md: separate request handling
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@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>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 08fcaeb..1db1a22 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -266,6 +266,37 @@
* 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 @@
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 @@
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;
}
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 561d22b..d8287d3 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -692,6 +692,7 @@
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,