FS-Cache: Count culled objects and objects rejected due to lack of space

Count the number of objects that get culled by the cache backend and the
number of objects that the cache backend declines to instantiate due to lack
of space in the cache.

These numbers are made available through /proc/fs/fscache/stats

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>

1 files changed, 21 insertions, 12 deletions

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 7f8e83f9d74e..1d60195fc518 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -97,7 +97,8 @@ static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  */
 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
-                                          struct dentry *dentry)
+                                          struct dentry *dentry,
+                                          enum fscache_why_object_killed why)
 {
         struct cachefiles_object *object;
         struct rb_node *p;
@@ -132,8 +133,9 @@ found_dentry:
                 pr_err("\n");
                 pr_err("Error: Can't preemptively bury live object\n");
                 cachefiles_printk_object(object, NULL);
-        } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
-                pr_err("Error: Object already preemptively buried\n");
+        } else {
+                if (why != FSCACHE_OBJECT_IS_STALE)
+                        fscache_object_mark_killed(&object->fscache, why);
         }
 
         write_unlock(&cache->active_lock);
@@ -265,7 +267,8 @@ requeue:
 static int cachefiles_bury_object(struct cachefiles_cache *cache,
                                   struct dentry *dir,
                                   struct dentry *rep,
-                                  bool preemptive)
+                                  bool preemptive,
+                                  enum fscache_why_object_killed why)
 {
         struct dentry *grave, *trap;
         struct path path, path_to_graveyard;
@@ -289,7 +292,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
                         ret = vfs_unlink(dir->d_inode, rep, NULL);
 
                         if (preemptive)
-                                cachefiles_mark_object_buried(cache, rep);
+                                cachefiles_mark_object_buried(cache, rep, why);
                 }
 
                 mutex_unlock(&dir->d_inode->i_mutex);
@@ -394,7 +397,7 @@ try_again:
                                             "Rename failed with error %d", ret);
 
                 if (preemptive)
-                        cachefiles_mark_object_buried(cache, rep);
+                        cachefiles_mark_object_buried(cache, rep, why);
         }
 
         unlock_rename(cache->graveyard, dir);
@@ -422,7 +425,7 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
 
         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 
-        if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
+        if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
                 /* object allocation for the same key preemptively deleted this
                  * object's file so that it could create its own file */
                 _debug("object preemptively buried");
@@ -433,7 +436,8 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
                  * may have been renamed */
                 if (dir == object->dentry->d_parent) {
                         ret = cachefiles_bury_object(cache, dir,
-                                                     object->dentry, false);
+                                                     object->dentry, false,
+                                                     FSCACHE_OBJECT_WAS_RETIRED);
                 } else {
                         /* it got moved, presumably by cachefilesd culling it,
                          * so it's no longer in the key path and we can ignore
@@ -522,7 +526,7 @@ lookup_again:
                 if (!next->d_inode) {
                         ret = cachefiles_has_space(cache, 1, 0);
                         if (ret < 0)
-                                goto create_error;
+                                goto no_space_error;
 
                         path.dentry = dir;
                         ret = security_path_mkdir(&path, next, 0);
@@ -551,7 +555,7 @@ lookup_again:
                 if (!next->d_inode) {
                         ret = cachefiles_has_space(cache, 1, 0);
                         if (ret < 0)
-                                goto create_error;
+                                goto no_space_error;
 
                         path.dentry = dir;
                         ret = security_path_mknod(&path, next, S_IFREG, 0);
@@ -602,7 +606,8 @@ lookup_again:
                          * mutex) */
                         object->dentry = NULL;
 
-                        ret = cachefiles_bury_object(cache, dir, next, true);
+                        ret = cachefiles_bury_object(cache, dir, next, true,
+                                                     FSCACHE_OBJECT_IS_STALE);
                         dput(next);
                         next = NULL;
 
@@ -610,6 +615,7 @@ lookup_again:
                                 goto delete_error;
 
                         _debug("redo lookup");
+                        fscache_object_retrying_stale(&object->fscache);
                         goto lookup_again;
                 }
         }
@@ -662,6 +668,8 @@ lookup_again:
         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
         return 0;
 
+no_space_error:
+        fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 create_error:
         _debug("create error %d", ret);
         if (ret == -EIO)
@@ -927,7 +935,8 @@ int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
         /*  actually remove the victim (drops the dir mutex) */
         _debug("bury");
 
-        ret = cachefiles_bury_object(cache, dir, victim, false);
+        ret = cachefiles_bury_object(cache, dir, victim, false,
+                                     FSCACHE_OBJECT_WAS_CULLED);
         if (ret < 0)
                 goto error;