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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