[PATCH V3 0/8] nvme: Refactor and expose per-controller timeout configuration

[Maurizio Lombardi <mlombard@redhat.com>]

This patchset tries to address some limitations in how the NVMe driver handles
command timeouts.
Currently, the driver relies heavily on global module parameters
(NVME_IO_TIMEOUT and NVME_ADMIN_TIMEOUT), making it difficult for users to
tune timeouts for specific controllers that may have very different
characteristics. Also, in some cases, manual changes to sysfs timeout values
are ignored by the driver logic.

For example this patchset removes the unconditional timeout assignment in
nvme_init_request. This allows the block layer to correctly apply the request
queue's timeout settings, ensuring that user-initiated changes via sysfs
are actually respected for all requests.

It introduces new sysfs attributes (admin_timeout and io_timeout) to the NVMe
controller. This allows users to configure distinct timeout requirements for
different controllers rather than relying on global module parameters.

Some examples:

Changes to the controller's io_timeout gets propagated to all
the associated namespaces' queues:

# find /sys -name 'io_timeout' 
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n1/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n2/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n3/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/io_timeout

# echo 27000 > /sys/devices/virtual/nvme-fabrics/ctl/nvme0/io_timeout
# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n1/queue/io_timeout
27000
# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n2/queue/io_timeout
27000
# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n3/queue/io_timeout
27000

When adding a namespace target-side, the io_timeout is inherited from
the controller's preferred timeout:

* target side *
# nvmetcli
/> cd subsystems/test-nqn/namespaces/4 
/subsystems/t.../namespaces/4> enable
The Namespace has been enabled.

************

* Host-side *
nvme nvme0: rescanning namespaces.
# find /sys -name 'io_timeout' 
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n1/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n2/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n3/queue/io_timeout
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n4/queue/io_timeout <-- new namespace
/sys/devices/virtual/nvme-fabrics/ctl/nvme0/io_timeout

# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme0/nvme0c0n4/queue/io_timeout
27000
***********

io_timeout and admin_timeout module parameters are used as default
values for new controllers:

# nvme connect -t tcp -a 10.37.153.138 -s 8000 -n test-nqn2
connecting to device: nvme1

# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme1/nvme1c1n1/queue/io_timeout
30000
# cat /sys/devices/virtual/nvme-fabrics/ctl/nvme1/admin_timeout
60000

V3: - Rebase on top of nvme 7.1 branch
    - add an admin_timeout variable to nvme_ctrl structure
    - Wait until the controller has reached the LIVE state
      for the first time before allowing the user to modify
      the timeouts, this prevents the dereferencing of the admin_q,
      fabrics_q and connect_q queues before their initialization.
    - move blk_put_queue(fabrics_q) to nvme_free_ctrl() to align it to
      admin_q teardown
    - modify nvmet-loop to avoid deleting and re-creating the admin_q queue
      when the controller enters the resetting state.
    - add a warning if nvme_alloc_admin_tag_set() is called twice against
      the same controller

V2: - Drop the RFC tag
    - apply the timeout settings to fabrics_q and connect_q too
    - Code style fixes
    - remove unnecessary check for null admin_q in __nvme_delete_io_queues()
    - Use DEVICE_ATTR() macro

Heyne, Maximilian (1):
  nvme: Let the blocklayer set timeouts for requests

Maurizio Lombardi (7):
  nvme: add sysfs attribute to change admin timeout per nvme controller
  nvme: pci: use admin queue timeout over NVME_ADMIN_TIMEOUT
  nvme: add sysfs attribute to change IO timeout per nvme controller
  nvme: use per controller timeout waits over depending on global
    default
  nvme-core: align fabrics_q teardown with admin_q in nvme_free_ctrl
  nvmet-loop: do not alloc admin tag set during reset
  nvme-core: warn on allocating admin tag set with existing queue

 drivers/nvme/host/apple.c  |  2 +-
 drivers/nvme/host/core.c   | 23 +++++-----
 drivers/nvme/host/nvme.h   |  4 +-
 drivers/nvme/host/pci.c    |  4 +-
 drivers/nvme/host/rdma.c   |  2 +-
 drivers/nvme/host/sysfs.c  | 89 ++++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/tcp.c    |  2 +-
 drivers/nvme/target/loop.c | 38 ++++++++--------
 8 files changed, 128 insertions(+), 36 deletions(-)

-- 
2.53.0