Commit f9cfe7e7 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md: Fix md_seq_ops() regressions 



Commit cf1b6d44 ("md: simplify md_seq_ops") introduce following
regressions:

1) If list all_mddevs is emptly, personalities and unused devices won't
   be showed to user anymore.
2) If seq_file buffer overflowed from md_seq_show(), then md_seq_start()
   will be called again, hence personalities will be showed to user
   again.
3) If seq_file buffer overflowed from md_seq_stop(), seq_read_iter()
   doesn't handle this, hence unused devices won't be showed to user.

Fix above problems by printing personalities and unused devices in
md_seq_show().

Fixes: cf1b6d44 ("md: simplify md_seq_ops")
Cc: stable@vger.kernel.org # v6.7+
Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240109133957.2975272-1-yukuai1@huaweicloud.com
parent 53889bca

drivers/md/md.c

+27 −13
Original line number Diff line number Diff line
@@ -8135,6 +8135,19 @@ static void status_unused(struct seq_file *seq) 
	seq_printf(seq, "\n");

}



static void status_personalities(struct seq_file *seq)

{

	struct md_personality *pers;



	seq_puts(seq, "Personalities : ");

	spin_lock(&pers_lock);

	list_for_each_entry(pers, &pers_list, list)

		seq_printf(seq, "[%s] ", pers->name);



	spin_unlock(&pers_lock);

	seq_puts(seq, "\n");

}



static int status_resync(struct seq_file *seq, struct mddev *mddev)

{

	sector_t max_sectors, resync, res;
@@ -8276,20 +8289,10 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev) 
static void *md_seq_start(struct seq_file *seq, loff_t *pos)

	__acquires(&all_mddevs_lock)

{

	struct md_personality *pers;



	seq_puts(seq, "Personalities : ");

	spin_lock(&pers_lock);

	list_for_each_entry(pers, &pers_list, list)

		seq_printf(seq, "[%s] ", pers->name);



	spin_unlock(&pers_lock);

	seq_puts(seq, "\n");

	seq->poll_event = atomic_read(&md_event_count);



	spin_lock(&all_mddevs_lock);



	return seq_list_start(&all_mddevs, *pos);

	return seq_list_start_head(&all_mddevs, *pos);

}



static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
@@ -8300,16 +8303,23 @@ static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos) 
static void md_seq_stop(struct seq_file *seq, void *v)

	__releases(&all_mddevs_lock)

{

	status_unused(seq);

	spin_unlock(&all_mddevs_lock);

}



static int md_seq_show(struct seq_file *seq, void *v)

{

	struct mddev *mddev = list_entry(v, struct mddev, all_mddevs);

	struct mddev *mddev;

	sector_t sectors;

	struct md_rdev *rdev;



	if (v == &all_mddevs) {

		status_personalities(seq);

		if (list_empty(&all_mddevs))

			status_unused(seq);

		return 0;

	}



	mddev = list_entry(v, struct mddev, all_mddevs);

	if (!mddev_get(mddev))

		return 0;
@@ -8385,6 +8395,10 @@ static int md_seq_show(struct seq_file *seq, void *v) 
	}

	spin_unlock(&mddev->lock);

	spin_lock(&all_mddevs_lock);



	if (mddev == list_last_entry(&all_mddevs, struct mddev, all_mddevs))

		status_unused(seq);



	if (atomic_dec_and_test(&mddev->active))

		__mddev_put(mddev);