Date: Thu, 28 Feb 2008 16:30:13 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: henrik@gulbra.net Cc: freebsd-usb@FreeBSD.org Subject: Re: kernel panic when unmount removed usbdrive Message-ID: <20080228.163013.1387160175.imp@bsdimp.com> In-Reply-To: <1204240017.82302.119.camel@Particle> References: <c0f49ea0802280727o5b27038cx426cf77ddfbfa9ec@mail.gmail.com> <20080228170826.1fa1cadd.torfinn.ingolfsen@broadpark.no> <1204240017.82302.119.camel@Particle>
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In message: <1204240017.82302.119.camel@Particle> Henrik Gulbrandsen <henrik@gulbra.net> writes: : Right now, your best bet is to take Warner's advice and try 8.0-CURRENT, : since none of the known patches have been merged to the 7.0 track yet. : However, I honestly don't know how he can get anything stable without : the final scsi_da.c patch, since I had something like 100% reproducible : crashes when I updated my system from late 7.0 to early 8.0. You might : want to apply patches from http://www.gulbra.net/freebsd-usb/ yourself, : but keep in mind that CURRENT is a moving target, so I can't guarantee : that the patches are still working perfectly. Also, please remember to : use -o sync when mounting the drive. The other case is less tested... Henrik, I've not forgotten your patches, but I haven't had the time to integrate them into the system. I hope to have them ready by 8.0, and if I'm lucky, in time to MFC for 7.1. Many of them are MFCable, although some of the underlying issues they expose can only be fixed properly in head since they may require ABI changes. The changes should really be done at the fs level, since the current patches will leak resources and potentially have other bad effects. I'd also like to have something between full sync and async when mounting removable file systems. You want synchronous metadata, but async data blocks for performance often times. I'm still exploring what this means... Finally, I'd like to thank you again publicly for taking the time and initiative to see through the difficulties of this problem and to persist in presenting your solution to the developers. It made me lose my fear of the buffer cache code, which ultimately will be a good thing. Warner
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