Re: PATCH for 2.4.3 - tinny mount code cleanup (kernel 0.97

[Martin Dalecki]

[e-mail] wrote:
> 
>     From: Martin Dalecki <[e-mail]>
> 
>     The attached patch is fixing georgeous "backward compatibility"
>     in the mount system command. It is removing two useless defines in
>     the kernel headers and finally doubles the number of possible
>     flags for the mount command.
> 
>     Please apply.
> 
> You have it all backwards. Your patch halves the number of
> possible flags. The present kernel can use 32 (or 31) flags.
> 
>     @@ -1317,10 +1313,6 @@
>          struct super_block *sb;
>          int retval = 0;
> 
>     -    /* Discard magic */
>     -    if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
>     -        flags &= ~MS_MGC_MSK;
>     -
>          /* Basic sanity checks */
> 
>          if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
> 
> You see what this code does: if the top half has this old magic
> (as it has today in 100% of all Linux installations),
> then the top half is ignored.
> If the value is non-conventional, it can be used to mean something.
> 
> Maybe you did not realize that mount still puts that value there?

Oops typo in find ./ ... grep on my side  maybe?

Anyway at least the comment there is at best missleading...

> The mount we use today will be around for many years to come.
> This "discard magic" part cannot be removed within five years.
> 
> Andries
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