Date: Thu, 4 Dec 2008 12:51:29 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: "Bruce M. Simpson" <bms@freebsd.org> Cc: josh.carroll@gmail.com, freebsd-fs@freebsd.org, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: ext2 inode size patch - RE: PR kern/124621 Message-ID: <20081204105129.GA2246@deviant.kiev.zoral.com.ua> In-Reply-To: <49378379.5050900@FreeBSD.org> References: <8cb6106e0811241129o642dcf28re4ae177c8ccbaa25@mail.gmail.com> <20081125140601.GH2042@deviant.kiev.zoral.com.ua> <8cb6106e0811250617q5fffb41exe20dfb8314fc4a9d@mail.gmail.com> <20081125142827.GI2042@deviant.kiev.zoral.com.ua> <8cb6106e0811250657q6fdf08b0x1e94f35fd0a7ed4f@mail.gmail.com> <20081125150342.GL2042@deviant.kiev.zoral.com.ua> <8cb6106e0812031453j6dc2f2f4i374145823c084eaa@mail.gmail.com> <49378379.5050900@FreeBSD.org>
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[-- Attachment #1 --] On Thu, Dec 04, 2008 at 07:15:05AM +0000, Bruce M. Simpson wrote: > Hi, > > The inode size for the ext3 filesystem which Gentoo created for my last > install defaulted to 256 bytes, so I got bit by this problem. > > I can't speak for the write path. but the read path looks just fine to > me, and the patch should go in ASAP. > > Josh Carroll wrote: > >>Ok, I describe my concern once more. I do not object against the checking > >>of the inode size. But, if inode size is changed, then some data is added > >>to the inode, that could (and usually does, otherwise why extend it ?) > >>change intrerpetation of the inode. Thus, we need a verification of the > >>fact that simply ignoring added fields does not damage filesystem or > >>cause user data corruption. Verification != testing. > >> > > If folk are paranoid, then add a check for dynamic inode size and > disable ext2fs writes by downgrading the mount in that case (We can do > that, right? Can someone make sure Josh gets the help he needs here?) > > As Josh points out, the ext2 inode size is stored in the superblock. > Whilst it may vary between ext2 filesystems, *the inode size itself does > not appear to be something which one can modify in an existing ext2/3 > filesystem*. > > Older ext2 filesystems may not contain the inode size field in the > superblock, and the patch appears to default to 128 for that case. The > double indirection thus introduced doesn't concern me, our ext2fs is not > performance critical code, and the superblock is likely to sit in L2/L3 > cache anyway (note: content free argument). > > Thanks to Josh for fixing this problem. Bruce, feel free to commit the patch. I do not want to spend time on ext2 in any form, and due to our (only partly jokingly) rule of the "last committer is the owner", I do not want to analyze ext2 bug reports after. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkk3tjEACgkQC3+MBN1Mb4gsMACfdZOmzO3B2qwkehgi1lWJWB+s anMAoNKxfWj1QQ6gOIYnXXIRE6bPZeWs =8ohK -----END PGP SIGNATURE-----
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