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Thu, 16 Jul 2026 22:12:34 -0700 (PDT) Received: from jwang-ThinkPad-T14-Gen-6.fritz.box ([2001:9e8:1455:9e00:bd6c:f8b2:6d2:3372]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49549c96f19sm22952255e9.9.2026.07.16.22.12.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Jul 2026 22:12:34 -0700 (PDT) From: Jack Wang To: Song Liu , Yu Kuai Cc: Li Nan , Xiao Ni , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, Jack Wang Subject: [PATCHv2] md: clear MD_CLOSING when array_state_store() bails on interrupted lock Date: Fri, 17 Jul 2026 07:12:33 +0200 Message-ID: <20260717051233.383373-1-jinpu.wang@ionos.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jack Wang Writing "clear", "readonly", "inactive" or "read_auto" to array_state calls mddev_set_closing_and_sync_blockdev(), which sets MD_CLOSING so the array cannot be reopened while it is being torn down. The flag is only cleared again at the tail of array_state_store() (for readonly, read_auto, inactive, or the failed-clear case). Between setting the flag and reaching that tail there is an early return: err = mddev_lock(mddev); if (err) return err; mddev_lock() is mutex_lock_interruptible() on reconfig_mutex. If the writing task is signalled while blocked there - easy to hit when the mutex is held for a long time by a running resync/recovery or reshape - it returns -EINTR and array_state_store() returns with MD_CLOSING still set. do_md_stop()/md_set_readonly() never ran, so the array keeps working internally, but every subsequent md_open() now returns -ENODEV for all callers: the device still shows up in /proc/mdstat and sysfs is fully populated, yet it cannot be opened and cannot be recovered without a reboot (the remaining clear paths either need the device open or re-enter test_and_set_bit(MD_CLOSING) and bail with -EBUSY before the clear). Route the interrupted-lock exit through a common label so the flag is released. Guard the clear with a set_closing flag that records whether this write actually set MD_CLOSING: when mddev->pers is already NULL (for example a concurrent STOP_ARRAY is mid-teardown) this write skips the mddev_set_closing_and_sync_blockdev() call above, so it must not clear a MD_CLOSING that the other thread owns - doing so could let the array be reopened while it is being destroyed. This also tightens the pre-existing tail clear, which had the same unconditional behaviour. mddev_unlock() is correctly skipped on the goto path since the lock was never acquired. Fixes: 99b902ac1725 ("md: sync blockdev before stopping raid or setting readonly") Assisted-by: Claude:claude-opus-4-8 [Claude Code] Signed-off-by: Jack Wang --- drivers/md/md.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index d1465bcd86c8..7b7a4d925907 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4649,6 +4649,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len) { int err = 0; enum array_state st = match_word(buf, array_states); + bool set_closing = false; /* No lock dependent actions */ switch (st) { @@ -4668,6 +4669,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len) err = mddev_set_closing_and_sync_blockdev(mddev, 0); if (err) return err; + set_closing = true; break; default: break; @@ -4696,7 +4698,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len) } err = mddev_lock(mddev); if (err) - return err; + goto out_clear_closing; switch (st) { case inactive: @@ -4769,8 +4771,17 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len) } mddev_unlock(mddev); - if (st == readonly || st == read_auto || st == inactive || - (err && st == clear)) +out_clear_closing: + /* + * Only clear MD_CLOSING if this write actually set it. Otherwise a + * concurrent teardown (e.g. STOP_ARRAY) may own the flag - this write + * would have skipped setting it above when mddev->pers was already + * NULL - and clearing it here would let the array be reopened while it + * is being destroyed. + */ + if (set_closing && + (st == readonly || st == read_auto || st == inactive || + (err && st == clear))) clear_bit(MD_CLOSING, &mddev->flags); return err ?: len; -- 2.43.0