linux-kernel - Re: [PATCH][man-pages] sync.2: syncfs() now returns errors if writeback fails

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Message-ID: <54c5ef29-0f12-5f55-8f54-73b20f56925e@gmail.com>
Date:   Thu, 25 Jun 2020 11:45:02 +0200
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:     Jeff Layton <jlayton@...nel.org>,
        Eric Biggers <ebiggers@...nel.org>
Cc:     mtk.manpages@...il.com, linux-man@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][man-pages] sync.2: syncfs() now returns errors if
 writeback fails

Hi Jeff,

Any progress with v2 of this patch?

Thanks,

Michael


On 6/10/20 11:19 PM, Jeff Layton wrote:
> On Wed, 2020-06-10 at 08:50 -0700, Eric Biggers wrote:
>> On Wed, Jun 10, 2020 at 06:33:47AM -0400, Jeff Layton wrote:
>>> A patch has been merged for v5.8 that changes how syncfs() reports
>>> errors. Change the sync() manpage accordingly.
>>>
>>> Signed-off-by: Jeff Layton <jlayton@...nel.org>
>>> ---
>>>  man2/sync.2 | 24 +++++++++++++++++++++++-
>>>  1 file changed, 23 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/man2/sync.2 b/man2/sync.2
>>> index 7198f3311b05..27e04cff5845 100644
>>> --- a/man2/sync.2
>>> +++ b/man2/sync.2
>>> @@ -86,11 +86,26 @@ to indicate the error.
>>>  is always successful.
>>>  .PP
>>>  .BR syncfs ()
>>> -can fail for at least the following reason:
>>> +can fail for at least the following reasons:
>>>  .TP
>>>  .B EBADF
>>>  .I fd
>>>  is not a valid file descriptor.
>>> +.TP
>>> +.B EIO
>>> +An error occurred during synchronization.
>>> +This error may relate to data written to any file on the filesystem, or on
>>> +metadata related to the filesytem itself.
>>> +.TP
>>> +.B ENOSPC
>>> +Disk space was exhausted while synchronizing.
>>> +.TP
>>> +.BR ENOSPC ", " EDQUOT
>>> +Data was written to a files on NFS or another filesystem which does not
>>> +allocate space at the time of a
>>> +.BR write (2)
>>> +system call, and some previous write failed due to insufficient
>>> +storage space.
>>>  .SH VERSIONS
>>>  .BR syncfs ()
>>>  first appeared in Linux 2.6.39;
>>> @@ -121,6 +136,13 @@ or
>>>  .BR syncfs ()
>>>  provide the same guarantees as fsync called on every file in
>>>  the system or filesystem respectively.
>>> +.PP
>>> +In mainline kernel versions prior to 5.8,
>>> +.\" commit 735e4ae5ba28c886d249ad04d3c8cc097dad6336
>>> +.BR syncfs ()
>>> +will only fail with EBADF when passed a bad file descriptor. In 5.8
>>> +and later kernels, it will also report an error if one or more inodes failed
>>> +to be written back since the last syncfs call.
>>
>> The sentence "In mainline kernel versions prior to 5.8, syncfs() will only fail
>> with EBADF when passed a bad file descriptor" is ambiguous.  It could mean that
>> EBADF can now mean other things too.
>>
>> Maybe write: "In mainline kernel versions prior to 5.8, syncfs() will only fail
>> when passed a bad file descriptor (EBADF)."
>>
>> - Eric
> 
> Good point. Fixed in my tree using your verbiage. I'll send out a v2
> patch once I give others a chance to comment.
> 
> Thanks!
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/