[ 02/82] btrfs: Init io_lock after cloning btrfs device struct

From: Ben Hutchings
Date: Mon Mar 18 2013 - 00:30:13 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit 1cba0cdf5e4dbcd9e5fa5b54d7a028e55e2ca057 upstream.

__btrfs_close_devices() clones btrfs device structs with
memcpy(). Some of the fields in the clone are reinitialized, but it's
missing to init io_lock. In mainline this goes unnoticed, but on RT it
leaves the plist pointing to the original about to be freed lock

Initialize io_lock after cloning, so no references to the original
struct are left.

Reported-and-tested-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
fs/btrfs/volumes.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -543,6 +543,7 @@ static int __btrfs_close_devices(struct
new_device->writeable = 0;
new_device->in_fs_metadata = 0;
new_device->can_discard = 0;
+ spin_lock_init(&new_device->io_lock);
list_replace_rcu(&device->dev_list, &new_device->dev_list);

call_rcu(&device->rcu, free_device);

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