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Date: Mon, 20 Aug 2007 11:08:30 +0200
From: giulio fedel <giulio.fedel@andorsystems.com>
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To: David Woodhouse <dwmw2@infradead.org>
Subject: Re: jffs2 kernel dump with 2.6.22-rc7
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Cc: Josh Boyer <jwboyer@gmail.com>, linux-mtd@lists.infradead.org,
	Joakim.Tjernlund@transmode.se
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It's ok for me.

     Giulio


David Woodhouse wrote:
> On Sat, 2007-08-18 at 16:42 -0500, Josh Boyer wrote:
...
> 
> Hm, maybe. On the other hand, it does make it clear that we're violating
> the "No writes to flash without alloc_sem" held assumption. That
> assumption, when you're holding alloc_sem, means you're allowed to hold
> on to a _valid_ node while not holding the erase_completion_lock
> spinlock, although you're not allowed to hold onto an invalid one
> (because it might disappear if the eraseblock in which it resides is
> deleted). If valid nodes can become invalid, that's going to be...
> fun :)
> 
> I think I'd prefer to make the can_mark_obsolete path also hold
> alloc_sem while it's doing its thing.
> 
> Giulio, please could you verify that this patch also fixes the problem?
> 
> diff --git a/fs/jffs2/write.c b/fs/jffs2/write.c
> index bc61859..664c164 100644
> --- a/fs/jffs2/write.c
> +++ b/fs/jffs2/write.c
> @@ -566,6 +566,9 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
>  		struct jffs2_full_dirent **prev = &dir_f->dents;
>  		uint32_t nhash = full_name_hash(name, namelen);
>  
> +		/* We don't actually want to reserve any space, but we do
> +		   want to be holding the alloc_sem when we write to flash */
> +		down(&c->alloc_sem);
>  		down(&dir_f->sem);
>  
>  		while ((*prev) && (*prev)->nhash <= nhash) {
> 
>