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-rw-r--r--fs/nfs/dir.c43
1 files changed, 41 insertions, 2 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 2bfbde0f7176..1b5f38f48dab 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2079,7 +2079,7 @@ MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache lengt
static void nfs_access_free_entry(struct nfs_access_entry *entry)
{
put_rpccred(entry->cred);
- kfree(entry);
+ kfree_rcu(entry, rcu_head);
smp_mb__before_atomic();
atomic_long_dec(&nfs_access_nr_entries);
smp_mb__after_atomic();
@@ -2257,6 +2257,38 @@ out_zap:
return -ENOENT;
}
+static int nfs_access_get_cached_rcu(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
+{
+ /* Only check the most recently returned cache entry,
+ * but do it without locking.
+ */
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct nfs_access_entry *cache;
+ int err = -ECHILD;
+ struct list_head *lh;
+
+ rcu_read_lock();
+ if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
+ goto out;
+ lh = rcu_dereference(nfsi->access_cache_entry_lru.prev);
+ cache = list_entry(lh, struct nfs_access_entry, lru);
+ if (lh == &nfsi->access_cache_entry_lru ||
+ cred != cache->cred)
+ cache = NULL;
+ if (cache == NULL)
+ goto out;
+ if (!nfs_have_delegated_attributes(inode) &&
+ !time_in_range_open(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo))
+ goto out;
+ res->jiffies = cache->jiffies;
+ res->cred = cache->cred;
+ res->mask = cache->mask;
+ err = 0;
+out:
+ rcu_read_unlock();
+ return err;
+}
+
static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
{
struct nfs_inode *nfsi = NFS_I(inode);
@@ -2300,6 +2332,11 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
cache->cred = get_rpccred(set->cred);
cache->mask = set->mask;
+ /* The above field assignments must be visible
+ * before this item appears on the lru. We cannot easily
+ * use rcu_assign_pointer, so just force the memory barrier.
+ */
+ smp_wmb();
nfs_access_add_rbtree(inode, cache);
/* Update accounting */
@@ -2339,7 +2376,9 @@ static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
trace_nfs_access_enter(inode);
- status = nfs_access_get_cached(inode, cred, &cache);
+ status = nfs_access_get_cached_rcu(inode, cred, &cache);
+ if (status != 0)
+ status = nfs_access_get_cached(inode, cred, &cache);
if (status == 0)
goto out_cached;