This is a note to let you know that I've just added the patch titled
md: separate request handling
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-separate-request-handling.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 393debc23c7820211d1c8253dd6a8408a7628fe7 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli@xxxxxx>
Date: Thu, 21 Sep 2017 10:23:35 -0700
Subject: md: separate request handling
From: Shaohua Li <shli@xxxxxx>
commit 393debc23c7820211d1c8253dd6a8408a7628fe7 upstream.
With commit cc27b0c78c79, pers->make_request could bail out without handling
the bio. If that happens, we should retry. The commit fixes md_make_request
but not other call sites. Separate the request handling part, so other call
sites can use it.
Reported-by: Nate Dailey <nate.dailey@xxxxxxxxxxx>
Fix: cc27b0c78c79(md: fix deadlock between mddev_suspend() and md_write_start())
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/md.c | 58 +++++++++++++++++++++++++++++++-------------------------
drivers/md/md.h | 1
2 files changed, 34 insertions(+), 25 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -266,6 +266,37 @@ static DEFINE_SPINLOCK(all_mddevs_lock);
* call has finished, the bio has been linked into some internal structure
* and so is visible to ->quiesce(), so we don't need the refcount any more.
*/
+void md_handle_request(struct mddev *mddev, struct bio *bio)
+{
+check_suspended:
+ rcu_read_lock();
+ if (mddev->suspended) {
+ DEFINE_WAIT(__wait);
+ for (;;) {
+ prepare_to_wait(&mddev->sb_wait, &__wait,
+ TASK_UNINTERRUPTIBLE);
+ if (!mddev->suspended)
+ break;
+ rcu_read_unlock();
+ schedule();
+ rcu_read_lock();
+ }
+ finish_wait(&mddev->sb_wait, &__wait);
+ }
+ atomic_inc(&mddev->active_io);
+ rcu_read_unlock();
+
+ if (!mddev->pers->make_request(mddev, bio)) {
+ atomic_dec(&mddev->active_io);
+ wake_up(&mddev->sb_wait);
+ goto check_suspended;
+ }
+
+ if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
+ wake_up(&mddev->sb_wait);
+}
+EXPORT_SYMBOL(md_handle_request);
+
static blk_qc_t md_make_request(struct request_queue *q, struct bio *bio)
{
const int rw = bio_data_dir(bio);
@@ -285,23 +316,6 @@ static blk_qc_t md_make_request(struct r
bio_endio(bio);
return BLK_QC_T_NONE;
}
-check_suspended:
- rcu_read_lock();
- if (mddev->suspended) {
- DEFINE_WAIT(__wait);
- for (;;) {
- prepare_to_wait(&mddev->sb_wait, &__wait,
- TASK_UNINTERRUPTIBLE);
- if (!mddev->suspended)
- break;
- rcu_read_unlock();
- schedule();
- rcu_read_lock();
- }
- finish_wait(&mddev->sb_wait, &__wait);
- }
- atomic_inc(&mddev->active_io);
- rcu_read_unlock();
/*
* save the sectors now since our bio can
@@ -310,20 +324,14 @@ check_suspended:
sectors = bio_sectors(bio);
/* bio could be mergeable after passing to underlayer */
bio->bi_opf &= ~REQ_NOMERGE;
- if (!mddev->pers->make_request(mddev, bio)) {
- atomic_dec(&mddev->active_io);
- wake_up(&mddev->sb_wait);
- goto check_suspended;
- }
+
+ md_handle_request(mddev, bio);
cpu = part_stat_lock();
part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
part_stat_unlock();
- if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
- wake_up(&mddev->sb_wait);
-
return BLK_QC_T_NONE;
}
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -686,6 +686,7 @@ extern void md_stop_writes(struct mddev
extern int md_rdev_init(struct md_rdev *rdev);
extern void md_rdev_clear(struct md_rdev *rdev);
+extern void md_handle_request(struct mddev *mddev, struct bio *bio);
extern void mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
Patches currently in stable-queue which might be from shli@xxxxxx are
queue-4.13/md-separate-request-handling.patch
queue-4.13/md-raid5-preserve-stripe_on_unplug_list-in-break_stripe_batch_list.patch
queue-4.13/md-fix-a-race-condition-for-flush-request-handling.patch
queue-4.13/md-raid5-fix-a-race-condition-in-stripe-batch.patch