smb: client: improve purging of cached referrals

Purge cached referrals that have a single target when reaching maximum
of cache size as the client won't need them to failover.  Otherwise
remove oldest cache entry.

Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c
index 3cf7c88489be456a073d54f5c8ffa8585bc49628..e496dbf8c6228f03c1733c9695e190677b5b4109 100644 (file)
--- a/fs/smb/client/dfs_cache.c
+++ b/fs/smb/client/dfs_cache.c
@@ -126,6 +126,7 @@ static inline void free_tgts(struct cache_entry *ce)
 
 static inline void flush_cache_ent(struct cache_entry *ce)
 {
+       cifs_dbg(FYI, "%s: %s\n", __func__, ce->path);
        hlist_del_init(&ce->hlist);
        kfree(ce->path);
        free_tgts(ce);
@@ -441,34 +442,31 @@ static struct cache_entry *alloc_cache_entry(struct dfs_info3_param *refs, int n
        return ce;
 }
 
-static void remove_oldest_entry_locked(void)
+/* Remove all referrals that have a single target or oldest entry */
+static void purge_cache(void)
 {
        int i;
        struct cache_entry *ce;
-       struct cache_entry *to_del = NULL;
-
-       WARN_ON(!rwsem_is_locked(&htable_rw_lock));
+       struct cache_entry *oldest = NULL;
 
        for (i = 0; i < CACHE_HTABLE_SIZE; i++) {
                struct hlist_head *l = &cache_htable[i];
+               struct hlist_node *n;
 
-               hlist_for_each_entry(ce, l, hlist) {
+               hlist_for_each_entry_safe(ce, n, l, hlist) {
                        if (hlist_unhashed(&ce->hlist))
                                continue;
-                       if (!to_del || timespec64_compare(&ce->etime,
-                                                         &to_del->etime) < 0)
-                               to_del = ce;
+                       if (ce->numtgts == 1)
+                               flush_cache_ent(ce);
+                       else if (!oldest ||
+                                timespec64_compare(&ce->etime,
+                                                   &oldest->etime) < 0)
+                               oldest = ce;
                }
        }
 
-       if (!to_del) {
-               cifs_dbg(FYI, "%s: no entry to remove\n", __func__);
-               return;
-       }
-
-       cifs_dbg(FYI, "%s: removing entry\n", __func__);
-       dump_ce(to_del);
-       flush_cache_ent(to_del);
+       if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES && oldest)
+               flush_cache_ent(oldest);
 }
 
 /* Add a new DFS cache entry */
@@ -484,7 +482,7 @@ static struct cache_entry *add_cache_entry_locked(struct dfs_info3_param *refs,
 
        if (atomic_read(&cache_count) >= CACHE_MAX_ENTRIES) {
                cifs_dbg(FYI, "%s: reached max cache size (%d)\n", __func__, CACHE_MAX_ENTRIES);
-               remove_oldest_entry_locked();
+               purge_cache();
        }
 
        rc = cache_entry_hash(refs[0].path_name, strlen(refs[0].path_name), &hash);