Commit c46203ac authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Trace filecache LRU activity 



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

Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 668ed92e

fs/nfsd/filecache.c

+31 −13
Original line number Diff line number Diff line
@@ -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 @@ nfsd_do_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	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,

fs/nfsd/trace.h

+39 −0
Original line number Diff line number Diff line
@@ -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,