Re: [PATCH] jffs2: safely remove obsolete dirent from the f->dents list

[David Woodhouse]

This looks a lot better than the first iteration; thank you for getting
it to this point. One last thing, I hope...
On Thu, 2018-03-29 at 20:00 +0800, Yufen Yu wrote:
> 
> --- a/fs/jffs2/jffs2_fs_i.h
> +++ b/fs/jffs2/jffs2_fs_i.h
> @@ -42,6 +42,12 @@ struct jffs2_inode_info {
> ÂÂÂÂÂÂÂÂ/* Directory entries */
> ÂÂÂÂÂÂÂÂstruct jffs2_full_dirent *dents;
> Â
> +ÂÂÂÂÂÂÂ/* Directory open refcount */
> +ÂÂÂÂÂÂÂatomic_t nr_dir_opening;
> +
> +ÂÂÂÂÂÂÂ/* obsolete dirent count in the list of 'dents' */
> +ÂÂÂÂÂÂÂunsigned int obsolete_count;
> +
> ÂÂÂÂÂÂÂÂ/* The target path if this is the inode of a symlink */
> ÂÂÂÂÂÂÂÂunsigned char *target;
> Â

You've made JFFS2_INVALID_LIMIT 64, which is reasonable enough
(although it's a bit of a weird name and possibly wants to be more
specific â invalid *what*?).

So the maximum interesting value of ->obsolete_count is 64. Which means
it might as well be a uint8_t and sit in the padding after the
'usercompr' field.

It might be useful to look at putting the mutually exclusive fields in
struct jffs2_inode_info into a union, and then we don't need the
additional space of the atomic_t either; we'll never need that *and*
the fragtree at the same time... will we?

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