From 85f5a4d666fd9be73856ed16bb36c5af5b406b29 Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Tue, 8 Jan 2019 19:47:38 +0100 Subject: [PATCH] rbd: don't return 0 on unmap if RBD_DEV_FLAG_REMOVING is set 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 Tested-by: Dongsheng Yang --- drivers/block/rbd.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 8e5140bbf241..1e92b61d0bd5 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -5986,7 +5986,6 @@ 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; @@ -6019,13 +6018,13 @@ 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) {