Re: [RFC/PATCH 0/1] ubi: Add ubiblock driver

Thomas Petazzoni
2012-11-21T10:00:46Z

Dear Ezequiel Garcia,

On Tue, 20 Nov 2012 19:39:38 -0300, Ezequiel Garcia wrote:

> * Read/write support
>
> Yes, this implementation supports read/write access.

While I think the original ubiblk that was read-only made sense to
allow the usage of read-only filesystems like squashfs, I am not sure a
read/write ubiblock is useful.

Using a standard block read/write filesystem on top of ubiblock is going
to cause damage to your flash. Even though UBI does wear-leveling, your
standard block read/write filesystem will think it has 512 bytes block
below him, and will do a crazy number of writes to small blocks. Even
though you have a one LEB cache, it is going to be defeated quite
strongly by the small random I/O of the read/write filesystem.

I am not sure letting people use read/write block filesystems on top of
flashes, even through UBI, is a good idea.

Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.