NFSD: Trace filecache LRU activity

Observe the operation of garbage collection and the lifetime of
filecache items.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index f58685f..e831a7b 100644 (file)
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -261,6 +261,18 @@ nfsd_file_flush(struct nfsd_file *nf)
                nfsd_reset_write_verifier(net_generic(nf->nf_net, nfsd_net_id));
 }
 
+static void nfsd_file_lru_add(struct nfsd_file *nf)
+{
+       if (list_lru_add(&nfsd_file_lru, &nf->nf_lru))
+               trace_nfsd_file_lru_add(nf);
+}
+
+static void nfsd_file_lru_remove(struct nfsd_file *nf)
+{
+       if (list_lru_del(&nfsd_file_lru, &nf->nf_lru))
+               trace_nfsd_file_lru_del(nf);
+}
+
 static void
 nfsd_file_do_unhash(struct nfsd_file *nf)
 {
@@ -280,8 +292,7 @@ nfsd_file_unhash(struct nfsd_file *nf)
 {
        if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
                nfsd_file_do_unhash(nf);
-               if (!list_empty(&nf->nf_lru))
-                       list_lru_del(&nfsd_file_lru, &nf->nf_lru);
+               nfsd_file_lru_remove(nf);
                return true;
        }
        return false;
@@ -444,27 +455,34 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
         * counter. Here we check the counter and then test and clear the flag.
         * That order is deliberate to ensure that we can do this locklessly.
         */
-       if (refcount_read(&nf->nf_ref) > 1)
-               goto out_skip;
+       if (refcount_read(&nf->nf_ref) > 1) {
+               trace_nfsd_file_gc_in_use(nf);
+               return LRU_SKIP;
+       }
 
        /*
         * Don't throw out files that are still undergoing I/O or
         * that have uncleared errors pending.
         */
-       if (nfsd_file_check_writeback(nf))
-               goto out_skip;
+       if (nfsd_file_check_writeback(nf)) {
+               trace_nfsd_file_gc_writeback(nf);
+               return LRU_SKIP;
+       }
 
-       if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags))
-               goto out_skip;
+       if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags)) {
+               trace_nfsd_file_gc_referenced(nf);
+               return LRU_SKIP;
+       }
 
-       if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags))
-               goto out_skip;
+       if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
+               trace_nfsd_file_gc_hashed(nf);
+               return LRU_SKIP;
+       }
 
        list_lru_isolate_move(lru, &nf->nf_lru, head);
        this_cpu_inc(nfsd_file_evictions);
+       trace_nfsd_file_gc_disposed(nf);
        return LRU_REMOVED;
-out_skip:
-       return LRU_SKIP;
 }
 
 /*
@@ -1017,7 +1035,7 @@ open_file:
        refcount_inc(&nf->nf_ref);
        __set_bit(NFSD_FILE_HASHED, &nf->nf_flags);
        __set_bit(NFSD_FILE_PENDING, &nf->nf_flags);
-       list_lru_add(&nfsd_file_lru, &nf->nf_lru);
+       nfsd_file_lru_add(nf);
        hlist_add_head_rcu(&nf->nf_node, &nfsd_file_hashtbl[hashval].nfb_head);
        ++nfsd_file_hashtbl[hashval].nfb_count;
        nfsd_file_hashtbl[hashval].nfb_maxcount = max(nfsd_file_hashtbl[hashval].nfb_maxcount,

diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 22f57fe..64a6c57 100644 (file)
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -895,6 +895,45 @@ TRACE_EVENT(nfsd_file_fsnotify_handle_event,
                        __entry->nlink, __entry->mode, __entry->mask)
 );
 
+DECLARE_EVENT_CLASS(nfsd_file_gc_class,
+       TP_PROTO(
+               const struct nfsd_file *nf
+       ),
+       TP_ARGS(nf),
+       TP_STRUCT__entry(
+               __field(void *, nf_inode)
+               __field(void *, nf_file)
+               __field(int, nf_ref)
+               __field(unsigned long, nf_flags)
+       ),
+       TP_fast_assign(
+               __entry->nf_inode = nf->nf_inode;
+               __entry->nf_file = nf->nf_file;
+               __entry->nf_ref = refcount_read(&nf->nf_ref);
+               __entry->nf_flags = nf->nf_flags;
+       ),
+       TP_printk("inode=%p ref=%d nf_flags=%s nf_file=%p",
+               __entry->nf_inode, __entry->nf_ref,
+               show_nf_flags(__entry->nf_flags),
+               __entry->nf_file
+       )
+);
+
+#define DEFINE_NFSD_FILE_GC_EVENT(name)                                        \
+DEFINE_EVENT(nfsd_file_gc_class, name,                                 \
+       TP_PROTO(                                                       \
+               const struct nfsd_file *nf                              \
+       ),                                                              \
+       TP_ARGS(nf))
+
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_lru_add);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_lru_del);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_gc_in_use);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_gc_writeback);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_gc_referenced);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_gc_hashed);
+DEFINE_NFSD_FILE_GC_EVENT(nfsd_file_gc_disposed);
+
 DECLARE_EVENT_CLASS(nfsd_file_lruwalk_class,
        TP_PROTO(
                unsigned long removed,