From 34825fb2c891ee56fdde84000f0b1bc83a12f42f Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Mon, 22 Nov 2010 02:21:38 +0000 Subject: [PATCH 2/3] Btrfs - fix race between btrfs_get_sb() and umount When mounting a btrfs file system btrfs_test_super() may attempt to use sb->s_fs_info, the btrfs root, of a super block that is going away and that has had the btrfs root set to NULL in its ->put_super(). But if the super block is going away it cannot be an existing super block so we can return false in this case. Signed-off-by: Ian Kent Signed-off-by: Chris Mason --- fs/btrfs/super.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 185702f..b169698 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -551,6 +551,12 @@ static int btrfs_test_super(struct super_block *s, void *data) struct btrfs_fs_devices *test_fs_devices = data; struct btrfs_root *root = btrfs_sb(s); + /* + * If this super block is going away, return false as it + * can't match as an existing super block. + */ + if (!atomic_read(&s->s_active)) + return 0; return root->fs_info->fs_devices == test_fs_devices; } -- 1.7.3.3