Date: Sat, 22 Dec 2018 22:59:11 +0000 (UTC) From: Bruce Evans <bde@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r342375 - head/sys/dev/md Message-ID: <201812222259.wBMMxB1c053909@repo.freebsd.org>
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Author: bde Date: Sat Dec 22 22:59:11 2018 New Revision: 342375 URL: https://svnweb.freebsd.org/changeset/base/342375 Log: Fix devstat on md devices, second attempt. r341765 depends on g_io_deliver() finishing initialization of the bio, but g_io_deliver() actually destroys the bio. INVARIANTS makes the bug obvious by overwriting the bio with garbage. Restore the old order for calling devstat (except don't restore not calling it for the error case), and translate to the devstat KPI so that this order works. Reviewed by: kib Modified: head/sys/dev/md/md.c Modified: head/sys/dev/md/md.c ============================================================================== --- head/sys/dev/md/md.c Sat Dec 22 21:49:25 2018 (r342374) +++ head/sys/dev/md/md.c Sat Dec 22 22:59:11 2018 (r342375) @@ -1241,12 +1241,22 @@ md_kthread(void *arg) error = sc->start(sc, bp); } + if (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE) { + /* + * Devstat uses (bio_bcount, bio_resid) for + * determining the length of the completed part of + * the i/o. g_io_deliver() will translate from + * bio_completed to that, but it also destroys the + * bio so we must do our own translation. + */ + bp->bio_bcount = bp->bio_length; + bp->bio_resid = (error == -1 ? bp->bio_bcount : 0); + devstat_end_transaction_bio(sc->devstat, bp); + } if (error != -1) { bp->bio_completed = bp->bio_length; g_io_deliver(bp, error); } - if (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE) - devstat_end_transaction_bio(sc->devstat, bp); } }
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