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, 16 insertions, 8 deletions

diff --git a/module/zfs/dmu_tx.c b/module/zfs/dmu_tx.c
index 89f45a781..62a8d471e 100644
--- a/module/zfs/dmu_tx.c
+++ b/module/zfs/dmu_tx.c
@@ -241,7 +241,7 @@ dmu_tx_count_write(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
 		return;
 
 	min_bs = SPA_MINBLOCKSHIFT;
-	max_bs = SPA_MAXBLOCKSHIFT;
+	max_bs = highbit64(txh->txh_tx->tx_objset->os_recordsize) - 1;
 	min_ibs = DN_MIN_INDBLKSHIFT;
 	max_ibs = DN_MAX_INDBLKSHIFT;
 
@@ -310,6 +310,14 @@ dmu_tx_count_write(dmu_tx_hold_t *txh, uint64_t off, uint64_t len)
 			 */
 			ASSERT(dn->dn_datablkshift != 0);
 			min_bs = max_bs = dn->dn_datablkshift;
+		} else {
+			/*
+			 * The blocksize can increase up to the recordsize,
+			 * or if it is already more than the recordsize,
+			 * up to the next power of 2.
+			 */
+			min_bs = highbit64(dn->dn_datablksz - 1);
+			max_bs = MAX(max_bs, highbit64(dn->dn_datablksz - 1));
 		}
 
 		/*
@@ -745,11 +753,11 @@ dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name)
 		bp = &dn->dn_phys->dn_blkptr[0];
 		if (dsl_dataset_block_freeable(dn->dn_objset->os_dsl_dataset,
 		    bp, bp->blk_birth))
-			txh->txh_space_tooverwrite += SPA_MAXBLOCKSIZE;
+			txh->txh_space_tooverwrite += MZAP_MAX_BLKSZ;
 		else
-			txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+			txh->txh_space_towrite += MZAP_MAX_BLKSZ;
 		if (!BP_IS_HOLE(bp))
-			txh->txh_space_tounref += SPA_MAXBLOCKSIZE;
+			txh->txh_space_tounref += MZAP_MAX_BLKSZ;
 		return;
 	}
 
@@ -1546,18 +1554,18 @@ dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object)
 
 	/* If blkptr doesn't exist then add space to towrite */
 	if (!(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) {
-		txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+		txh->txh_space_towrite += SPA_OLD_MAXBLOCKSIZE;
 	} else {
 		blkptr_t *bp;
 
 		bp = &dn->dn_phys->dn_spill;
 		if (dsl_dataset_block_freeable(dn->dn_objset->os_dsl_dataset,
 		    bp, bp->blk_birth))
-			txh->txh_space_tooverwrite += SPA_MAXBLOCKSIZE;
+			txh->txh_space_tooverwrite += SPA_OLD_MAXBLOCKSIZE;
 		else
-			txh->txh_space_towrite += SPA_MAXBLOCKSIZE;
+			txh->txh_space_towrite += SPA_OLD_MAXBLOCKSIZE;
 		if (!BP_IS_HOLE(bp))
-			txh->txh_space_tounref += SPA_MAXBLOCKSIZE;
+			txh->txh_space_tounref += SPA_OLD_MAXBLOCKSIZE;
 	}
 }