Enforce "-F" flag on resuming recv of full/newfs on existing dataset

When receiving full/newfs on existing dataset, then it should be done
with "-F" flag. Its enforced for initial receive in checks done in
zfs_receive_one function of libzfs. Similarly, on resuming full/newfs
recv on existing dataset, it should be done with "-F" flag.

When dataset doesn't exist, then full/new recv is done on newly created
dataset and it's marked INCONSISTENT. But when receiving on existing
dataset, recv is first done on %recv and its marked INCONSISTENT.
Existing dataset is not marked INCONSISTENT. Resume of full/newfs
receive with dataset not INCONSISTENT indicates that its resuming newfs
on existing dataset. So, enforce "-F" flag in this case.

Also return an error from dmu_recv_resume_begin_check() in zfs kernel,
when its resuming full/newfs recv without force.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Chunwei Chen <[email protected]>
Signed-off-by: Jitendra Patidar <[email protected]>
Closes #13856
Closes #13857 

1 files changed, 11 insertions, 0 deletions

diff --git a/module/zfs/dmu_recv.c b/module/zfs/dmu_recv.c
index 0f3181f76..e22b6b13a 100644
--- a/module/zfs/dmu_recv.c
+++ b/module/zfs/dmu_recv.c
@@ -1045,13 +1045,24 @@ dmu_recv_resume_begin_check(void *arg, dmu_tx_t *tx)
 		dsflags |= DS_HOLD_FLAG_DECRYPT;
 	}
 
+	boolean_t recvexist = B_TRUE;
 	if (dsl_dataset_hold_flags(dp, recvname, dsflags, FTAG, &ds) != 0) {
 		/* %recv does not exist; continue in tofs */
+		recvexist = B_FALSE;
 		error = dsl_dataset_hold_flags(dp, tofs, dsflags, FTAG, &ds);
 		if (error != 0)
 			return (error);
 	}
 
+	/*
+	 * Resume of full/newfs recv on existing dataset should be done with
+	 * force flag
+	 */
+	if (recvexist && drrb->drr_fromguid == 0 && !drc->drc_force) {
+		dsl_dataset_rele_flags(ds, dsflags, FTAG);
+		return (SET_ERROR(ZFS_ERR_RESUME_EXISTS));
+	}
+
 	/* check that ds is marked inconsistent */
 	if (!DS_IS_INCONSISTENT(ds)) {
 		dsl_dataset_rele_flags(ds, dsflags, FTAG);