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Date:   Tue, 12 Apr 2022 21:13:19 +0800
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Subject: Re: [PATCH v2 3/5] NFS: Don't report ENOSPC write errors twice
To:     Trond Myklebust <trondmy@hammerspace.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "trondmy@kernel.org" <trondmy@kernel.org>
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From:   "chenxiaosong (A)" <chenxiaosong2@huawei.com>
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在 2022/4/12 20:16, Trond Myklebust 写道:
> I understand all that. The point you appear to be missing is that this
> is in fact in agreement with the documented behaviour in the write(2)
> and fsync(2) manpages. These errors are supposed to be reported once,
> even if they were caused by a write to a different file descriptor.
> 
> In fact, even with your change, if you make the second 'dd' call fsync
> (by adding a conv=fsync), I would expect it to report the exact same
> ENOSPC error, and that would be correct behaviour!
> 
> So my patches are more concerned with the fact that we appear to be
> reporting the same error more than once, rather than the fact that
> we're reporting them in the second attempt at I/O. As far as I'm
> concerned, that is the main change that is needed to meet the behaviour
> that is documented in the manpages.


After merging my patchset, when make the second 'dd' call fsync (by 
adding a conv=fsync), it can report ENOSPC error by calling fsync() syscall.

And when make the second 'dd' sync write (by adding a oflag=sync), it 
can report ENOSPC error too:

```c
write
   ksys_write
     vfs_write
       new_sync_write
         call_write_iter
           nfs_file_write
             generic_write_sync
               vfs_fsync_range
                 nfs_file_fsync
```