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Date: Sun, 20 May 2007 18:29:19 +0200 From: Uwe Bugla <uwe.bugla@....de> To: Kay Sievers <kay.sievers@...y.org> Cc: "Kay Sievers" <kay.sievers@...y.org>, "Ray Lee" <ray-lk@...rabbit.org>, "Al Viro" <viro@....linux.org.uk>, "Uwe Bugla" <uwe.bugla@....de>, "Ken Chen" <kenchen@...gle.com>, linux-kernel@...r.kernel.org, "Andrew Morton" <akpm@...ux-foundation.org>, "Michal Piotrowski" <michal.k.k.piotrowski@...il.com>, Andreas Schwab <schwab@...e.de>, Andrey Borzenkov <arvidjaar@...l.ru> Subject: Re: bug in 2.6.22-rc2: loop mount limited to one single iso image Am Sonntag, 20. Mai 2007 18:16 schrieben Sie: > On Sun, 2007-05-20 at 09:10 -0700, Ray Lee wrote: > > On 5/20/07, Kay Sievers <kay.sievers@...y.org> wrote: > > > On 5/20/07, Ray Lee <ray-lk@...rabbit.org> wrote: > > > > On 5/19/07, Al Viro <viro@....linux.org.uk> wrote: > > > > > On Sat, May 19, 2007 at 11:16:59PM -0700, Ray Lee wrote: > > > > > > Ken? Ball's in your court. As the patch isn't providing a killer > > > > > > feature for 2.6.22, I'd suggest just reverting it for now until > > > > > > the issues are ironed out. > > > > > > > > > > Hold it. The real question here is which logics do we want there. > > > > > IOW, and how many device nodes do we want to appear and _when_ do > > > > > we want them to appear? > > > > > > > > The when part is what looks to make it racy. I'm guessing that we're > > > > relying on udev to create those loop nodes. If so, I think any scheme > > > > that creates more on demand would give transient mount errors while > > > > it's waiting on udev to create more nodes. > > > > > > > > Perhaps if we were to start with 8 loop nodes at init (as we have in > > > > 2.6.21), and then always maintain a margin of 8 (or 4, or...) when > > > > they start being used or detached? > > > > > > Until the tools can request dynamic loop device allocation from the > > > kernel before they want to use the device, you can create as many as > > > needed "static" loop* nodes in /lib/udev/devices/, which will be > > > copied to /dev/ early on every bootup. > > > > Except that's different than current behavior presented to userspace. > > IOW, we broke userspace for anyone using udev. Which is, y'know, a lot > > of us. > > > > We're at -rc2 right now. Given that, it looks like we have two > > options. First is to revert all this for now and try again when the > > patch has had more testing and agreement (as this isn't a major > > feature we're talking about here; it's effectively just a cleanup that > > happened to have unfortunate side-effects). > > > > The second option is that we could have the loop device start with 8 > > nodes populated, which would match current behavior. > > > > A third option of requiring new userspace for 2.6.22 is a non-starter. > > Right, providing "preallocated" devices, 8 or the number given in > max_loop, sounds like the best option until the tools can handle that. > > Thanks, > Kay OK people, this is what I did just to resolve the issue for now: 1. copied loop.c from 2.6.21 into the 2.6.22-rc2 tree 2. changed exactly two entries from "invalidate_bdev(bdev, 0)" to "invalidate_bdev(bdev)" Output is: a. a compilable kernel b. all four iso images are mounted as expected Andrey's path however (i. e. copying his attached version of loop.c into the 2.6.22-rc2 kernel tree) led to: a. an incompilable kernel b. endless messages trying to compile loop.c going like this (just a part of them - not complete anyway!): drivers/block/loop.c:1350: error: stray '\240' in program drivers/block/loop.c:1350: error: stray '\240' in program drivers/block/loop.c:1350: error: stray '\240' in program drivers/block/loop.c:1350: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c:1351: error: stray '\240' in program drivers/block/loop.c: In function 'loop_register_transfer': drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program drivers/block/loop.c:1367: error: stray '\240' in program Thanks to Ray! Well done! Best regards Uwe - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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