Commit f5b3108e authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Trond Myklebust
Browse files

NFS: use a hash table for delegation lookup 



nfs_delegation_find_inode currently has to walk the entire list of
delegations per inode, which can become pretty large, and can become even
larger when increasing the delegation watermark.

Add a hash table to speed up the delegation lookup, sized as a fraction
of the delegation watermark.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250718081509.2607553-6-hch@lst.de


Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 2fb4af5e

fs/nfs/delegation.c

+27 −1
Original line number Diff line number Diff line
@@ -30,6 +30,13 @@ 
static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;

module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);



static struct hlist_head *nfs_delegation_hash(struct nfs_server *server,

		const struct nfs_fh *fhandle)

{

	return server->delegation_hash_table +

		(nfs_fhandle_hash(fhandle) & server->delegation_hash_mask);

}



static void __nfs_free_delegation(struct nfs_delegation *delegation)

{

	put_cred(delegation->cred);
@@ -367,6 +374,7 @@ nfs_detach_delegation_locked(struct nfs_inode *nfsi, 
		spin_unlock(&delegation->lock);

		return NULL;

	}

	hlist_del_init_rcu(&delegation->hash);

	list_del_rcu(&delegation->super_list);

	delegation->inode = NULL;

	rcu_assign_pointer(nfsi->delegation, NULL);
@@ -529,6 +537,8 @@ int nfs_inode_set_delegation(struct inode *inode, const struct cred *cred, 
	spin_unlock(&inode->i_lock);



	list_add_tail_rcu(&delegation->super_list, &server->delegations);

	hlist_add_head_rcu(&delegation->hash,

			nfs_delegation_hash(server, &NFS_I(inode)->fh));

	rcu_assign_pointer(nfsi->delegation, delegation);

	delegation = NULL;
@@ -1166,11 +1176,12 @@ static struct inode * 
nfs_delegation_find_inode_server(struct nfs_server *server,

				 const struct nfs_fh *fhandle)

{

	struct hlist_head *head = nfs_delegation_hash(server, fhandle);

	struct nfs_delegation *delegation;

	struct super_block *freeme = NULL;

	struct inode *res = NULL;



	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {

	hlist_for_each_entry_rcu(delegation, head, hash) {

		spin_lock(&delegation->lock);

		if (delegation->inode != NULL &&

		    !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
@@ -1577,3 +1588,18 @@ bool nfs4_delegation_flush_on_close(const struct inode *inode) 
	rcu_read_unlock();

	return ret;

}



int nfs4_delegation_hash_alloc(struct nfs_server *server)

{

	int delegation_buckets, i;



	delegation_buckets = roundup_pow_of_two(nfs_delegation_watermark / 16);

	server->delegation_hash_mask = delegation_buckets - 1;

	server->delegation_hash_table = kmalloc_array(delegation_buckets,

			sizeof(*server->delegation_hash_table), GFP_KERNEL);

	if (!server->delegation_hash_table)

		return -ENOMEM;

	for (i = 0; i < delegation_buckets; i++)

		INIT_HLIST_HEAD(&server->delegation_hash_table[i]);

	return 0;

}

fs/nfs/delegation.h

+3 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
 * NFSv4 delegation

 */

struct nfs_delegation {

	struct hlist_node hash;

	struct list_head super_list;

	const struct cred *cred;

	struct inode *inode;
@@ -123,4 +124,6 @@ static inline int nfs_have_delegated_mtime(struct inode *inode) 
						 NFS_DELEGATION_FLAG_TIME);

}



int nfs4_delegation_hash_alloc(struct nfs_server *server);



#endif

fs/nfs/nfs4client.c

+5 −0
Original line number Diff line number Diff line
@@ -802,6 +802,7 @@ static void nfs4_destroy_server(struct nfs_server *server) 
	unset_pnfs_layoutdriver(server);

	nfs4_purge_state_owners(server, &freeme);

	nfs4_free_state_owners(&freeme);

	kfree(server->delegation_hash_table);

}



/*
@@ -1096,6 +1097,10 @@ static int nfs4_server_common_setup(struct nfs_server *server, 
{

	int error;



	error = nfs4_delegation_hash_alloc(server);

	if (error)

		return error;



	/* data servers support only a subset of NFSv4.1 */

	if (is_ds_only_client(server->nfs_client))

		return -EPROTONOSUPPORT;

fs/nfs/nfs4proc.c

+21 −1
Original line number Diff line number Diff line
@@ -10967,6 +10967,26 @@ static const struct inode_operations nfs4_file_inode_operations = { 
	.listxattr	= nfs4_listxattr,

};



static struct nfs_server *nfs4_clone_server(struct nfs_server *source,

		struct nfs_fh *fh, struct nfs_fattr *fattr,

		rpc_authflavor_t flavor)

{

	struct nfs_server *server;

	int error;



	server = nfs_clone_server(source, fh, fattr, flavor);

	if (IS_ERR(server))

		return server;



	error = nfs4_delegation_hash_alloc(server);

	if (error) {

		nfs_free_server(server);

		return ERR_PTR(error);

	}



	return server;

}



const struct nfs_rpc_ops nfs_v4_clientops = {

	.version	= 4,			/* protocol version */

	.dentry_ops	= &nfs4_dentry_operations,
@@ -11019,7 +11039,7 @@ const struct nfs_rpc_ops nfs_v4_clientops = { 
	.init_client	= nfs4_init_client,

	.free_client	= nfs4_free_client,

	.create_server	= nfs4_create_server,

	.clone_server	= nfs_clone_server,

	.clone_server	= nfs4_clone_server,

	.discover_trunking = nfs4_discover_trunking,

	.enable_swap	= nfs4_enable_swap,

	.disable_swap	= nfs4_disable_swap,

include/linux/nfs_fs_sb.h

+2 −0
Original line number Diff line number Diff line
@@ -255,6 +255,8 @@ struct nfs_server { 
	struct list_head	layouts;

	struct list_head	delegations;

	atomic_long_t		nr_active_delegations;

	unsigned int		delegation_hash_mask;

	struct hlist_head	*delegation_hash_table;

	struct list_head	ss_copies;

	struct list_head	ss_src_copies;