xfs: rework the inline directory verifiers

The inline directory verifiers should be called on the inode fork data,
which means after iformat_local on the read side, and prior to
ifork_flush on the write side.  This makes the fork verifier more
consistent with the way buffer verifiers work -- i.e. they will operate
on the memory buffer that the code will be reading and writing directly.

Furthermore, revise the verifier function to return -EFSCORRUPTED so
that we don't flood the logs with corruption messages and assert
notices.  This has been a particular problem with xfs/348, which
triggers the XFS_WANT_CORRUPTED_RETURN assertions, which halts the
kernel when CONFIG_XFS_DEBUG=y.  Disk corruption isn't supposed to do
that, at least not in a verifier.

Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index 132dc59..7fb8365 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -140,7 +140,7 @@ typedef struct xfs_ifork {
 struct xfs_ifork *xfs_iext_state_to_fork(struct xfs_inode *ip, int state);
 
 int		xfs_iformat_fork(struct xfs_inode *, struct xfs_dinode *);
-int		xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
+void		xfs_iflush_fork(struct xfs_inode *, struct xfs_dinode *,
 				struct xfs_inode_log_item *, int);
 void		xfs_idestroy_fork(struct xfs_inode *, int);
 void		xfs_idata_realloc(struct xfs_inode *, int, int);