4.20-stable review patch. If anyone has any objections, please let me know.
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From: Ilya Dryomov idryomov@gmail.com
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: Ilya Dryomov idryomov@gmail.com Tested-by: Dongsheng Yang dongsheng.yang@easystack.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/rbd.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
--- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -5986,7 +5986,6 @@ static ssize_t do_rbd_remove(struct bus_ struct list_head *tmp; int dev_id; char opt_buf[6]; - bool already = false; bool force = false; int ret;
@@ -6019,13 +6018,13 @@ static ssize_t do_rbd_remove(struct 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) {