xfs: track cowblocks separately in i_flags

The EOFBLOCKS/COWBLOCKS tags are totally separate things, so track them
with separate i_flags.  Right now we're abusing IEOFBLOCKS for both,
which is totally bogus because we won't tag the inode with COWBLOCKS if
IEOFBLOCKS was set by a previous tagging of the inode with EOFBLOCKS.
Found by wiring up clonerange to fsstress in xfs/017.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index b2136af..d383e39 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -232,6 +232,7 @@ static inline bool xfs_is_reflink_inode(struct xfs_inode *ip)
  * log recovery to replay a bmap operation on the inode.
  */
 #define XFS_IRECOVERY		(1 << 11)
+#define XFS_ICOWBLOCKS		(1 << 12)/* has the cowblocks tag set */
 
 /*
  * Per-lifetime flags need to be reset when re-using a reclaimable inode during