Date: Wed, 8 Dec 1999 11:03:16 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Ben Rosengart <ben@skunk.org> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Getting a new MAP_ flag into mmap() prior to 4.x freeze Message-ID: <199912081903.LAA40643@apollo.backplane.com> References: <Pine.BSF.4.21.9912081331550.26891-100000@penelope.skunk.org>
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:I assume that this flag would require write permission to the file, to
:prevent bad security implications?
:
:--
: Ben Rosengart
You can set the flag without write permission but it will not do anything
in that case. The only way to get a page marked such that the syncer
doesn't sync it is if you mmap() an area of memory and then take
write-faults on pages within that area, which requires write permission
to succeed. Only pages dirtied through a mmap marked to not sync will
not sync.
Things like file meta-data always sync, though if the only data written
to a file is through such an mmap() the filesystem will not have much
to do there.
-Matt
Matthew Dillon
<dillon@backplane.com>
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