Illumos 5027 - zfs large block support

5027 zfs large block support
Reviewed by: Alek Pinchuk <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Josef 'Jeff' Sipek <[email protected]>
Reviewed by: Richard Elling <[email protected]>
Reviewed by: Saso Kiselkov <[email protected]>
Reviewed by: Brian Behlendorf <[email protected]>
Approved by: Dan McDonald <[email protected]>

References:
  https://www.illumos.org/issues/5027
  https://github.com/illumos/illumos-gate/commit/b515258

Porting Notes:

* Included in this patch is a tiny ISP2() cleanup in zio_init() from
Illumos 5255.

* Unlike the upstream Illumos commit this patch does not impose an
arbitrary 128K block size limit on volumes.  Volumes, like filesystems,
are limited by the zfs_max_recordsize=1M module option.

* By default the maximum record size is limited to 1M by the module
option zfs_max_recordsize.  This value may be safely increased up to
16M which is the largest block size supported by the on-disk format.
At the moment, 1M blocks clearly offer a significant performance
improvement but the benefits of going beyond this for the majority
of workloads are less clear.

* The illumos version of this patch increased DMU_MAX_ACCESS to 32M.
This was determined not to be large enough when using 16M blocks
because the zfs_make_xattrdir() function will fail (EFBIG) when
assigning a TX.  This was immediately observed under Linux because
all newly created files must have a security xattr created and
that was failing.  Therefore, we've set DMU_MAX_ACCESS to 64M.

* On 32-bit platforms a hard limit of 1M is set for blocks due
to the limited virtual address space.  We should be able to relax
this one the ABD patches are merged.

Ported-by: Brian Behlendorf <[email protected]>
Closes #354

1 files changed, 7 insertions, 0 deletions

diff --git a/module/zfs/dsl_destroy.c b/module/zfs/dsl_destroy.c
index 4623f5dd5..0e2238f99 100644
--- a/module/zfs/dsl_destroy.c
+++ b/module/zfs/dsl_destroy.c
@@ -277,6 +277,10 @@ dsl_destroy_snapshot_sync_impl(dsl_dataset_t *ds, boolean_t defer, dmu_tx_t *tx)
 
 	obj = ds->ds_object;
 
+	if (ds->ds_large_blocks) {
+		ASSERT0(zap_contains(mos, obj, DS_FIELD_LARGE_BLOCKS));
+		spa_feature_decr(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS, tx);
+	}
 	if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
 		ASSERT3P(ds->ds_prev, ==, NULL);
 		VERIFY0(dsl_dataset_hold_obj(dp,
@@ -738,6 +742,9 @@ dsl_destroy_head_sync_impl(dsl_dataset_t *ds, dmu_tx_t *tx)
 		ASSERT0(ds->ds_reserved);
 	}
 
+	if (ds->ds_large_blocks)
+		spa_feature_decr(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS, tx);
+
 	dsl_scan_ds_destroyed(ds, tx);
 
 	obj = ds->ds_object;