2020-07-28 20:18:38

by Frank van der Linden

[permalink] [raw]
Subject: [PATCH] NFSv4.2: xattr cache: get rid of cache discard work queue

Caches should be small enough to discard them inline, so do that
instead of using a work queue.

Signed-off-by: Frank van der Linden <[email protected]>
---
fs/nfs/nfs42xattr.c | 37 +++++--------------------------------
1 file changed, 5 insertions(+), 32 deletions(-)

diff --git a/fs/nfs/nfs42xattr.c b/fs/nfs/nfs42xattr.c
index 23fdab977a2a..86777996cfec 100644
--- a/fs/nfs/nfs42xattr.c
+++ b/fs/nfs/nfs42xattr.c
@@ -75,7 +75,6 @@ struct nfs4_xattr_cache {
spinlock_t listxattr_lock;
struct inode *inode;
struct nfs4_xattr_entry *listxattr;
- struct work_struct work;
};

struct nfs4_xattr_entry {
@@ -101,8 +100,6 @@ static struct list_lru nfs4_xattr_large_entry_lru;

static struct kmem_cache *nfs4_xattr_cache_cachep;

-static struct workqueue_struct *nfs4_xattr_cache_wq;
-
/*
* Hashing helper functions.
*/
@@ -365,9 +362,8 @@ nfs4_xattr_cache_unlink(struct inode *inode)
}

/*
- * Discard a cache. Usually called by a worker, since walking all
- * the entries can take up some cycles that we don't want to waste
- * in the I/O path. Can also be called from the shrinker callback.
+ * Discard a cache. Called by get_cache() if there was an old,
+ * invalid cache. Can also be called from a shrinker callback.
*
* The cache is dead, it has already been unlinked from its inode,
* and no longer appears on the cache LRU list.
@@ -414,21 +410,6 @@ nfs4_xattr_discard_cache(struct nfs4_xattr_cache *cache)
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}

-static void
-nfs4_xattr_discard_cache_worker(struct work_struct *work)
-{
- struct nfs4_xattr_cache *cache = container_of(work,
- struct nfs4_xattr_cache, work);
-
- nfs4_xattr_discard_cache(cache);
-}
-
-static void
-nfs4_xattr_reap_cache(struct nfs4_xattr_cache *cache)
-{
- queue_work(nfs4_xattr_cache_wq, &cache->work);
-}
-
/*
* Get a referenced copy of the cache structure. Avoid doing allocs
* while holding i_lock. Which means that we do some optimistic allocation,
@@ -513,10 +494,10 @@ nfs4_xattr_get_cache(struct inode *inode, int add)

out:
/*
- * Discarding an old cache is done via a workqueue.
+ * Discard the now orphaned old cache.
*/
if (oldcache != NULL)
- nfs4_xattr_reap_cache(oldcache);
+ nfs4_xattr_discard_cache(oldcache);

return cache;
}
@@ -1008,7 +989,6 @@ static void nfs4_xattr_cache_init_once(void *p)
atomic_long_set(&cache->nent, 0);
nfs4_xattr_hash_init(cache);
cache->listxattr = NULL;
- INIT_WORK(&cache->work, nfs4_xattr_discard_cache_worker);
INIT_LIST_HEAD(&cache->lru);
INIT_LIST_HEAD(&cache->dispose);
}
@@ -1039,13 +1019,9 @@ int __init nfs4_xattr_cache_init(void)
if (ret)
goto out2;

- nfs4_xattr_cache_wq = alloc_workqueue("nfs4_xattr", WQ_MEM_RECLAIM, 0);
- if (nfs4_xattr_cache_wq == NULL)
- goto out1;
-
ret = register_shrinker(&nfs4_xattr_cache_shrinker);
if (ret)
- goto out0;
+ goto out1;

ret = register_shrinker(&nfs4_xattr_entry_shrinker);
if (ret)
@@ -1058,8 +1034,6 @@ int __init nfs4_xattr_cache_init(void)
unregister_shrinker(&nfs4_xattr_entry_shrinker);
out:
unregister_shrinker(&nfs4_xattr_cache_shrinker);
-out0:
- destroy_workqueue(nfs4_xattr_cache_wq);
out1:
list_lru_destroy(&nfs4_xattr_cache_lru);
out2:
@@ -1079,5 +1053,4 @@ void nfs4_xattr_cache_exit(void)
list_lru_destroy(&nfs4_xattr_entry_lru);
list_lru_destroy(&nfs4_xattr_cache_lru);
kmem_cache_destroy(nfs4_xattr_cache_cachep);
- destroy_workqueue(nfs4_xattr_cache_wq);
}
--
2.17.2