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| author | Nate Dailey <nate.dailey@stratus.com> | 2016-02-29 10:43:58 -0500 |
|---|---|---|
| committer | Shaohua Li <shli@fb.com> | 2016-03-17 14:24:51 -0700 |
| commit | ccfc7bf1f09d6190ef86693ddc761d5fe3fa47cb (patch) | |
| tree | ac865debfb6c95c6daf0092fe248b7960131835c | |
| parent | d85326cf86d7f52d1ac23c38f745470066acc76f (diff) | |
| download | lwn-ccfc7bf1f09d6190ef86693ddc761d5fe3fa47cb.tar.gz lwn-ccfc7bf1f09d6190ef86693ddc761d5fe3fa47cb.zip | |
raid1: include bio_end_io_list in nr_queued to prevent freeze_array hang
If raid1d is handling a mix of read and write errors, handle_read_error's
call to freeze_array can get stuck.
This can happen because, though the bio_end_io_list is initially drained,
writes can be added to it via handle_write_finished as the retry_list
is processed. These writes contribute to nr_pending but are not included
in nr_queued.
If a later entry on the retry_list triggers a call to handle_read_error,
freeze array hangs waiting for nr_pending == nr_queued+extra. The writes
on the bio_end_io_list aren't included in nr_queued so the condition will
never be satisfied.
To prevent the hang, include bio_end_io_list writes in nr_queued.
There's probably a better way to handle decrementing nr_queued, but this
seemed like the safest way to avoid breaking surrounding code.
I'm happy to supply the script I used to repro this hang.
Fixes: 55ce74d4bfe1b(md/raid1: ensure device failure recorded before write request returns.)
Cc: stable@vger.kernel.org (v4.3+)
Signed-off-by: Nate Dailey <nate.dailey@stratus.com>
Signed-off-by: Shaohua Li <shli@fb.com>
| -rw-r--r-- | drivers/md/raid1.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index d1d5363b17f4..39fb21e048e6 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -2274,6 +2274,7 @@ static void handle_write_finished(struct r1conf *conf, struct r1bio *r1_bio) if (fail) { spin_lock_irq(&conf->device_lock); list_add(&r1_bio->retry_list, &conf->bio_end_io_list); + conf->nr_queued++; spin_unlock_irq(&conf->device_lock); md_wakeup_thread(conf->mddev->thread); } else { @@ -2391,8 +2392,10 @@ static void raid1d(struct md_thread *thread) LIST_HEAD(tmp); spin_lock_irqsave(&conf->device_lock, flags); if (!test_bit(MD_CHANGE_PENDING, &mddev->flags)) { - list_add(&tmp, &conf->bio_end_io_list); - list_del_init(&conf->bio_end_io_list); + while (!list_empty(&conf->bio_end_io_list)) { + list_move(conf->bio_end_io_list.prev, &tmp); + conf->nr_queued--; + } } spin_unlock_irqrestore(&conf->device_lock, flags); while (!list_empty(&tmp)) { |