On Mon, Jan 26, 2015 at 12:10:53PM +0100, Manuel Bouyer wrote:
> [...]
>
> I agree that hidding this to the nestiobuf API is probably the right thing
> to do. But I'm also looking for a fix that is safe to pull up to netbsd-5
> and netbsd-6 (the problem was first noticed on netbsd-5, and I reproduced
> it, and tested the patch, on netbsd-6). So if the attached
> patch looks semantically correct, I'll commit it and request pullups.
> Then I'll look at a better fix that can be commited to HEAD pulled up
> to netbsd-7.
with the patch this time ...
--
Manuel Bouyer <[email protected]>
NetBSD: 26 ans d'experience feront toujours la difference
--
Index: vnd.c
===================================================================
RCS file: /cvsroot/src/sys/dev/vnd.c,v
retrieving revision 1.219.8.2
diff -u -p -u -r1.219.8.2 vnd.c
--- vnd.c 5 Jul 2012 18:12:46 -0000 1.219.8.2
+++ vnd.c 26 Jan 2015 11:11:40 -0000
@@ -782,15 +782,10 @@ handle_with_strategy(struct vnd_softc *v
size_t resid, sz;
off_t bn, offset;
struct vnode *vp;
+ struct buf *nbp;
flags = obp->b_flags;
- if (!(flags & B_READ)) {
- vp = bp->b_vp;
- mutex_enter(vp->v_interlock);
- vp->v_numoutput++;
- mutex_exit(vp->v_interlock);
- }
/* convert to a byte offset within the file. */
bn = obp->b_rawblkno * vnd->sc_dkdev.dk_label->d_secsize;
@@ -807,9 +802,8 @@ handle_with_strategy(struct vnd_softc *v
*/
error = 0;
bp->b_resid = bp->b_bcount;
- for (offset = 0, resid = bp->b_resid; resid;
+ for (offset = 0, resid = bp->b_resid; /* true */;
resid -= sz, offset += sz) {
- struct buf *nbp;
daddr_t nbn;
int off, nra;
@@ -862,10 +856,33 @@ handle_with_strategy(struct vnd_softc *v
nbp->vb_buf.b_flags, nbp->vb_buf.b_data,
nbp->vb_buf.b_bcount);
#endif
+ if (resid == sz) {
+ break;
+ }
VOP_STRATEGY(vp, nbp);
bn += sz;
}
- nestiobuf_done(bp, skipped, error);
+ if (!(flags & B_READ)) {
+ struct vnode *w_vp;
+ /*
+ * this is the last nested buf, account for
+ * the parent buf write too.
+ * This has to be done last, so that
+ * fsync won't wait for this write which
+ * has to chance to complete before all nested bufs
+ * have been queued. But it has to be done
+ * before the last VOP_STRATEGY()
+ * or the call to nestiobuf_done().
+ */
+ w_vp = bp->b_vp;
+ mutex_enter(w_vp->v_interlock);
+ w_vp->v_numoutput++;
+ mutex_exit(w_vp->v_interlock);
+ }
+ if (skipped)
+ nestiobuf_done(bp, skipped, error);
+ else
+ VOP_STRATEGY(vp, nbp);
}
static void
