Author: kib
Date: Tue Aug 27 01:31:12 2013
New Revision: 254945
URL: http://svnweb.freebsd.org/changeset/base/254945
Log:
When allocating a pbuf for the cluster write, do not sleep waiting
for the available pbuf when passed vnode is backing md(4). Other i/o
directed to the same md device might already hold pbufs, and then we
could deadlock since only our progress can free a pbuf needed for
wakeup.
Obtained from: projects/vm6
Reminded and tested by: pho
MFC after: 1 week
Modified:
head/sys/kern/vfs_cluster.c
Modified: head/sys/kern/vfs_cluster.c
==============================================================================
--- head/sys/kern/vfs_cluster.c Tue Aug 27 01:08:55 2013 (r254944)
+++ head/sys/kern/vfs_cluster.c Tue Aug 27 01:31:12 2013 (r254945)
@@ -837,7 +837,9 @@ cluster_wbuild(struct vnode *vp, long si
(tbp->b_bcount != tbp->b_bufsize) ||
(tbp->b_bcount != size) ||
(len == 1) ||
- ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
+ ((bp = (vp->v_vflag & VV_MD) != 0 ?
+ trypbuf(&cluster_pbuf_freecnt) :
+ getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
totalwritten += tbp->b_bufsize;
bawrite(tbp);
++start_lbn;
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