From patchwork Fri Feb 18 20:18:51 2011
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From: Chris Mason <chris.mason@oracle.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Sterba <dave@jikos.cz>, linux-btrfs <linux-btrfs@vger.kernel.org>,
	bugzilla-daemon <bugzilla-daemon@bugzilla.kernel.org>,
	bugme-daemon <bugme-daemon@bugzilla.kernel.org>, fox <fox@murder.cz>
Subject: Re: [Bugme-new] [Bug 29302] New: Null pointer dereference with
	large max_sectors_kb
In-reply-to: <20110218115603.5f235b07.akpm@linux-foundation.org>
References: <bug-29302-10286@https.bugzilla.kernel.org/>
	<20110217153719.9ecc67df.akpm@linux-foundation.org>
	<20110218174315.GD5615@twin.jikos.cz> <1298056463-sup-4453@think>
	<20110218115603.5f235b07.akpm@linux-foundation.org>
Date: Fri, 18 Feb 2011 15:18:51 -0500
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diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index d39a989..d8f7ee0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -757,6 +757,10 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 	tree_root->fs_info = fs_info;
 
 	bdev = fs_devices->latest_bdev;
+	if (!bdev) {
+		printk(KERN_CRIT "btrfs read devices failed on %s\n", dev_name);
+		goto error_close_devices;
+	}
 	s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
 	if (IS_ERR(s))
 		goto error_s;