From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932824AbeD0WWz (ORCPT ); Fri, 27 Apr 2018 18:22:55 -0400 Received: from twosheds.infradead.org ([90.155.92.209]:49064 "EHLO twosheds.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753569AbeD0WWw (ORCPT ); Fri, 27 Apr 2018 18:22:52 -0400 Message-ID: <1524867762.18504.89.camel@infradead.org> Subject: Re: [PATCH] jffs2: safely remove obsolete dirent from the f->dents list From: David Woodhouse To: Yufen Yu Cc: Joakim.Tjernlund@infinera.com, viro@zeniv.linux.org.uk, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org In-Reply-To: <20180329120023.33169-1-yuyufen@huawei.com> References: <20180329120023.33169-1-yuyufen@huawei.com> Face: 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 Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-seZyAtsnIeSdQMmE/nRt" Date: Fri, 27 Apr 2018 23:22:42 +0100 Mime-Version: 1.0 X-Mailer: Evolution 3.18.5.2-0ubuntu3.2 X-SRS-Rewrite: SMTP reverse-path rewritten from by twosheds.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-seZyAtsnIeSdQMmE/nRt Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable This looks a lot better than the first iteration; thank you for getting it to this point. One last thing, I hope... On Thu, 2018-03-29 at 20:00 +0800, Yufen Yu wrote: >=20 > --- a/fs/jffs2/jffs2_fs_i.h > +++ b/fs/jffs2/jffs2_fs_i.h > @@ -42,6 +42,12 @@ struct jffs2_inode_info { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* Directory entries */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct jffs2_full_dirent = *dents; > =C2=A0 > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* Directory open refcount */ > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0atomic_t nr_dir_opening; > + > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* obsolete dirent count in th= e list of 'dents' */ > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0unsigned int obsolete_count; > + > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* The target path if thi= s is the inode of a symlink */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0unsigned char *target; > =C2=A0 You've made JFFS2_INVALID_LIMIT 64, which is reasonable enough (although it's a bit of a weird name and possibly wants to be more specific =E2=80=94 invalid *what*?). So the maximum interesting value of ->obsolete_count is 64. Which means it might as well be a uint8_t and sit in the padding after the 'usercompr' field. It might be useful to look at putting the mutually exclusive fields in struct jffs2_inode_info into a union, and then we don't need the additional space of the atomic_t either; we'll never need that *and* the fragtree at the same time... will we? --=-seZyAtsnIeSdQMmE/nRt Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEFQw ggUxMIIEGaADAgECAhBNRhEyk/HZ7naOeTHWrzuAMA0GCSqGSIb3DQEBCwUAMIGXMQswCQYDVQQG EwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYD VQQKExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RPIFJTQSBDbGllbnQgQXV0aGVu dGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTAeFw0xNzEyMjEwMDAwMDBaFw0xODEyMjEyMzU5 NTlaMCQxIjAgBgkqhkiG9w0BCQEWE2R3bXcyQGluZnJhZGVhZC5vcmcwggEiMA0GCSqGSIb3DQEB AQUAA4IBDwAwggEKAoIBAQDgzLNWa18DNpGUj/ZeH0Sgz53ESIbzdPw3OJeuNP6jZhxZojbyfxbM 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