unimore/kernel-hacking-2024-linux-steffo
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NFSD: simplify error paths in nfsd_svc()

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The error paths in nfsd_svc() are needlessly complex and can result in a
final call to svc_put() without nfsd_last_thread() being called.  This
results in the listening sockets not being closed properly.

The per-netns setup provided by nfsd_startup_new() and removed by
nfsd_shutdown_net() is needed precisely when there are running threads.
So we don't need nfsd_up_before.  We don't need to know if it *was* up.
We only need to know if any threads are left.  If none are, then we must
call nfsd_shutdown_net().  But we don't need to do that explicitly as
nfsd_last_thread() does that for us.

So simply call nfsd_last_thread() before the last svc_put() if there are
no running threads.  That will always do the right thing.

Also discard:
 pr_info("nfsd: last server has exited, flushing export cache\n");
It may not be true if an attempt to start the first server failed, and
it isn't particularly helpful and it simply reports normal behaviour.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
NeilBrown 2023-09-25 12:06:44 +10:00 committed by Chuck Lever
parent 1f121e2de4
commit bf32075256
1 changed files with 4 additions and 10 deletions
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14
fs/nfsd/nfssvc.c
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@ -572,7 +572,6 @@ static void nfsd_last_thread(struct net *net)
return;
nfsd_shutdown_net(net);
pr_info("nfsd: last server has exited, flushing export cache\n");
nfsd_export_flush(net);
}
@ -786,7 +785,6 @@ int
nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
{
int error;
bool nfsd_up_before;
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
struct svc_serv *serv;
@ -806,8 +804,6 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
error = nfsd_create_serv(net);
if (error)
goto out;
nfsd_up_before = nn->nfsd_net_up;
serv = nn->nfsd_serv;
error = nfsd_startup_net(net, cred);
@ -815,17 +811,15 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
goto out_put;
error = svc_set_num_threads(serv, NULL, nrservs);
if (error)
goto out_shutdown;
goto out_put;
error = serv->sv_nrthreads;
if (error == 0)
nfsd_last_thread(net);
out_shutdown:
if (error < 0 && !nfsd_up_before)
nfsd_shutdown_net(net);
out_put:
/* Threads now hold service active */
if (xchg(&nn->keep_active, 0))
svc_put(serv);
if (serv->sv_nrthreads == 0)
nfsd_last_thread(net);
svc_put(serv);
out:
mutex_unlock(&nfsd_mutex);