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    SubjectRe: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption
    On Tue, Nov 16, 2010 at 01:56:31PM +0100, 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 <djwong@us.ibm.com>
    > > ---
    > >
    > > 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().

    It seems to work ok for me, so:

    Acked-by: Darrick J. Wong <djwong@us.ibm.com>

    I will make the same change to ext3.

    --D
    >
    > Thanks.
    >
    > -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;
    > }
    >
    > --
    > 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


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