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, 13 insertions, 1 deletions

diff --git a/module/zfs/zfeature_common.c b/module/zfs/zfeature_common.c
index 461456275..609a72ab3 100644
--- a/module/zfs/zfeature_common.c
+++ b/module/zfs/zfeature_common.c
@@ -56,7 +56,8 @@ valid_char(char c, boolean_t after_colon)
 {
 	return ((c >= 'a' && c <= 'z') ||
 	    (c >= '0' && c <= '9') ||
-	    c == (after_colon ? '_' : '.'));
+	    (after_colon && c == '_') ||
+	    (!after_colon && (c == '.' || c == '-')));
 }
 
 /*
@@ -230,4 +231,15 @@ zpool_feature_init(void)
 	    "com.delphix:embedded_data", "embedded_data",
 	    "Blocks which compress very well use even less space.",
 	    B_FALSE, B_TRUE, B_TRUE, NULL);
+
+	{
+	static const spa_feature_t large_blocks_deps[] = {
+		SPA_FEATURE_EXTENSIBLE_DATASET,
+		SPA_FEATURE_NONE
+	};
+	zfeature_register(SPA_FEATURE_LARGE_BLOCKS,
+	    "org.open-zfs:large_blocks", "large_blocks",
+	    "Support for blocks larger than 128KB.", B_FALSE, B_FALSE, B_FALSE,
+	    large_blocks_deps);
+	}
 }