Date: Tue, 22 Mar 2016 21:59:05 -0700 From: Bryan Drewery <bdrewery@FreeBSD.org> To: "cem@FreeBSD.org" <cem@FreeBSD.org> Cc: Benjamin Kaduk <bjkfbsd@gmail.com>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r297201 - in head: share/man/man4 sys/dev/filemon Message-ID: <1FEF661F-FDEC-4711-A381-4EAA4ACDBA1D@FreeBSD.org> In-Reply-To: <CAG6CVpUMAHN8S_wjz57BGHfJ0OTHdboLt2Wz2gvxD%2BSmwEAqGA@mail.gmail.com> References: <201603222241.u2MMf7ub090070@repo.freebsd.org> <CAG6CVpUxC6Nov7ocy5eEpcQFLd%2BQdXUxZWs49kTesWZo_VqncQ@mail.gmail.com> <D2476F6F-8C58-489D-9654-DFF2AEB9941F@FreeBSD.org> <CAJ5_RoD1J_LOvN5hzSF_DsUHd_mtn=XZDYcZU5xOBiyRSVjVDg@mail.gmail.com> <CAG6CVpUMAHN8S_wjz57BGHfJ0OTHdboLt2Wz2gvxD%2BSmwEAqGA@mail.gmail.com>
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> On Mar 22, 2016, at 20:18, Conrad Meyer <cem@FreeBSD.org> wrote: >=20 >> On Tue, Mar 22, 2016 at 7:46 PM, Benjamin Kaduk <bjkfbsd@gmail.com> wrote= : >>> On Tue, Mar 22, 2016 at 9:11 PM, Bryan Drewery <bdrewery@freebsd.org> wr= ote: >>>=20 >>> The manpage for close(2) does document some errors, one being ENOSPC. T= he >>> close(2) behavior of returning write(2), really VOP_WRITE(9), errors tho= ugh >>> is specific to filemon since all of the writes are hidden and this is th= e >>> only place to return an error. >>> ... >>=20 >> filemon is not unique in this regard; the AFS filesystem buffers writes >> locally and in some cases errors writing to the remote server can be dela= yed >> until close(). >=20 > Right. filemon is not the only case. Another example would be TCP > socket fds, e.g., when the connection is RST after write(2) queues > data on the outgoing sockbuf but before it is transmitted. >=20 I'm really not saying it's the only case. I'm saying close(2) returning a do= zen write(2) errors is not normal and is documented here because it is expec= ted here. Anyone could write a module or FS that returns some random error o= n close(2). That doesn't mean it should be documented directly in close(2). = Consider the next commit here also returns EFAULT and ENAMELEN, which defin= itely are special case. There are only 2 filemon consumers, script(1) and b= make. For bmake there is a patch in testing to utilize the close(2) error, s= ince it's currently ignored. For script(1) I need to fix it still. If there are errors that are common and missing from close(2), please do doc= ument them. As Benjamin referenced, most people never fathom that it can ev= en fail. I know that NFS errors are not widely documented too. Bryan=
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