Remove GRUB restrictions

The GRUB restrictions are based around the pool's bootfs property.
Given the current situation where GRUB is not staying current with
OpenZFS pool features, having either a non-ZFS /boot or a separate
pool with limited features are pretty much the only long-term answers
for GRUB support.  Only the second case matters in this context.  For
the restrictions to be useful, the bootfs property would have to be set
on the boot pool, because that is where we need the restrictions, as
that is the pool that GRUB reads from. The documentation for bootfs
describes it as pointing to the root pool. That's also how it's used in
the initramfs. ZFS does not allow setting bootfs to point to a dataset
in another pool. (If it did, it'd be difficult-to-impossible to enforce
these restrictions cross-pool). Accordingly, bootfs is pretty much
useless for GRUB scenarios moving forward.

Even for users who have only one pool, the existing restrictions for
GRUB are incomplete. They don't prevent you from enabling the
unsupported checksums, for example. For that reason, I have ripped out
all the GRUB restrictions.

A little longer-term, I think extending the proposed features=portable
system to define a features=grub is a much more useful approach. The
user could set that on the boot pool at creation, and things would
Just Work.

Reviewed-by: Paul Dagnelie <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Richard Laager <[email protected]>
Closes #8627 

5 files changed, 2 insertions, 89 deletions

diff --git a/lib/libzfs/libzfs_pool.c b/lib/libzfs/libzfs_pool.c
index f848cb3cf..b75ab3ec1 100644
--- a/lib/libzfs/libzfs_pool.c
+++ b/lib/libzfs/libzfs_pool.c
@@ -3143,7 +3143,6 @@ zpool_vdev_attach(zpool_handle_t *zhp, const char *old_disk,
 	uint_t children;
 	nvlist_t *config_root;
 	libzfs_handle_t *hdl = zhp->zpool_hdl;
-	boolean_t rootpool = zpool_is_bootable(zhp);
 
 	if (replacing)
 		(void) snprintf(msg, sizeof (msg), dgettext(TEXT_DOMAIN,
@@ -3211,18 +3210,8 @@ zpool_vdev_attach(zpool_handle_t *zhp, const char *old_disk,
 
 	zcmd_free_nvlists(&zc);
 
-	if (ret == 0) {
-		if (rootpool) {
-			/*
-			 * XXX need a better way to prevent user from
-			 * booting up a half-baked vdev.
-			 */
-			(void) fprintf(stderr, dgettext(TEXT_DOMAIN, "Make "
-			    "sure to wait until resilver is done "
-			    "before rebooting.\n"));
-		}
+	if (ret == 0)
 		return (0);
-	}
 
 	switch (errno) {
 	case ENOTSUP:
@@ -3652,13 +3641,6 @@ zpool_vdev_remove(zpool_handle_t *zhp, const char *path)
 		return (zfs_error(hdl, EZFS_BADVERSION, msg));
 	}
 
-	if (!islog && !avail_spare && !l2cache && zpool_is_bootable(zhp)) {
-		zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
-		    "root pool can not have removed devices, "
-		    "because GRUB does not understand them"));
-		return (zfs_error(hdl, EINVAL, msg));
-	}
-
 	zc.zc_guid = fnvlist_lookup_uint64(tgt, ZPOOL_CONFIG_GUID);
 
 	if (zfs_ioctl(hdl, ZFS_IOC_VDEV_REMOVE, &zc) == 0)
diff --git a/man/man5/zpool-features.5 b/man/man5/zpool-features.5
index 3f690c334..0416afaa3 100644
--- a/man/man5/zpool-features.5
+++ b/man/man5/zpool-features.5
@@ -340,9 +340,6 @@ can turn on the \fBedonr\fR checksum on any dataset using the
 and will return to being \fBenabled\fR once all filesystems that have
 ever had their checksum set to \fBedonr\fR are destroyed.
 
-The \fBedonr\fR feature is not supported by GRUB and must not be used on
-the pool if GRUB needs to access the pool (e.g. for /boot).
-
 FreeBSD does not support the \fBedonr\fR feature.
 .RE
 
@@ -827,9 +824,6 @@ can turn on the \fBsha512\fR checksum on any dataset using
 \fBactive\fR once a \fBchecksum\fR property has been set to \fBsha512\fR,
 and will return to being \fBenabled\fR once all filesystems that have
 ever had their checksum set to \fBsha512\fR are destroyed.
-
-The \fBsha512\fR feature is not supported by GRUB and must not be used on
-the pool if GRUB needs to access the pool (e.g. for /boot).
 .RE
 
 .sp
@@ -861,9 +855,6 @@ can turn on the \fBskein\fR checksum on any dataset using
 \fBactive\fR once a \fBchecksum\fR property has been set to \fBskein\fR,
 and will return to being \fBenabled\fR once all filesystems that have
 ever had their checksum set to \fBskein\fR are destroyed.
-
-The \fBskein\fR feature is not supported by GRUB and must not be used on
-the pool if GRUB needs to access the pool (e.g. for /boot).
 .RE
 
 .sp
diff --git a/man/man8/zfsprops.8 b/man/man8/zfsprops.8
index 5a2b45e64..1fcb07c6f 100644
--- a/man/man8/zfsprops.8
+++ b/man/man8/zfsprops.8
@@ -762,8 +762,6 @@ The
 and
 .Sy edonr
 checksum algorithms require enabling the appropriate features on the pool.
-These pool features are not supported by GRUB and must not be used on the
-pool if GRUB needs to access the pool (e.g. for /boot).
 FreeBSD does not support the
 .Sy edonr
 algorithm.
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 79b88e911..e358404db 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -621,7 +621,6 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
 
 			if (!error) {
 				objset_t *os;
-				uint64_t propval;
 
 				if (strval == NULL || strval[0] == '\0') {
 					objnum = zpool_prop_default_numeric(
@@ -633,27 +632,9 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
 				if (error != 0)
 					break;
 
-				/*
-				 * Must be ZPL, and its property settings
-				 * must be supported by GRUB (compression
-				 * is not gzip, and large dnodes are not
-				 * used).
-				 */
-
+				/* Must be ZPL. */
 				if (dmu_objset_type(os) != DMU_OST_ZFS) {
 					error = SET_ERROR(ENOTSUP);
-				} else if ((error =
-				    dsl_prop_get_int_ds(dmu_objset_ds(os),
-				    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
-				    &propval)) == 0 &&
-				    !BOOTFS_COMPRESS_VALID(propval)) {
-					error = SET_ERROR(ENOTSUP);
-				} else if ((error =
-				    dsl_prop_get_int_ds(dmu_objset_ds(os),
-				    zfs_prop_to_name(ZFS_PROP_DNODESIZE),
-				    &propval)) == 0 &&
-				    propval != ZFS_DNSIZE_LEGACY) {
-					error = SET_ERROR(ENOTSUP);
 				} else {
 					objnum = dmu_objset_id(os);
 				}
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 10b37a4ad..a58fd99ad 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -301,23 +301,6 @@ history_str_get(zfs_cmd_t *zc)
 }
 
 /*
- * Check to see if the named dataset is currently defined as bootable
- */
-static boolean_t
-zfs_is_bootfs(const char *name)
-{
-	objset_t *os;
-
-	if (dmu_objset_hold(name, FTAG, &os) == 0) {
-		boolean_t ret;
-		ret = (dmu_objset_id(os) == spa_bootfs(dmu_objset_spa(os)));
-		dmu_objset_rele(os, FTAG);
-		return (ret);
-	}
-	return (B_FALSE);
-}
-
-/*
  * Return non-zero if the spa version is less than requested version.
  */
 static int
@@ -4478,18 +4461,6 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 				}
 				spa_close(spa, FTAG);
 			}
-
-			/*
-			 * If this is a bootable dataset then
-			 * verify that the compression algorithm
-			 * is supported for booting. We must return
-			 * something other than ENOTSUP since it
-			 * implies a downrev pool version.
-			 */
-			if (zfs_is_bootfs(dsname) &&
-			    !BOOTFS_COMPRESS_VALID(intval)) {
-				return (SET_ERROR(ERANGE));
-			}
 		}
 		break;
 
@@ -4531,16 +4502,6 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 		    intval != ZFS_DNSIZE_LEGACY) {
 			spa_t *spa;
 
-			/*
-			 * If this is a bootable dataset then
-			 * we don't allow large (>512B) dnodes,
-			 * because GRUB doesn't support them.
-			 */
-			if (zfs_is_bootfs(dsname) &&
-			    intval != ZFS_DNSIZE_LEGACY) {
-				return (SET_ERROR(EDOM));
-			}
-
 			if ((err = spa_open(dsname, &spa, FTAG)) != 0)
 				return (err);