Commit d2f277e2 authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fsnotify: rename fsnotify_{get,put}_sb_connectors() 



Instead of counting the number of connectors in an sb, we would like
to count the number of watched objects per priority group.

As a start, create an accessor fsnotify_sb_watched_objects() to
s_fsnotify_connectors and rename the fsnotify_{get,put}_sb_connectors()
helpers to fsnotify_{get,put}_sb_watchers() to better describes the
counter.

Increment the counter at the end of fsnotify_attach_connector_to_object()
if connector was attached instead of decrementing it on race to connect.

This is fine, because fsnotify_delete_sb() cannot be running in parallel
to fsnotify_attach_connector_to_object() which requires a reference to
a filesystem object.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-2-amir73il@gmail.com>
parent 4d69c58e

fs/notify/fsnotify.c

+2 −2
Original line number Diff line number Diff line
@@ -92,8 +92,8 @@ 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));

	wait_var_event(fsnotify_sb_watched_objects(sb),

		       !atomic_long_read(fsnotify_sb_watched_objects(sb)));

}



/*

fs/notify/mark.c

+37 −30
Original line number Diff line number Diff line
@@ -116,10 +116,43 @@ __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn) 
	return *fsnotify_conn_mask_p(conn);

}



static void fsnotify_get_sb_watched_objects(struct super_block *sb)

{

	atomic_long_inc(fsnotify_sb_watched_objects(sb));

}



static void fsnotify_put_sb_watched_objects(struct super_block *sb)

{

	if (atomic_long_dec_and_test(fsnotify_sb_watched_objects(sb)))

		wake_up_var(fsnotify_sb_watched_objects(sb));

}



static void fsnotify_get_inode_ref(struct inode *inode)

{

	ihold(inode);

	atomic_long_inc(&inode->i_sb->s_fsnotify_connectors);

	fsnotify_get_sb_watched_objects(inode->i_sb);

}



static void fsnotify_put_inode_ref(struct inode *inode)

{

	fsnotify_put_sb_watched_objects(inode->i_sb);

	iput(inode);

}



static void fsnotify_get_sb_watchers(struct fsnotify_mark_connector *conn)

{

	struct super_block *sb = fsnotify_connector_sb(conn);



	if (sb)

		fsnotify_get_sb_watched_objects(sb);

}



static void fsnotify_put_sb_watchers(struct fsnotify_mark_connector *conn)

{

	struct super_block *sb = fsnotify_connector_sb(conn);



	if (sb)

		fsnotify_put_sb_watched_objects(sb);

}



/*
@@ -213,31 +246,6 @@ static void fsnotify_connector_destroy_workfn(struct work_struct *work) 
	}

}



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_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(

					struct fsnotify_mark_connector *conn,

					unsigned int *type)
@@ -261,7 +269,7 @@ static void *fsnotify_detach_connector_from_object( 
		fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;

	}



	fsnotify_put_sb_connectors(conn);

	fsnotify_put_sb_watchers(conn);

	rcu_assign_pointer(*(conn->obj), NULL);

	conn->obj = NULL;

	conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;
@@ -549,8 +557,6 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp, 
	conn->flags = 0;

	conn->type = obj_type;

	conn->obj = connp;

	conn->flags = 0;

	fsnotify_get_sb_connectors(conn);



	/*

	 * cmpxchg() provides the barrier so that readers of *connp can see
@@ -558,10 +564,11 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp, 
	 */

	if (cmpxchg(connp, NULL, conn)) {

		/* Someone else created list structure for us */

		fsnotify_put_sb_connectors(conn);

		kmem_cache_free(fsnotify_mark_connector_cachep, conn);

		return 0;

	}



	fsnotify_get_sb_watchers(conn);

	return 0;

}

include/linux/fsnotify.h

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
/* Are there any inode/mount/sb objects that are being watched at all? */

static inline bool fsnotify_sb_has_watchers(struct super_block *sb)

{

	return atomic_long_read(&sb->s_fsnotify_connectors);

	return atomic_long_read(fsnotify_sb_watched_objects(sb));

}



/*

include/linux/fsnotify_backend.h

+5 −0
Original line number Diff line number Diff line
@@ -483,6 +483,11 @@ struct fsnotify_mark_connector { 
	struct hlist_head list;

};



static inline atomic_long_t *fsnotify_sb_watched_objects(struct super_block *sb)

{

	return &sb->s_fsnotify_connectors;

}



/*

 * A mark is simply an object attached to an in core inode which allows an

 * fsnotify listener to indicate they are either no longer interested in events