hfsplus: get rid of write_super

This patch makes hfsplus stop using the VFS '->write_super()' method along with
the 's_dirt' superblock flag, because they are on their way out.

The whole "superblock write-out" VFS infrastructure is served by the
'sync_supers()' kernel thread, which wakes up every 5 (by default) seconds and
writes out all dirty superblocks using the '->write_super()' call-back.  But the
problem with this thread is that it wastes power by waking up the system every
5 seconds, even if there are no diry superblocks, or there are no client
file-systems which would need this (e.g., btrfs does not use
'->write_super()'). So we want to kill it completely and thus, we need to make
file-systems to stop using the '->write_super()' VFS service, and then remove
it together with the kernel thread.

Tested using fsstress from the LTP project.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 66a9365..558dbb4 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -153,8 +153,11 @@ struct hfsplus_sb_info {
 	gid_t gid;
 
 	int part, session;
-
 	unsigned long flags;
+
+	int work_queued;               /* non-zero delayed work is queued */
+	struct delayed_work sync_work; /* FS sync delayed work */
+	spinlock_t work_lock;          /* protects sync_work and work_queued */
 };
 
 #define HFSPLUS_SB_WRITEBACKUP	0
@@ -428,6 +431,7 @@ int hfsplus_show_options(struct seq_file *, struct dentry *);
 
 /* super.c */
 struct inode *hfsplus_iget(struct super_block *, unsigned long);
+void hfsplus_mark_mdb_dirty(struct super_block *sb);
 
 /* tables.c */
 extern u16 hfsplus_case_fold_table[];