Commit 1463b38e authored by NeilBrown's avatar NeilBrown Committed by Chuck Lever
Browse files

NFSD: simplify per-net file cache management 



We currently have a 'laundrette' for closing cached files - a different
work-item for each network-namespace.

These 'laundrettes' (aka struct nfsd_fcache_disposal) are currently on a
list, and are freed using rcu.

The list is not necessary as we have a per-namespace structure (struct
nfsd_net) which can hold a link to the nfsd_fcache_disposal.
The use of kfree_rcu is also unnecessary as the cache is cleaned of all
files associated with a given namespace, and no new files can be added,
before the nfsd_fcache_disposal is freed.

So add a '->fcache_disposal' link to nfsd_net, and discard the list
management and rcu usage.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 1e37d0e5

fs/nfsd/filecache.c

+15 −61
Original line number Diff line number Diff line
@@ -44,12 +44,9 @@ struct nfsd_fcache_bucket { 
static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);



struct nfsd_fcache_disposal {

	struct list_head list;

	struct work_struct work;

	struct net *net;

	spinlock_t lock;

	struct list_head freeme;

	struct rcu_head rcu;

};



static struct workqueue_struct *nfsd_filecache_wq __read_mostly;
@@ -62,8 +59,6 @@ static long nfsd_file_lru_flags; 
static struct fsnotify_group		*nfsd_file_fsnotify_group;

static atomic_long_t			nfsd_filecache_count;

static struct delayed_work		nfsd_filecache_laundrette;

static DEFINE_SPINLOCK(laundrette_lock);

static LIST_HEAD(laundrettes);



static void nfsd_file_gc(void);
@@ -367,19 +362,13 @@ nfsd_file_list_remove_disposal(struct list_head *dst, 
static void

nfsd_file_list_add_disposal(struct list_head *files, struct net *net)

{

	struct nfsd_fcache_disposal *l;

	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	struct nfsd_fcache_disposal *l = nn->fcache_disposal;



	rcu_read_lock();

	list_for_each_entry_rcu(l, &laundrettes, list) {

		if (l->net == net) {

	spin_lock(&l->lock);

	list_splice_tail_init(files, &l->freeme);

	spin_unlock(&l->lock);

	queue_work(nfsd_filecache_wq, &l->work);

			break;

		}

	}

	rcu_read_unlock();

}



static void
@@ -755,7 +744,7 @@ nfsd_file_cache_purge(struct net *net) 
}



static struct nfsd_fcache_disposal *

nfsd_alloc_fcache_disposal(struct net *net)

nfsd_alloc_fcache_disposal(void)

{

	struct nfsd_fcache_disposal *l;
@@ -763,7 +752,6 @@ nfsd_alloc_fcache_disposal(struct net *net) 
	if (!l)

		return NULL;

	INIT_WORK(&l->work, nfsd_file_delayed_close);

	l->net = net;

	spin_lock_init(&l->lock);

	INIT_LIST_HEAD(&l->freeme);

	return l;
@@ -772,61 +760,27 @@ nfsd_alloc_fcache_disposal(struct net *net) 
static void

nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l)

{

	rcu_assign_pointer(l->net, NULL);

	cancel_work_sync(&l->work);

	nfsd_file_dispose_list(&l->freeme);

	kfree_rcu(l, rcu);

}



static void

nfsd_add_fcache_disposal(struct nfsd_fcache_disposal *l)

{

	spin_lock(&laundrette_lock);

	list_add_tail_rcu(&l->list, &laundrettes);

	spin_unlock(&laundrette_lock);

}



static void

nfsd_del_fcache_disposal(struct nfsd_fcache_disposal *l)

{

	spin_lock(&laundrette_lock);

	list_del_rcu(&l->list);

	spin_unlock(&laundrette_lock);

}



static int

nfsd_alloc_fcache_disposal_net(struct net *net)

{

	struct nfsd_fcache_disposal *l;



	l = nfsd_alloc_fcache_disposal(net);

	if (!l)

		return -ENOMEM;

	nfsd_add_fcache_disposal(l);

	return 0;

	kfree(l);

}



static void

nfsd_free_fcache_disposal_net(struct net *net)

{

	struct nfsd_fcache_disposal *l;

	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	struct nfsd_fcache_disposal *l = nn->fcache_disposal;



	rcu_read_lock();

	list_for_each_entry_rcu(l, &laundrettes, list) {

		if (l->net != net)

			continue;

		nfsd_del_fcache_disposal(l);

		rcu_read_unlock();

	nfsd_free_fcache_disposal(l);

		return;

	}

	rcu_read_unlock();

}



int

nfsd_file_cache_start_net(struct net *net)

{

	return nfsd_alloc_fcache_disposal_net(net);

	struct nfsd_net *nn = net_generic(net, nfsd_net_id);



	nn->fcache_disposal = nfsd_alloc_fcache_disposal();

	return nn->fcache_disposal ? 0 : -ENOMEM;

}



void

fs/nfsd/netns.h

+2 −0
Original line number Diff line number Diff line
@@ -185,6 +185,8 @@ struct nfsd_net { 


	/* utsname taken from the process that starts the server */

	char			nfsd_name[UNX_MAXNODENAME+1];



	struct nfsd_fcache_disposal *fcache_disposal;

};



/* Simple check to find out if a given net was properly initialized */