NFSv4: Use RCU to protect delegations
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 93a9f4b..56f4f6a 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -27,6 +27,13 @@
kfree(delegation);
}
+static void nfs_free_delegation_callback(struct rcu_head *head)
+{
+ struct nfs_delegation *delegation = container_of(head, struct nfs_delegation, rcu);
+
+ nfs_free_delegation(delegation);
+}
+
static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
{
struct inode *inode = state->inode;
@@ -133,10 +140,10 @@
delegation->inode = inode;
spin_lock(&clp->cl_lock);
- if (nfsi->delegation == NULL) {
- list_add(&delegation->super_list, &clp->cl_delegations);
- nfsi->delegation = delegation;
+ if (rcu_dereference(nfsi->delegation) == NULL) {
+ list_add_rcu(&delegation->super_list, &clp->cl_delegations);
nfsi->delegation_state = delegation->type;
+ rcu_assign_pointer(nfsi->delegation, delegation);
delegation = NULL;
} else {
if (memcmp(&delegation->stateid, &nfsi->delegation->stateid,
@@ -157,7 +164,7 @@
int res = 0;
res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid);
- nfs_free_delegation(delegation);
+ call_rcu(&delegation->rcu, nfs_free_delegation_callback);
return res;
}
@@ -191,16 +198,16 @@
static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi, const nfs4_stateid *stateid)
{
- struct nfs_delegation *delegation = nfsi->delegation;
+ struct nfs_delegation *delegation = rcu_dereference(nfsi->delegation);
if (delegation == NULL)
goto nomatch;
if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
sizeof(delegation->stateid.data)) != 0)
goto nomatch;
- list_del_init(&delegation->super_list);
- nfsi->delegation = NULL;
+ list_del_rcu(&delegation->super_list);
nfsi->delegation_state = 0;
+ rcu_assign_pointer(nfsi->delegation, NULL);
return delegation;
nomatch:
return NULL;
@@ -213,7 +220,7 @@
struct nfs_delegation *delegation;
int err = 0;
- if (nfsi->delegation_state != 0) {
+ if (rcu_dereference(nfsi->delegation) != NULL) {
spin_lock(&clp->cl_lock);
delegation = nfs_detach_delegation_locked(nfsi, NULL);
spin_unlock(&clp->cl_lock);
@@ -235,20 +242,23 @@
if (clp == NULL)
return;
restart:
- spin_lock(&clp->cl_lock);
- list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
if (delegation->inode->i_sb != sb)
continue;
inode = igrab(delegation->inode);
if (inode == NULL)
continue;
- nfs_detach_delegation_locked(NFS_I(inode), NULL);
+ spin_lock(&clp->cl_lock);
+ delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL);
spin_unlock(&clp->cl_lock);
- __nfs_inode_return_delegation(inode, delegation);
+ rcu_read_unlock();
+ if (delegation != NULL)
+ __nfs_inode_return_delegation(inode, delegation);
iput(inode);
goto restart;
}
- spin_unlock(&clp->cl_lock);
+ rcu_read_unlock();
}
static int nfs_do_expire_all_delegations(void *ptr)
@@ -259,23 +269,26 @@
allow_signal(SIGKILL);
restart:
- spin_lock(&clp->cl_lock);
if (test_bit(NFS4CLNT_STATE_RECOVER, &clp->cl_state) != 0)
goto out;
if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0)
goto out;
- list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
inode = igrab(delegation->inode);
if (inode == NULL)
continue;
- nfs_detach_delegation_locked(NFS_I(inode), NULL);
+ spin_lock(&clp->cl_lock);
+ delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL);
spin_unlock(&clp->cl_lock);
- __nfs_inode_return_delegation(inode, delegation);
+ rcu_read_unlock();
+ if (delegation)
+ __nfs_inode_return_delegation(inode, delegation);
iput(inode);
goto restart;
}
+ rcu_read_unlock();
out:
- spin_unlock(&clp->cl_lock);
nfs_put_client(clp);
module_put_and_exit(0);
}
@@ -306,18 +319,21 @@
if (clp == NULL)
return;
restart:
- spin_lock(&clp->cl_lock);
- list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
inode = igrab(delegation->inode);
if (inode == NULL)
continue;
- nfs_detach_delegation_locked(NFS_I(inode), NULL);
+ spin_lock(&clp->cl_lock);
+ delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL);
spin_unlock(&clp->cl_lock);
- __nfs_inode_return_delegation(inode, delegation);
+ rcu_read_unlock();
+ if (delegation != NULL)
+ __nfs_inode_return_delegation(inode, delegation);
iput(inode);
goto restart;
}
- spin_unlock(&clp->cl_lock);
+ rcu_read_unlock();
}
struct recall_threadargs {
@@ -391,14 +407,14 @@
{
struct nfs_delegation *delegation;
struct inode *res = NULL;
- spin_lock(&clp->cl_lock);
- list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
if (nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
res = igrab(delegation->inode);
break;
}
}
- spin_unlock(&clp->cl_lock);
+ rcu_read_unlock();
return res;
}
@@ -408,10 +424,10 @@
void nfs_delegation_mark_reclaim(struct nfs_client *clp)
{
struct nfs_delegation *delegation;
- spin_lock(&clp->cl_lock);
- list_for_each_entry(delegation, &clp->cl_delegations, super_list)
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list)
delegation->flags |= NFS_DELEGATION_NEED_RECLAIM;
- spin_unlock(&clp->cl_lock);
+ rcu_read_unlock();
}
/*
@@ -419,39 +435,35 @@
*/
void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
{
- struct nfs_delegation *delegation, *n;
- LIST_HEAD(head);
- spin_lock(&clp->cl_lock);
- list_for_each_entry_safe(delegation, n, &clp->cl_delegations, super_list) {
+ struct nfs_delegation *delegation;
+restart:
+ rcu_read_lock();
+ list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
if ((delegation->flags & NFS_DELEGATION_NEED_RECLAIM) == 0)
continue;
- list_move(&delegation->super_list, &head);
- NFS_I(delegation->inode)->delegation = NULL;
- NFS_I(delegation->inode)->delegation_state = 0;
+ spin_lock(&clp->cl_lock);
+ delegation = nfs_detach_delegation_locked(NFS_I(delegation->inode), NULL);
+ spin_unlock(&clp->cl_lock);
+ rcu_read_unlock();
+ if (delegation != NULL)
+ call_rcu(&delegation->rcu, nfs_free_delegation_callback);
+ goto restart;
}
- spin_unlock(&clp->cl_lock);
- while(!list_empty(&head)) {
- delegation = list_entry(head.next, struct nfs_delegation, super_list);
- list_del(&delegation->super_list);
- nfs_free_delegation(delegation);
- }
+ rcu_read_unlock();
}
int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
{
- struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs_delegation *delegation;
- int res = 0;
+ int ret = 0;
- if (nfsi->delegation_state == 0)
- return 0;
- spin_lock(&clp->cl_lock);
- delegation = nfsi->delegation;
+ rcu_read_lock();
+ delegation = rcu_dereference(nfsi->delegation);
if (delegation != NULL) {
memcpy(dst->data, delegation->stateid.data, sizeof(dst->data));
- res = 1;
+ ret = 1;
}
- spin_unlock(&clp->cl_lock);
- return res;
+ rcu_read_unlock();
+ return ret;
}
diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index 8f79a31..5874ce7 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -22,6 +22,7 @@
long flags;
loff_t maxsize;
__u64 change_attr;
+ struct rcu_head rcu;
};
int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res);
@@ -45,11 +46,16 @@
static inline int nfs_have_delegation(struct inode *inode, int flags)
{
+ struct nfs_delegation *delegation;
+ int ret = 0;
+
flags &= FMODE_READ|FMODE_WRITE;
- smp_rmb();
- if ((NFS_I(inode)->delegation_state & flags) == flags)
- return 1;
- return 0;
+ rcu_read_lock();
+ delegation = rcu_dereference(NFS_I(inode)->delegation);
+ if (delegation != NULL && (delegation->type & flags) == flags)
+ ret = 1;
+ rcu_read_unlock();
+ return ret;
}
#else