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From: Mateusz Guzik <mjg@FreeBSD.org>
Date: Sat, 4 Jul 2015 15:46:39 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r285135 - head/sys/kern
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Author: mjg
Date: Sat Jul  4 15:46:39 2015
New Revision: 285135
URL: https://svnweb.freebsd.org/changeset/base/285135

Log:
  vfs: use shared vnode locking when looking up ".." in vop_stdvptocnp
  
  Briefly discussed with: kib

Modified:
  head/sys/kern/vfs_default.c

Modified: head/sys/kern/vfs_default.c
==============================================================================
--- head/sys/kern/vfs_default.c	Sat Jul  4 15:42:03 2015	(r285134)
+++ head/sys/kern/vfs_default.c	Sat Jul  4 15:46:39 2015	(r285135)
@@ -810,7 +810,7 @@ vop_stdvptocnp(struct vop_vptocnp_args *
 	VREF(vp);
 	locked = VOP_ISLOCKED(vp);
 	VOP_UNLOCK(vp, 0);
-	NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
+	NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF, UIO_SYSSPACE,
 	    "..", vp, td);
 	flags = FREAD;
 	error = vn_open_cred(&nd, &flags, 0, VN_OPEN_NOAUDIT, cred, NULL);
@@ -830,7 +830,7 @@ vop_stdvptocnp(struct vop_vptocnp_args *
 		VOP_UNLOCK(mvp, 0);
 		vn_close(mvp, FREAD, cred, td);
 		VREF(*dvp);
-		vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
+		vn_lock(*dvp, LK_SHARED | LK_RETRY);
 		covered = 1;
 	}
 
@@ -859,15 +859,15 @@ vop_stdvptocnp(struct vop_vptocnp_args *
 		    (dp->d_fileno == fileno)) {
 			if (covered) {
 				VOP_UNLOCK(*dvp, 0);
-				vn_lock(mvp, LK_EXCLUSIVE | LK_RETRY);
+				vn_lock(mvp, LK_SHARED | LK_RETRY);
 				if (dirent_exists(mvp, dp->d_name, td)) {
 					error = ENOENT;
 					VOP_UNLOCK(mvp, 0);
-					vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
+					vn_lock(*dvp, LK_SHARED | LK_RETRY);
 					goto out;
 				}
 				VOP_UNLOCK(mvp, 0);
-				vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
+				vn_lock(*dvp, LK_SHARED | LK_RETRY);
 			}
 			i -= dp->d_namlen;