linux/drivers/block/rbd.c
Ilya Dryomov e7254cb5da rbd: don't return 0 on unmap if RBD_DEV_FLAG_REMOVING is set
commit 85f5a4d666 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

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Tested-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-05-02 21:41:17 +01:00

5624 lines
143 KiB