All of lore.kernel.org
 help / color / mirror / Atom feed
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

  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 \
    --subject='Re: [PATCH 02/12] ext4: Remove redundant sb checksum recomputation' \
    /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

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.