linux-ext4 - Re: [PATCH] ext4: do not BUG when INLINE_DATA

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Message-ID: <CAF3JpA5wakELyyOZVYC2MmAoQa9P_nj3AqesZ-PAHN31Omp8Rw@mail.gmail.com>
Date: Thu, 17 Jul 2025 12:53:49 -0700
From: Moon Hee Lee <moonhee.lee.ca@...il.com>
To: "Theodore Ts'o" <tytso@....edu>
Cc: syzbot+544248a761451c0df72f@...kaller.appspotmail.com, 
	adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] ext4: do not BUG when INLINE_DATA_FL lacks system.data xattr

On Thu, Jul 17, 2025 at 9:59 AM Moon Hee Lee <moonhee.lee.ca@...il.com> wrote:

Just a quick follow-up to close the loop:

>
> The current patch addresses ext4_update_inline_data() directly, but the
> same condition also leads to a BUG_ON in ext4_create_inline_data() [2],
> which the earlier approach intended to prevent as well.

I missed that ext4_create_inline_data expects the xattr to be absent at
that point, since it's about to create it. The BUG_ON(!is.s.not_found)
enforces that expectation.

The patch I sent earlier didn’t account for this correctly. Returning an
error when the xattr was not found would have broken valid behavior in
the create path.

Thanks again for resolving this with a simple and correct fix. Per-site
handling makes sense here, as each path has different expectations about
the xattr state.

Best regards,
Moonhee