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Message-ID: <20200709123655.y7p7idrqukdi2he5@work>
Date: Thu, 9 Jul 2020 14:36:55 +0200
From: Lukas Czerner <lczerner@...hat.com>
To: Jan Kara <jack@...e.cz>
Cc: Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: don't BUG on inconsistent journal feature
On Thu, Jul 09, 2020 at 11:58:54AM +0200, Jan Kara wrote:
> A customer has reported a BUG_ON in ext4_clear_journal_err() hitting
> during an LTP testing. Either this has been caused by a test setup
> issue where the filesystem was being overwritten while LTP was mounting
> it or the journal replay has overwritten the superblock with invalid
> data. In either case it is preferable we don't take the machine down
> with a BUG_ON. So handle the situation of unexpectedly missing
> has_journal feature more gracefully by a WARN_ON_ONCE and bailing out
> with error.
>
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
> fs/ext4/super.c | 35 ++++++++++++++++++++++++-----------
> 1 file changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 330957ed1f05..d8b7222cb86c 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -68,8 +68,8 @@ static int ext4_show_options(struct seq_file *seq, struct dentry *root);
> static int ext4_commit_super(struct super_block *sb, int sync);
> static void ext4_mark_recovery_complete(struct super_block *sb,
> struct ext4_super_block *es);
> -static void ext4_clear_journal_err(struct super_block *sb,
> - struct ext4_super_block *es);
> +static int ext4_clear_journal_err(struct super_block *sb,
> + struct ext4_super_block *es);
> static int ext4_sync_fs(struct super_block *sb, int wait);
> static int ext4_remount(struct super_block *sb, int *flags, char *data);
> static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf);
> @@ -4956,7 +4956,8 @@ static journal_t *ext4_get_journal(struct super_block *sb,
> struct inode *journal_inode;
> journal_t *journal;
>
> - BUG_ON(!ext4_has_feature_journal(sb));
> + if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> + return NULL;
>
> journal_inode = ext4_get_journal_inode(sb, journal_inum);
> if (!journal_inode)
> @@ -4986,7 +4987,8 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
> struct ext4_super_block *es;
> struct block_device *bdev;
>
> - BUG_ON(!ext4_has_feature_journal(sb));
> + if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> + return NULL;
>
> bdev = ext4_blkdev_get(j_dev, sb);
> if (bdev == NULL)
> @@ -5078,7 +5080,8 @@ static int ext4_load_journal(struct super_block *sb,
> int err = 0;
> int really_read_only;
>
> - BUG_ON(!ext4_has_feature_journal(sb));
> + if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> + return -EFSCORRUPTED;
>
> if (journal_devnum &&
> journal_devnum != le32_to_cpu(es->s_journal_dev)) {
> @@ -5148,7 +5151,12 @@ static int ext4_load_journal(struct super_block *sb,
> }
>
> EXT4_SB(sb)->s_journal = journal;
> - ext4_clear_journal_err(sb, es);
> + err = ext4_clear_journal_err(sb, es);
> + if (err) {
> + EXT4_SB(sb)->s_journal = NULL;
> + jbd2_journal_destroy(journal);
> + return err;
> + }
>
> if (!really_read_only && journal_devnum &&
> journal_devnum != le32_to_cpu(es->s_journal_dev)) {
> @@ -5250,7 +5258,7 @@ static void ext4_mark_recovery_complete(struct super_block *sb,
> journal_t *journal = EXT4_SB(sb)->s_journal;
>
> if (!ext4_has_feature_journal(sb)) {
> - BUG_ON(journal != NULL);
> + WARN_ON_ONCE(journal != NULL);
Hi Jan,
If this ever happens we will hapily continue with fs operation after
mount, or remount (remount is ro, so that is probably ok ?) without
journal feature, but with s_journal set ? I am not quite sure what the
consequences might be, are you sure this is ok ?
-Lukas
> return;
> }
> jbd2_journal_lock_updates(journal);
> @@ -5271,14 +5279,15 @@ static void ext4_mark_recovery_complete(struct super_block *sb,
> * has recorded an error from a previous lifetime, move that error to the
> * main filesystem now.
> */
> -static void ext4_clear_journal_err(struct super_block *sb,
> +static int ext4_clear_journal_err(struct super_block *sb,
> struct ext4_super_block *es)
> {
> journal_t *journal;
> int j_errno;
> const char *errstr;
>
> - BUG_ON(!ext4_has_feature_journal(sb));
> + if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
> + return -EFSCORRUPTED;
>
> journal = EXT4_SB(sb)->s_journal;
>
> @@ -5303,6 +5312,7 @@ static void ext4_clear_journal_err(struct super_block *sb,
> jbd2_journal_clear_err(journal);
> jbd2_journal_update_sb_errno(journal);
> }
> + return 0;
> }
>
> /*
> @@ -5622,8 +5632,11 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
> * been changed by e2fsck since we originally mounted
> * the partition.)
> */
> - if (sbi->s_journal)
> - ext4_clear_journal_err(sb, es);
> + if (sbi->s_journal) {
> + err = ext4_clear_journal_err(sb, es);
> + if (err)
> + goto restore_opts;
> + }
> sbi->s_mount_state = le16_to_cpu(es->s_state);
>
> err = ext4_setup_super(sb, es, 0);
> --
> 2.16.4
>
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