linux-kernel - [PATCH 13/14] Unionfs: don't purge lower sb data on remount

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Message-Id: <12070840223433-git-send-email-ezk@cs.sunysb.edu>
Date:	Tue,  1 Apr 2008 17:06:55 -0400
From:	Erez Zadok <ezk@...sunysb.edu>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	viro@....linux.org.uk, hch@...radead.org,
	Erez Zadok <ezk@...sunysb.edu>
Subject: [PATCH 13/14] Unionfs: don't purge lower sb data on remount

This is no longer needed, as we don't have upper and lower pages.  Plus this
was racy, requiring the unexported inode_lock variable.

Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
---
 fs/unionfs/dentry.c |   11 -----------
 fs/unionfs/super.c  |    8 +++++---
 2 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index 5e498c2..ee0da4f 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -273,17 +273,6 @@ static inline void purge_inode_data(struct inode *inode)
 	 */
 }
 
-void purge_sb_data(struct super_block *sb)
-{
-	struct inode *inode;
-
-	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
-		if (inode->i_state & (I_FREEING|I_WILL_FREE))
-			continue;
-		purge_inode_data(inode);
-	}
-}
-
 /*
  * Revalidate a single file/symlink/special dentry.  Assume that info nodes
  * of the dentry and its parent are locked.  Assume that parent(s) are all
diff --git a/fs/unionfs/super.c b/fs/unionfs/super.c
index 4cddc83..82b4045 100644
--- a/fs/unionfs/super.c
+++ b/fs/unionfs/super.c
@@ -747,10 +747,12 @@ out_no_change:
 	 * function).  This revalidation will happen lazily and
 	 * incrementally, as users perform operations on cached inodes.  We
 	 * would like to encourage this revalidation to happen sooner if
-	 * possible, so we try to invalidate as many other pages in our
-	 * superblock as we can.
+	 * possible, so we like to try to invalidate as many other pages in
+	 * our superblock as we can.  We used to call drop_pagecache_sb() or
+	 * a variant thereof, but either method was racy (drop_caches alone
+	 * is known to be racy).  So now we let the revalidation happen on a
+	 * per file basis in ->d_revalidate.
 	 */
-	purge_sb_data(sb);
 
 	/* grab new lower super references; release old ones */
 	for (i = 0; i < new_branches; i++)
-- 
1.5.2.2

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