We use md_write_start() to increase the count of pending writes, and
md_write_end() to decrement the count. We currently count bios
submitted to md/raid5. Change it count stripe_heads that a WRITE bio
has been attached to.
So now, raid5_make_request() calls md_write_start() and then
md_write_end() to keep the count elevated during the setup of the
request.
add_stripe_bio() calls md_write_start() for each stripe_head, and the
completion routines always call md_write_end(), instead of only
calling it when raid5_dec_bi_active_stripes() returns 0.
make_discard_request also calls md_write_start/end().
The parallel between md_write_{start,end} and use of bi_phys_segments
can be seen in that:
Whenever we set bi_phys_segments to 1, we now call md_write_start.
Whenever we increment it on non-read requests with
raid5_inc_bi_active_stripes(), we now call md_write_start().
Whenever we decrement bi_phys_segments on non-read requsts with
raid5_dec_bi_active_stripes(), we now call md_write_end().
This reduces our dependence on keeping a per-bio count of active
stripes in bi_phys_segments.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
drivers/md/raid5-cache.c | 2 +-
drivers/md/raid5.c | 27 +++++++++++++--------------
2 files changed, 14 insertions(+), 15 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 302dea3296ba..4b211f914d17 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -265,8 +265,8 @@ r5c_return_dev_pending_writes(struct r5conf *conf, struct r5dev *dev,
while (wbi && wbi->bi_iter.bi_sector <
dev->sector + STRIPE_SECTORS) {
wbi2 = r5_next_bio(wbi, dev->sector);
+ md_write_end(conf->mddev);
if (!raid5_dec_bi_active_stripes(wbi)) {
- md_write_end(conf->mddev);
bio_list_add(return_bi, wbi);
}
wbi = wbi2;
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3c7e106c12a2..760b726943c9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3075,6 +3075,7 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
bi->bi_next = *bip;
*bip = bi;
raid5_inc_bi_active_stripes(bi);
+ md_write_start(conf->mddev, bi);
if (forwrite) {
/* check if page is covered */
@@ -3198,10 +3199,9 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
bi->bi_error = -EIO;
- if (!raid5_dec_bi_active_stripes(bi)) {
- md_write_end(conf->mddev);
+ md_write_end(conf->mddev);
+ if (!raid5_dec_bi_active_stripes(bi))
bio_list_add(return_bi, bi);
- }
bi = nextbi;
}
if (bitmap_end)
@@ -3222,10 +3222,9 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
bi->bi_error = -EIO;
- if (!raid5_dec_bi_active_stripes(bi)) {
- md_write_end(conf->mddev);
+ md_write_end(conf->mddev);
+ if (!raid5_dec_bi_active_stripes(bi))
bio_list_add(return_bi, bi);
- }
bi = bi2;
}
@@ -3582,10 +3581,9 @@ static void handle_stripe_clean_event(struct r5conf *conf,
while (wbi && wbi->bi_iter.bi_sector <
dev->sector + STRIPE_SECTORS) {
wbi2 = r5_next_bio(wbi, dev->sector);
- if (!raid5_dec_bi_active_stripes(wbi)) {
- md_write_end(conf->mddev);
+ md_write_end(conf->mddev);
+ if (!raid5_dec_bi_active_stripes(wbi))
bio_list_add(return_bi, wbi);
- }
wbi = wbi2;
}
bitmap_endwrite(conf->mddev->bitmap, sh->sector,
@@ -5268,6 +5266,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
bi->bi_next = NULL;
bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
+ md_write_start(mddev, bi);
stripe_sectors = conf->chunk_sectors *
(conf->raid_disks - conf->max_degraded);
@@ -5314,6 +5313,7 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
sh->dev[d].towrite = bi;
set_bit(R5_OVERWRITE, &sh->dev[d].flags);
raid5_inc_bi_active_stripes(bi);
+ md_write_start(mddev, bi);
sh->overwrite_disks++;
}
spin_unlock_irq(&sh->stripe_lock);
@@ -5336,9 +5336,9 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
release_stripe_plug(mddev, sh);
}
+ md_write_end(mddev);
remaining = raid5_dec_bi_active_stripes(bi);
if (remaining == 0) {
- md_write_end(mddev);
bio_endio(bi);
}
}
@@ -5373,8 +5373,6 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
do_flush = bi->bi_opf & REQ_PREFLUSH;
}
- md_write_start(mddev, bi);
-
/*
* If array is degraded, better not do chunk aligned read because
* later we might have to read it again in order to reconstruct
@@ -5397,6 +5395,7 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
last_sector = bio_end_sector(bi);
bi->bi_next = NULL;
bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
+ md_write_start(mddev, bi);
prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
@@ -5531,11 +5530,11 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
}
finish_wait(&conf->wait_for_overlap, &w);
+ if (rw == WRITE)
+ md_write_end(mddev);
remaining = raid5_dec_bi_active_stripes(bi);
if (remaining == 0) {
- if ( rw == WRITE )
- md_write_end(mddev);
trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
bi, 0);
--
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