xfs: convert drop_writes to use the errortag mechanism

We now have enhanced error injection that can control the frequency
with which errors happen, so convert drop_writes to use this.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
index e2278af6..a2f23d2 100644
--- a/fs/xfs/xfs_error.c
+++ b/fs/xfs/xfs_error.c
@@ -55,6 +55,7 @@
 	XFS_RANDOM_REFCOUNT_FINISH_ONE,
 	XFS_RANDOM_BMAP_FINISH_ONE,
 	XFS_RANDOM_AG_RESV_CRITICAL,
+	XFS_RANDOM_DROP_WRITES,
 };
 
 struct xfs_errortag_attr {
@@ -157,6 +158,7 @@
 XFS_ERRORTAG_ATTR_RW(refcount_finish_one,	XFS_ERRTAG_REFCOUNT_FINISH_ONE);
 XFS_ERRORTAG_ATTR_RW(bmap_finish_one,	XFS_ERRTAG_BMAP_FINISH_ONE);
 XFS_ERRORTAG_ATTR_RW(ag_resv_critical,	XFS_ERRTAG_AG_RESV_CRITICAL);
+XFS_ERRORTAG_ATTR_RW(drop_writes,	XFS_ERRTAG_DROP_WRITES);
 
 static struct attribute *xfs_errortag_attrs[] = {
 	XFS_ERRORTAG_ATTR_LIST(noerror),
@@ -187,6 +189,7 @@
 	XFS_ERRORTAG_ATTR_LIST(refcount_finish_one),
 	XFS_ERRORTAG_ATTR_LIST(bmap_finish_one),
 	XFS_ERRORTAG_ATTR_LIST(ag_resv_critical),
+	XFS_ERRORTAG_ATTR_LIST(drop_writes),
 	NULL,
 };