[Cluster-devel] [PATCH] mkfs.gfs2: Improve alignment of first resource group

[Andrew Price]

Currently the first rgrp is aligned to the whole stripe width and the
second rgrp is aligned to (stripe width + 1 stripe unit) and so on, to
spread them across an array. However, that means that there could be a
large amount of space wasted between the superblock and the first
resource group, and can result in the iovec used to zero that space
exceeding IOV_MAX and failing mkfs.gfs2 (since 6cefaf33d5) if the array
has a sufficiently large number of LUNs. Instead, align the first
resource group to a stripe unit so that the gap is minimised. Resource
groups are still spread across the array as the alignment of subsequent
ones are handled separately.

Resolves: rhbz#1698858

Signed-off-by: Andrew Price <anprice at redhat.com>
---
 gfs2/libgfs2/rgrp.c | 2 +-
 tests/mkfs.at       | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/gfs2/libgfs2/rgrp.c b/gfs2/libgfs2/rgrp.c
index 3cdaccae..20ce5807 100644
--- a/gfs2/libgfs2/rgrp.c
+++ b/gfs2/libgfs2/rgrp.c
@@ -332,7 +332,7 @@ static uint64_t align_block(const uint64_t base, const uint64_t align)
  */
 uint64_t lgfs2_rgrp_align_addr(const lgfs2_rgrps_t rgs, uint64_t addr)
 {
-	return align_block(addr, rgs->align);
+	return align_block(addr, rgs->align_off);
 }
 
 /**
diff --git a/tests/mkfs.at b/tests/mkfs.at
index 2739561f..57785a0d 100644
--- a/tests/mkfs.at
+++ b/tests/mkfs.at
@@ -122,6 +122,8 @@ AT_KEYWORDS(mkfs.gfs2 mkfs)
 AT_CHECK([$GFS_MKFS -p lock_nolock -o test_topology=0:512:65536:393216:512 $GFS_TGT], 0, [ignore], [ignore])
 # Check rgrp alignment to minimum_io_size: 65536 / 4096 == 16
 AT_CHECK([gfs2_edit -p rindex $GFS_TGT | grep ri_addr | awk '{print $2, $2 % 16; if ($2 % 16 != 0) { exit 1 }}'], 0, [ignore], [ignore])
+# rhbz#1698858
+AT_CHECK([$GFS_MKFS -p lock_nolock -o test_topology=0:512:131072:6291456:512 $GFS_TGT], 0, [ignore], [ignore])
 AT_CLEANUP
 
 AT_SETUP([Values of rg_skip])
-- 
2.20.1