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Date:      Fri, 27 Dec 2019 16:43:34 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r356126 - head/sys/ufs/ffs
Message-ID:  <201912271643.xBRGhY4q005393@repo.freebsd.org>
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Author: kib
Date: Fri Dec 27 16:43:34 2019
New Revision: 356126
URL: https://svnweb.freebsd.org/changeset/base/356126

Log:
  ufs: do not leave non-reclaimed vnodes with zero i_mode around.
  
  After a recent change, vput() relocks even the exclusively locked
  vnode before inactivating it.  Before that, UFS could safely
  instantiate a vnode for cleared inode, then the last vput() after
  ffs_vgetf() noted that ip->i_mode == 0 and recycled.  Now, it is
  possible for other threads to note the half-constructed vnode, e.g. to
  insert it into hash, which makes other threads to use it despite mode
  is zero, before inactivation and reclaim.
  
  Handle the found cases in SU code, by explicitly doing reclaim.
  Assert that other places get fully constructed inode from ffs_vgetf(),
  which cannot be cleared before dependencies are resolved.
  
  Reported and tested by:	pho
  Reviewed by:	mckusick
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/ufs/ffs/ffs_softdep.c

Modified: head/sys/ufs/ffs/ffs_softdep.c
==============================================================================
--- head/sys/ufs/ffs/ffs_softdep.c	Fri Dec 27 16:28:43 2019	(r356125)
+++ head/sys/ufs/ffs/ffs_softdep.c	Fri Dec 27 16:43:34 2019	(r356126)
@@ -8052,7 +8052,9 @@ handle_complete_freeblocks(freeblks, flags)
 		    flags, &vp, FFSV_FORCEINSMQ) != 0)
 			return (EBUSY);
 		ip = VTOI(vp);
-		if (DIP(ip, i_modrev) == freeblks->fb_modrev) {
+		if (ip->i_mode == 0) {
+			vgone(vp);
+		} else if (DIP(ip, i_modrev) == freeblks->fb_modrev) {
 			DIP_SET(ip, i_blocks, DIP(ip, i_blocks) - spare);
 			ip->i_flag |= IN_CHANGE;
 			/*
@@ -9835,6 +9837,7 @@ handle_workitem_remove(dirrem, flags)
 	if (ffs_vgetf(mp, oldinum, flags, &vp, FFSV_FORCEINSMQ) != 0)
 		return (EBUSY);
 	ip = VTOI(vp);
+	MPASS(ip->i_mode != 0);
 	ACQUIRE_LOCK(ump);
 	if ((inodedep_lookup(mp, oldinum, 0, &inodedep)) == 0)
 		panic("handle_workitem_remove: lost inodedep");
@@ -12530,6 +12533,7 @@ restart:
 			VOP_UNLOCK(vp, 0);
 			error = ffs_vgetf(mp, parentino, LK_EXCLUSIVE,
 			    &pvp, FFSV_FORCEINSMQ);
+			MPASS(VTOI(pvp)->i_mode != 0);
 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 			if (VN_IS_DOOMED(vp)) {
 				if (error == 0)
@@ -13172,6 +13176,7 @@ restart:
 			if ((error = ffs_vgetf(mp, inum, LK_EXCLUSIVE, &vp,
 			    FFSV_FORCEINSMQ)))
 				break;
+			MPASS(VTOI(vp)->i_mode != 0);
 			error = flush_newblk_dep(vp, mp, 0);
 			/*
 			 * If we still have the dependency we might need to
@@ -13236,6 +13241,7 @@ retry:
 			if ((error = ffs_vgetf(mp, inum, LK_EXCLUSIVE, &vp,
 			    FFSV_FORCEINSMQ)))
 				break;
+			MPASS(VTOI(vp)->i_mode != 0);
 			error = ffs_update(vp, 1);
 			vput(vp);
 			if (error)
@@ -13830,6 +13836,7 @@ clear_remove(mp)
 				softdep_error("clear_remove: vget", error);
 				goto finish_write;
 			}
+			MPASS(VTOI(vp)->i_mode != 0);
 			if ((error = ffs_syncvnode(vp, MNT_NOWAIT, 0)))
 				softdep_error("clear_remove: fsync", error);
 			bo = &vp->v_bufobj;
@@ -13911,7 +13918,9 @@ clear_inodedeps(mp)
 			return;
 		}
 		vfs_unbusy(mp);
-		if (ino == lastino) {
+		if (VTOI(vp)->i_mode == 0) {
+			vgone(vp);
+		} else if (ino == lastino) {
 			if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)))
 				softdep_error("clear_inodedeps: fsync1", error);
 		} else {

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