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SubjectRe: [PATCH] SUNRPC: have soft RPC tasks return -ETIMEDOUT instead of -EIO on major connect timeout

On Sat, 2008-03-29 at 08:49 -0400, Jeff Layton wrote:
> NFSv4 background mounts do not currently work correctly. While we could
> try to fix this in userspace, I think it's really a kernel problem...
> When a soft RPC tasks experiences a major timeout during a connection
> attempt, it does an rpc_exit with a return code of -EIO. For NFSv4
> mounts, this makes the mount() syscall return -EIO. mount.nfs4 then
> interprets that as a "permanent" error, and won't attempt a background
> mount when bg is specified. Fix this by making call_timeout() do the
> rpc_exit() with an error of -ETIMEDOUT.
> This fixes the background mount issue, but does make other syscalls
> on soft mounts return ETIMEDOUT instead of EIO in this situation.
> Comments welcome.
> Signed-off-by: Jeff Layton <>
> ---
> net/sunrpc/clnt.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index 8c6a7f1..b6d409e 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -1162,7 +1162,7 @@ call_timeout(struct rpc_task *task)
> if (RPC_IS_SOFT(task)) {
> printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
> clnt->cl_protname, clnt->cl_server);
> - rpc_exit(task, -EIO);
> + rpc_exit(task, -ETIMEDOUT);
> return;
> }

While that may be acceptable for the mount() syscall, I don't think
POSIX applications are quite ready to deal with ETIMEDOUT as an error
for stat() or chdir().

Userland has the clnt_geterr() function that returns more detailed 'RPC
level' errors. While that 'error function call' approach doesn't work in
a multi-threaded environment, we might still be able to add the
equivalent of a pointer to an 'rpc_err' structure to the rpc_task, and
then have functions like call_timeout() (and especially call_verify()!)
fill in more detailed error info if that pointer is non-zero?


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