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Commit 99725535 authored by Ilya Dryomov's avatar Ilya Dryomov Committed by Greg Kroah-Hartman
Browse files

rbd: don't return 0 on unmap if RBD_DEV_FLAG_REMOVING is set 



commit 85f5a4d666fd9be73856ed16bb36c5af5b406b29 upstream.

There is a window between when RBD_DEV_FLAG_REMOVING is set and when
the device is removed from rbd_dev_list.  During this window, we set
"already" and return 0.

Returning 0 from write(2) can confuse userspace tools because
0 indicates that nothing was written.  In particular, "rbd unmap"
will retry the write multiple times a second:

  10:28:05.463299 write(4, "0", 1)        = 0
  10:28:05.463509 write(4, "0", 1)        = 0
  10:28:05.463720 write(4, "0", 1)        = 0
  10:28:05.463942 write(4, "0", 1)        = 0
  10:28:05.464155 write(4, "0", 1)        = 0

Cc: stable@vger.kernel.org
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
Tested-by: default avatarDongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c7ca8e94

drivers/block/rbd.c

+4 −5
Original line number Diff line number Diff line
@@ -5982,7 +5982,6 @@ static ssize_t do_rbd_remove(struct bus_type *bus, 
	struct list_head *tmp;

	int dev_id;

	char opt_buf[6];

	bool already = false;

	bool force = false;

	int ret;
@@ -6015,13 +6014,13 @@ static ssize_t do_rbd_remove(struct bus_type *bus, 
		spin_lock_irq(&rbd_dev->lock);

		if (rbd_dev->open_count && !force)

			ret = -EBUSY;

		else

			already = test_and_set_bit(RBD_DEV_FLAG_REMOVING,

							&rbd_dev->flags);

		else if (test_and_set_bit(RBD_DEV_FLAG_REMOVING,

					  &rbd_dev->flags))

			ret = -EINPROGRESS;

		spin_unlock_irq(&rbd_dev->lock);

	}

	spin_unlock(&rbd_dev_list_lock);

	if (ret < 0 || already)

	if (ret)

		return ret;



	if (force) {