Commit 619c8c76 authored Nov 22, 2010 by Ian Kent Committed by Chris Mason Nov 27, 2010

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 <raven@themaw.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent bc1cbf1f

fs/btrfs/super.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -566,6 +566,12 @@ 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;
		}

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