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authorXie Yongji <xieyongji@bytedance.com>2022-03-04 13:00:57 +0300
committerMichael S. Tsirkin <mst@redhat.com>2022-03-06 14:06:50 +0300
commitdacc73ed0b88f1a787ec20385f42ca9dd9eddcd0 (patch)
treeee6fb4913ad18aebc267b078fba42747c181db02
parente2ae38cf3d91837a493cb2093c87700ff3cbe667 (diff)
downloadlinux-dacc73ed0b88f1a787ec20385f42ca9dd9eddcd0.tar.xz
virtio-blk: Don't use MAX_DISCARD_SEGMENTS if max_discard_seg is zero
Currently the value of max_discard_segment will be set to MAX_DISCARD_SEGMENTS (256) with no basis in hardware if device set 0 to max_discard_seg in configuration space. It's incorrect since the device might not be able to handle such large descriptors. To fix it, let's follow max_segments restrictions in this case. Fixes: 1f23816b8eb8 ("virtio_blk: add discard and write zeroes support") Signed-off-by: Xie Yongji <xieyongji@bytedance.com> Link: https://lore.kernel.org/r/20220304100058.116-1-xieyongji@bytedance.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r--drivers/block/virtio_blk.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c443cd64fc9b..7fc2c8b97077 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -925,9 +925,15 @@ static int virtblk_probe(struct virtio_device *vdev)
virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
&v);
+
+ /*
+ * max_discard_seg == 0 is out of spec but we always
+ * handled it.
+ */
+ if (!v)
+ v = sg_elems - 2;
blk_queue_max_discard_segments(q,
- min_not_zero(v,
- MAX_DISCARD_SEGMENTS));
+ min(v, MAX_DISCARD_SEGMENTS));
blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
}