svn commit: r313495 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Feb  9 23:35:57 2017
New Revision: 313495
URL: https://svnweb.freebsd.org/changeset/base/313495

Log:
  Do not establish advisory locks when doing open(O_EXLOCK) or open(O_SHLOCK)
  for files which do not have DTYPE_VNODE type.
  
  Both flock(2) and fcntl(2) syscalls refuse to acquire advisory lock on
  a file which type is not DTYPE_VNODE.  Do the same when lock is
  requested from open(2).
  
  Restructure the block in vn_open_vnode() which handles O_EXLOCK and
  O_SHLOCK open flags to make it easier to quit its execution earlier
  with an error.
  
  Tested by:	pho (previous version)
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/kern/vfs_vnops.c

Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c	Thu Feb  9 23:33:06 2017	(r313494)
+++ head/sys/kern/vfs_vnops.c	Thu Feb  9 23:35:57 2017	(r313495)
@@ -349,8 +349,12 @@ vn_open_vnode(struct vnode *vp, int fmod
 	if ((error = VOP_OPEN(vp, fmode, cred, td, fp)) != 0)
 		return (error);
 
-	if (fmode & (O_EXLOCK | O_SHLOCK)) {
+	while ((fmode & (O_EXLOCK | O_SHLOCK)) != 0) {
 		KASSERT(fp != NULL, ("open with flock requires fp"));
+		if (fp->f_type != DTYPE_VNODE) {
+			error = EBADF;
+			break;
+		}
 		lock_flags = VOP_ISLOCKED(vp);
 		VOP_UNLOCK(vp, 0);
 		lf.l_whence = SEEK_SET;
@@ -367,8 +371,12 @@ vn_open_vnode(struct vnode *vp, int fmod
 		if (error == 0)
 			fp->f_flag |= FHASLOCK;
 		vn_lock(vp, lock_flags | LK_RETRY);
-		if (error == 0 && vp->v_iflag & VI_DOOMED)
+		if (error != 0)
+			break;
+		if ((vp->v_iflag & VI_DOOMED) != 0) {
 			error = ENOENT;
+			break;
+		}
 
 		/*
 		 * Another thread might have used this vnode as an
@@ -376,20 +384,20 @@ vn_open_vnode(struct vnode *vp, int fmod
 		 * Ensure the vnode is still able to be opened for
 		 * writing after the lock has been obtained.
 		 */
-		if (error == 0 && accmode & VWRITE)
+		if ((accmode & VWRITE) != 0)
 			error = vn_writechk(vp);
+		break;
+	}
 
-		if (error != 0) {
-			fp->f_flag |= FOPENFAILED;
-			fp->f_vnode = vp;
-			if (fp->f_ops == &badfileops) {
-				fp->f_type = DTYPE_VNODE;
-				fp->f_ops = &vnops;
-			}
-			vref(vp);
+	if (error != 0) {
+		fp->f_flag |= FOPENFAILED;
+		fp->f_vnode = vp;
+		if (fp->f_ops == &badfileops) {
+			fp->f_type = DTYPE_VNODE;
+			fp->f_ops = &vnops;
 		}
-	}
-	if (error == 0 && fmode & FWRITE) {
+		vref(vp);
+	} else if  ((fmode & FWRITE) != 0) {
 		VOP_ADD_WRITECOUNT(vp, 1);
 		CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
 		    __func__, vp, vp->v_writecount);