xfs: use xfs_sync_inodes() for device flushing

Currently xfs_device_flush calls sync_blockdev() which is
a no-op for XFS as all it's metadata is held in a different
address to the one sync_blockdev() works on.

Call xfs_sync_inodes() instead to flush all the delayed
allocation blocks out. To do this as efficiently as possible,
do it via two passes - one to do an async flush of all the
dirty blocks and a second to wait for all the IO to complete.
This requires some modification to the xfs-sync_inodes_ag()
flush code to do efficiently.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/linux-2.6/xfs_fs_subr.c

@@ -74,14 +74,14 @@ xfs_flush_pages(
 
 	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
 		xfs_iflags_clear(ip, XFS_ITRUNCATED);
-		ret = filemap_fdatawrite(mapping);
+		ret = -filemap_fdatawrite(mapping);
+	}
 	if (flags & XFS_B_ASYNC)
-			return -ret;
+		return ret;
-		ret2 = filemap_fdatawait(mapping);
+	ret2 = xfs_wait_on_pages(ip, first, last);
 	if (!ret)
 		ret = ret2;
-	}
+	return ret;
-	return -ret;
 }
 
 int

fs/xfs/linux-2.6/xfs_sync.c

@@ -62,12 +62,6 @@ xfs_sync_inodes_ag(
 	uint32_t	first_index = 0;
 	int		error = 0;
 	int		last_error = 0;
-	int		fflag = XFS_B_ASYNC;
-
-	if (flags & SYNC_DELWRI)
-		fflag = XFS_B_DELWRI;
-	if (flags & SYNC_WAIT)
-		fflag = 0;		/* synchronous overrides all */
 
 	do {
 		struct inode	*inode;
@@ -128,11 +122,23 @@ xfs_sync_inodes_ag(
 		 * If we have to flush data or wait for I/O completion
 		 * we need to hold the iolock.
 		 */
-		if ((flags & SYNC_DELWRI) && VN_DIRTY(inode)) {
+		if (flags & SYNC_DELWRI) {
+			if (VN_DIRTY(inode)) {
+				if (flags & SYNC_TRYLOCK) {
+					if (xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
+						lock_flags |= XFS_IOLOCK_SHARED;
+				} else {
 					xfs_ilock(ip, XFS_IOLOCK_SHARED);
 					lock_flags |= XFS_IOLOCK_SHARED;
-			error = xfs_flush_pages(ip, 0, -1, fflag, FI_NONE);
+				}
-			if (flags & SYNC_IOWAIT)
+				if (lock_flags & XFS_IOLOCK_SHARED) {
+					error = xfs_flush_pages(ip, 0, -1,
+							(flags & SYNC_WAIT) ? 0
+								: XFS_B_ASYNC,
+							FI_NONE);
+				}
+			}
+			if (VN_CACHED(inode) && (flags & SYNC_IOWAIT))
 				xfs_ioend_wait(ip);
 		}
 		xfs_ilock(ip, XFS_ILOCK_SHARED);
@@ -400,9 +406,9 @@ xfs_syncd_queue_work(
 	void		*data,
 	void		(*syncer)(struct xfs_mount *, void *))
 {
-	struct bhv_vfs_sync_work *work;
+	struct xfs_sync_work *work;
 
-	work = kmem_alloc(sizeof(struct bhv_vfs_sync_work), KM_SLEEP);
+	work = kmem_alloc(sizeof(struct xfs_sync_work), KM_SLEEP);
 	INIT_LIST_HEAD(&work->w_list);
 	work->w_syncer = syncer;
 	work->w_data = data;
@@ -445,23 +451,24 @@ xfs_flush_inode(
  * (IOW, "If at first you don't succeed, use a Bigger Hammer").
  */
 STATIC void
-xfs_flush_device_work(
+xfs_flush_inodes_work(
 	struct xfs_mount *mp,
 	void		*arg)
 {
 	struct inode	*inode = arg;
-	sync_blockdev(mp->m_super->s_bdev);
+	xfs_sync_inodes(mp, SYNC_DELWRI | SYNC_TRYLOCK);
+	xfs_sync_inodes(mp, SYNC_DELWRI | SYNC_TRYLOCK | SYNC_IOWAIT);
 	iput(inode);
 }
 
 void
-xfs_flush_device(
+xfs_flush_inodes(
 	xfs_inode_t	*ip)
 {
 	struct inode	*inode = VFS_I(ip);
 
 	igrab(inode);
-	xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_device_work);
+	xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inodes_work);
 	delay(msecs_to_jiffies(500));
 	xfs_log_force(ip->i_mount, (xfs_lsn_t)0, XFS_LOG_FORCE|XFS_LOG_SYNC);
 }
@@ -497,7 +504,7 @@ xfssyncd(
 {
 	struct xfs_mount	*mp = arg;
 	long			timeleft;
-	bhv_vfs_sync_work_t	*work, *n;
+	xfs_sync_work_t		*work, *n;
 	LIST_HEAD		(tmp);
 
 	set_freezable();

fs/xfs/linux-2.6/xfs_sync.h

@@ -21,18 +21,19 @@
 struct xfs_mount;
 struct xfs_perag;
 
-typedef struct bhv_vfs_sync_work {
+typedef struct xfs_sync_work {
 	struct list_head	w_list;
 	struct xfs_mount	*w_mount;
 	void			*w_data;	/* syncer routine argument */
 	void			(*w_syncer)(struct xfs_mount *, void *);
-} bhv_vfs_sync_work_t;
+} xfs_sync_work_t;
 
 #define SYNC_ATTR		0x0001	/* sync attributes */
 #define SYNC_DELWRI		0x0002	/* look at delayed writes */
 #define SYNC_WAIT		0x0004	/* wait for i/o to complete */
 #define SYNC_BDFLUSH		0x0008	/* BDFLUSH is calling -- don't block */
 #define SYNC_IOWAIT		0x0010  /* wait for all I/O to complete */
+#define SYNC_TRYLOCK		0x0020  /* only try to lock inodes */
 
 int xfs_syncd_init(struct xfs_mount *mp);
 void xfs_syncd_stop(struct xfs_mount *mp);
@@ -44,7 +45,7 @@ int xfs_quiesce_data(struct xfs_mount *mp);
 void xfs_quiesce_attr(struct xfs_mount *mp);
 
 void xfs_flush_inode(struct xfs_inode *ip);
-void xfs_flush_device(struct xfs_inode *ip);
+void xfs_flush_inodes(struct xfs_inode *ip);
 
 int xfs_reclaim_inode(struct xfs_inode *ip, int locked, int sync_mode);
 int xfs_reclaim_inodes(struct xfs_mount *mp, int noblock, int mode);

fs/xfs/xfs_iomap.c

@@ -361,7 +361,7 @@ xfs_flush_space(
 		return 0;
 	case 2:
 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
-		xfs_flush_device(ip);
+		xfs_flush_inodes(ip);
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		*fsynced = 3;
 		return 0;

fs/xfs/xfs_mount.h

@@ -313,7 +313,7 @@ typedef struct xfs_mount {
 #endif
 	struct xfs_mru_cache	*m_filestream;  /* per-mount filestream data */
 	struct task_struct	*m_sync_task;	/* generalised sync thread */
-	bhv_vfs_sync_work_t	m_sync_work;	/* work item for VFS_SYNC */
+	xfs_sync_work_t		m_sync_work;	/* work item for VFS_SYNC */
 	struct list_head	m_sync_list;	/* sync thread work item list */
 	spinlock_t		m_sync_lock;	/* work item list lock */
 	int			m_sync_seq;	/* sync thread generation no. */