iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

NFSD: simplify per-net file cache management

Browse Source 
[ Upstream commit 1463b38e7cf34d4cc60f41daff459ad807b2e408 ]

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: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
NeilBrown 2021-12-01 10:58:14 +11:00 committed by Greg Kroah-Hartman
parent 677fd67d8b
commit e8f923e1e9
2 changed files with 17 additions and 61 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
fs/nfsd/filecache.c
View File

@ -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);
@ -366,19 +361,13 @@ 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();
spin_lock(&l->lock);
list_splice_tail_init(files, &l->freeme);
spin_unlock(&l->lock);
queue_work(nfsd_filecache_wq, &l->work);
}
static void
@ -754,7 +743,7 @@ 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;
@ -762,7 +751,6 @@ 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;
@ -771,61 +759,27 @@ 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();
nfsd_free_fcache_disposal(l);
}
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

2
fs/nfsd/netns.h
View File

@ -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 */