From 2d678f779aba26a93314c8ee1142c3985fa25cb6 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Tue, 27 Jun 2017 10:09:16 -0700
Subject: [PATCH] Cap maximum aggregate IO size
Commit 8542ef8 allowed optional IOs to be aggregated beyond
the specified aggregation limit. Since the aggregation limit
was also used to enforce the maximum block size, setting
`zfs_vdev_aggregation_limit=16777216` could result in an
attempt to allocate an ABD larger than 16M.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6259
Closes #6270
---
module/zfs/vdev_queue.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
index 2439f2951c..6b3e872915 100644
--- a/module/zfs/vdev_queue.c
+++ b/module/zfs/vdev_queue.c
@@ -521,13 +521,14 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
uint64_t maxgap = 0;
uint64_t size;
uint64_t limit;
+ int maxblocksize;
boolean_t stretch = B_FALSE;
avl_tree_t *t = vdev_queue_type_tree(vq, zio->io_type);
enum zio_flag flags = zio->io_flags & ZIO_FLAG_AGG_INHERIT;
abd_t *abd;
- limit = MAX(MIN(zfs_vdev_aggregation_limit,
- spa_maxblocksize(vq->vq_vdev->vdev_spa)), 0);
+ maxblocksize = spa_maxblocksize(vq->vq_vdev->vdev_spa);
+ limit = MAX(MIN(zfs_vdev_aggregation_limit, maxblocksize), 0);
if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE || limit == 0)
return (NULL);
@@ -584,6 +585,7 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
(dio->io_flags & ZIO_FLAG_AGG_INHERIT) == flags &&
(IO_SPAN(first, dio) <= limit ||
(dio->io_flags & ZIO_FLAG_OPTIONAL)) &&
+ IO_SPAN(first, dio) <= maxblocksize &&
IO_GAP(last, dio) <= maxgap) {
last = dio;
if (!(last->io_flags & ZIO_FLAG_OPTIONAL))
@@ -635,6 +637,7 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio)
return (NULL);
size = IO_SPAN(first, last);
+ ASSERT3U(size, <=, maxblocksize);
abd = abd_alloc_for_io(size, B_TRUE);
if (abd == NULL)