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, 2 insertions, 2 deletions

diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 6975ada62..1699ea7e7 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -1329,7 +1329,7 @@ arc_buf_alloc(spa_t *spa, uint64_t size, void *tag, arc_buf_contents_t type)
 	arc_buf_hdr_t *hdr;
 	arc_buf_t *buf;
 
-	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
+	VERIFY3U(size, <=, spa_maxblocksize(spa));
 	hdr = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE);
 	ASSERT(BUF_EMPTY(hdr));
 	hdr->b_size = size;
@@ -3289,7 +3289,7 @@ top:
 		 * Gracefully handle a damaged logical block size as a
 		 * checksum error by passing a dummy zio to the done callback.
 		 */
-		if (size > SPA_MAXBLOCKSIZE) {
+		if (size > spa_maxblocksize(spa)) {
 			if (done) {
 				rzio = zio_null(pio, spa, NULL,
 				    NULL, NULL, zio_flags);