MFV r274273:

ZFS large block support.

Please note that booting from datasets that have recordsize greater
than 128KB is not supported (but it's Okay to enable the feature on
the pool).  This *may* remain unchanged because of memory constraint.

Limited safety belt is provided for mounted root filesystem but use
caution is advised.

Illumos issue:
    5027 zfs large block support

MFC after:	1 month

1 files changed, 6 insertions, 0 deletions

diff --git a/sys/boot/zfs/zfsimpl.c b/sys/boot/zfs/zfsimpl.c
index 16b57c7..8d21c57 100644
--- a/sys/boot/zfs/zfsimpl.c
+++ b/sys/boot/zfs/zfsimpl.c
@@ -57,6 +57,7 @@ static const char *features_for_read[] = {
 	"com.delphix:hole_birth",
 	"com.delphix:extensible_dataset",
 	"com.delphix:embedded_data",
+	"org.open-zfs:large_blocks",
 	NULL
 };
 
@@ -1222,6 +1223,11 @@ dnode_read(const spa_t *spa, const dnode_phys_t *dnode, off_t offset, void *buf,
 	int nlevels = dnode->dn_nlevels;
 	int i, rc;
 
+	if (bsize > SPA_MAXBLOCKSIZE) {
+		printf("ZFS: I/O error - blocks larger than 128K are not supported\n");
+		return (EIO);
+	}
+
 	/*
 	 * Note: bsize may not be a power of two here so we need to do an
 	 * actual divide rather than a bitshift.