From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [md PATCH 11/15] md/raid5: don't test ->writes_pending in raid5_remove_disk Date: Wed, 15 Mar 2017 14:05:14 +1100 Message-ID: <148954711407.18641.13319777867112915321.stgit@noble> References: <148954692173.18641.1294690639716682540.stgit@noble> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <148954692173.18641.1294690639716682540.stgit@noble> Sender: linux-raid-owner@vger.kernel.org To: Shaohua Li Cc: linux-raid@vger.kernel.org, hch@lst.de List-Id: linux-raid.ids This test on ->writes_pending cannot be safe as the counter can be incremented at any moment and cannot be locked against. Change it to test conf->active_stripes, which at least can be locked against. More changes are still needed. A future patch will change ->writes_pending, and testing it here will be very inconvenient. Signed-off-by: NeilBrown --- drivers/md/raid5.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 4e906e5903e8..5eb3764bafd3 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -7528,9 +7528,12 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev) /* * we can't wait pending write here, as this is called in * raid5d, wait will deadlock. + * neilb: there is no locking about new writes here, + * so this cannot be safe. */ - if (atomic_read(&mddev->writes_pending)) + if (atomic_read(&conf->active_stripes)) { return -EBUSY; + } log_exit(conf); return 0; }