From: Richard Tobin <richard@inf.ed.ac.uk>
To: "Erik E. Fair" <fair-tuhs@netbsd.org>,
The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] Unix filesystem semantics history - files with holes
Date: Thu, 11 Apr 2019 16:57:48 +0100 (BST) [thread overview]
Message-ID: <20190411155748.8791B255ADDC@macaroni.inf.ed.ac.uk> (raw)
In-Reply-To: Erik E. Fair's message of Wed, 10 Apr 2019 19:37:05 -0700
> When did the Unix filesystem add the semantics for "files with holes" (large,
> sparse files)?
It was there in the first edition:
https://www.bell-labs.com/usr/dmr/www/pdfs/man51.pdf
The FILE SYSTEM (V) man page includes a last paragraph identical to
that of FILSYS (V) in seventh edition:
If block b in a file exists, it is not necessary that all blocks
less than b exist. A zero block number either in the address words
of the the i-node or in an indirect block indicates that the
corresponding block has never been allocated. Such a missing block
reads as if it contained all zero words.
The first edition indirect blocks were a bit different though: if the
file was bigger than 8 blocks (4kB), all the blocks in the inode were
(singly) indirect.
-- Richard
--
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
next reply other threads:[~2019-04-11 16:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-11 15:57 Richard Tobin [this message]
2019-04-11 19:09 ` William Corcoran
2019-04-11 19:49 ` Bakul Shah
-- strict thread matches above, loose matches on Subject: below --
2019-04-11 2:37 Erik E. Fair
2019-04-11 5:28 ` Ronald Natalie
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=20190411155748.8791B255ADDC@macaroni.inf.ed.ac.uk \
--to=richard@inf.ed.ac.uk \
--cc=fair-tuhs@netbsd.org \
--cc=tuhs@tuhs.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).