From: Eric Sandeen Subject: Re: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption Date: Tue, 16 Nov 2010 11:43:25 -0600 Message-ID: <4CE2C2BD.1080202@redhat.com> References: <20101115214831.GA18195@tux1.beaverton.ibm.com> <4CE1AC38.9040201@redhat.com> <20101115230346.GB18195@tux1.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Darrick J. Wong" , "Theodore Ts'o" , "Patrick J. LoPresti" , linux-kernel , linux-ext4 , Mingming Cao To: Lukas Czerner Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33549 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755943Ab0KPSk7 (ORCPT ); Tue, 16 Nov 2010 13:40:59 -0500 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On 11/16/10 6:56 AM, Lukas Czerner wrote: > On Mon, 15 Nov 2010, Darrick J. Wong wrote: > >> At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path >> out of that function returns ret. However, the generic_check_addressable >> clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g. >> a group checksum error) returns 0 even though the mount should fail. This >> causes vfs_kern_mount in turn to think that the mount succeeded, leading to an >> oops. >> >> A simple fix is to avoid using ret for the generic_check_addressable check, >> which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2. >> >> v2: Return -EFBIG in the error case, per Eric Sandeen's suggestion. >> >> Signed-off-by: Darrick J. Wong >> --- >> >> fs/ext4/super.c | 6 +++--- >> 1 files changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/fs/ext4/super.c b/fs/ext4/super.c >> index 40131b7..120c034 100644 >> --- a/fs/ext4/super.c >> +++ b/fs/ext4/super.c >> @@ -3257,13 +3257,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) >> * Test whether we have more sectors than will fit in sector_t, >> * and whether the max offset is addressable by the page cache. >> */ >> - ret = generic_check_addressable(sb->s_blocksize_bits, >> - ext4_blocks_count(es)); >> - if (ret) { >> + if (generic_check_addressable(sb->s_blocksize_bits, >> + ext4_blocks_count(es))) { >> ext4_msg(sb, KERN_ERR, "filesystem" >> " too large to mount safely on this system"); >> if (sizeof(sector_t) < 8) >> ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled"); >> + ret = -EFBIG; >> goto failed_mount; >> } >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > Hi, > > the untested diff below seems like a more general solution to me, > since it allows to return the actual error from > generic_check_addressable(). > > Thanks. good point, we can get -EINVAL or -EFBIG back, can't we. Thanks, -Eric > -Lukas > > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 61182fe..3d89b72 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -3268,13 +3268,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > * Test whether we have more sectors than will fit in sector_t, > * and whether the max offset is addressable by the page cache. > */ > - ret = generic_check_addressable(sb->s_blocksize_bits, > + err = generic_check_addressable(sb->s_blocksize_bits, > ext4_blocks_count(es)); > - if (ret) { > + if (err) { > ext4_msg(sb, KERN_ERR, "filesystem" > " too large to mount safely on this system"); > if (sizeof(sector_t) < 8) > ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled"); > + ret = err; > goto failed_mount; > } >