Date: Wed, 11 Mar 2015 23:48:31 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Oliver Pinter <oliver.pinter@hardenedbsd.org> Cc: int0dster@gmail.com, FreeBSD Hackers <freebsd-hackers@freebsd.org>, Shawn Webb <shawn.webb@hardenedbsd.org> Subject: Re: file system change notifications Message-ID: <20150311224831.GB18699@dft-labs.eu> In-Reply-To: <CAPQ4ffvOUDemE4YMPQ89mQAZ_ojUy9Ou8OFkaihS-NEFz42YfQ@mail.gmail.com> References: <C4BD68D4-0570-4731-AFA2-CDD4DD5490E5@westryn.net> <CAF10W3yCgeZfz9B4hEepTM1A5wdL60L9fhBGWONrMJ_75jMiww@mail.gmail.com> <F2A12ACA-3D13-4789-94CA-BCBDE4A0A87B@westryn.net> <CAPQ4ffvOUDemE4YMPQ89mQAZ_ojUy9Ou8OFkaihS-NEFz42YfQ@mail.gmail.com>
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On Wed, Mar 11, 2015 at 11:11:14PM +0100, Oliver Pinter wrote: > Take a look at dazuko kernel module. Probably you should forward port > them, because they are obsoleted. > I checked the module out of curiosity. Their approach was to wrap various syscalls and work from there. This is used to be the common approach several years back it has a lot of shortcomings, complete lack of reliability being the biggest one. As for better implementation: current namecache does not guarantee name resolution (even if name was entered) and not all names end up in the cache in the first place. Lack of reliability comes from the fact that the cache does not pin vnodes in any way. The cache is also protected with one sx lock and requires users to get and drop refs during lookups. As such, I would say that the best course of action is implementing new cache instead of hacking current implementatin. Then something could be made on top of that. > On Wed, Mar 11, 2015 at 10:54 PM, Kim Shrier <kim@westryn.net> wrote: > > On Mar 11, 2015, at 1:14 PM, Ivan Krivonos <int0dster@gmail.com> wrote: > >> > >> Hi, > >> > >> Have not read this paper, but why just don`t kqueue() ? > >> > > > > Apparently, you have to have a file descriptor for every file you want to > > monitor, if I read things right. This is prohibitive with 100,000+ files. > > It also means that you cannot unmount a file system if you are monitoring > > any files in it, since the file system is considered busy. > > > > Kim > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" -- Mateusz Guzik <mjguzik gmail.com>
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