Re: [PATCH v7 3/8] nbd: clear queue limits on disconnect

["yu kuai" <yukuai@fygo.io>]

在 2026/8/5 14:58, Yang Erkun 写道:

> An inactive nbd device may refuse any I/O operations. The nbd_config_put
> function calls invalidate_disk, which sets the device capacity to zero
> to reject all read and write I/O. For zero-sector flush I/O requests
> from blkdev_issue_flush, if the write cache is disabled, the zero-sector
> flush I/O immediately returns 0 in submit_bio_noacct. However, since
> nbd_config_put does not clear the write cache state, an inactive nbd
> device might still have the write cache enabled. In this situation,
> zero-sector flush I/O will return -EIO because there is no active socket.
> Additionally, BLK_FEAT_FUA and BLK_FEAT_ROTATIONAL flags may also remain
> stale, resetting all of them ensures consistent behavior.
>
> The limits update uses queue_limits_commit_update() (the non-freezing
> variant) because config_refs == 0 here means every fd is closed and recv
> threads have drained, so no in-flight I/O can read q->limits concurrently.
>
> Signed-off-by: Yang Erkun<yangerkun@huawei.com>
> ---
>   drivers/block/nbd.c | 43 ++++++++++++++++++++++++++-----------------
>   1 file changed, 26 insertions(+), 17 deletions(-)
Reviewed-by: Yu Kuai <yukuai@fygo.io>

-- 
Thanks,
Kuai