linux-kernel - [PATCH AUTOSEL 4.19 17/36] nvme: fix srcu locking on error return in nvme_get_ns_from

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Message-Id: <20190604232333.7185-17-sashal@kernel.org>
Date:   Tue,  4 Jun 2019 19:23:12 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Christoph Hellwig <hch@....de>,
        Keith Busch <keith.busch@...el.com>,
        Chaitanya Kulkarni <chaitanya.kulkarni@....com>,
        Sasha Levin <sashal@...nel.org>, linux-nvme@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.19 17/36] nvme: fix srcu locking on error return in nvme_get_ns_from_disk

From: Christoph Hellwig <hch@....de>

[ Upstream commit 100c815cbd56480b3e31518475b04719c363614a ]

If we can't get a namespace don't leak the SRCU lock.  nvme_ioctl was
working around this, but nvme_pr_command wasn't handling this properly.
Just do what callers would usually expect.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Keith Busch <keith.busch@...el.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvme/host/core.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index abfb46378cc1..44d8077fbe95 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1277,9 +1277,14 @@ static struct nvme_ns *nvme_get_ns_from_disk(struct gendisk *disk,
 {
 #ifdef CONFIG_NVME_MULTIPATH
 	if (disk->fops == &nvme_ns_head_ops) {
+		struct nvme_ns *ns;
+
 		*head = disk->private_data;
 		*srcu_idx = srcu_read_lock(&(*head)->srcu);
-		return nvme_find_path(*head);
+		ns = nvme_find_path(*head);
+		if (!ns)
+			srcu_read_unlock(&(*head)->srcu, *srcu_idx);
+		return ns;
 	}
 #endif
 	*head = NULL;
@@ -1326,9 +1331,9 @@ static int nvme_ioctl(struct block_device *bdev, fmode_t mode,
 
 	ns = nvme_get_ns_from_disk(bdev->bd_disk, &head, &srcu_idx);
 	if (unlikely(!ns))
-		ret = -EWOULDBLOCK;
-	else
-		ret = nvme_ns_ioctl(ns, cmd, arg);
+		return -EWOULDBLOCK;
+
+	ret = nvme_ns_ioctl(ns, cmd, arg);
 	nvme_put_ns_from_disk(head, srcu_idx);
 	return ret;
 }
-- 
2.20.1