fsnotify: remove destroy_list from fsnotify_mark

destroy_list is used to track marks which still need waiting for srcu
period end before they can be freed.  However by the time mark is added to
destroy_list it isn't in group's list of marks anymore and thus we can
reuse fsnotify_mark->g_list for queueing into destroy_list.  This saves
two pointers for each fsnotify_mark.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 442847a02b8f..0f313f93c586 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -212,7 +212,11 @@ struct fsnotify_mark {
          * in kernel that found and may be using this mark. */
         atomic_t refcnt;                /* active things looking at this mark */
         struct fsnotify_group *group;   /* group this mark is for */
-        struct list_head g_list;        /* list of marks by group->i_fsnotify_marks */
+        struct list_head g_list;        /* list of marks by group->i_fsnotify_marks
+                                         * Also reused for queueing mark into
+                                         * destroy_list when it's waiting for
+                                         * the end of SRCU period before it can
+                                         * be freed */
         spinlock_t lock;                /* protect group and inode */
         struct hlist_node obj_list;     /* list of marks for inode / vfsmount */
         struct list_head free_list;     /* tmp list used when freeing this mark */
@@ -227,7 +231,6 @@ struct fsnotify_mark {
 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY  0x08
 #define FSNOTIFY_MARK_FLAG_ALIVE                0x10
         unsigned int flags;             /* vfsmount or inode mark? */
-        struct list_head destroy_list;
         void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
 };