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From: Colin Ian King <colin.king@canonical.com>
To: linux-btrfs@vger.kernel.org
Subject: BZ#101951, Overlayfs on top of btrfs causes kernel oops + freeze
Date: Tue, 16 Feb 2016 15:38:53 +0000	[thread overview]
Message-ID: <56C3428D.1010000@canonical.com> (raw)

Hi there,

bug: https://bugzilla.kernel.org/show_bug.cgi?id=101951 and also
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1532145

Commit 4bacc9c9234c7c8eec44f5ed4e960d9f96fa0f01 ("overlayfs: Make f_path
always point to the overlay and f_inode to the underlay") resulted in an
issue when using a combination of btrfs and overlayfs.  This is
noticeable when doing a fsync() on a file in a chroot with overlayfs on
top of btrfs; we hit a kernel oops in btrfs_sync_file() on
atomic_inc(&root->log_batch) because root is NULL.

I've debugged this further and found that in btrfs_sync_file():

	struct inode *inode = d_inode(dentry);

does not return the inode I expected when using the stacked overlay fs,
where as:

	struct inode *inode = file_inode(file);

does.

However, I'm not well at all well versed in btrfs, so I am not confident
this is a actually correct.  Any comments?

Colin

             reply	other threads:[~2016-02-16 15:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-16 15:38 Colin Ian King [this message]
2016-02-16 15:51 ` BZ#101951, Overlayfs on top of btrfs causes kernel oops + freeze Filipe Manana
2016-02-16 16:08   ` Colin Ian King
2016-02-16 16:11     ` Filipe Manana
2016-02-16 16:17       ` Colin Ian King

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