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Date: Wed, 29 Sep 2010 02:48:28 +0200 From: Janjaap Bos <janjaap@....nl> To: Jens Axboe <jaxboe@...ionio.com> Cc: Chris Frey <cdfrey@...rsquare.net>, Richard Weinberger <richard@....at>, Andrew Morton <akpm@...ux-foundation.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "jdike@...toit.com" <jdike@...toit.com>, "user-mode-linux-devel@...ts.sourceforge.net" <user-mode-linux-devel@...ts.sourceforge.net>, "user-mode-linux-user@...ts.sourceforge.net" <user-mode-linux-user@...ts.sourceforge.net>, "geert@...ux-m68k.org" <geert@...ux-m68k.org>, "martin.petersen@...cle.com" <martin.petersen@...cle.com>, "adobriyan@...il.com" <adobriyan@...il.com>, "syzop@...nscan.org" <syzop@...nscan.org> Subject: Re: [PATCH 1/1] um: ubd: Fix data corruption On Wed, 2010-09-29 at 08:10 +0900, Jens Axboe wrote: > It looks like that if we need to restart the requeue, then > we use the initial position and not the current index. Does > this help? > > diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c > index 1bcd208..81ee063 100644 > --- a/arch/um/drivers/ubd_kern.c > +++ b/arch/um/drivers/ubd_kern.c > @@ -162,7 +162,7 @@ struct ubd { > spinlock_t lock; > struct scatterlist sg[MAX_SG]; > struct request *request; > - int start_sg, end_sg; > + int start_sg, end_sg, rq_off; > }; > > #define DEFAULT_COW { \ > @@ -187,6 +187,7 @@ struct ubd { > .request = NULL, \ > .start_sg = 0, \ > .end_sg = 0, \ > + .rq_off = 0, \ > } > > /* Protected by ubd_lock */ > @@ -1241,10 +1242,11 @@ static void do_ubd_request(struct request_queue *q) > dev->request = req; > dev->start_sg = 0; > dev->end_sg = blk_rq_map_sg(q, req, dev->sg); > + dev->rq_off = 0; > } > > req = dev->request; > - sector = blk_rq_pos(req); > + sector = blk_rq_pos(req) + dev->rq_off; > while(dev->start_sg < dev->end_sg){ > struct scatterlist *sg = &dev->sg[dev->start_sg]; > > @@ -1273,6 +1275,7 @@ static void do_ubd_request(struct request_queue *q) > } > > dev->start_sg++; > + dev->rq_off += sg->length >> 9; > } > dev->end_sg = 0; > dev->request = NULL; > Yes, this works. I quickly tested it on current git version, and it does not require the work-around. So far no corruption seen. Thanks! -Janjaap -- 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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