lkml.org 
[lkml]   [2022]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.4 03/43] virtio-blk: Dont use MAX_DISCARD_SEGMENTS if max_discard_seg is zero
    Date
    From: Xie Yongji <xieyongji@bytedance.com>

    [ Upstream commit dacc73ed0b88f1a787ec20385f42ca9dd9eddcd0 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/block/virtio_blk.c | 10 ++++++++--
    1 file changed, 8 insertions(+), 2 deletions(-)

    diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
    index 816eb2db7308..4b3645e648ee 100644
    --- a/drivers/block/virtio_blk.c
    +++ b/drivers/block/virtio_blk.c
    @@ -980,9 +980,15 @@ 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);
    }
    --
    2.34.1


    \
     
     \ /
      Last update: 2022-03-14 12:58    [W:4.109 / U:0.024 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site