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Date:      Tue, 1 Jan 2013 16:14:48 +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: r244925 - in head/sys: kern sys ufs/ffs
Message-ID:  <201301011614.r01GEmKA093100@svn.freebsd.org>
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Author: kib
Date: Tue Jan  1 16:14:48 2013
New Revision: 244925
URL: http://svnweb.freebsd.org/changeset/base/244925

Log:
  The process_deferred_inactive() function locks the vnodes of the ufs
  mount, which means that is must not be called while the snaplock is
  owned.  The vfs_write_resume(9) does call the function as the
  VFS_SUSP_CLEAN() method, which is too early and falls into the region
  still protected by snaplock.
  
  Add yet another flag for the vfs_write_resume_flags() to avoid calling
  suspension cleanup handler after the suspend is lifted, and use it in
  the ffs_snapshot() call to vfs_write_resume.
  
  Reported and tested by:	pho
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/kern/vfs_vnops.c
  head/sys/sys/vnode.h
  head/sys/ufs/ffs/ffs_snapshot.c

Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c	Tue Jan  1 12:48:24 2013	(r244924)
+++ head/sys/kern/vfs_vnops.c	Tue Jan  1 16:14:48 2013	(r244925)
@@ -1667,7 +1667,8 @@ vfs_write_resume_flags(struct mount *mp,
 			mp->mnt_writeopcount++;
 		}
 		MNT_IUNLOCK(mp);
-		VFS_SUSP_CLEAN(mp);
+		if ((flags & VR_NO_SUSPCLR) == 0)
+			VFS_SUSP_CLEAN(mp);
 	} else if ((flags & VR_START_WRITE) != 0) {
 		MNT_REF(mp);
 		vn_start_write_locked(mp, 0);

Modified: head/sys/sys/vnode.h
==============================================================================
--- head/sys/sys/vnode.h	Tue Jan  1 12:48:24 2013	(r244924)
+++ head/sys/sys/vnode.h	Tue Jan  1 16:14:48 2013	(r244925)
@@ -393,6 +393,7 @@ extern int		vttoif_tab[];
 #define	V_XSLEEP	0x0004	/* vn_start_write: just return after sleep */
 
 #define	VR_START_WRITE	0x0001	/* vfs_write_resume: start write atomically */
+#define	VR_NO_SUSPCLR	0x0002	/* vfs_write_resume: do not clear suspension */
 
 #define	VREF(vp)	vref(vp)
 

Modified: head/sys/ufs/ffs/ffs_snapshot.c
==============================================================================
--- head/sys/ufs/ffs/ffs_snapshot.c	Tue Jan  1 12:48:24 2013	(r244924)
+++ head/sys/ufs/ffs/ffs_snapshot.c	Tue Jan  1 16:14:48 2013	(r244925)
@@ -687,7 +687,7 @@ out1:
 	/*
 	 * Resume operation on filesystem.
 	 */
-	vfs_write_resume_flags(vp->v_mount, VR_START_WRITE);
+	vfs_write_resume_flags(vp->v_mount, VR_START_WRITE | VR_NO_SUSPCLR);
 	if (collectsnapstats && starttime.tv_sec > 0) {
 		nanotime(&endtime);
 		timespecsub(&endtime, &starttime);

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