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[src/netbsd-7]: src/sys/dev Pull up following revision(s) (requested by bouye...
details: https://anonhg.NetBSD.org/src/rev/7b4ecacae8cf
branches: netbsd-7
changeset: 798919:7b4ecacae8cf
user: martin <martin%NetBSD.org@localhost>
date: Wed Jan 28 19:16:21 2015 +0000
description:
Pull up following revision(s) (requested by bouyer in ticket #468):
sys/dev/vnd.c: revision 1.240
sys/dev/vnd.c: revision 1.241
As discussed in
http://mail-index.netbsd.org/tech-kern/2015/01/24/msg018339.html
don't bump v_numoutput if we need to vn_lock() the vnode before queuing
the corresponding I/O, because this may deadlock with genfs_do_putpages()
when called with the vnode locked (as can happen with fsync(2)).
Instead bump is just before the last VOP_STRATEGY(), or before calling
nestiobuf_done().
Thanks to Taylor R Campbell for review.
Fix typo in comment
diffstat:
sys/dev/vnd.c | 40 +++++++++++++++++++++++++++++-----------
1 files changed, 29 insertions(+), 11 deletions(-)
diffs (82 lines):
diff -r ee635f182407 -r 7b4ecacae8cf sys/dev/vnd.c
--- a/sys/dev/vnd.c Wed Jan 28 19:00:28 2015 +0000
+++ b/sys/dev/vnd.c Wed Jan 28 19:16:21 2015 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: vnd.c,v 1.232.2.2 2014/11/11 10:42:22 martin Exp $ */
+/* $NetBSD: vnd.c,v 1.232.2.3 2015/01/28 19:16:21 martin Exp $ */
/*-
* Copyright (c) 1996, 1997, 1998, 2008 The NetBSD Foundation, Inc.
@@ -91,7 +91,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.232.2.2 2014/11/11 10:42:22 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.232.2.3 2015/01/28 19:16:21 martin Exp $");
#if defined(_KERNEL_OPT)
#include "opt_vnd.h"
@@ -795,15 +795,10 @@
size_t resid, sz;
off_t bn, offset;
struct vnode *vp;
+ struct buf *nbp = NULL;
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;
@@ -820,9 +815,8 @@
*/
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;
@@ -875,10 +869,34 @@
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 no 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);
+ }
+ KASSERT(skipped != 0 || nbp != NULL);
+ if (skipped)
+ nestiobuf_done(bp, skipped, error);
+ else
+ VOP_STRATEGY(vp, nbp);
}
static void
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