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/vdev_disk.c b/module/zfs/vdev_disk.c
index db13b7bc4..0196f3945 100644
--- a/module/zfs/vdev_disk.c
+++ b/module/zfs/vdev_disk.c
@@ -552,9 +552,9 @@ retry:
 			goto retry;
 		}
 
-		dr->dr_bio[i] = bio_alloc(GFP_NOIO,
-		    bio_nr_pages(bio_ptr, bio_size));
 		/* bio_alloc() with __GFP_WAIT never returns NULL */
+		dr->dr_bio[i] = bio_alloc(GFP_NOIO,
+		    MIN(bio_nr_pages(bio_ptr, bio_size), BIO_MAX_PAGES));
 		if (unlikely(dr->dr_bio[i] == NULL)) {
 			vdev_disk_dio_free(dr);
 			return (ENOMEM);