FS-Cache: Add counters for entry/exit to/from cache operation functions

Count entries to and exits from cache operation table functions.  Maintain
these as a single counter that's added to or removed from as appropriate.

Signed-off-by: David Howells <dhowells@redhat.com>

7 files changed, 134 insertions, 9 deletions

diff --git a/Documentation/filesystems/caching/fscache.txt b/Documentation/filesystems/caching/fscache.txt
index cac09e11ca30..b6c32c080ab1 100644
--- a/Documentation/filesystems/caching/fscache.txt
+++ b/Documentation/filesystems/caching/fscache.txt
@@ -274,6 +274,22 @@ proc files.
                 dfr=N   Number of async ops queued for deferred release
                 rel=N   Number of async ops released
                 gc=N    Number of deferred-release async ops garbage collected
+        CacheOp alo=N   Number of in-progress alloc_object() cache ops
+                luo=N   Number of in-progress lookup_object() cache ops
+                luc=N   Number of in-progress lookup_complete() cache ops
+                gro=N   Number of in-progress grab_object() cache ops
+                upo=N   Number of in-progress update_object() cache ops
+                dro=N   Number of in-progress drop_object() cache ops
+                pto=N   Number of in-progress put_object() cache ops
+                syn=N   Number of in-progress sync_cache() cache ops
+                atc=N   Number of in-progress attr_changed() cache ops
+                rap=N   Number of in-progress read_or_alloc_page() cache ops
+                ras=N   Number of in-progress read_or_alloc_pages() cache ops
+                alp=N   Number of in-progress allocate_page() cache ops
+                als=N   Number of in-progress allocate_pages() cache ops
+                wrp=N   Number of in-progress write_page() cache ops
+                ucp=N   Number of in-progress uncache_page() cache ops
+                dsp=N   Number of in-progress dissociate_pages() cache ops
 
 
  (*) /proc/fs/fscache/histogram
diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c
index 724384ef96de..6a3c48abd677 100644
--- a/fs/fscache/cache.c
+++ b/fs/fscache/cache.c
@@ -381,11 +381,15 @@ void fscache_withdraw_cache(struct fscache_cache *cache)
 
         /* make sure all pages pinned by operations on behalf of the netfs are
          * written to disk */
+        fscache_stat(&fscache_n_cop_sync_cache);
         cache->ops->sync_cache(cache);
+        fscache_stat_d(&fscache_n_cop_sync_cache);
 
         /* dissociate all the netfs pages backed by this cache from the block
          * mappings in the cache */
+        fscache_stat(&fscache_n_cop_dissociate_pages);
         cache->ops->dissociate_pages(cache);
+        fscache_stat_d(&fscache_n_cop_dissociate_pages);
 
         /* we now have to destroy all the active objects pertaining to this
          * cache - which we do by passing them off to thread pool to be
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 9b5187328230..432482edc738 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -249,7 +249,9 @@ static int fscache_alloc_object(struct fscache_cache *cache,
 
         /* ask the cache to allocate an object (we may end up with duplicate
          * objects at this stage, but we sort that out later) */
+        fscache_stat(&fscache_n_cop_alloc_object);
         object = cache->ops->alloc_object(cache, cookie);
+        fscache_stat_d(&fscache_n_cop_alloc_object);
         if (IS_ERR(object)) {
                 fscache_stat(&fscache_n_object_no_alloc);
                 ret = PTR_ERR(object);
@@ -270,8 +272,11 @@ static int fscache_alloc_object(struct fscache_cache *cache,
         /* only attach if we managed to allocate all we needed, otherwise
          * discard the object we just allocated and instead use the one
          * attached to the cookie */
-        if (fscache_attach_object(cookie, object) < 0)
+        if (fscache_attach_object(cookie, object) < 0) {
+                fscache_stat(&fscache_n_cop_put_object);
                 cache->ops->put_object(object);
+                fscache_stat_d(&fscache_n_cop_put_object);
+        }
 
         _leave(" = 0");
         return 0;
@@ -287,7 +292,9 @@ object_already_extant:
         return 0;
 
 error_put:
+        fscache_stat(&fscache_n_cop_put_object);
         cache->ops->put_object(object);
+        fscache_stat_d(&fscache_n_cop_put_object);
 error:
         _leave(" = %d", ret);
         return ret;
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index fe02973a9516..b85cc8906818 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -208,11 +208,33 @@ extern atomic_t fscache_n_checkaux_okay;
 extern atomic_t fscache_n_checkaux_update;
 extern atomic_t fscache_n_checkaux_obsolete;
 
+extern atomic_t fscache_n_cop_alloc_object;
+extern atomic_t fscache_n_cop_lookup_object;
+extern atomic_t fscache_n_cop_lookup_complete;
+extern atomic_t fscache_n_cop_grab_object;
+extern atomic_t fscache_n_cop_update_object;
+extern atomic_t fscache_n_cop_drop_object;
+extern atomic_t fscache_n_cop_put_object;
+extern atomic_t fscache_n_cop_sync_cache;
+extern atomic_t fscache_n_cop_attr_changed;
+extern atomic_t fscache_n_cop_read_or_alloc_page;
+extern atomic_t fscache_n_cop_read_or_alloc_pages;
+extern atomic_t fscache_n_cop_allocate_page;
+extern atomic_t fscache_n_cop_allocate_pages;
+extern atomic_t fscache_n_cop_write_page;
+extern atomic_t fscache_n_cop_uncache_page;
+extern atomic_t fscache_n_cop_dissociate_pages;
+
 static inline void fscache_stat(atomic_t *stat)
 {
         atomic_inc(stat);
 }
 
+static inline void fscache_stat_d(atomic_t *stat)
+{
+        atomic_dec(stat);
+}
+
 extern const struct file_operations fscache_stats_fops;
 #else
 
diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index ad1644f073bd..0d65c0c92b46 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -144,13 +144,17 @@ static void fscache_object_state_machine(struct fscache_object *object)
         case FSCACHE_OBJECT_UPDATING:
                 clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
                 fscache_stat(&fscache_n_updates_run);
+                fscache_stat(&fscache_n_cop_update_object);
                 object->cache->ops->update_object(object);
+                fscache_stat_d(&fscache_n_cop_update_object);
                 goto active_transit;
 
                 /* handle an object dying during lookup or creation */
         case FSCACHE_OBJECT_LC_DYING:
                 object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
+                fscache_stat(&fscache_n_cop_lookup_complete);
                 object->cache->ops->lookup_complete(object);
+                fscache_stat_d(&fscache_n_cop_lookup_complete);
 
                 spin_lock(&object->lock);
                 object->state = FSCACHE_OBJECT_DYING;
@@ -416,7 +420,9 @@ static void fscache_initialise_object(struct fscache_object *object)
                          * binding on to us, so we need to make sure we don't
                          * add ourself to the list multiple times */
                         if (list_empty(&object->dep_link)) {
+                                fscache_stat(&fscache_n_cop_grab_object);
                                 object->cache->ops->grab_object(object);
+                                fscache_stat_d(&fscache_n_cop_grab_object);
                                 list_add(&object->dep_link,
                                          &parent->dependents);
 
@@ -478,7 +484,9 @@ static void fscache_lookup_object(struct fscache_object *object)
                object->cache->tag->name);
 
         fscache_stat(&fscache_n_object_lookups);
+        fscache_stat(&fscache_n_cop_lookup_object);
         object->cache->ops->lookup_object(object);
+        fscache_stat_d(&fscache_n_cop_lookup_object);
 
         if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
                 set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
@@ -602,7 +610,9 @@ static void fscache_object_available(struct fscache_object *object)
         }
         spin_unlock(&object->lock);
 
+        fscache_stat(&fscache_n_cop_lookup_complete);
         object->cache->ops->lookup_complete(object);
+        fscache_stat_d(&fscache_n_cop_lookup_complete);
         fscache_enqueue_dependents(object);
 
         fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
@@ -625,7 +635,9 @@ static void fscache_drop_object(struct fscache_object *object)
         list_del_init(&object->cache_link);
         spin_unlock(&cache->object_list_lock);
 
+        fscache_stat(&fscache_n_cop_drop_object);
         cache->ops->drop_object(object);
+        fscache_stat_d(&fscache_n_cop_drop_object);
 
         if (parent) {
                 _debug("release parent OBJ%x {%d}",
@@ -640,7 +652,9 @@ static void fscache_drop_object(struct fscache_object *object)
         }
 
         /* this just shifts the object release to the slow work processor */
+        fscache_stat(&fscache_n_cop_put_object);
         object->cache->ops->put_object(object);
+        fscache_stat_d(&fscache_n_cop_put_object);
 
         _leave("");
 }
@@ -730,8 +744,12 @@ static int fscache_object_slow_work_get_ref(struct slow_work *work)
 {
         struct fscache_object *object =
                 container_of(work, struct fscache_object, work);
+        int ret;
 
-        return object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
+        fscache_stat(&fscache_n_cop_grab_object);
+        ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
+        fscache_stat_d(&fscache_n_cop_grab_object);
+        return ret;
 }
 
 /*
@@ -742,7 +760,9 @@ static void fscache_object_slow_work_put_ref(struct slow_work *work)
         struct fscache_object *object =
                 container_of(work, struct fscache_object, work);
 
-        return object->cache->ops->put_object(object);
+        fscache_stat(&fscache_n_cop_put_object);
+        object->cache->ops->put_object(object);
+        fscache_stat_d(&fscache_n_cop_put_object);
 }
 
 /*
@@ -779,7 +799,9 @@ static void fscache_enqueue_dependents(struct fscache_object *object)
 
                 /* sort onto appropriate lists */
                 fscache_enqueue_object(dep);
+                fscache_stat(&fscache_n_cop_put_object);
                 dep->cache->ops->put_object(dep);
+                fscache_stat_d(&fscache_n_cop_put_object);
 
                 if (!list_empty(&object->dependents))
                         cond_resched_lock(&object->lock);
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index c5973e38ce39..250dfd34c07b 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -71,7 +71,9 @@ static void fscache_attr_changed_op(struct fscache_operation *op)
 
         if (fscache_object_is_active(object)) {
                 fscache_set_op_state(op, "CallFS");
+                fscache_stat(&fscache_n_cop_attr_changed);
                 ret = object->cache->ops->attr_changed(object);
+                fscache_stat_d(&fscache_n_cop_attr_changed);
                 fscache_set_op_state(op, "Done");
                 if (ret < 0)
                         fscache_abort_object(object);
@@ -300,11 +302,15 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
 
         /* ask the cache to honour the operation */
         if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
+                fscache_stat(&fscache_n_cop_allocate_page);
                 ret = object->cache->ops->allocate_page(op, page, gfp);
+                fscache_stat_d(&fscache_n_cop_allocate_page);
                 if (ret == 0)
                         ret = -ENODATA;
         } else {
+                fscache_stat(&fscache_n_cop_read_or_alloc_page);
                 ret = object->cache->ops->read_or_alloc_page(op, page, gfp);
+                fscache_stat_d(&fscache_n_cop_read_or_alloc_page);
         }
 
         if (ret == -ENOMEM)
@@ -358,7 +364,6 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
                                   void *context,
                                   gfp_t gfp)
 {
-        fscache_pages_retrieval_func_t func;
         struct fscache_retrieval *op;
         struct fscache_object *object;
         int ret;
@@ -413,11 +418,17 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
         }
 
         /* ask the cache to honour the operation */
-        if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags))
-                func = object->cache->ops->allocate_pages;
-        else
-                func = object->cache->ops->read_or_alloc_pages;
-        ret = func(op, pages, nr_pages, gfp);
+        if (test_bit(FSCACHE_COOKIE_NO_DATA_YET, &object->cookie->flags)) {
+                fscache_stat(&fscache_n_cop_allocate_pages);
+                ret = object->cache->ops->allocate_pages(
+                        op, pages, nr_pages, gfp);
+                fscache_stat_d(&fscache_n_cop_allocate_pages);
+        } else {
+                fscache_stat(&fscache_n_cop_read_or_alloc_pages);
+                ret = object->cache->ops->read_or_alloc_pages(
+                        op, pages, nr_pages, gfp);
+                fscache_stat_d(&fscache_n_cop_read_or_alloc_pages);
+        }
 
         if (ret == -ENOMEM)
                 fscache_stat(&fscache_n_retrievals_nomem);
@@ -500,7 +511,9 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
         }
 
         /* ask the cache to honour the operation */
+        fscache_stat(&fscache_n_cop_allocate_page);
         ret = object->cache->ops->allocate_page(op, page, gfp);
+        fscache_stat_d(&fscache_n_cop_allocate_page);
 
         if (ret < 0)
                 fscache_stat(&fscache_n_allocs_nobufs);
@@ -578,7 +591,9 @@ static void fscache_write_op(struct fscache_operation *_op)
 
         if (page) {
                 fscache_set_op_state(&op->op, "Store");
+                fscache_stat(&fscache_n_cop_write_page);
                 ret = object->cache->ops->write_page(op, page);
+                fscache_stat_d(&fscache_n_cop_write_page);
                 fscache_set_op_state(&op->op, "EndWrite");
                 fscache_end_page_write(cookie, page);
                 page_cache_release(page);
@@ -786,7 +801,9 @@ void __fscache_uncache_page(struct fscache_cookie *cookie, struct page *page)
         if (TestClearPageFsCache(page) &&
             object->cache->ops->uncache_page) {
                 /* the cache backend releases the cookie lock */
+                fscache_stat(&fscache_n_cop_uncache_page);
                 object->cache->ops->uncache_page(object, page);
+                fscache_stat_d(&fscache_n_cop_uncache_page);
                 goto done;
         }
 
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index 65deb99e756b..20233fb44bfd 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -93,6 +93,23 @@ atomic_t fscache_n_checkaux_okay;
 atomic_t fscache_n_checkaux_update;
 atomic_t fscache_n_checkaux_obsolete;
 
+atomic_t fscache_n_cop_alloc_object;
+atomic_t fscache_n_cop_lookup_object;
+atomic_t fscache_n_cop_lookup_complete;
+atomic_t fscache_n_cop_grab_object;
+atomic_t fscache_n_cop_update_object;
+atomic_t fscache_n_cop_drop_object;
+atomic_t fscache_n_cop_put_object;
+atomic_t fscache_n_cop_sync_cache;
+atomic_t fscache_n_cop_attr_changed;
+atomic_t fscache_n_cop_read_or_alloc_page;
+atomic_t fscache_n_cop_read_or_alloc_pages;
+atomic_t fscache_n_cop_allocate_page;
+atomic_t fscache_n_cop_allocate_pages;
+atomic_t fscache_n_cop_write_page;
+atomic_t fscache_n_cop_uncache_page;
+atomic_t fscache_n_cop_dissociate_pages;
+
 /*
  * display the general statistics
  */
@@ -192,6 +209,26 @@ static int fscache_stats_show(struct seq_file *m, void *v)
                    atomic_read(&fscache_n_op_deferred_release),
                    atomic_read(&fscache_n_op_release),
                    atomic_read(&fscache_n_op_gc));
+
+        seq_printf(m, "CacheOp: alo=%d luo=%d luc=%d gro=%d\n",
+                   atomic_read(&fscache_n_cop_alloc_object),
+                   atomic_read(&fscache_n_cop_lookup_object),
+                   atomic_read(&fscache_n_cop_lookup_complete),
+                   atomic_read(&fscache_n_cop_grab_object));
+        seq_printf(m, "CacheOp: upo=%d dro=%d pto=%d atc=%d syn=%d\n",
+                   atomic_read(&fscache_n_cop_update_object),
+                   atomic_read(&fscache_n_cop_drop_object),
+                   atomic_read(&fscache_n_cop_put_object),
+                   atomic_read(&fscache_n_cop_attr_changed),
+                   atomic_read(&fscache_n_cop_sync_cache));
+        seq_printf(m, "CacheOp: rap=%d ras=%d alp=%d als=%d wrp=%d ucp=%d dsp=%d\n",
+                   atomic_read(&fscache_n_cop_read_or_alloc_page),
+                   atomic_read(&fscache_n_cop_read_or_alloc_pages),
+                   atomic_read(&fscache_n_cop_allocate_page),
+                   atomic_read(&fscache_n_cop_allocate_pages),
+                   atomic_read(&fscache_n_cop_write_page),
+                   atomic_read(&fscache_n_cop_uncache_page),
+                   atomic_read(&fscache_n_cop_dissociate_pages));
         return 0;
 }