[PATCHv2 0/2] nvme: fixup MD RAID usage

[Hannes Reinecke]

Hi all,

ever since the implementation NVMe-oF does not work together with MD RAID.
MD RAID expects the device to return an I/O error on failure, and to remove
the block device if the underlying hardware is removed.
This is contrary to the implementation of NVMe-oF, which will keep on retrying
I/O while the controller is being reset, and will only remove the block device
once the last _user_ is gone.

While we already have a 'fast_io_fail_tmo' setting which would ensure
that I/O errors are returned after the timeout expired, this attribute
has to be set during the initial 'connect' call.
So the first patch adds a 'fasi_io_fail_tmo' controller sysfs
attribute which allows the admin to modify it during runtime.
To fixup the second issue a new attribute 'no_path_detach' is
implemented, which will cause the disk to be removed as once the
last controller holding a path to the namespace is removed (ie after
all reconnect attempts for that controllers are exhausted).

This is a rework of the earlier path by Keith Busch ('nvme-mpath: delete disk
after last connection'). Kudos to him for suggesting this approach.

Changes to v1:
- Integrated reviews from Sagi
- Use fast_io_fail_tmo instead of a new sysfs attribute
- Rename attribute to 'no_path_detach'

Hannes Reinecke (2):
  nvme: add 'fast_io_fail_tmo' controller sysfs attribute
  nvme: delete disk when last path is gone

 drivers/nvme/host/core.c      | 41 ++++++++++++++++++++++++++++++++++-
 drivers/nvme/host/multipath.c | 31 +++++++++++++++++++++++++-
 drivers/nvme/host/nvme.h      | 21 +++++++++++++++---
 3 files changed, 88 insertions(+), 5 deletions(-)

-- 
2.29.2