From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lpp01m010-f49.google.com ([209.85.215.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SLwgW-0005TW-73 for linux-mtd@lists.infradead.org; Sun, 22 Apr 2012 13:18:36 +0000 Received: by lagy4 with SMTP id y4so9582259lag.36 for ; Sun, 22 Apr 2012 06:18:33 -0700 (PDT) Message-ID: <1335100558.28267.11.camel@brekeke> Subject: Re: [PATCH] [JFFS2] check xattr data integrity during the scan. From: Artem Bityutskiy To: Jean-Christophe DUBOIS Date: Sun, 22 Apr 2012 16:15:58 +0300 In-Reply-To: <1334175816-20688-1-git-send-email-jcd@tribudubois.net> References: <1334175816-20688-1-git-send-email-jcd@tribudubois.net> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-CwXjPd40oDKx+KDSH+xX" Mime-Version: 1.0 Cc: linux-mtd@lists.infradead.org Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-CwXjPd40oDKx+KDSH+xX Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2012-04-11 at 22:23 +0200, Jean-Christophe DUBOIS wrote: > If the system was powered off while JFFS2 was creating or moving > (GC) an extended attribute node, it might happen at next reboot > that the node CRC is OK but the data (name and value) might be > incomplete and therefore corrupted. >=20 > During the mount scan we need to check the xattr data integrity to > weed out bad ones and keep good ones (whith an earlier version). >=20 > Whitout this check the xattr data integrity problem was detected > a lot later and was not cured automatically (-EIO was returned). >=20 > Signed-off-by: Jean-Christophe DUBOIS > --- AFAIR, the whole idea of having 2 CRC checksums in JFFS2 nodes is to speed up scanning. E.g., if we hit an inode node, we check only "node_crc" to validate the "metadata", insert the inode to the in-memory data structures, and read the next node. We do not check the data CRC (data_crc), otherwise scanning would be much slower. If the data are corrupted, we notice this later, wen reading it. The same is done for xattrs - during scanning we do not check the data payload. I do not say this is ideal design, but it is how it is. So I do not think your patch should be merged. --=20 Best Regards, Artem Bityutskiy --=-CwXjPd40oDKx+KDSH+xX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAABAgAGBQJPlASOAAoJECmIfjd9wqK05HIQAJQZWhNuL5f8GwIWZmV0C5EZ jD8gzNfHwso19uJ1lurmbUYABJ+7yzoqiOVj0aMwfiEr8m/jqt0VM8ib7hYhv95Z 6KUR9aY3zAq6BaKT36cmFcNG6ZpVYvXDfwFbZ2v7hIWtGq9I3ART8ppaQqMxi5rd sUFSn62MToX3nAqbUDzBmmLM1H6LXcUVjdSiBHy02fSuNhWpezJvu0V61rzt4fJl qgYk+cFLMcYooHtu0YpTVApVCtSk7ZuPAi1t+T6EOJLkR8exrxHAempJwjeAf+Qh Caq8tW+9EryVrL58fksh8n6P6XzxDgQV1M0VbcM5ThVAspIStPbOAdvi0mXvhgx9 7LbuRurUYyS03vmI+iN3KaZyWLcbzyZ+pXNKCyGui7pzbejIrFSawrf+IvFwoe07 IBFrusvYT48YeZfL4J2gxpzFnEpCuYoUgfE6CHT5my38ohJ5pwiVsHcscH2QO6vS K9LP9OZevQAQax8EwKAPPaCdMRsxxFvALNB04dcWCUccMd6kTFWV3xC7tt3ctvnG 8LrwN+UMPUKg5dlnnZsYUaeuTGhJ0/D2+6GkLova0hDlgrCkbT4J+vFP6G1b4WV1 YmiBhXSq9U4TI3SSPmiueixf/EYSIlVgKw9aB+NaMycfDZAg+stiW/3xqch3LHxk woZc/2+/rH16ef6bmY5a =0Y0N -----END PGP SIGNATURE----- --=-CwXjPd40oDKx+KDSH+xX--