linux-ext4 - Re: [PATCH 2/2] ext4: Do not create EA inode under buffer lock

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Message-ID: <20240503040306.GH1743554@mit.edu>
Date: Fri, 3 May 2024 00:03:06 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: Jan Kara <jack@...e.cz>
Cc: linux-ext4@...r.kernel.org,
        syzbot+a43d4f48b8397d0e41a9@...kaller.appspotmail.com
Subject: Re: [PATCH 2/2] ext4: Do not create EA inode under buffer lock

On Thu, Mar 21, 2024 at 05:26:50PM +0100, Jan Kara wrote:
> ext4_xattr_set_entry() creates new EA inodes while holding buffer lock
> on the external xattr block. This is problematic as it nests all the
> allocation locking (which acquires locks on other buffers) under the
> buffer lock. This can even deadlock when the filesystem is corrupted and
> e.g. quota file is setup to contain xattr block as data block. Move the
> allocation of EA inode out of ext4_xattr_set_entry() into the callers.
> 
> Reported-by: syzbot+a43d4f48b8397d0e41a9@...kaller.appspotmail.com
> Signed-off-by: Jan Kara <jack@...e.cz>

Applied, thanks.

					- Ted