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Date:      Wed, 15 Sep 2010 11:05:42 +0000 (UTC)
From:      Andriy Gapon <avg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r212657 - in head/sys/cddl: compat/opensolaris/sys contrib/opensolaris/uts/common/fs/zfs
Message-ID:  <201009151105.o8FB5ggc034485@svn.freebsd.org>

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Author: avg
Date: Wed Sep 15 11:05:41 2010
New Revision: 212657
URL: http://svn.freebsd.org/changeset/base/212657

Log:
  zfs vn_has_cached_data: take into account v_object->cache != NULL
  
  This mirrors code in tmpfs.
  This changge shouldn't affect much read path, it may cause unnecessary
  vm_page_lookup calls in the case where v_object has no active or inactive
  pages but has some cache pages.  I believe this situation to be non-essential.
  
  In write path this change should allow us to properly detect the above
  case and free a cache page when we write to a range that corresponds to it.
  If this situation is undetected then we could have a discrepancy between
  data in page cache and in ARC or on disk.
  
  This change allows us to re-enable vn_has_cached_data() check in zfs_write.
  
  NOTE: strictly speaking resident_page_count and cache fields of v_object
  should be exmined under VM_OBJECT_LOCK, but for this particular usage
  we may get away with it.
  
  Discussed with:	alc, kib
  Approved by:	pjd
  Tested with:	tools/regression/fsx
  MFC after:	3 weeks

Modified:
  head/sys/cddl/compat/opensolaris/sys/vnode.h
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c

Modified: head/sys/cddl/compat/opensolaris/sys/vnode.h
==============================================================================
--- head/sys/cddl/compat/opensolaris/sys/vnode.h	Wed Sep 15 11:04:02 2010	(r212656)
+++ head/sys/cddl/compat/opensolaris/sys/vnode.h	Wed Sep 15 11:05:41 2010	(r212657)
@@ -69,7 +69,9 @@ vn_is_readonly(vnode_t *vp)
 #define	vn_vfsunlock(vp)	do { } while (0)
 #define	vn_ismntpt(vp)		((vp)->v_type == VDIR && (vp)->v_mountedhere != NULL)
 #define	vn_mountedvfs(vp)	((vp)->v_mountedhere)
-#define	vn_has_cached_data(vp)	((vp)->v_object != NULL && (vp)->v_object->resident_page_count > 0)
+#define	vn_has_cached_data(vp)	\
+	((vp)->v_object != NULL && ((vp)->v_object->resident_page_count > 0 \
+				    || (vp)->v_object->cache != NULL))
 #define	vn_exists(vp)		do { } while (0)
 #define	vn_invalid(vp)		do { } while (0)
 #define	vn_renamepath(tdvp, svp, tnm, lentnm)	do { } while (0)

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	Wed Sep 15 11:04:02 2010	(r212656)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	Wed Sep 15 11:05:41 2010	(r212657)
@@ -933,17 +933,7 @@ again:
 			uioskip(uio, tx_bytes);
 		}
 
-		/*
-		 * XXXPJD: There are some cases (triggered by fsx) where
-		 *         vn_has_cached_data(vp) returns false when it should
-		 *         return true. This should be investigated.
-		 */
-#if 0
-		if (tx_bytes && vn_has_cached_data(vp))
-#else
-		if (tx_bytes && vp->v_object != NULL)
-#endif
-		{
+		if (tx_bytes && vn_has_cached_data(vp)) {
 			update_pages(vp, woff, tx_bytes, zfsvfs->z_os,
 			    zp->z_id, uio->uio_segflg, tx);
 		}



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