From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>,
linux-fsdevel@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Christoph Hellwig <hch@lst.de>,
Chuck Lever <chuck.lever@oracle.com>, Jan Kara <jack@suse.cz>
Subject: Re: VFS caching of file extents
Date: Thu, 29 Aug 2024 06:00:56 +0200 [thread overview]
Message-ID: <20240829040056.GA4142@lst.de> (raw)
In-Reply-To: <20240829015750.GB6216@frogsfrogsfrogs>
> Wouldn't readplus (and maybe a sparse copy program) rather have
> something that is "SEEK_DATA, fill the buffer with data from that file
> position, and tell me what pos the data came from"?
Or rather a read operation that returns a length but no data if there
is a hole. Either way a potentially incoherent VFS cache is the wrong
way to implement it.
> I also suspect that devising a "simple" mapping tree for simple
> filesystems will quickly devolve into a mess of figuring out their adhoc
> locking and making that work.
Heh. If simple really is the file systems just using the buffer_head
helpers without any magic it might actually not be that bad, but once
it gets a little more complicated I tend to agree.
But the first thing would be to establish if we actually need it at all,
or if the buffer_head caching of their metadata is actually enough for
the file systems.
next prev parent reply other threads:[~2024-08-29 4:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-28 19:34 VFS caching of file extents Matthew Wilcox
2024-08-28 19:46 ` Chuck Lever
2024-08-28 19:50 ` Matthew Wilcox
2024-08-29 6:05 ` Dave Chinner
2024-08-28 20:30 ` Josef Bacik
2024-08-28 23:46 ` Dave Chinner
2024-08-29 1:57 ` Darrick J. Wong
2024-08-29 4:00 ` Christoph Hellwig [this message]
2024-08-29 13:52 ` Chuck Lever III
2024-08-29 22:36 ` Dave Chinner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240829040056.GA4142@lst.de \
--to=hch@lst.de \
--cc=chuck.lever@oracle.com \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=djwong@kernel.org \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).