Merge tag 'fscache-next-20210829' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache updates from David Howells:
 "Preparatory work for the fscache rewrite that's being worked on and
  fix some bugs. These include:

   - Always select netfs stats when enabling fscache stats since they're
     displayed through the same procfile.

   - Add a cookie debug ID that can be used in tracepoints instead of a
     pointer and cache it in the netfs_cache_resources struct rather
     than in the netfs_read_request struct to make it more available.

   - Use file_inode() in cachefiles rather than dereferencing
     file->f_inode directly.

   - Provide a procfile to display fscache cookies.

   - Remove the fscache and cachefiles histogram procfiles.

   - Remove the fscache object list procfile.

   - Avoid using %p in fscache and cachefiles as the value is hashed and
     not comparable to the register dump in an oops trace.

   - Fix the cookie hash function to actually achieve useful dispersion.

   - Fix fscache_cookie_put() so that it doesn't dereference the cookie
     pointer in the tracepoint after the refcount has been decremented
     (we're only allowed to do that if we decremented it to zero).

   - Use refcount_t rather than atomic_t for the fscache_cookie
     refcount"

* tag 'fscache-next-20210829' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  fscache: Use refcount_t for the cookie refcount instead of atomic_t
  fscache: Fix fscache_cookie_put() to not deref after dec
  fscache: Fix cookie key hashing
  cachefiles: Change %p in format strings to something else
  fscache: Change %p in format strings to something else
  fscache: Remove the object list procfile
  fscache, cachefiles: Remove the histogram stuff
  fscache: Procfile to display cookies
  fscache: Add a cookie debug ID and use that in traces
  cachefiles: Use file_inode() rather than accessing ->f_inode
  netfs: Move cookie debug ID to struct netfs_cache_resources
  fscache: Select netfs stats if fscache stats are enabled

3 files changed, 4 insertions, 6 deletions

diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 3235ddbdcc09..8d39491c5f9f 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -147,7 +147,6 @@ struct fscache_retrieval {
 	fscache_rw_complete_t	end_io_func;	/* function to call on I/O completion */
 	void			*context;	/* netfs read context (pinned) */
 	struct list_head	to_do;		/* list of things to be done by the backend */
-	unsigned long		start_time;	/* time at which retrieval started */
 	atomic_t		n_pages;	/* number of pages to be retrieved */
 };
 
@@ -385,9 +384,6 @@ struct fscache_object {
 	struct list_head	dependents;	/* FIFO of dependent objects */
 	struct list_head	dep_link;	/* link in parent's dependents list */
 	struct list_head	pending_ops;	/* unstarted operations on this object */
-#ifdef CONFIG_FSCACHE_OBJECT_LIST
-	struct rb_node		objlist_link;	/* link in global object list */
-#endif
 	pgoff_t			store_limit;	/* current storage limit */
 	loff_t			store_limit_l;	/* current storage limit */
 };
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index abc1c4737fb8..a4dab5998613 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -123,15 +123,17 @@ struct fscache_netfs {
  * - indices are created on disk just-in-time
  */
 struct fscache_cookie {
-	atomic_t			usage;		/* number of users of this cookie */
+	refcount_t			ref;		/* number of users of this cookie */
 	atomic_t			n_children;	/* number of children of this cookie */
 	atomic_t			n_active;	/* number of active users of netfs ptrs */
+	unsigned int			debug_id;
 	spinlock_t			lock;
 	spinlock_t			stores_lock;	/* lock on page store tree */
 	struct hlist_head		backing_objects; /* object(s) backing this file/index */
 	const struct fscache_cookie_def	*def;		/* definition */
 	struct fscache_cookie		*parent;	/* parent of this entry */
 	struct hlist_bl_node		hash_link;	/* Link in hash table */
+	struct list_head		proc_link;	/* Link in proc list */
 	void				*netfs_data;	/* back pointer to netfs */
 	struct radix_tree_root		stores;		/* pages to be stored on this cookie */
 #define FSCACHE_COOKIE_PENDING_TAG	0		/* pages tag: pending write to cache */
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 9062adfa2fb9..5d6a4158a9a6 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -102,6 +102,7 @@ struct netfs_cache_resources {
 	const struct netfs_cache_ops	*ops;
 	void				*cache_priv;
 	void				*cache_priv2;
+	unsigned int			debug_id;	/* Cookie debug ID */
 };
 
 /*
@@ -137,7 +138,6 @@ struct netfs_read_request {
 	struct list_head	subrequests;	/* Requests to fetch I/O from disk or net */
 	void			*netfs_priv;	/* Private data for the netfs */
 	unsigned int		debug_id;
-	unsigned int		cookie_debug_id;
 	atomic_t		nr_rd_ops;	/* Number of read ops in progress */
 	atomic_t		nr_wr_ops;	/* Number of write ops in progress */
 	size_t			submitted;	/* Amount submitted for I/O so far */