[systemd-devel] [PATCH] readahead: ARM: fix rotational media detection for MMC

[Zbigniew Jędrzejewski-Szmek]

On Tue, May 13, 2014 at 02:14:20PM +0000, Chaiken, Alison wrote:
> I wrote:
> > The ARM runtime reports the major device type associated with
> > /proc/self/mountinfo as MMC_BLOCK_MAJOR, causing on_ssd() in
> > readahead-common.c to return false.   on_ssd() should return true, as
> > MMC like SSD is not rotational.
> 
> Lennart writes:
> > Not following here. fs_on_ssd() will actually check for the high-level
> > ID_SSD property, as well as the "queue/rotational" sysfs attribute for
> > the block device.
> 
> Those other checks are not reached, as the beginning of fs_on_ssd() has
>         if (major(st.st_dev) == 0) {}
> encapsulating them, and major(st.st_dev)=MMC_BLOCK_MAJOR, not 0.
No, those other checks are *below* the if.

What do

1. udevadm info /dev/mmcXXX | grep SSD
2. cat /sys/class/block/mmcXXX/queue/rotational

say?

Zbyszek