Author: rmacklem
Date: Thu Dec 25 14:44:04 2014
New Revision: 276200
URL: https://svnweb.freebsd.org/changeset/base/276200
Log:
Fix the comment introduced in r276192 so that it clearly
states that the change is needed to avoid a deadlock.
Suggested by: kib
MFC after: 1 week
Modified:
head/sys/kern/vfs_default.c
Modified: head/sys/kern/vfs_default.c
==============================================================================
--- head/sys/kern/vfs_default.c Thu Dec 25 13:38:51 2014 (r276199)
+++ head/sys/kern/vfs_default.c Thu Dec 25 14:44:04 2014 (r276200)
@@ -407,9 +407,10 @@ vop_stdadvlock(struct vop_advlock_args *
vp = ap->a_vp;
if (ap->a_fl->l_whence == SEEK_END) {
/*
- * The NFSv4 server will LOR/deadlock if a vn_lock() call
- * is done on vp. Fortunately, vattr.va_size is only
- * needed for SEEK_END and the NFSv4 server only uses SEEK_SET.
+ * The NFSv4 server must avoid doing a vn_lock() here, since it
+ * can deadlock the nfsd threads, due to a LOR. Fortunately
+ * the NFSv4 server always uses SEEK_SET and this code is
+ * only required for the SEEK_END case.
*/
vn_lock(vp, LK_SHARED | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, curthread->td_ucred);
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