From: Jan Kara <jack@suse.cz>
To: Andreas Dilger <adilger@dilger.ca>
Cc: Jan Kara <jack@suse.cz>, Eric Biggers <ebiggers@kernel.org>,
Ted Tso <tytso@mit.edu>,
linux-ext4@vger.kernel.org
Subject: Re: [PATCH 02/12] ext4: Remove redundant sb checksum recomputation
Date: Mon, 30 Nov 2020 11:59:43 +0100 [thread overview]
Message-ID: <20201130105943.GI11250@quack2.suse.cz> (raw)
In-Reply-To: <301139FC-B346-4199-B26E-1FF0CB970746@dilger.ca>
On Sun 29-11-20 15:11:05, Andreas Dilger wrote:
> On Nov 27, 2020, at 4:33 AM, Jan Kara <jack@suse.cz> wrote:
> >
> > Superblock is written out either through ext4_commit_super() or through
> > ext4_handle_dirty_super(). In both cases we recompute the checksum so it
> > is not necessary to recompute it after updating superblock free inodes &
> > blocks counters.
>
> I searched through the code to see where s_sbh is being used, and it
> looks like there is one case that doesn't update the checksum using
> ext4_handle_dirty_super(), namely:
>
> ext4_file_ioctl(cmd=FS_IOC_GET_ENCRYPTION_PWSALT)
> {
> err = ext4_journal_get_write_access(handle, sbi->s_sbh);
> if (err)
> goto pwsalt_err_journal;
> generate_random_uuid(sbi->s_es->s_encrypt_pw_salt);
> err = ext4_handle_dirty_metadata(handle, NULL,
> sbi->s_sbh);
>
> I don't think that is a problem with this patch, per se, but looks like
> a bug that could be hit in rare cases with fscrypt + metadata_csum. It
> would only happen once per filesystem, and would normally be hidden by
> later superblock updates, but should probably be fixed anyway.
Yeah, good spotting. I'll write a fix for this.
> Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Thanks for review!
Honza
>
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> > fs/ext4/super.c | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index 2b08b162075c..61e6e5f156f3 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -5004,13 +5004,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> > block = ext4_count_free_clusters(sb);
> > ext4_free_blocks_count_set(sbi->s_es,
> > EXT4_C2B(sbi, block));
> > - ext4_superblock_csum_set(sb);
> > err = percpu_counter_init(&sbi->s_freeclusters_counter, block,
> > GFP_KERNEL);
> > if (!err) {
> > unsigned long freei = ext4_count_free_inodes(sb);
> > sbi->s_es->s_free_inodes_count = cpu_to_le32(freei);
> > - ext4_superblock_csum_set(sb);
> > err = percpu_counter_init(&sbi->s_freeinodes_counter, freei,
> > GFP_KERNEL);
> > }
> > --
> > 2.16.4
> >
>
>
> Cheers, Andreas
>
>
>
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-11-30 11:00 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 11:33 [PATCH 00/12] ext4: Various fixes of ext4 handling of fs errors Jan Kara
2020-11-27 11:33 ` [PATCH 01/12] ext4: Don't remount read-only with errors=continue on reboot Jan Kara
2020-11-29 21:33 ` Andreas Dilger
2020-12-16 4:59 ` Theodore Y. Ts'o
2020-11-27 11:33 ` [PATCH 02/12] ext4: Remove redundant sb checksum recomputation Jan Kara
2020-11-29 22:11 ` Andreas Dilger
2020-11-30 10:59 ` Jan Kara [this message]
2020-12-16 5:01 ` Theodore Y. Ts'o
2020-11-27 11:33 ` [PATCH 03/12] ext4: Standardize error message in ext4_protect_reserved_inode() Jan Kara
2020-11-29 21:39 ` Andreas Dilger
2020-12-16 5:04 ` Theodore Y. Ts'o
2020-11-27 11:33 ` [PATCH 04/12] ext4: Make ext4_abort() use __ext4_error() Jan Kara
2020-11-29 22:12 ` Andreas Dilger
2020-12-16 5:07 ` Theodore Y. Ts'o
2020-11-27 11:33 ` [PATCH 05/12] ext4: Move functions in super.c Jan Kara
2020-11-29 22:13 ` Andreas Dilger
2020-12-16 5:09 ` Theodore Y. Ts'o
2020-11-27 11:33 ` [PATCH 06/12] ext4: Simplify ext4 error translation Jan Kara
2020-11-29 21:57 ` Andreas Dilger
2020-12-16 5:11 ` Theodore Y. Ts'o
2020-11-27 11:34 ` [PATCH 07/12] ext4: Defer saving error info from atomic context Jan Kara
2020-12-16 5:31 ` Theodore Y. Ts'o
2020-12-16 5:40 ` Theodore Y. Ts'o
2020-12-16 9:56 ` Jan Kara
2020-11-27 11:34 ` [PATCH 08/12] ext4: Combine ext4_handle_error() and save_error_info() Jan Kara
2020-12-14 19:23 ` harshad shirwadkar
2020-12-16 10:11 ` Jan Kara
2020-12-16 10:24 ` Jan Kara
2020-11-27 11:34 ` [PATCH 09/12] ext4: Drop sync argument of ext4_commit_super() Jan Kara
2020-12-14 19:25 ` harshad shirwadkar
2020-11-27 11:34 ` [PATCH 10/12] ext4: Protect superblock modifications with a buffer lock Jan Kara
2020-11-27 11:34 ` [PATCH 11/12] ext4: Save error info to sb through journal if available Jan Kara
2020-11-27 11:34 ` [PATCH 12/12] ext4: Use sbi instead of EXT4_SB(sb) in ext4_update_super() Jan Kara
2020-12-14 19:07 ` [PATCH 00/12] ext4: Various fixes of ext4 handling of fs errors harshad shirwadkar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201130105943.GI11250@quack2.suse.cz \
--to=jack@suse.cz \
--cc=adilger@dilger.ca \
--cc=ebiggers@kernel.org \
--cc=linux-ext4@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.