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ANDROID: virtio_blk: Remove BUG_ON for discard/zero ops

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The virtio_blk driver used by cuttlefish can crash if discard/zero ops,
added in 4.20, pass through virtio_queue_rq(). Our theory is that this
happens because multiple discards are merged, causing nr_phys_segments
to be increased beyond the sg_elem size. This makes sense as a
discard/zero is a form of I/O not backed by specific data.

This patch should be submitted upstream once the true root cause has
been tracked down and full analysis of the issue has been done.

Originally-by: Satya Tangirala <satyat@google.com>
Bug: 144592287
Test: boot cuttlefish with f2fs userdata and wait 1 minute
Change-Id: Ic73e08035c91ec9c718e6496930b326d084062a4
Signed-off-by: Alistair Delva <adelva@google.com>
This commit is contained in:
Alistair Delva 2019-11-15 15:38:06 -08:00
parent 852619242c
commit 187c494456
1 changed files with 4 additions and 2 deletions
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6
drivers/block/virtio_blk.c
View File

@ -282,8 +282,6 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
bool unmap = false;
u32 type;
BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
switch (req_op(req)) {
case REQ_OP_READ:
case REQ_OP_WRITE:
@ -311,6 +309,10 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
return BLK_STS_IOERR;
}
BUG_ON(type != VIRTIO_BLK_T_DISCARD &&
type != VIRTIO_BLK_T_WRITE_ZEROES &&
(req->nr_phys_segments + 2 > vblk->sg_elems));
vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, type);
vbr->out_hdr.sector = type ?
0 : cpu_to_virtio64(vblk->vdev, blk_rq_pos(req));