From mboxrd@z Thu Jan  1 00:00:00 1970
From: jiangyiwen <jiangyiwen@huawei.com>
Subject: Why don't return -EOPNOTSUPP?
Date: Tue, 2 Feb 2016 19:57:37 +0800
Message-ID: <56B099B1.2060304@huawei.com>
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Cc: dm-devel@redhat.com, "Qijiang (Joseph, Euler)" <joseph.qi@huawei.com>, xuejiufei@huawei.com
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Hi Lukas,
I have a question about commit 8af1954d172a("blkdev: Do not return
-EOPNOTSUPP if discard is supported"). That is we issue a
WRITE SAME request to device and return failed with EOPNOTSUPP,
but blkdev_issue_write_same ignore this error and return
success to caller. In this way, this will cause an inconsistent state
between upper layer and bottom layer.

I don't know why don't return EOPNOTSUPP if part of devices support
discard, because I think that blkdev_issue_discard should return
EOPNOTSUPP to caller even if some of devices support discard.

Thanks,
Yiwen Jiang.