Date: Tue, 25 Nov 2008 10:48:26 -0500 From: "Peter C. Lai" <peter@simons-rock.edu> To: Josh Carroll <josh.carroll@gmail.com> Cc: freebsd-fs@freebsd.org, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: ext2 inode size patch - RE: PR kern/124621 Message-ID: <20081125154826.GI27780@cesium.hyperfine.info> In-Reply-To: <8cb6106e0811250711x39775d2asd601e8a53eaaeac7@mail.gmail.com> 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> <8cb6106e0811250711x39775d2asd601e8a53eaaeac7@mail.gmail.com>
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On 2008-11-25 10:11:09AM -0500, 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. > > Ok, I see your point. I will do some more research into the ext2 inode > structure on disk and see what happens when inode size > 128. Possibly overstating the obvious, but since e2fsprogs were the ones who actually initiated the change in default inode size, maybe start digging through that to see what it actually does with the other 128 bytes (the changelog and some posts on comp.os.linux seem to suggest is that it has something to do with optimizing extended attributes/acls; basically extended acls being inaccessible to kernels that ignore the extra data, and 2.4 kernels refusing to mount those filesystems at all (presumably due to the same assumption we've been making)). -- =========================================================== Peter C. Lai | Bard College at Simon's Rock Systems Administrator | 84 Alford Rd. Information Technology Svcs. | Gt. Barrington, MA 01230 USA peter AT simons-rock.edu | (413) 528-7428 ===========================================================
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