SUNRPC/NFSD: clean up get/put functions.

svc_destroy() is poorly named - it doesn't necessarily destroy the svc,
it might just reduce the ref count.
nfsd_destroy() is poorly named for the same reason.

This patch:
 - removes the refcount functionality from svc_destroy(), moving it to
   a new svc_put().  Almost all previous callers of svc_destroy() now
   call svc_put().
 - renames nfsd_destroy() to nfsd_put() and improves the code, using
   the new svc_destroy() rather than svc_put()
 - removes a few comments that explain the important for balanced
   get/put calls.  This should be obvious.

The only non-trivial part of this is that svc_destroy() would call
svc_sock_update() on a non-final decrement.  It can no longer do that,
and svc_put() isn't really a good place of it.  This call is now made
from svc_exit_thread() which seems like a good place.  This makes the
call *before* sv_nrthreads is decremented rather than after.  This
is not particularly important as the call just sets a flag which
causes sv_nrthreads set be checked later.  A subsequent patch will
improve the ordering.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 6e5e742a42b8..edbc7579b4aa 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -267,10 +267,6 @@ static struct svc_serv *nfs_callback_create_svc(int minorversion)
 	 * Check whether we're already up and running.
 	 */
 	if (cb_info->serv)
-		/*
-		 * Note: increase service usage, because later in case of error
-		 * svc_destroy() will be called.
-		 */
 		return svc_get(cb_info->serv);
 
 	switch (minorversion) {
@@ -333,16 +329,10 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
 		goto err_start;
 
 	cb_info->users++;
-	/*
-	 * svc_create creates the svc_serv with sv_nrthreads == 1, and then
-	 * svc_prepare_thread increments that. So we need to call svc_destroy
-	 * on both success and failure so that the refcount is 1 when the
-	 * thread exits.
-	 */
 err_net:
 	if (!cb_info->users)
 		cb_info->serv = NULL;
-	svc_destroy(serv);
+	svc_put(serv);
 err_create:
 	mutex_unlock(&nfs_callback_mutex);
 	return ret;
@@ -368,7 +358,7 @@ void nfs_callback_down(int minorversion, struct net *net)
 	if (cb_info->users == 0) {
 		svc_get(serv);
 		serv->sv_ops->svo_setup(serv, NULL, 0);
-		svc_destroy(serv);
+		svc_put(serv);
 		dprintk("nfs_callback_down: service destroyed\n");
 		cb_info->serv = NULL;
 	}