[PATCH] xfs: fix bogus m_maxagi check in xfs_iget

[Christoph Hellwig]

These days inode64 should only control which AGs we allocate new inodes
from, while we still try to support reading all existing inodes.  To make
this actually work the check ontop of xfs_iget needs to be relaxed to allow
inodes in all allocation groups instead of just those that we allow
allocating inodes from.  Note that we can't simply remove the check - it
prevents us from accessing invalid data when fed invalid inode numbers
from NFS or bulkstat.

Signed-off-by: Christoph Hellwig <hch at lst.de>

Index: xfs/fs/xfs/xfs_iget.c
===================================================================
--- xfs.orig/fs/xfs/xfs_iget.c	2010-10-05 10:56:05.749253507 +0200
+++ xfs/fs/xfs/xfs_iget.c	2010-10-06 20:22:36.189003262 +0200
@@ -365,8 +365,8 @@ xfs_iget(
 	xfs_perag_t	*pag;
 	xfs_agino_t	agino;
 
-	/* the radix tree exists only in inode capable AGs */
-	if (XFS_INO_TO_AGNO(mp, ino) >= mp->m_maxagi)
+	/* reject inode numbers outside existing AGs */
+	if (XFS_INO_TO_AGNO(mp, ino) >= mp->m_sb.sb_agcount)
 		return EINVAL;
 
 	/* get the perag structure and ensure that it's inode capable */