On Sun 31-07-16 23:09:09, Ted Tso wrote:
> On Fri, Jul 29, 2016 at 08:42:10AM +0200, Jan Kara wrote:
> >
> > I have written some fixes, working on testing them... So hopefully I can
> > submit them later today or next week.
>
> How complicated are the fixes? This should work as a temporary
> workaround and it going to be very simple to backport.
Relatively simple but there are still some bugs lurking - I have the
original issue fixed but I have implemented xfstests which stress the inode
expansion code in various ways and so far they are still able to crash the
kernel... Tomorrow I will be looking more into it and hopefully will be
able to finish the fixes.
Regarding your patch - I think it's a reasonable band-aid although I'll
have to backport proper fixes to 4.4 anyway (it's a base of our next
enterprise release), which is where i_projid got introduced as well, so
eventually we will have proper stable fixes for all relevant kernels
anyway.
Honza
> commit e92d5b1cf6af642bc5018562e58044fd771f82bf
> Author: Theodore Ts'o <tytso@xxxxxxx>
> Date: Sun Jul 31 23:08:28 2016 -0400
>
> ext4: suppress inode growth for file systems w/o project quota
>
> We have not added a new "extra" inode field in a very long time, and
> the code to deal with moving the extended attributes down to make room
> for the extra inode fields has bitrotted and can cause kernel BUGS.
>
> Very few people will likely use project quotas (and those that do will
> likely be creating a new file system from scratch) so as a temporary
> pallative until we are sure the inode expansion code is all sane,
> let's not try to expand the inode "extra" fields if the project
> feature has not been enabled.
>
> Cc: stable@xxxxxxxxxxxxxxx # v4.4+
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c13a4e4..e2622ba 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3968,6 +3968,17 @@ no_journal:
> if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
> sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
> EXT4_GOOD_OLD_INODE_SIZE;
> + /*
> + * This is a temporary hack; we have not added a new
> + * "extra" inode field in a long time, and the code to
> + * expand the inode structure has bitrotted and can
> + * cause kernel BUG's. If the file system does not
> + * have the project feature, let's not try to expand
> + * the inode's extra size as a temporary pallitive
> + * until we can fix up the inode expansion code.
> + */
> + if (!ext4_has_feature_project(sb))
> + sbi->s_want_extra_isize -= sizeof(__le32);
> if (ext4_has_feature_extra_isize(sb)) {
> if (sbi->s_want_extra_isize <
> le16_to_cpu(es->s_want_extra_isize))
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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