This is a note to let you know that I've just added the patch titled
NFSD: Trace filecache LRU activity
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-trace-filecache-lru-activity.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 737f426a604edd1762c0a004a0ebb5315f98070f
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Fri Jul 8 14:25:11 2022 -0400
NFSD: Trace filecache LRU activity
[ Upstream commit c46203acddd9b9200dbc53d0603c97355fd3a03b ]
Observe the operation of garbage collection and the lifetime of
filecache items.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index d9b5f1e183976..a995a744a7481 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -260,6 +260,18 @@ 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)
{
@@ -279,8 +291,7 @@ 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;
@@ -443,27 +454,34 @@ 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;
}
/*
@@ -1016,7 +1034,7 @@ 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,
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index b354c984d6abd..40ee80b6a2a79 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -894,6 +894,45 @@ 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,
