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virtio-blk: Bypass error action and I/O accounting on invalid r/w 

When a device model's I/O operation fails, we execute the error
action.  This lets layers above QEMU implement thin provisioning, or
attempt to correct errors before they reach the guest.  But when the
I/O operation fails because it's invalid, reporting the error to the
guest is the only sensible action.

If the guest's read or write asks for an invalid sector range, fail
the request right away, without considering the error action.  No
change with error action BDRV_ACTION_REPORT.

Furthermore, bypass I/O accounting, because we want to track only I/O
that actually reaches the block layer.

The next commit will extend "invalid sector range" to cover attempts
to read/write beyond the end of the medium.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
master
Markus Armbruster 2014-07-09 19:07:30 +02:00 committed by Kevin Wolf
parent d0e14376ee
commit 42e38c1fd0
1 changed files with 8 additions and 6 deletions
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14
hw/block/virtio-blk.c
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@ -307,15 +307,16 @@ static void virtio_blk_handle_write(VirtIOBlockReq *req, MultiReqBuffer *mrb)
sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &req->out.sector);
bdrv_acct_start(req->dev->bs, &req->acct, req->qiov.size, BDRV_ACCT_WRITE);
trace_virtio_blk_handle_write(req, sector, req->qiov.size / 512);
if (!virtio_blk_sect_range_ok(req->dev, sector, req->qiov.size)) {
virtio_blk_rw_complete(req, -EIO);
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
virtio_blk_free_request(req);
return;
}
bdrv_acct_start(req->dev->bs, &req->acct, req->qiov.size, BDRV_ACCT_WRITE);
if (mrb->num_writes == 32) {
virtio_submit_multiwrite(req->dev->bs, mrb);
}
@ -337,14 +338,15 @@ static void virtio_blk_handle_read(VirtIOBlockReq *req)
sector = virtio_ldq_p(VIRTIO_DEVICE(req->dev), &req->out.sector);
bdrv_acct_start(req->dev->bs, &req->acct, req->qiov.size, BDRV_ACCT_READ);
trace_virtio_blk_handle_read(req, sector, req->qiov.size / 512);
if (!virtio_blk_sect_range_ok(req->dev, sector, req->qiov.size)) {
virtio_blk_rw_complete(req, -EIO);
virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR);
virtio_blk_free_request(req);
return;
}
bdrv_acct_start(req->dev->bs, &req->acct, req->qiov.size, BDRV_ACCT_READ);
bdrv_aio_readv(req->dev->bs, sector, &req->qiov,
req->qiov.size / BDRV_SECTOR_SIZE,
virtio_blk_rw_complete, req);