linux-kernel - [PATCH 1/6] autofs4 - correct offset mount expire check

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Date:	Thu, 23 Oct 2008 10:35:13 +0800
From:	Ian Kent <raven@...maw.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	autofs mailing list <autofs@...ux.kernel.org>
Subject: [PATCH 1/6] autofs4 - correct offset mount expire check

When checking a directory tree in autofs_tree_busy() we can incorrectly
decide that the tree isn't busy. This happens for the case of an active
offset mount as autofs4_follow_mount() follows past the active offset
mount, which has an open file handle used for expires, causing the file
handle not to count toward the busyness check.

Signed-off-by: Ian Kent <raven@...maw.net>
Signed-off-by: Jeff Moyer <jmoyer@...hat.com>

---

 fs/autofs4/expire.c |   19 +++++++++++++++----
 1 files changed, 15 insertions(+), 4 deletions(-)


diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index cde2f8e..4b6fb3f 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -56,12 +56,23 @@ static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
 	mntget(mnt);
 	dget(dentry);
 
-	if (!autofs4_follow_mount(&mnt, &dentry))
+	if (!follow_down(&mnt, &dentry))
 		goto done;
 
-	/* This is an autofs submount, we can't expire it */
-	if (is_autofs4_dentry(dentry))
-		goto done;
+	if (is_autofs4_dentry(dentry)) {
+		struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+
+		/* This is an autofs submount, we can't expire it */
+		if (sbi->type == AUTOFS_TYPE_INDIRECT)
+			goto done;
+
+		/*
+		 * Otherwise it's an offset mount and we need to check
+		 * if we can umount its mount, if there is one.
+		 */
+		if (!d_mountpoint(dentry))
+			goto done;
+	}
 
 	/* Update the expiry counter if fs is busy */
 	if (!may_umount_tree(mnt)) {

--
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