From 312045eef985b61d74c28047ecd8eca6719d9516 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 21 Dec 2015 11:01:21 +1100 Subject: [PATCH] md: remove check for MD_RECOVERY_NEEDED in action_store. md currently doesn't allow a 'sync_action' such as 'reshape' to be set while MD_RECOVERY_NEEDED is set. This s a problem, particularly since commit 738a273806ee as that can cause ->check_shape to call mddev_resume() which sets MD_RECOVERY_NEEDED. So by the time we come to start 'reshape' it is very likely that MD_RECOVERY_NEEDED is still set. Testing for this flag is not really needed and is in any case very racy as it can be set at any moment - asynchronously. Any race between setting a sync_action and setting MD_RECOVERY_NEEDED must already be handled properly in some locked code, probably md_check_recovery(), so remove the test here. The test on MD_RECOVERY_RUNNING is also racy in the 'reshape' case so we should test it again after getting mddev_lock(). As this fixes a race and a regression which can cause 'reshape' to fail, it is suitable for -stable kernels since 4.1 Reported-by: Xiao Ni Fixes: 738a273806ee ("md/raid5: fix allocation of 'scribble' array.") Cc: stable@vger.kernel.org (v4.1+) Signed-off-by: NeilBrown --- drivers/md/md.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index dbedc58d8c00..61aacab424cf 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4326,8 +4326,7 @@ action_store(struct mddev *mddev, const char *page, size_t len) } mddev_unlock(mddev); } - } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) || - test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) + } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) return -EBUSY; else if (cmd_match(page, "resync")) clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery); @@ -4340,8 +4339,12 @@ action_store(struct mddev *mddev, const char *page, size_t len) return -EINVAL; err = mddev_lock(mddev); if (!err) { - clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery); - err = mddev->pers->start_reshape(mddev); + if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) + err = -EBUSY; + else { + clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery); + err = mddev->pers->start_reshape(mddev); + } mddev_unlock(mddev); } if (err) -- 2.20.1