Re: [PATCH v2] sync.2: syncfs() now returns errors if writeback fails

Michael Kerrisk (man-pages)
2020-06-26T09:06:26Z

Hi Jeff,

On 6/26/20 1:37 AM, 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@kernel.org>

Thanks. Patch applied. (I've not yet pushed it, in case any
review comments might still come in.)

Cheers,

Michael

> ---
> man2/sync.2 | 24 +++++++++++++++++++++++-
> 1 file changed, 23 insertions(+), 1 deletion(-)
>
> v2: update the NOTES verbiage according to Eric's suggestion
>
> diff --git a/man2/sync.2 b/man2/sync.2
> index 7198f3311b05..61e994c5affc 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 when passed a bad file descriptor (EBADF). 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.
> .SH BUGS
> Before version 1.3.20 Linux did not wait for I/O to complete
> before returning.
>

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