Pool allocation classes

Allocation Classes add the ability to have allocation classes in a
pool that are dedicated to serving specific block categories, such
as DDT data, metadata, and small file blocks. A pool can opt-in to
this feature by adding a 'special' or 'dedup' top-level VDEV.

Reviewed by: Pavel Zakharov <[email protected]>
Reviewed-by: Richard Laager <[email protected]>
Reviewed-by: Alek Pinchuk <[email protected]>
Reviewed-by: Håkan Johansson <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
Reviewed-by: DHE <[email protected]>
Reviewed-by: Richard Elling <[email protected]>
Reviewed-by: Gregor Kopka <[email protected]>
Reviewed-by: Kash Pande <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Matthew Ahrens <[email protected]>
Signed-off-by: Don Brady <[email protected]>
Closes #5182 

1 files changed, 2 insertions, 0 deletions

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 88b574d4a..8779eb358 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -2281,6 +2281,8 @@ dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
 	bzero(zp->zp_salt, ZIO_DATA_SALT_LEN);
 	bzero(zp->zp_iv, ZIO_DATA_IV_LEN);
 	bzero(zp->zp_mac, ZIO_DATA_MAC_LEN);
+	zp->zp_zpl_smallblk = DMU_OT_IS_FILE(zp->zp_type) ?
+	    os->os_zpl_special_smallblock : 0;
 
 	ASSERT3U(zp->zp_compress, !=, ZIO_COMPRESS_INHERIT);
 }