Hi Anna,
We have a similar but slightly different requirement.
You change allows a user to force a xprt's remote address to anything, allowing
it to connect to a different address than what it originally had.
The original server/xprt address starts as the one that userspace mount program
provides, possibly after resolving the servername used in the mount command.
Our requirement is that that server name remains same but its address changes,
aka, DNS failover.
Such cases (which I believe are more common) can be handled fully automatically,
by resolving the server name before every xprt reconnect. CIFS does this.
NFS also has fs/nfs/dns_resolve.c which we can use to do the name resolution,
though it's currently not being used for this specific use.
Did you have a similar requirement in mind, and/or did you consider the above?
Would like to know your thoughts.
Thanks,
Tomar
-----Original Message-----
From: Anna Schumaker <schumakeranna@xxxxxxxxx> On Behalf Of schumaker.anna@xxxxxxxxx
Sent: 13 March 2021 02:48
To: linux-nfs@xxxxxxxxxxxxxxx
Cc: Anna.Schumaker@xxxxxxxxxx
Subject: [PATCH v3 0/5] SUNRPC: Create sysfs files for changing IP address
From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
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
--
2.29.2
