Date: Sun, 17 Feb 2013 07:55:28 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Bruce Evans <brde@optusnet.com.au> Cc: fs@freebsd.org Subject: Re: cleaning files beyond EOF Message-ID: <20130217055528.GB2522@kib.kiev.ua> In-Reply-To: <20130217113031.N9271@besplex.bde.org> References: <20130217113031.N9271@besplex.bde.org>
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--lnVtgFsQ/+aGFUA8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Feb 17, 2013 at 11:33:58AM +1100, Bruce Evans wrote: > I have a (possibly damaged) ffs data block with nonzero data beyond > EOF. Is anything responsible for clearing this data when the file > is mmapped()? >=20 > At least old versions of gcc mmap() the file and have a bug checking > for EOF. They read the garbage beyond the end and get confused. Does the 'damaged' status of the data block mean that it contain the garbage after EOF on disk ? UFS uses a small wrapper around vnode_generic_getpages() as the VOP_GETPAGES(), the wrapping code can be ignored for the current purpose. vnode_generic_getpages() iterates over the the pages after the bstrategy() and marks the part of the page after EOF valid and zeroes it, using vm_page_set_valid_range(). --lnVtgFsQ/+aGFUA8 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) iQIcBAEBAgAGBQJRIHDQAAoJEJDCuSvBvK1BVvIQAII9S5yh7gY5/sDH53QfKv7T 6r1ekPRmUgcSMGcFMwH6N88uVOckdXFcROIJKmgKDvjQzzdvif3SPzBFwShm55rg zsqs5IuEi+xJtn2N6TQOdgTiV+//GLonIKXMjrQluF0qm9+BhP9bUmSrkIzHGV5P Lf20n3EMok3hF03cxdJrDI0jHJ+wUpZTee1SELq/fcMHK04R0BCtsVgulHwRnrr9 N+fdhpB5Eh85LH5OEALgiF2x5deK/khhauPyFRymg+s2N57w7EsxxQHAyYnuz/KN sDY0FOlvNLqwzBGtomrJnRWY+d6RQiKlcxvWkBUP9leOFnuGnRVc1MjYHhNP/Htz GzAeQKLLuDIroSZy5IbcGrLzc2XQIKix1ILPtfffV/2Vn/bQCXHC1EGqPfQl2UqK 8K90QjVR0z7mBvbaiW8QgoN/2Dy0UvqYwOTBrAzAET6tRmH/nOuCAqhzsBAvssY1 tjRS5nqeF3S/AbalZtDNM7TmNZOlWTlLYUrvDuct/C68CkWGejYYFGMoGOuL2/vC hGb5pSH9IDNG5NP3mtoXylukmplgUnhPOiXyxLLGAoFnVTL5nGJaxlUwu8XElOxq +3xNgLt2mkR4er8mx9WaB3moistCIU1LEI4M/kQEOQLQfTWxdc7hC2P8hvm6IN0V TCvwmJrtvt+it4vdaTpg =lL16 -----END PGP SIGNATURE----- --lnVtgFsQ/+aGFUA8--
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