fsnotify: count all objects with attached connectors

Rename s_fsnotify_inode_refs to s_fsnotify_connectors and count all
objects with attached connectors, not only inodes with attached
connectors.

This will be used to optimize fsnotify() calls on sb without any
type of marks.

Link: https://lore.kernel.org/r/20210810151220.285179-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Matthew Bobrowski <repnop@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 30d422b..963e6ce 100644 (file)
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -87,15 +87,15 @@ static void fsnotify_unmount_inodes(struct super_block *sb)
 
        if (iput_inode)
                iput(iput_inode);
-       /* Wait for outstanding inode references from connectors */
-       wait_var_event(&sb->s_fsnotify_inode_refs,
-                      !atomic_long_read(&sb->s_fsnotify_inode_refs));
 }
 
 void fsnotify_sb_delete(struct super_block *sb)
 {
        fsnotify_unmount_inodes(sb);
        fsnotify_clear_marks_by_sb(sb);
+       /* Wait for outstanding object references from connectors */
+       wait_var_event(&sb->s_fsnotify_connectors,
+                      !atomic_long_read(&sb->s_fsnotify_connectors));
 }
 
 /*

diff --git a/fs/notify/fsnotify.h b/fs/notify/fsnotify.h
index ff2063e..87d8a50 100644 (file)
--- a/fs/notify/fsnotify.h
+++ b/fs/notify/fsnotify.h
@@ -27,6 +27,21 @@ static inline struct super_block *fsnotify_conn_sb(
        return container_of(conn->obj, struct super_block, s_fsnotify_marks);
 }
 
+static inline struct super_block *fsnotify_connector_sb(
+                               struct fsnotify_mark_connector *conn)
+{
+       switch (conn->type) {
+       case FSNOTIFY_OBJ_TYPE_INODE:
+               return fsnotify_conn_inode(conn)->i_sb;
+       case FSNOTIFY_OBJ_TYPE_VFSMOUNT:
+               return fsnotify_conn_mount(conn)->mnt.mnt_sb;
+       case FSNOTIFY_OBJ_TYPE_SB:
+               return fsnotify_conn_sb(conn);
+       default:
+               return NULL;
+       }
+}
+
 /* destroy all events sitting in this groups notification queue */
 extern void fsnotify_flush_notify(struct fsnotify_group *group);
 

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 2d8c46e..95006d1 100644 (file)
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -172,7 +172,7 @@ static void fsnotify_connector_destroy_workfn(struct work_struct *work)
 static void fsnotify_get_inode_ref(struct inode *inode)
 {
        ihold(inode);
-       atomic_long_inc(&inode->i_sb->s_fsnotify_inode_refs);
+       atomic_long_inc(&inode->i_sb->s_fsnotify_connectors);
 }
 
 static void fsnotify_put_inode_ref(struct inode *inode)
@@ -180,8 +180,24 @@ static void fsnotify_put_inode_ref(struct inode *inode)
        struct super_block *sb = inode->i_sb;
 
        iput(inode);
-       if (atomic_long_dec_and_test(&sb->s_fsnotify_inode_refs))
-               wake_up_var(&sb->s_fsnotify_inode_refs);
+       if (atomic_long_dec_and_test(&sb->s_fsnotify_connectors))
+               wake_up_var(&sb->s_fsnotify_connectors);
+}
+
+static void fsnotify_get_sb_connectors(struct fsnotify_mark_connector *conn)
+{
+       struct super_block *sb = fsnotify_connector_sb(conn);
+
+       if (sb)
+               atomic_long_inc(&sb->s_fsnotify_connectors);
+}
+
+static void fsnotify_put_sb_connectors(struct fsnotify_mark_connector *conn)
+{
+       struct super_block *sb = fsnotify_connector_sb(conn);
+
+       if (sb && atomic_long_dec_and_test(&sb->s_fsnotify_connectors))
+               wake_up_var(&sb->s_fsnotify_connectors);
 }
 
 static void *fsnotify_detach_connector_from_object(
@@ -203,6 +219,7 @@ static void *fsnotify_detach_connector_from_object(
                fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;
        }
 
+       fsnotify_put_sb_connectors(conn);
        rcu_assign_pointer(*(conn->obj), NULL);
        conn->obj = NULL;
        conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;
@@ -504,6 +521,7 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
                inode = fsnotify_conn_inode(conn);
                fsnotify_get_inode_ref(inode);
        }
+       fsnotify_get_sb_connectors(conn);
 
        /*
         * cmpxchg() provides the barrier so that readers of *connp can see

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6405742..bea8ec5 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1507,8 +1507,11 @@ struct super_block {
        /* Number of inodes with nlink == 0 but still referenced */
        atomic_long_t s_remove_count;
 
-       /* Pending fsnotify inode refs */
-       atomic_long_t s_fsnotify_inode_refs;
+       /*
+        * Number of inode/mount/sb objects that are being watched, note that
+        * inodes objects are currently double-accounted.
+        */
+       atomic_long_t s_fsnotify_connectors;
 
        /* Being remounted read-only */
        int s_readonly_remount;