md: Fix md_seq_ops() regressions

commit f9cfe7e7f9 upstream.

Commit cf1b6d4441 ("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: cf1b6d4441 ("md: simplify md_seq_ops")
Cc: stable@vger.kernel.org # v6.7+
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240109133957.2975272-1-yukuai1@huaweicloud.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yu Kuai 2024-01-09 21:39:57 +08:00 • committed by Greg Kroah-Hartman
commit 11a74717dc