This is a note to let you know that I've just added the patch titled
NFSD: simplify per-net file cache management
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-simplify-per-net-file-cache-management.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 47410849ed2ffece288a34f43ca867af67cd6983
Author: NeilBrown <neilb@xxxxxxx>
Date: Wed Dec 1 10:58:14 2021 +1100
NFSD: simplify per-net file cache management
[ 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@xxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 8cd7d5d6955a0..b6ef8256c9c64 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -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
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 021acdc0d03bb..9e8b77d2a3a47 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -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 */
