Commit 6278c86a authored by Anna Schumaker's avatar Anna Schumaker Committed by Trond Myklebust
Browse files

NFS: Clean up locking the nfs_versions list 



This patch replaces the nfs_version_mutex and nfs_version_lock with a
single RW lock that protects access to the nfs_versions list.

The mutex around request_module() seemed unnecessary to me, and I
couldn't find any other callers using a lock around calls to
request_module() when I looked.

At the same time, I saw fs/filesystems.c using a RW lock to protect
their filesystems list. This seems like a better idea than a spinlock to
me, so I'm also making that change while I'm here.

Signed-off-by: default avatarAnna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent ff7afaec

fs/nfs/client.c

+8 −11
Original line number Diff line number Diff line
@@ -55,8 +55,7 @@ 
#define NFSDBG_FACILITY		NFSDBG_CLIENT



static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);

static DEFINE_SPINLOCK(nfs_version_lock);

static DEFINE_MUTEX(nfs_version_mutex);

static DEFINE_RWLOCK(nfs_version_lock);

static LIST_HEAD(nfs_versions);



/*
@@ -79,16 +78,16 @@ const struct rpc_program nfs_program = { 
static struct nfs_subversion *find_nfs_version(unsigned int version)

{

	struct nfs_subversion *nfs;

	spin_lock(&nfs_version_lock);

	read_lock(&nfs_version_lock);



	list_for_each_entry(nfs, &nfs_versions, list) {

		if (nfs->rpc_ops->version == version) {

			spin_unlock(&nfs_version_lock);

			read_unlock(&nfs_version_lock);

			return nfs;

		}

	}



	spin_unlock(&nfs_version_lock);

	read_unlock(&nfs_version_lock);

	return ERR_PTR(-EPROTONOSUPPORT);

}
@@ -97,10 +96,8 @@ struct nfs_subversion *get_nfs_version(unsigned int version) 
	struct nfs_subversion *nfs = find_nfs_version(version);



	if (IS_ERR(nfs)) {

		mutex_lock(&nfs_version_mutex);

		request_module("nfsv%d", version);

		nfs = find_nfs_version(version);

		mutex_unlock(&nfs_version_mutex);

	}



	if (!IS_ERR(nfs) && !try_module_get(nfs->owner))
@@ -115,23 +112,23 @@ void put_nfs_version(struct nfs_subversion *nfs) 


void register_nfs_version(struct nfs_subversion *nfs)

{

	spin_lock(&nfs_version_lock);

	write_lock(&nfs_version_lock);



	list_add(&nfs->list, &nfs_versions);

	nfs_version[nfs->rpc_ops->version] = nfs->rpc_vers;



	spin_unlock(&nfs_version_lock);

	write_unlock(&nfs_version_lock);

}

EXPORT_SYMBOL_GPL(register_nfs_version);



void unregister_nfs_version(struct nfs_subversion *nfs)

{

	spin_lock(&nfs_version_lock);

	write_lock(&nfs_version_lock);



	nfs_version[nfs->rpc_ops->version] = NULL;

	list_del(&nfs->list);



	spin_unlock(&nfs_version_lock);

	write_unlock(&nfs_version_lock);

}

EXPORT_SYMBOL_GPL(unregister_nfs_version);