linux-kernel - [PATCH 4/4] vfs: Block intuitively in the case of BSD accounting files

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Date:	Mon, 14 Apr 2014 00:42:09 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Rob Landley <rob@...dley.net>,
	Miklos Szeredi <miklos@...redi.hu>,
	Christoph Hellwig <hch@...radead.org>,
	Karel Zak <kzak@...hat.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	Fengguang Wu <fengguang.wu@...el.com>, tytso@....edu
Subject: [PATCH 4/4] vfs: Block intuitively in the case of BSD accounting files


Have the mntput that started the BSD accounting files closing block
until the superblock has been succesfully freed.  This is what used to
happen until fput started calling mntput assynchronously, and is arguably
the right thing to do in the case of umount.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 fs/namespace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index ac589ad9f22d..b10db3d69943 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1015,11 +1015,14 @@ static void mntput_no_expire(struct mount *mnt)
 		return;
 	}
 	if (unlikely(mnt->mnt_pinned)) {
+		init_completion(&undone);
+		mnt->mnt_undone = &undone;
 		mnt_add_count(mnt, mnt->mnt_pinned);
 		mnt->mnt_pinned = 0;
 		rcu_read_unlock();
 		unlock_mount_hash();
 		acct_auto_close_mnt(&mnt->mnt);
+		wait_for_completion(&undone);
 		return;
 	}
 	if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) {
@@ -1048,7 +1051,10 @@ static void mntput_no_expire(struct mount *mnt)
 	 * queue where the stack is guaranteed to be shallow.
 	 */
 	init_completion(&undone);
-	mnt->mnt_undone = &undone;
+	if (!mnt->mnt_undone)
+		mnt->mnt_undone = &undone;
+	else
+		complete(&undone);
 
 	INIT_WORK(&mnt->mnt_cleanup_work, cleanup_mnt_work);
 	schedule_work(&mnt->mnt_cleanup_work);
-- 
1.9.1

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