Hi!
Is all ok with this one, or I should send v3? :)
With regards,
Pavel Skripkin
On Fri, 30 Apr 2021 21:50:46 +0300
Pavel Skripkin <paskripkin@xxxxxxxxx> wrote:
> static int kthread(void *_create) will return -ENOMEM
> or -EINTR in case of internal failure or
> kthread_stop() call happens before threadfn call.
>
> To prevent fancy error checking and make code
> more straightforward we moved all cleanup code out
> of kmmpd threadfn.
>
> Also, dropped struct mmpd_data at all. Now struct super_block
> is a threadfn data and struct buffer_head embedded into
> struct ext4_sb_info.
>
> Reported-by: syzbot+d9e482e303930fa4f6ff@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
> ---
> fs/ext4/ext4.h | 4 ++++
> fs/ext4/mmp.c | 28 +++++++++++++---------------
> fs/ext4/super.c | 10 ++++------
> 3 files changed, 21 insertions(+), 21 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 826a56e3bbd2..62210cbea84b 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1490,6 +1490,7 @@ struct ext4_sb_info {
> struct kobject s_kobj;
> struct completion s_kobj_unregister;
> struct super_block *s_sb;
> + struct buffer_head *s_mmp_bh;
>
> /* Journaling */
> struct journal_s *s_journal;
> @@ -3663,6 +3664,9 @@ extern struct ext4_io_end_vec
> *ext4_last_io_end_vec(ext4_io_end_t *io_end); /* mmp.c */
> extern int ext4_multi_mount_protect(struct super_block *,
> ext4_fsblk_t);
> +/* mmp.c */
> +extern void ext4_stop_mmpd(struct ext4_sb_info *sbi);
> +
> /* verity.c */
> extern const struct fsverity_operations ext4_verityops;
>
> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
> index 795c3ff2907c..623bad399612 100644
> --- a/fs/ext4/mmp.c
> +++ b/fs/ext4/mmp.c
> @@ -127,9 +127,9 @@ void __dump_mmp_msg(struct super_block *sb,
> struct mmp_struct *mmp, */
> static int kmmpd(void *data)
> {
> - struct super_block *sb = ((struct mmpd_data *) data)->sb;
> - struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
> + struct super_block *sb = (struct super_block *) data;
> struct ext4_super_block *es = EXT4_SB(sb)->s_es;
> + struct buffer_head *bh = EXT4_SB(sb)->s_mmp_bh;
> struct mmp_struct *mmp;
> ext4_fsblk_t mmp_block;
> u32 seq = 0;
> @@ -245,12 +245,18 @@ static int kmmpd(void *data)
> retval = write_mmp_block(sb, bh);
>
> exit_thread:
> - EXT4_SB(sb)->s_mmp_tsk = NULL;
> - kfree(data);
> - brelse(bh);
> return retval;
> }
>
> +void ext4_stop_mmpd(struct ext4_sb_info *sbi)
> +{
> + if (sbi->s_mmp_tsk) {
> + kthread_stop(sbi->s_mmp_tsk);
> + brelse(sbi->s_mmp_bh);
> + sbi->s_mmp_tsk = NULL;
> + }
> +}
> +
> /*
> * Get a random new sequence number but make sure it is not greater
> than
> * EXT4_MMP_SEQ_MAX.
> @@ -275,7 +281,6 @@ int ext4_multi_mount_protect(struct super_block
> *sb, struct ext4_super_block *es = EXT4_SB(sb)->s_es;
> struct buffer_head *bh = NULL;
> struct mmp_struct *mmp = NULL;
> - struct mmpd_data *mmpd_data;
> u32 seq;
> unsigned int mmp_check_interval =
> le16_to_cpu(es->s_mmp_update_interval); unsigned int wait_time = 0;
> @@ -364,24 +369,17 @@ int ext4_multi_mount_protect(struct super_block
> *sb, goto failed;
> }
>
> - mmpd_data = kmalloc(sizeof(*mmpd_data), GFP_KERNEL);
> - if (!mmpd_data) {
> - ext4_warning(sb, "not enough memory for mmpd_data");
> - goto failed;
> - }
> - mmpd_data->sb = sb;
> - mmpd_data->bh = bh;
> + EXT4_SB(sb)->s_mmp_bh = bh;
>
> /*
> * Start a kernel thread to update the MMP block
> periodically. */
> - EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data,
> "kmmpd-%.*s",
> + EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, sb, "kmmpd-%.*s",
> (int)sizeof(mmp->mmp_bdevname),
> bdevname(bh->b_bdev,
> mmp->mmp_bdevname));
> if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
> EXT4_SB(sb)->s_mmp_tsk = NULL;
> - kfree(mmpd_data);
> ext4_warning(sb, "Unable to create kmmpd thread for
> %s.", sb->s_id);
> goto failed;
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index b9693680463a..539f89c5431f 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1244,8 +1244,8 @@ static void ext4_put_super(struct super_block
> *sb) ext4_xattr_destroy_cache(sbi->s_ea_block_cache);
> sbi->s_ea_block_cache = NULL;
>
> - if (sbi->s_mmp_tsk)
> - kthread_stop(sbi->s_mmp_tsk);
> + ext4_stop_mmpd(sbi);
> +
> brelse(sbi->s_sbh);
> sb->s_fs_info = NULL;
> /*
> @@ -5156,8 +5156,7 @@ static int ext4_fill_super(struct super_block
> *sb, void *data, int silent) failed_mount3:
> flush_work(&sbi->s_error_work);
> del_timer_sync(&sbi->s_err_report);
> - if (sbi->s_mmp_tsk)
> - kthread_stop(sbi->s_mmp_tsk);
> + ext4_stop_mmpd(sbi);
> failed_mount2:
> rcu_read_lock();
> group_desc = rcu_dereference(sbi->s_group_desc);
> @@ -5952,8 +5951,7 @@ static int ext4_remount(struct super_block *sb,
> int *flags, char *data) */
> ext4_mark_recovery_complete(sb, es);
> }
> - if (sbi->s_mmp_tsk)
> - kthread_stop(sbi->s_mmp_tsk);
> + ext4_stop_mmpd(sbi);
> } else {
> /* Make sure we can mount this feature set
> readwrite */ if (ext4_has_feature_readonly(sb) ||
