From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Liu Bo <obuil.liubo@gmail.com>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>, <stable@kernel.org>
Subject: Re: [PATCH] ext4: make sure enough credits are reserved for dioread_nolock writes
Date: Tue, 25 Dec 2018 23:07:13 -0500 [thread overview]
Message-ID: <20181226040713.GA4158@mit.edu> (raw)
In-Reply-To: <CANQeFDAL=Bx6dq69Rzmz_OWXkXMz=KzLvEkw4rQSSqMW9OHWMQ@mail.gmail.com>
On Tue, Dec 25, 2018 at 04:10:25PM -0800, Liu Bo wrote:
>
> I had a patch[1] to address the problem but with adding reservation
> only when we need to (in ext4_ext_try_to_merge_up).
Sorry, I had forgotten that you had that patch pending. I believe
that merging up isn't the only case we need to worry about, though.
For example, if we write into the middle of a larger unwritten region,
we might havec to change a single region into three regions, which
might require a node split --- and in that case, it's not optional, as
would be in the try_to_merge_up situation. If we don't have enough
credits to do a node split our only choices would be mark the file
system as corrupted, or to fail the write with ENOSPC (which would be
very confusing to the user/application).
Cheers,
- Ted
next prev parent reply other threads:[~2018-12-26 4:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-25 5:33 [PATCH] ext4: make sure enough credits are reserved for dioread_nolock writes Theodore Ts'o
2018-12-26 0:10 ` Liu Bo
2018-12-26 4:07 ` Theodore Y. Ts'o [this message]
2019-01-01 23:40 ` Liu Bo
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