Make rollbacks fail gracefully

Support for rolling back datasets require a functional ZPL, which we currently
do not have.  The zfs command does not check for ZPL support before attempting
a rollback, and in preparation for rolling back a zvol it removes the minor
node of the device.  To prevent the zvol device node from disappearing after a
failed rollback operation, this change wraps the zfs_do_rollback() function in
an #ifdef HAVE_ZPL and returns ENOSYS in the absence of a ZPL.  This is
consistent with the behavior of other ZPL dependent commands such as mount.

The orginal error message observed with this bug was rather confusing:

    internal error: Unknown error 524
    Aborted

This was because zfs_ioc_rollback() returns ENOTSUP if we don't HAVE_ZPL, but
Linux actually has no such error code.  It should instead return EOPNOTSUPP, as
that is how ENOTSUP is defined in user space.  With that we would have gotten
the somewhat more helpful message

    cannot rollback 'tank/fish': unsupported version

This is rather a moot point with the above changes since we will no longer make
that ioctl call without a ZPL.  But, this change updates the error code just in
case.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index b0e6180eac86176715e1ea25890dbd4f83acfb1a..5f22e434ef293ba6e1febadc641ff4bc5e9d2178 100644 (file)
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -2340,6 +2340,7 @@ typedef struct rollback_cbdata {
  * 'cb_dependent' is set, then this is a dependent and we should report it
  * without checking the transaction group.
  */
+#ifdef HAVE_ZPL
 static int
 rollback_check(zfs_handle_t *zhp, void *data)
 {
@@ -2399,10 +2400,12 @@ rollback_check(zfs_handle_t *zhp, void *data)
        zfs_close(zhp);
        return (0);
 }
+#endif /* HAVE_ZPL */
 
 static int
 zfs_do_rollback(int argc, char **argv)
 {
+#ifdef HAVE_ZPL
        int ret;
        int c;
        boolean_t force = B_FALSE;
@@ -2484,6 +2487,9 @@ out:
                return (0);
        else
                return (1);
+#else
+       return ENOSYS;
+#endif /*HAVE_ZPL*/
 }
 
 /*

diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 45e118e537396fc05ea0433ca148bfd4ea50adc0..2856ba7c427cd9949f4da42d699ccbf44b8ff64d 100644 (file)
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -3291,7 +3291,7 @@ out:
                dsl_dataset_rele(ds, FTAG);
        return (error);
 #else
-       return (ENOTSUP);
+       return (EOPNOTSUPP);
 #endif /* HAVE_ZPL */
 }