[XFS] Combine the XFS and Linux inodes

To avoid issues with different lifecycles of XFS and Linux inodes, embedd
the linux inode inside the XFS inode. This means that the linux inode has
the same lifecycle as the XFS inode, even when it has been released by the
OS. XFS inodes don't live much longer than this (a short stint in reclaim
at most), so there isn't significant memory usage penalties here.

Version 3 o kill xfs_icount()

Version 2 o remove unused commented out code from xfs_iget(). o kill
useless cast in VFS_I()

SGI-PV: 988141

SGI-Modid: xfs-linux-melb:xfs-kern:32323a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index a671457..7fb577c 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -2833,6 +2833,7 @@
 	if (!ip->i_update_core && (ip->i_itemp == NULL)) {
 		xfs_ilock(ip, XFS_ILOCK_EXCL);
 		xfs_iflock(ip);
+		xfs_iflags_set(ip, XFS_IRECLAIMABLE);
 		return xfs_finish_reclaim(ip, 1, XFS_IFLUSH_DELWRI_ELSE_SYNC);
 	} else {
 		xfs_mount_t	*mp = ip->i_mount;
@@ -2841,8 +2842,6 @@
 		XFS_MOUNT_ILOCK(mp);
 		spin_lock(&ip->i_flags_lock);
 		__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
-		VFS_I(ip)->i_private = NULL;
-		ip->i_vnode = NULL;
 		spin_unlock(&ip->i_flags_lock);
 		list_add_tail(&ip->i_reclaim, &mp->m_del_inodes);
 		XFS_MOUNT_IUNLOCK(mp);
@@ -2857,10 +2856,6 @@
 	int		sync_mode)
 {
 	xfs_perag_t	*pag = xfs_get_perag(ip->i_mount, ip->i_ino);
-	struct inode	*vp = VFS_I(ip);
-
-	if (vp && VN_BAD(vp))
-		goto reclaim;
 
 	/* The hash lock here protects a thread in xfs_iget_core from
 	 * racing with us on linking the inode back with a vnode.
@@ -2870,7 +2865,7 @@
 	write_lock(&pag->pag_ici_lock);
 	spin_lock(&ip->i_flags_lock);
 	if (__xfs_iflags_test(ip, XFS_IRECLAIM) ||
-	    (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) && vp == NULL)) {
+	    !__xfs_iflags_test(ip, XFS_IRECLAIMABLE)) {
 		spin_unlock(&ip->i_flags_lock);
 		write_unlock(&pag->pag_ici_lock);
 		if (locked) {
@@ -2904,15 +2899,13 @@
 	 * In the case of a forced shutdown we rely on xfs_iflush() to
 	 * wait for the inode to be unpinned before returning an error.
 	 */
-	if (xfs_iflush(ip, sync_mode) == 0) {
+	if (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) {
 		/* synchronize with xfs_iflush_done */
 		xfs_iflock(ip);
 		xfs_ifunlock(ip);
 	}
 
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
- reclaim:
 	xfs_ireclaim(ip);
 	return 0;
 }