[PATCH] ubifs: Add zstd support

[Sascha Hauer]

On Thu, Jun 23, 2022 at 12:45:21PM +0200, Uwe Kleine-König wrote:
> Hello,
> 
> On Mon, Feb 07, 2022 at 04:14:57PM +0100, Sascha Hauer wrote:
> > zstd shows a good compression rate and is faster than lzo. This adds
> > UBIFS support for it.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> 
> This patch is part of 2022.03.0 with commit cd1610d8ab30 ("ubifs: Add
> zstd support")
> 
> Since then there is a warning in my imx builds (using imx_defconfig):
> 
>   CC      fs/ubifs/super.o
> fs/ubifs/super.c: In function ‘validate_inode’:
> fs/ubifs/super.c:89:28: warning: comparison is always false due to limited range of data type [-Wtype-limits]
>    89 |         if (ui->compr_type >= UBIFS_COMPR_TYPES_CNT) {
>       |                            ^~
> 
> That's because UBIFS_COMPR_TYPES_CNT is now 4 and ui->compr_type is an
> unsigned int compr_type:2.

Same here.

> 
> I wonder if the check should just be dropped now that all bits are used,
> but I don't feel confident enough to say that's the right thing to do.

The code is the same in the Kernel, but the Kernel has -Wtype-limits
disabled.

I'd say we can remove this check. You could increase your kernel patch
count by suggesting the same there.

Sascha

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