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@xxxxxxxxxxxxxxx
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
---
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 63f73e8a1ab5..2f91dee0ab5f 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) {
--
2.14.4
