Hi!
> From: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
>
> [ Upstream commit 4e58543e7da4859c4ba61d15493e3522b6ad71fd ]
>
> It turns out that the .freeze_super and .thaw_super operations require
> the filesystem to manage the superblock refcount itself. We are using
> the freeze_super() and thaw_super() helpers to mostly take care of that
> for us, but this means that the superblock may no longer be around by
> when thaw_super() returns, and gfs2_thaw_super() will then access freed
> memory. Take an extra superblock reference in gfs2_thaw_super() to fix
> that.
Patch was broken during backport.
> +++ b/fs/gfs2/super.c
> @@ -1013,6 +1013,7 @@ static int gfs2_freeze(struct super_block *sb)
> goto out;
> }
>
> + atomic_inc(&sb->s_active);
> for (;;) {
> error = gfs2_lock_fs_check_clean(sdp, &sdp->sd_freeze_gh);
> if (!error)
> @@ -1034,6 +1035,7 @@ static int gfs2_freeze(struct super_block *sb)
> error = 0;
> out:
> mutex_unlock(&sdp->sd_freeze_mutex);
> + deactivate_super(sb);
> return error;
> }
Notice the goto out? That now jumps around the atomic_inc, but we
still do decrease. This will break 4.19, please fix or drop.
BR,
Pavel
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