On Fri, Oct 30, 2015 at 09:43:28AM +0800, Tom Yan wrote:
> So I noticed that SSD detection does work on unpartitioned devices in
> mkfs.btrfs somehow:
> https://bugzilla.kernel.org/show_bug.cgi?id=102921
>
> Later I found out that it breaks at blkid_devno_to_wholedisk() in is_ssd():
> http://git.kernel.org/cgit/linux/kernel/git/kdave/btrfs-progs.git/tree/mkfs.c?h=v4.2.3#n1103
>
> which Elliot had shown an example with strace:
> https://lists.01.org/pipermail/linux-nvdimm/2015-September/002109.html
>
> And I think the problem occurs in the sysfs_get_devname() here:
> https://git.kernel.org/cgit/utils/util-linux/util-linux.git/tree/lib/sysfs.c?h=v2.27#n785
>
> Since sysfs_get_devname() has to call sysfs_readlink() later, which
> output a long full device path in /sys, I don't think we should call
> it directly with the buffer "diskname", which people won't expect that
> it has to be large enough to carry the path in the middle of the
> process. For example in is_sdd(), a char array of size 32 is used
> ("wholedisk").
You're right. The function sysfs_get_devname() is not too elegant as
it uses devname buffer for readlink. Fixed, the bugfix will be in
v2.27.1.
Thanks!
Karel
--
Karel Zak
http://karelzak.blogspot.com
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