[Buildroot] [PATCH 2/2] fs/f2fs: add support for creating a f2fs image

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Fri, 26 Oct 2018 22:00:16 +0200, Grzegorz Blach wrote:
> This patch makes possible to create rootfs image using f2fs filesystem.
> 
> Signed-off-by: Grzegorz Blach <grzegorz@blach.pl>

I have applied, after doing a number of changes, mainly splitting into
separate patches, as suggested by Yann E. Morin.

However, now that you have added F2FS support, it would be good if you
could add a test in our test suite for this filesystem. Look at
support/testing/tests/fs/ for the other filesystem tests that we have.
Could you add something like this ?

> +config BR2_TARGET_ROOTFS_F2FS_COLD_FILES
> +	string "extension list for cold files"

Any reason for having added this option for cold files, but not the
symmetric option for hot files ?

> +	help
> +	  Specify a file extension list in order f2fs to treat them
> +	  as cold files. The default list includes most of multimedia
> +	  file extensions such as jpg, gif, mpeg, mkv, and so on.

I've seen this after committing, but the help text of mkfs.f2fs seems
to imply that the list of extensions should be comma separated. If
that's the case, it should be mentioned in the help text, because most
Buildroot options use space-separated lists, not comma-separated ones.

> +config BR2_TARGET_ROOTFS_F2FS_OVERPROVISION
> +	int "size for overprovision area (0 for auto calculation)"

Actually 0 is not auto-calculation. 0 will not pass any -O option, and
therefore mkfs.f2fs will use its default of 5%.

Also, this option doesn't give the size, but the ratio.

I've fixed both aspects when committing.

> +	dd if=/dev/zero of=$@ bs=1 count=0 seek=$(F2FS_SIZE)

I've replaced by a truncate, as suggested by Yann.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com