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Date:      Thu, 29 Aug 2019 07:45:24 +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: r351597 - head/sys/ufs/ffs
Message-ID:  <201908290745.x7T7jOav075406@repo.freebsd.org>
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Author: kib
Date: Thu Aug 29 07:45:23 2019
New Revision: 351597
URL: https://svnweb.freebsd.org/changeset/base/351597

Log:
  UFS: stop reusing the vnode for reallocated inode.
  
  In ffs_valloc(), force reclaim existing vnode on inode reuse, instead
  of trying to re-initialize the same vnode for new purposes.  This is
  done in preparation of changes to the vp->v_object lifecycle handling.
  
  A new FFSV_REPLACE flag to ffs_vgetf() directs the function to
  vgone(9) the vnode if found in vfs hash, instead of returning it.
  
  Reviewed by:	markj, mckusick
  Tested by:	pho
  Sponsored by:	The FreeBSD Foundation
  Differential revision:	https://reviews.freebsd.org/D21412

Modified:
  head/sys/ufs/ffs/ffs_alloc.c
  head/sys/ufs/ffs/ffs_extern.h
  head/sys/ufs/ffs/ffs_vfsops.c

Modified: head/sys/ufs/ffs/ffs_alloc.c
==============================================================================
--- head/sys/ufs/ffs/ffs_alloc.c	Thu Aug 29 07:39:31 2019	(r351596)
+++ head/sys/ufs/ffs/ffs_alloc.c	Thu Aug 29 07:45:23 2019	(r351597)
@@ -1137,10 +1137,15 @@ retry:
 					(allocfcn_t *)ffs_nodealloccg);
 	if (ino == 0)
 		goto noinodes;
-	error = ffs_vget(pvp->v_mount, ino, LK_EXCLUSIVE, vpp);
+
+	/*
+	 * Get rid of the cached old vnode, force allocation of a new vnode
+	 * for this inode.
+	 */
+	error = ffs_vgetf(pvp->v_mount, ino, LK_EXCLUSIVE, vpp, FFSV_REPLACE);
 	if (error) {
 		error1 = ffs_vgetf(pvp->v_mount, ino, LK_EXCLUSIVE, vpp,
-		    FFSV_FORCEINSMQ);
+		    FFSV_FORCEINSMQ | FFSV_REPLACE);
 		ffs_vfree(pvp, ino, mode);
 		if (error1 == 0) {
 			ip = VTOI(*vpp);
@@ -1176,7 +1181,6 @@ dup_alloc:
 		ip->i_din2->di_birthtime = ts.tv_sec;
 		ip->i_din2->di_birthnsec = ts.tv_nsec;
 	}
-	ufs_prepare_reclaim(*vpp);
 	ip->i_flag = 0;
 	(*vpp)->v_vflag = 0;
 	(*vpp)->v_type = VNON;

Modified: head/sys/ufs/ffs/ffs_extern.h
==============================================================================
--- head/sys/ufs/ffs/ffs_extern.h	Thu Aug 29 07:39:31 2019	(r351596)
+++ head/sys/ufs/ffs/ffs_extern.h	Thu Aug 29 07:45:23 2019	(r351597)
@@ -121,6 +121,7 @@ void	process_deferred_inactive(struct mount *mp);
  * Flags to ffs_vgetf
  */
 #define	FFSV_FORCEINSMQ	0x0001
+#define	FFSV_REPLACE	0x0002
 
 /*
  * Flags to ffs_reload

Modified: head/sys/ufs/ffs/ffs_vfsops.c
==============================================================================
--- head/sys/ufs/ffs/ffs_vfsops.c	Thu Aug 29 07:39:31 2019	(r351596)
+++ head/sys/ufs/ffs/ffs_vfsops.c	Thu Aug 29 07:45:23 2019	(r351597)
@@ -1671,9 +1671,17 @@ ffs_vgetf(mp, ino, flags, vpp, ffs_flags)
 	struct vnode *vp;
 	int error;
 
+	MPASS((ffs_flags & FFSV_REPLACE) == 0 || (flags & LK_EXCLUSIVE) != 0);
+
 	error = vfs_hash_get(mp, ino, flags, curthread, vpp, NULL, NULL);
-	if (error || *vpp != NULL)
+	if (error != 0)
 		return (error);
+	if (*vpp != NULL) {
+		if ((ffs_flags & FFSV_REPLACE) == 0)
+			return (0);
+		vgone(*vpp);
+		vput(*vpp);
+	}
 
 	/*
 	 * We must promote to an exclusive lock for vnode creation.  This
@@ -1735,8 +1743,19 @@ ffs_vgetf(mp, ino, flags, vpp, ffs_flags)
 	}
 	vp->v_vflag &= ~VV_FORCEINSMQ;
 	error = vfs_hash_insert(vp, ino, flags, curthread, vpp, NULL, NULL);
-	if (error || *vpp != NULL)
+	if (error != 0)
 		return (error);
+	if (*vpp != NULL) {
+		/*
+		 * Calls from ffs_valloc() (i.e. FFSV_REPLACE set)
+		 * operate on empty inode, which must not be found by
+		 * other threads until fully filled.  Vnode for empty
+		 * inode must be not re-inserted on the hash by other
+		 * thread, after removal by us at the beginning.
+		 */
+		MPASS((ffs_flags & FFSV_REPLACE) == 0);
+		return (0);
+	}
 
 	/* Read in the disk contents for the inode, copy into the inode. */
 	error = bread(ump->um_devvp, fsbtodb(fs, ino_to_fsba(fs, ino)),

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