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NFS: Enforce an upper limit on the number of cached access call 

This may be used to limit the number of cached credentials building up
inside the access cache.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2014-07-21 13:53:48 -04:00
parent bae6746ff3
commit 3a505845cd
1 changed files with 35 additions and 7 deletions
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42
fs/nfs/dir.c
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@ -2028,6 +2028,10 @@ static DEFINE_SPINLOCK(nfs_access_lru_lock);
static LIST_HEAD(nfs_access_lru_list);
static atomic_long_t nfs_access_nr_entries;
static unsigned long nfs_access_max_cachesize = ULONG_MAX;
module_param(nfs_access_max_cachesize, ulong, 0644);
MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length");
static void nfs_access_free_entry(struct nfs_access_entry *entry)
{
put_rpccred(entry->cred);
@ -2048,19 +2052,14 @@ static void nfs_access_free_list(struct list_head *head)
}
}
unsigned long
nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
static unsigned long
nfs_do_access_cache_scan(unsigned int nr_to_scan)
{
LIST_HEAD(head);
struct nfs_inode *nfsi, *next;
struct nfs_access_entry *cache;
int nr_to_scan = sc->nr_to_scan;
gfp_t gfp_mask = sc->gfp_mask;
long freed = 0;
if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
return SHRINK_STOP;
spin_lock(&nfs_access_lru_lock);
list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
struct inode *inode;
@ -2093,12 +2092,40 @@ nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
return freed;
}
unsigned long
nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
{
int nr_to_scan = sc->nr_to_scan;
gfp_t gfp_mask = sc->gfp_mask;
if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
return SHRINK_STOP;
return nfs_do_access_cache_scan(nr_to_scan);
}
unsigned long
nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc)
{
return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
}
static void
nfs_access_cache_enforce_limit(void)
{
long nr_entries = atomic_long_read(&nfs_access_nr_entries);
unsigned long diff;
unsigned int nr_to_scan;
if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize)
return;
nr_to_scan = 100;
diff = nr_entries - nfs_access_max_cachesize;
if (diff < nr_to_scan)
nr_to_scan = diff;
nfs_do_access_cache_scan(nr_to_scan);
}
static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
{
struct rb_root *root_node = &nfsi->access_cache;
@ -2244,6 +2271,7 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
&nfs_access_lru_list);
spin_unlock(&nfs_access_lru_lock);
}
nfs_access_cache_enforce_limit();
}
EXPORT_SYMBOL_GPL(nfs_access_add_cache);