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NFSD: Trace filecache LRU activity

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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>
This commit is contained in:
Chuck Lever 2022-07-08 14:25:11 -04:00
parent 668ed92e65
commit c46203acdd
2 changed files with 70 additions and 13 deletions
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44
fs/nfsd/filecache.c
View File

@ -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,

39
fs/nfsd/trace.h
View File

@ -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,