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From: Konstantin Belousov <kib@FreeBSD.org>
Date: Mon, 14 Jul 2014 08:41:14 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r268607 - head/sys/kern
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Author: kib
Date: Mon Jul 14 08:41:13 2014
New Revision: 268607
URL: http://svnweb.freebsd.org/changeset/base/268607

Log:
  In kern_linkat(), avoid passing doomed vnode to the VOP.
  
  Tested by:	pho
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/kern/vfs_syscalls.c

Modified: head/sys/kern/vfs_syscalls.c
==============================================================================
--- head/sys/kern/vfs_syscalls.c	Mon Jul 14 08:34:54 2014	(r268606)
+++ head/sys/kern/vfs_syscalls.c	Mon Jul 14 08:41:13 2014	(r268607)
@@ -1554,6 +1554,7 @@ kern_linkat(struct thread *td, int fd1, 
 	bwillwrite();
 	NDINIT_AT(&nd, LOOKUP, follow | AUDITVNODE1, segflg, path1, fd1, td);
 
+again:
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
@@ -1576,8 +1577,7 @@ kern_linkat(struct thread *td, int fd1, 
 				vput(nd.ni_dvp);
 			vrele(nd.ni_vp);
 			error = EEXIST;
-		} else if ((error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY))
-		    == 0) {
+		} else if ((error = vn_lock(vp, LK_EXCLUSIVE)) == 0) {
 			error = can_hardlink(vp, td->td_ucred);
 			if (error == 0)
 #ifdef MAC
@@ -1588,6 +1588,12 @@ kern_linkat(struct thread *td, int fd1, 
 				error = VOP_LINK(nd.ni_dvp, vp, &nd.ni_cnd);
 			VOP_UNLOCK(vp, 0);
 			vput(nd.ni_dvp);
+		} else {
+			vput(nd.ni_dvp);
+			NDFREE(&nd, NDF_ONLY_PNBUF);
+			vrele(vp);
+			vn_finished_write(mp);
+			goto again;
 		}
 		NDFREE(&nd, NDF_ONLY_PNBUF);
 	}