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alistair23-linux
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md: separate request handling 

With commit cc27b0c78c, 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@stratus.com>
Fix: cc27b0c78c79(md: fix deadlock between mddev_suspend() and md_write_start())
Cc: stable@vger.kernel.org
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
hifive-unleashed-5.1
Shaohua Li 2017-09-21 10:23:35 -07:00
parent 4a704d6db0
commit 393debc23c
2 changed files with 34 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
drivers/md/md.c
View File

@ -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 request_queue *q, struct bio *bio)
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;
}

1
drivers/md/md.h
View File

@ -692,6 +692,7 @@ extern void md_stop_writes(struct mddev *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,