Date: Mon, 23 Aug 1999 08:47:34 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Greg Lehey <grog@lemis.com> Cc: Matthew Dillon <dillon@apollo.backplane.com>, FreeBSD Hackers <hackers@FreeBSD.ORG>, FreeBSD Committers <cvs-committers@FreeBSD.ORG>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu> Subject: Re: Mandatory locking? Message-ID: <7324.935390854@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 23 Aug 1999 15:28:49 %2B0930." <19990823152849.H83273@freebie.lemis.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <19990823152849.H83273@freebie.lemis.com>, Greg Lehey writes: >> Why should it be made unavailable ? > >So that certain multiple accesses can be done atomically. You don't need that. You initialize a index to 0, and whenever the sector with that index is written, you increment it. At any one time you know that all parityblocks <= your index are valid. All you need to do to recover you index then is to have an ioctl which will read one sector at a time, mark the buffer dirty write it out again. I have seen sources for two well-respected RAID-5 products which do it this way. >I'm a little surprised that there's any objection to the concept of >mandatory locking. Too many of us have had wedged systems because of it I guess... -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?7324.935390854>