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NFSv4: Convert open state lookup to use RCU

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Further reduce contention on the inode->i_lock.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2018-09-02 19:15:15 -04:00
parent 0de43976fb
commit 9ae075fdd1
2 changed files with 7 additions and 6 deletions
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1
fs/nfs/nfs4_fs.h
View File

@ -191,6 +191,7 @@ struct nfs4_state {
atomic_t count;
wait_queue_head_t waitq;
struct rcu_head rcu_head;
};

12
fs/nfs/nfs4state.c
View File

@ -684,7 +684,7 @@ __nfs4_find_state_byowner(struct inode *inode, struct nfs4_state_owner *owner)
struct nfs_inode *nfsi = NFS_I(inode);
struct nfs4_state *state;
list_for_each_entry(state, &nfsi->open_states, inode_states) {
list_for_each_entry_rcu(state, &nfsi->open_states, inode_states) {
if (state->owner != owner)
continue;
if (!nfs4_valid_open_stateid(state))
@ -698,7 +698,7 @@ __nfs4_find_state_byowner(struct inode *inode, struct nfs4_state_owner *owner)
static void
nfs4_free_open_state(struct nfs4_state *state)
{
kfree(state);
kfree_rcu(state, rcu_head);
}
struct nfs4_state *
@ -707,9 +707,9 @@ nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner)
struct nfs4_state *state, *new;
struct nfs_inode *nfsi = NFS_I(inode);
spin_lock(&inode->i_lock);
rcu_read_lock();
state = __nfs4_find_state_byowner(inode, owner);
spin_unlock(&inode->i_lock);
rcu_read_unlock();
if (state)
goto out;
new = nfs4_alloc_open_state();
@ -720,7 +720,7 @@ nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner)
state = new;
state->owner = owner;
atomic_inc(&owner->so_count);
list_add(&state->inode_states, &nfsi->open_states);
list_add_rcu(&state->inode_states, &nfsi->open_states);
ihold(inode);
state->inode = inode;
spin_unlock(&inode->i_lock);
@ -746,7 +746,7 @@ void nfs4_put_open_state(struct nfs4_state *state)
if (!atomic_dec_and_lock(&state->count, &owner->so_lock))
return;
spin_lock(&inode->i_lock);
list_del(&state->inode_states);
list_del_rcu(&state->inode_states);
list_del(&state->open_states);
spin_unlock(&inode->i_lock);
spin_unlock(&owner->so_lock);