On Saturday, February 16, 2019, Abel Abraham Camarillo Ojeda < acam...@verlet.org> wrote:
> > > On Saturday, February 16, 2019, Maximilian Lorlacks < > maxlor...@protonmail.com> wrote: > >> >> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ >> On Thursday, January 31, 2019 11:31 PM, Alexander Bluhm < >> alexander.bl...@gmx.net> wrote: >> >> > On Thu, Jan 31, 2019 at 04:26:45PM -0500, Ted Unangst wrote: >> > >> > > Instead, we note that the write failed and mark a flag in the vnode. >> Future >> > > calls to fsync will then return EIO when this flag is set. We clear >> the flag >> > > when the vnode is released. >> > >> > Sounds reasonable. >> > >> > OK bluhm@ >> >> People may object to errors being lost when the vnode is released, >> as that would lose errors in a scenario like write -> close -> open >> -> fsync. I do not claim to know if anyone actually does that in the >> wild, however. > > > Sorry for my incomplete comment, but I remember a lengthy discussion in > the postgres mailing list about fsync, retries of it, loss of state and > such, they were very concerned about openbsd behavior I think... > > Will try to find that thread ... > Is this related? https://lwn.net/Articles/752063/ Again, sorry if it's noise > > >> >> If the above diff is accepted, it may be worth to also add the >> following diff to fsync.2 to document the behavior: >> >> diff --git lib/libc/sys/fsync.2 lib/libc/sys/fsync.2 >> index c9831ca09..5ee765986 100644 >> --- lib/libc/sys/fsync.2 >> +++ lib/libc/sys/fsync.2 >> @@ -66,6 +66,19 @@ and >> .Fn fdatasync >> should be used by programs that require a file to be in a known state, >> for example, in building a simple transaction facility. >> +.Pp >> +If >> +.Fn fsync >> +or >> +.Fn fdatasync >> +fails with >> +.Er EIO , >> +the state of the on-disk data may only have been partially written. >> +Future attempts to call these functions will continue failing with >> +.Er EIO >> +until the all copies of the underlying >> +.Fa fd >> +have been closed. >> .Sh RETURN VALUES >> .Rv -std fsync fdatasync >> .Sh ERRORS >> >>
