *sh)
md_wakeup_thread(conf->mddev->thread);
}

- if (!bio_list_empty(&s.return_bi))
- return_io(&s.return_bi);
-
clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
}

diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 1ef71273b9b2..9051631cb7f0 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -272,7 +272,6 @@ struct stripe_head_state {
int dec_preread_active;
unsigned long ops_request;

- struct bio_list return_bi;
struct md_rdev *blocked_rdev;
int handle_bad_blocks;
int log_failed;
@@ -776,7 +775,7 @@ extern void r5c_release_extra_page(struct stripe_head *sh);
extern void r5c_use_extra_page(struct stripe_head *sh);
extern void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
extern void r5c_handle_cached_data_endio(struct r5conf *conf,
- struct stripe_head *sh, int disks, struct bio_list *return_bi);
+ struct stripe_head *sh, int disks);
extern int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh,
struct stripe_head_state *s);
extern void r5c_make_stripe_write_out(struct stripe_head *sh);