There is a iobarrier in raid1 because the contend between nornalIO and
resyncIO.It suspend all nornal IO when reysync.
But if nornal IO is outrange the resync windwos,there is no contend.
So I rewrite the iobarrier.
I patition the whole space into three parts.
|---------|-----------|------------|-----------|----------
Pa next_resync Pb Pc
Firtly i introduce some concept:
1:RESYNC_WINDOW: For resync, there are 32 sync requests at most.A sync
request is RESYNC_BLOCK_SIZE(64*1024).So the RESYNC_WINDOW is 32 *
RESYNC_BLOCK_SIZE, that is 2MB.
2:next_resync mean the next start sector which will being do sync.
3:Pa means a position which before RESYNC_WINDOW distance from
next_resync.
4:Pb means a position which after 3 * RESYNC_WINDOW distance from
next_resync.
5:Pc means a position which after 6 * RESYNC_WINDOWS disttance from
next_resync.
NornalIO will be partitioned into four types.
NoIO1: it means the end sector of bio is smaller or equal the Pa.
NoIO2: it means the start sector of bio larger or equal Pc.
NoIO3: it means the start sector of bio larger or equal Pb.For those
tyeps, i don't care the location of end sector.
NoIO4: it means the location between Pa and Pb.
For NoIO1,it don't use iobarrier.
For NoIO4,it used the original iobarrier mechanism.The nornalIO and
syncIO must be contend.
For NoIO2/3, i add two filed in struct r1conf "after_resync_three_count,
after_resync_six_count".They indicate the count of
two types.For those, they don't wait.They only add the relevant the
counter.
For resync action, if there are NoIO4s, it must be wait.If not,it
forward.But if there are NoIO3,it must wait until the counter of NoIO3
became zero.If there are NoIO2, it must wait until the counter of NoIO2
became zero.
There is a problem which when and how to change from NoIO2 to NoIO3.Only
so, the sync action can forward.
I add a filed in struct r1conf "after_resync_sector".It means the
position Pb.What condition will change?
A: if after_resync_sector == MaxSector, it means there are no NoIO2/3.
So after_resync_sector = Pb.
B: if after_resync_six_count == 0 && after_resync_six_count != 0, it
means after_resync_sector forward 3 * RESYNC_WINDOW.
There is anthor problem which how to differentiate when NoIO2 became
NoIO3.For example: firstly r1bioA is NoIO2.Before r1bioA completed,
there is no NoIO3.So r1bioA will be became to NoIO3.
At generil,we should use flags and list_head. The codes should:
>list_splice_init(six_head, three_head);
>after_reysnc_three_count = after_resync_six_count;
>after_resync_six_count = 0;
>list_for_each_entry(three_head){
> clear_bit(RESYNC_SIX_FLAG),
> set_bit(RESYNC_THREE_FLAG),
>}
If there are many NoIO2, it will take too long in list_for_each_entry.
Avoid this, i add a filed in struct r1bio
"after_threetimes_resync_sector".
I used this to record the position Pb when call wait_barrier in func
make_request.
For NoIO1/4, the value is zero.
In func allow_barrier, it check the conf->after_resync_sector.
If after_threetimes_resync_sector == conf->after_resync_sector,it mean
there is no transition which NoIO2 to NoIO3.In this condtion
if bio->bi_sector > conf->after_resync_sector + 3 * RESYNC_WINWOD
it means the bio is NoIO2;
else
it means the bio si NoIO3.
If after_threetimes_resync_sector != conf->after_resync_sector,it mean
there is a trnasiton which NoIO2 to NoIO3.Because there is at most one
transtions.So it only means the bio is NoIO2.
For one bio,there are many r1bio.So we make sure the
r1bio->after_threetimes_resync_sector is the same value.
If we met blocked_dev, it must call allow_barrier and wait_barrier.
So the first and the second value of conf->after_resync_sector will
change.If there are many r1bio's with differnet
after_threetimes_resync_sector.For the relevant bio, it depent on the
last value of r1bio.It will cause error.To avoid this, we must wait
former r1bios completes.
Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
---
drivers/md/raid1.c | 153 +++++++++++++++++++++++++++++++++++++++++++++--------
drivers/md/raid1.h | 4 ++
2 files changed, 134 insertions(+), 23 deletions(-)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 2fd74ec..92909ea 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -66,7 +66,9 @@
*/
static int max_queued_requests = 1024;
-static void allow_barrier(struct r1conf *conf);
+static void allow_barrier(struct r1conf *conf,
+ sector_t after_threetimes_resync_sector,
+ sector_t bi_start_sector);
static void lower_barrier(struct r1conf *conf);
static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
@@ -84,10 +86,11 @@ static void r1bio_pool_free(void *r1_bio, void *data)
}
#define RESYNC_BLOCK_SIZE (64*1024)
-//#define RESYNC_BLOCK_SIZE PAGE_SIZE
+#define RESYNC_DEPTH 32
#define RESYNC_SECTORS (RESYNC_BLOCK_SIZE >> 9)
#define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
-#define RESYNC_WINDOW (2048*1024)
+#define RESYNC_WINDOW (RESYNC_BLOCK_SIZE * RESYNC_DEPTH)
+#define RESYNC_WINDOW_SECTORS (RESYNC_WINDOW >> 9)
static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
{
@@ -225,13 +228,17 @@ 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;
-
+ unsigned long flags;
+ sector_t after_threetimes_resync_sector =
+ r1_bio->after_threetimes_resync_sector;
+ sector_t bi_start_sector = bio->bi_sector;
+
if (bio->bi_phys_segments) {
- unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
bio->bi_phys_segments--;
done = (bio->bi_phys_segments == 0);
spin_unlock_irqrestore(&conf->device_lock, flags);
+ wake_up(&conf->wait_barrier);
} else
done = 1;
@@ -243,7 +250,8 @@ 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);
+ allow_barrier(conf, after_threetimes_resync_sector,
+ bi_start_sector);
}
}
@@ -814,8 +822,6 @@ static void flush_pending_writes(struct r1conf *conf)
* there is no normal IO happeing. It must arrange to call
* lower_barrier when the particular background IO completes.
*/
-#define RESYNC_DEPTH 32
-
static void raise_barrier(struct r1conf *conf)
{
spin_lock_irq(&conf->resync_lock);
@@ -826,11 +832,18 @@ static void raise_barrier(struct r1conf *conf)
/* block any new IO from starting */
conf->barrier++;
-
- /* Now wait for all pending IO to complete */
+ /* For those conditions, we must wait
+ * A:array is in freeze state.
+ * B:When starting resync and there are normal IO
+ * C:There is no nornal io after three times in resync window
+ * D: total barrier are less than RESYNC_DEPTH*/
wait_event_lock_irq(conf->wait_barrier,
- !conf->freeze_array &&
- !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
+ !conf->freeze_array &&
+ ((conf->next_resync < RESYNC_WINDOW_SECTORS
+ && !conf->nr_pending)
+ || (conf->next_resync + RESYNC_SECTORS
+ <= conf->after_resync_sector))
+ && conf->barrier < RESYNC_DEPTH,
conf->resync_lock);
spin_unlock_irq(&conf->resync_lock);
@@ -846,10 +859,57 @@ static void lower_barrier(struct r1conf *conf)
wake_up(&conf->wait_barrier);
}
-static void wait_barrier(struct r1conf *conf)
+static sector_t wait_barrier(struct r1conf *conf, struct bio *bio)
{
+ sector_t sector = 0;
spin_lock_irq(&conf->resync_lock);
- if (conf->barrier) {
+ if (conf->barrier || unlikely(conf->freeze_array)) {
+ if (unlikely(!conf->freeze_array && bio) &&
+ bio_data_dir(bio) == WRITE &&
+ conf->next_resync > RESYNC_WINDOW_SECTORS) {
+ if (bio_end_sector(bio) <= conf->next_resync -
+ RESYNC_WINDOW_SECTORS)
+ goto no_wait;
+ if (conf->after_resync_sector == MaxSector) {
+ if (bio->bi_sector >= conf->next_resync +
+ 6 * RESYNC_WINDOW_SECTORS) {
+ if (conf->after_resync_six_count +
+ conf->after_resync_three_count == 0)
+ conf->after_resync_sector =
+ conf->next_resync + 3 *
+ RESYNC_WINDOW_SECTORS;
+ conf->after_resync_six_count++;
+ sector = conf->after_resync_sector;
+ goto no_wait;
+ }
+ if (bio->bi_sector >= conf->next_resync +
+ 3 * RESYNC_WINDOW_SECTORS) {
+ if (conf->after_resync_six_count +
+ conf->after_resync_three_count == 0)
+ conf->after_resync_sector =
+ conf->next_resync + 3 *
+ RESYNC_WINDOW_SECTORS;
+ conf->after_resync_three_count++;
+ sector = conf->after_resync_sector;
+ goto no_wait;
+ }
+
+ } else {
+ if (bio->bi_sector >= conf->after_resync_sector + 3 *
+ RESYNC_WINDOW_SECTORS) {
+ conf->after_resync_six_count++;
+ sector = conf->after_resync_sector;
+ goto no_wait;
+ }
+ if (bio->bi_sector >= conf->after_resync_sector) {
+ conf->after_resync_three_count++;
+ sector = conf->after_resync_sector;
+ goto no_wait;
+ }
+ }
+ } else if (unlikely(!conf->freeze_array && bio) &&
+ bio_data_dir(bio) != WRITE)
+ goto no_wait;
conf->nr_waiting++;
/* Wait for the barrier to drop.
* However if there are already pending
@@ -869,15 +929,46 @@ static void wait_barrier(struct r1conf *conf)
conf->resync_lock);
conf->nr_waiting--;
}
+no_wait:
conf->nr_pending++;
spin_unlock_irq(&conf->resync_lock);
+ return sector;
}
-static void allow_barrier(struct r1conf *conf)
+static void
+allow_barrier(struct r1conf *conf,
+ sector_t after_threetimes_resync_sector,
+ sector_t bi_start_sector)
{
unsigned long flags;
spin_lock_irqsave(&conf->resync_lock, flags);
conf->nr_pending--;
+
+ if (after_threetimes_resync_sector) {
+ if (after_threetimes_resync_sector ==
+ conf->after_resync_sector) {
+ if (bi_start_sector >= (after_threetimes_resync_sector
+ + 3 * RESYNC_WINDOW_SECTORS))
+ conf->after_resync_six_count--;
+ else
+ conf->after_resync_three_count--;
+ } else
+ conf->after_resync_three_count--;
+
+ if (!conf->after_resync_three_count) {
+ if (conf->after_resync_six_count) {
+ conf->after_resync_three_count =
+ conf->after_resync_six_count;
+ conf->after_resync_six_count = 0;
+ conf->after_resync_sector +=
+ 3 * RESYNC_WINDOW_SECTORS;
+ } else
+ conf->after_resync_sector = MaxSector;
+ }
+ BUG_ON(conf->after_resync_three_count < 0 ||
+ conf->after_resync_six_count < 0);
+ }
+
spin_unlock_irqrestore(&conf->resync_lock, flags);
wake_up(&conf->wait_barrier);
}
@@ -908,8 +999,8 @@ static void unfreeze_array(struct r1conf *conf)
/* reverse the effect of the freeze */
spin_lock_irq(&conf->resync_lock);
conf->freeze_array = 0;
- wake_up(&conf->wait_barrier);
spin_unlock_irq(&conf->resync_lock);
+ wake_up(&conf->wait_barrier);
}
@@ -1012,6 +1103,7 @@ static void make_request(struct mddev *mddev, struct bio * bio)
int first_clone;
int sectors_handled;
int max_sectors;
+ sector_t after_threetimes_resync_sector = 0;
/*
* Register the new request and wait if the reconstruction
@@ -1041,7 +1133,7 @@ static void make_request(struct mddev *mddev, struct bio * bio)
finish_wait(&conf->wait_barrier, &w);
}
- wait_barrier(conf);
+ after_threetimes_resync_sector = wait_barrier(conf, bio);
bitmap = mddev->bitmap;
@@ -1057,7 +1149,6 @@ static void make_request(struct mddev *mddev, struct bio * bio)
r1_bio->state = 0;
r1_bio->mddev = mddev;
r1_bio->sector = bio->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.
@@ -1162,6 +1253,8 @@ read_again:
disks = conf->raid_disks * 2;
retry_write:
+ r1_bio->after_threetimes_resync_sector = after_threetimes_resync_sector;
+
blocked_rdev = NULL;
rcu_read_lock();
max_sectors = r1_bio->sectors;
@@ -1230,14 +1323,23 @@ read_again:
if (unlikely(blocked_rdev)) {
/* Wait for this device to become unblocked */
int j;
-
+ sector_t old = after_threetimes_resync_sector;
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);
+ allow_barrier(conf, old, bio->bi_sector);
md_wait_for_blocked_rdev(blocked_rdev, mddev);
- wait_barrier(conf);
+ after_threetimes_resync_sector = wait_barrier(conf, bio);
+ /*
+ * We must make sure the multi r1bios of bio have
+ * the same value of after_threetimes_resync_sector
+ */
+ if (bio->bi_phys_segments && old &&
+ old != after_threetimes_resync_sector)
+ /*wait the former r1bio(s) completed*/
+ wait_event(conf->wait_barrier,
+ bio->bi_phys_segments == 1);
goto retry_write;
}
@@ -1437,11 +1539,13 @@ static void print_conf(struct r1conf *conf)
static void close_sync(struct r1conf *conf)
{
- wait_barrier(conf);
- allow_barrier(conf);
+ wait_barrier(conf, NULL);
+ allow_barrier(conf, 0, 0);
mempool_destroy(conf->r1buf_pool);
conf->r1buf_pool = NULL;
+ conf->next_resync = 0;
+ conf->after_resync_sector = conf->mddev->dev_sectors;
}
static int raid1_spare_active(struct mddev *mddev)
@@ -2712,6 +2816,9 @@ static struct r1conf *setup_conf(struct mddev *mddev)
conf->pending_count = 0;
conf->recovery_disabled = mddev->recovery_disabled - 1;
+ conf->after_resync_sector = MaxSector;
+ conf->after_resync_six_count = conf->after_resync_three_count = 0;
+
err = -EIO;
for (i = 0; i < conf->raid_disks * 2; i++) {
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index 8afd300..3ab1405 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -40,6 +40,9 @@ struct r1conf {
* where that is.
*/
sector_t next_resync;
+ sector_t after_resync_sector;
+ int after_resync_three_count;
+ int after_resync_six_count;
spinlock_t device_lock;
@@ -112,6 +115,7 @@ struct r1bio {
* in this BehindIO request
*/
sector_t sector;
+ sector_t after_threetimes_resync_sector;
int sectors;
unsigned long state;
struct mddev *mddev;
--
1.8.1.2
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