From: "Bryan Henderson" <hbryan@us.ibm.com>
To: Alexander Viro <viro@math.psu.edu>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Jean-Marc Saffroy <saffroy@ri.silicomp.fr>,
Linus Torvalds <torvalds@transmeta.com>
Subject: Re: [RFD] readonly/read-write semantics
Date: Tue, 4 Sep 2001 12:50:48 -0700 [thread overview]
Message-ID: <OF40F28F05.61359C2E-ON87256ABD.006684BD@boulder.ibm.com> (raw)
>>
>> 1) I want to see files open for write have nothing to do with it. Unix
>> open/close is not a transaction, it's just a connection. Some
applications
>> manage to use open/close as a transaction, but we're seeing less and
less
>> of that as more sophisticated facilities for transactions become
available.
>>
>> How many times have we all been frustrated trying to remount read only
when
>> some log file that hasn't been written to for hours is open for write?
>>
>> A file write is in progress when a write() system call hasn't returned,
not
>> when the file is open for write.
>
>Uh-oh... How about shared mappings?
It's always shared mappings, isn't it? :-)
Virtual memory access to the file is even easier, though. A write in
progress is an individual store to virtual memory. The only way you could
even see it is if a page fault is in progress. So the most you would need
to wait for in going into the hard "read only" state I defined is for any
page I/O to complete. And for the "no new writes" state, you just write
protect all the pages (and any new ones that fault in too).
next reply other threads:[~2001-09-04 19:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-09-04 19:50 Bryan Henderson [this message]
2001-09-05 2:15 ` Alexander Viro
-- strict thread matches above, loose matches on Subject: below --
2001-09-05 2:34 Bryan Henderson
2001-09-04 18:39 Bryan Henderson
2001-09-01 0:38 Bryan Henderson
2001-08-31 23:35 Bryan Henderson
2001-09-01 4:23 ` Alexander Viro
2001-09-01 14:42 ` Ingo Oeser
2001-09-01 16:44 ` Alexander Viro
2001-09-01 17:13 ` Nicholas Knight
2001-09-04 2:07 ` Jean-Marc Saffroy
2001-09-04 4:09 ` Alexander Viro
2001-09-04 9:26 ` Xavier Bestel
2001-09-04 10:15 ` Alexander Viro
2001-09-04 10:20 ` Xavier Bestel
2001-09-04 10:28 ` Alexander Viro
2001-09-04 10:59 ` Xavier Bestel
2001-09-04 11:29 ` Alexander Viro
2001-09-04 17:03 ` Pavel Machek
2001-09-04 16:58 ` Pavel Machek
2001-08-31 17:18 [Q] [VFS] NULL f_dentry for opened files ; possible race condition Jean-Marc Saffroy
2001-08-31 20:56 ` [RFD] readonly/read-write semantics Alexander Viro
2001-09-01 13:08 ` Juan Quintela
2001-09-04 1:16 ` Jean-Marc Saffroy
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