linux-kernel - [PATCH 2.6.19-rc3-mm1] VFS: BKL is not required for remount

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Message-ID: <45460CEF.2060801@sw.ru>
Date:	Mon, 30 Oct 2006 17:32:15 +0300
From:	Vasily Averin <vvs@...ru>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	David Howells <dhowells@...hat.com>,
	Jan Blunck <jblunck@...e.de>, Andrew Morton <akpm@...l.org>,
	Alexander Viro <viro@...iv.linux.org.uk>
CC:	Kirill Korotaev <dev@...nvz.org>, devel@...nvz.org
Subject: [PATCH 2.6.19-rc3-mm1] VFS: BKL is not required for remount_fs()

From: Vasily Averin <vvs@...ru>

according to Documentation/filesystems/Locking remount_fs() is not requires BKL

Signed-off-by:	Vasily Averin <vvs@...ru>

--- linux-2.6.19-rc3-mm1/fs/namespace.c.blkrm	2006-10-30 14:36:09.000000000 +0300
+++ linux-2.6.19-rc3-mm1/fs/namespace.c	2006-10-30 14:33:05.000000000 +0300
@@ -594,10 +594,8 @@ static int do_umount(struct vfsmount *mn
 		 */
 		down_write(&sb->s_umount);
 		if (!(sb->s_flags & MS_RDONLY)) {
-			lock_kernel();
 			DQUOT_OFF(sb);
 			retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
-			unlock_kernel();
 		}
 		up_write(&sb->s_umount);
 		return retval;
--- linux-2.6.19-rc3-mm1/fs/super.c.blkrm	2006-10-30 14:36:01.000000000 +0300
+++ linux-2.6.19-rc3-mm1/fs/super.c	2006-10-30 14:33:05.000000000 +0300
@@ -609,16 +609,8 @@ static void do_emergency_remount(unsigne
 		sb->s_count++;
 		spin_unlock(&sb_lock);
 		down_read(&sb->s_umount);
-		if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
-			/*
-			 * ->remount_fs needs lock_kernel().
-			 *
-			 * What lock protects sb->s_flags??
-			 */
-			lock_kernel();
+		if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY))
 			do_remount_sb(sb, MS_RDONLY, NULL, 1);
-			unlock_kernel();
-		}
 		drop_super(sb);
 		spin_lock(&sb_lock);
 	}

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