From: Theodore Ts'o <tytso@mit.edu>
To: Josef Bacik <jbacik@fb.com>
Cc: Omar Sandoval <osandov@osandov.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
kernel-team@fb.com
Subject: Re: [RFC PATCH] coredump: avoid ext4 auto_da_alloc for core file
Date: Tue, 5 Jul 2016 12:57:15 -0400 [thread overview]
Message-ID: <20160705165715.GH15193@thunk.org> (raw)
In-Reply-To: <e906173a-a589-ec6a-73e0-ecf899e86b0e@fb.com>
On Tue, Jul 05, 2016 at 11:01:40AM -0400, Josef Bacik wrote:
> > > Omar, this probably breaks the case where we do
> > > fallocate(FALLOC_FL_KEEP_SIZE), the i_size will be 0 but there will be
> > > blocks to truncate. Probably want to check i_blocks or something. Thanks,
> >
> > Sure, but this is in the coredump code; do we care there? What are
> > the odds that someone will have fallocated blocks beyond i_size in a
> > file named "core"? And if so, it's not like it's going to make the
> > coredump invalid or non-useful in any way.
>
> Wow I totally didn't notice this was in coredump.c, I thought it was in ext4
> code because you said it failed regression tests, which I assumed were your
> ext4 tests. Ignore me. Thanks,
Yeah, Omar's original patch was something he described as a "hack" to
the coredump code. I actually don't think it's that bad, but it does
make sense to have ext4 not enable the "replace-via-truncate" code
when the truncate is a no-op, but it turns out this is a bit tricky
because the places where we set i_size and where we decide to truncate
beyond i_size are separated. I tried to do something simple but it
didn't quite work right; I'll look into why it didn't work hopefully
later today.
- Ted
prev parent reply other threads:[~2016-07-05 16:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-15 17:42 [RFC PATCH] coredump: avoid ext4 auto_da_alloc for core file Omar Sandoval
2016-06-29 18:34 ` Omar Sandoval
2016-07-04 2:24 ` Theodore Ts'o
2016-07-04 15:11 ` Theodore Ts'o
2016-07-05 13:42 ` Josef Bacik
2016-07-05 14:37 ` Theodore Ts'o
2016-07-05 15:01 ` Josef Bacik
2016-07-05 16:57 ` Theodore Ts'o [this message]
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