xfs: split xfs_sync_inodes

xfs_sync_inodes is used to write back either file data or inode metadata.
In general we always do these separately, except for one fishy case in
xfs_fs_put_super that does both. So separate xfs_sync_inodes into
separate xfs_sync_data and xfs_sync_attr functions. In xfs_fs_put_super
we first call the data sync and then the attr sync as that was the previous
order. The moved log force in that path doesn't make a difference because
we will force the log again as part of the real unmount process.

The filesystem readonly checks are not performed by the new function but
instead moved into the callers, given that most callers alredy have it
further up in the stack. Also add debug checks that we do not pass in
incorrect flags in the new xfs_sync_data and xfs_sync_attr function and
fix the one place that did pass in a wrong flag.

Also remove a comment mentioning xfs_sync_inodes that has been incorrect
for a while because we always take either the iolock or ilock in the
sync path these days.

Signed-off-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Eric Sandeen <[e-mail]>

fs/xfs/linux-2.6/xfs_quotaops.c

···
 {
 	struct xfs_mount	*mp = XFS_M(sb);
 
+	if (sb->s_flags & MS_RDONLY)
+		return -EROFS;
 	if (!XFS_IS_QUOTA_RUNNING(mp))
 		return -ENOSYS;
-	return -xfs_sync_inodes(mp, SYNC_DELWRI);
+	return -xfs_sync_data(mp, 0);
 }
 
 STATIC int

fs/xfs/linux-2.6/xfs_super.c

···
 	int			unmount_event_flags = 0;
 
 	xfs_syncd_stop(mp);
-	xfs_sync_inodes(mp, SYNC_ATTR|SYNC_DELWRI);
+
+	if (!(sb->s_flags & MS_RDONLY)) {
+		/*
+		 * XXX(hch): this should be SYNC_WAIT.
+		 *
+		 * Or more likely not needed at all because the VFS is already
+		 * calling ->sync_fs after shutting down all filestem
+		 * operations and just before calling ->put_super.
+		 */
+		xfs_sync_data(mp, 0);
+		xfs_sync_attr(mp, 0);
+	}
 
 #ifdef HAVE_DMAPI
 	if (mp->m_flags & XFS_MOUNT_DMAPI) {

fs/xfs/linux-2.6/xfs_sync.c

···
 	return error;
 }
 
+/*
+ * Write out pagecache data for the whole filesystem.
+ */
 int
-xfs_sync_inodes(
-	xfs_mount_t	*mp,
-	int		flags)
+xfs_sync_data(
+	struct xfs_mount	*mp,
+	int			flags)
 {
-	int		error = 0;
-	int		lflags = XFS_LOG_FORCE;
+	int			error;
 
-	if (mp->m_flags & XFS_MOUNT_RDONLY)
-		return 0;
+	ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT|SYNC_IOWAIT)) == 0);
 
-	if (flags & SYNC_WAIT)
-		lflags |= XFS_LOG_SYNC;
+	error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags,
+				      XFS_ICI_NO_TAG);
+	if (error)
+		return XFS_ERROR(error);
 
-	if (flags & SYNC_DELWRI)
-		error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags, XFS_ICI_NO_TAG);
+	xfs_log_force(mp, 0,
+		      (flags & SYNC_WAIT) ?
+		       XFS_LOG_FORCE | XFS_LOG_SYNC :
+		       XFS_LOG_FORCE);
+	return 0;
+}
 
-	if (flags & SYNC_ATTR)
-		error = xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags, XFS_ICI_NO_TAG);
+/*
+ * Write out inode metadata (attributes) for the whole filesystem.
+ */
+int
+xfs_sync_attr(
+	struct xfs_mount	*mp,
+	int			flags)
+{
+	ASSERT((flags & ~SYNC_WAIT) == 0);
 
-	if (!error && (flags & SYNC_DELWRI))
-		xfs_log_force(mp, 0, lflags);
-	return XFS_ERROR(error);
+	return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
+				     XFS_ICI_NO_TAG);
 }
 
 STATIC int
···
 	int error;
 
 	/* push non-blocking */
-	xfs_sync_inodes(mp, SYNC_DELWRI|SYNC_BDFLUSH);
+	xfs_sync_data(mp, 0);
 	xfs_qm_sync(mp, SYNC_BDFLUSH);
 	xfs_filestream_flush(mp);
 
 	/* push and block */
-	xfs_sync_inodes(mp, SYNC_DELWRI|SYNC_WAIT|SYNC_IOWAIT);
+	xfs_sync_data(mp, SYNC_WAIT|SYNC_IOWAIT);
 	xfs_qm_sync(mp, SYNC_WAIT);
 
 	/* write superblock and hoover up shutdown errors */
···
 	 * logged before we can write the unmount record.
 	 */
 	do {
-		xfs_sync_inodes(mp, SYNC_ATTR|SYNC_WAIT);
+		xfs_sync_attr(mp, SYNC_WAIT);
 		pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
 		if (!pincount) {
 			delay(50);
···
 	void		*arg)
 {
 	struct inode	*inode = arg;
-	xfs_sync_inodes(mp, SYNC_DELWRI | SYNC_TRYLOCK);
-	xfs_sync_inodes(mp, SYNC_DELWRI | SYNC_TRYLOCK | SYNC_IOWAIT);
+	xfs_sync_data(mp, SYNC_TRYLOCK);
+	xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_IOWAIT);
 	iput(inode);
 }
 

fs/xfs/linux-2.6/xfs_sync.h

···
 	struct completion	*w_completion;
 } 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 */
···
 int xfs_syncd_init(struct xfs_mount *mp);
 void xfs_syncd_stop(struct xfs_mount *mp);
 
-int xfs_sync_inodes(struct xfs_mount *mp, int flags);
+int xfs_sync_attr(struct xfs_mount *mp, int flags);
+int xfs_sync_data(struct xfs_mount *mp, int flags);
 int xfs_sync_fsdata(struct xfs_mount *mp, int flags);
 
 int xfs_quiesce_data(struct xfs_mount *mp);

fs/xfs/xfs_filestream.c

···
 	 * waiting for the lock because someone else is waiting on the lock we
 	 * hold and we cannot drop that as we are in a transaction here.
 	 *
-	 * Lucky for us, this inversion is rarely a problem because it's a
-	 * directory inode that we are trying to lock here and that means the
-	 * only place that matters is xfs_sync_inodes() and SYNC_DELWRI is
-	 * used. i.e. freeze, remount-ro, quotasync or unmount.
+	 * Lucky for us, this inversion is not a problem because it's a
+	 * directory inode that we are trying to lock here.
 	 *
 	 * So, if we can't get the iolock without sleeping then just give up
 	 */