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NFS: Clean up locking the nfs_versions list

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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: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Anna Schumaker 2024-10-01 16:33:40 -04:00 committed by Trond Myklebust
parent ff7afaeca1
commit 6278c86a6c
1 changed files with 8 additions and 11 deletions
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19
fs/nfs/client.c
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@ -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);