[v3,0/5] SUNRPC: Create sysfs files for changing IP address

Message

Anna Schumaker March 12, 2021, 9:18 p.m. UTC

From: Anna Schumaker <[e-mail]>

It's possible for an NFS server to go down but come back up with a
different IP address. These patches provide a way for administrators to
handle this issue by providing a new IP address for xprt sockets to
connect to.

Chuck has suggested some ideas for future work that could also use this
interface, such as:
- srcaddr: To move between network devices on the client
- type: "tcp", "rdma", "local"
- bound: 0 for autobind, or the result of the most recent rpcbind query
- connected: either true or false
- last: read-only timestamp of the last operation to use the transport
- device: A symlink to the physical network device

Changes in v3:
- Rename functions and objects to make future expansion easier
- Put files under /sys/kernel/sunrpc/client/ instead of
  /sys/kernel/sunrpc/net/, again for future expansions
- Clean up use of WARN_ON_ONCE() in xs_connect()
- Fix up locking, reference counting, and RCU usage
- Unconditionally create files so userspace tools don't need to guess
  what is supported (We return an error message now instead)

Changes in v2:
- Put files under /sys/kernel/sunrpc/ instead of /sys/net/sunrpc/
- Rename file from "address" to "dstaddr"

Thoughts?
Anna


Anna Schumaker (5):
  sunrpc: Create a sunrpc directory under /sys/kernel/
  sunrpc: Create a client/ subdirectory in the sunrpc sysfs
  sunrpc: Create per-rpc_clnt sysfs kobjects
  sunrpc: Prepare xs_connect() for taking NULL tasks
  sunrpc: Create a per-rpc_clnt file for managing the destination IP
    address

 include/linux/sunrpc/clnt.h |   1 +
 net/sunrpc/Makefile         |   2 +-
 net/sunrpc/clnt.c           |   5 +
 net/sunrpc/sunrpc_syms.c    |   8 ++
 net/sunrpc/sysfs.c          | 191 ++++++++++++++++++++++++++++++++++++
 net/sunrpc/sysfs.h          |  20 ++++
 net/sunrpc/xprtsock.c       |   2 +-
 7 files changed, 227 insertions(+), 2 deletions(-)
 create mode 100644 net/sunrpc/sysfs.c
 create mode 100644 net/sunrpc/sysfs.h

Comments

Olga Kornievskaia March 24, 2021, 5:29 p.m. UTC | #1

On Fri, Mar 12, 2021 at 4:19 PM <[e-mail]> wrote:
>
> From: Anna Schumaker <[e-mail]>
>
> It's possible for an NFS server to go down but come back up with a
> different IP address. These patches provide a way for administrators to
> handle this issue by providing a new IP address for xprt sockets to
> connect to.
>
> Chuck has suggested some ideas for future work that could also use this
> interface, such as:
> - srcaddr: To move between network devices on the client
> - type: "tcp", "rdma", "local"
> - bound: 0 for autobind, or the result of the most recent rpcbind query
> - connected: either true or false
> - last: read-only timestamp of the last operation to use the transport
> - device: A symlink to the physical network device
>
> Changes in v3:
> - Rename functions and objects to make future expansion easier
> - Put files under /sys/kernel/sunrpc/client/ instead of
>   /sys/kernel/sunrpc/net/, again for future expansions
> - Clean up use of WARN_ON_ONCE() in xs_connect()
> - Fix up locking, reference counting, and RCU usage
> - Unconditionally create files so userspace tools don't need to guess
>   what is supported (We return an error message now instead)
>
> Changes in v2:
> - Put files under /sys/kernel/sunrpc/ instead of /sys/net/sunrpc/
> - Rename file from "address" to "dstaddr"
>
> Thoughts?

Reviewed-by/Tested-by this version. Works OK for me.

I would like to note that the interface doesn't or rather perhaps
cannot do any error checking. So if the "user" were to echo a
nonsensical data into the sysfs (echo foobar > <sysfspath>), that
breaks the existing connection. However, if a proper IP were to be
entered to correct it, things will go back to normal.

> Anna
>
>
> Anna Schumaker (5):
>   sunrpc: Create a sunrpc directory under /sys/kernel/
>   sunrpc: Create a client/ subdirectory in the sunrpc sysfs
>   sunrpc: Create per-rpc_clnt sysfs kobjects
>   sunrpc: Prepare xs_connect() for taking NULL tasks
>   sunrpc: Create a per-rpc_clnt file for managing the destination IP
>     address
>
>  include/linux/sunrpc/clnt.h |   1 +
>  net/sunrpc/Makefile         |   2 +-
>  net/sunrpc/clnt.c           |   5 +
>  net/sunrpc/sunrpc_syms.c    |   8 ++
>  net/sunrpc/sysfs.c          | 191 ++++++++++++++++++++++++++++++++++++
>  net/sunrpc/sysfs.h          |  20 ++++
>  net/sunrpc/xprtsock.c       |   2 +-
>  7 files changed, 227 insertions(+), 2 deletions(-)
>  create mode 100644 net/sunrpc/sysfs.c
>  create mode 100644 net/sunrpc/sysfs.h
>
> --
> 2.29.2
>