'zfs share -a' should handle 'canmount=noauto'

The 'zfs share -a' currently skips any filesystems which
have 'canmount=noauto' set. This behavior is unexpected since the
one would expect 'zfs share -a' to share any mounted filesystem
that has the 'sharenfs' property already set.

This changes the behavior of 'zfs share -a' to allow the sharing
of 'canmount=noauto' datasets if they are mounted.

Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Signed-off-by: George Wilson <gwilson@delphix.com>
External-issue: DLPX-71313
Closes #10688

cmd/zfs/zfs_main.c

@@ -6627,6 +6627,14 @@ share_mount_one(zfs_handle_t *zhp, int op, int flags, char *protocol,
 		    zfs_get_name(zhp));
 		return (1);
 	} else if (canmount == ZFS_CANMOUNT_NOAUTO && !explicit) {
+		/*
+		 * When performing a 'zfs mount -a', we skip any mounts for
+		 * datasets that have 'noauto' set. Sharing a dataset with
+		 * 'noauto' set is only allowed if it's mounted.
+		 */
+		if (op == OP_MOUNT)
+			return (0);
+		if (op == OP_SHARE && !zfs_is_mounted(zhp, NULL))
 			return (0);
 	}
 

tests/zfs-tests/tests/functional/cli_root/zfs_set/canmount_002_pos.ksh

@@ -41,8 +41,10 @@
 # STRATEGY:
 # 1. Setup a pool and create fs, volume, snapshot clone within it.
 # 2. Set canmount=noauto for each dataset and check the return value
-#    and check if it still can be mounted by mount -a.
+#    and check if it still can be mounted by mount -a or shared by
+#    share -a
 # 3. mount each dataset(except volume) to see if it can be mounted.
+# 4. verify that a mounted dataset can be shared by share -a.
 #
 
 verify_runnable "both"
@@ -100,6 +102,7 @@ log_onexit cleanup
 
 set -A old_mnt
 set -A old_canmount
+set -A old_sharenfs
 typeset tmpmnt=/tmpmount$$
 typeset ds
 
@@ -113,6 +116,7 @@ while (( i < ${#dataset_pos[*]} )); do
 	ds=${dataset_pos[i]}
 	old_mnt[i]=$(get_prop mountpoint $ds)
 	old_canmount[i]=$(get_prop canmount $ds)
+	old_sharenfs[i]=$(get_prop sharenfs $ds)
 	(( i = i + 1 ))
 done
 
@@ -121,6 +125,7 @@ while (( i < ${#dataset_pos[*]} )) ; do
 	dataset=${dataset_pos[i]}
 	set_n_check_prop "noauto" "canmount" "$dataset"
 	log_must zfs set mountpoint=$tmpmnt $dataset
+	log_must zfs set sharenfs=on $dataset
 	if  ismounted $dataset; then
 		zfs unmount -a > /dev/null 2>&1
 		log_must mounted $dataset
@@ -128,6 +133,8 @@ while (( i < ${#dataset_pos[*]} )) ; do
 		log_must unmounted $dataset
 		log_must zfs mount -a
 		log_must unmounted $dataset
+		log_must zfs share -a
+		log_mustnot is_exported $tmpmnt
 	else
 		log_must zfs mount -a
 		log_must unmounted $dataset
@@ -137,6 +144,10 @@ while (( i < ${#dataset_pos[*]} )) ; do
 
 	log_must zfs mount $dataset
 	log_must mounted $dataset
+	log_must zfs share -a
+	log_must is_exported $tmpmnt
+
+	log_must zfs set sharenfs="${old_sharenfs[i]}" $dataset
 	log_must zfs set canmount="${old_canmount[i]}" $dataset
 	log_must zfs set mountpoint="${old_mnt[i]}" $dataset
 	(( i = i + 1 ))