In some parts of the kernel (e.g. planned configfs integration into usb
gadget) there is a need to programmatically create config groups
(directories) but it would be preferable to disallow creating them by
the user. This is more or less what default_groups used to be for.
But e.g. in the mass storage gadget, after storing the number of
luns (logical units) into some configfs attribute, the corresponding lun#
directories should be created, their number is not known up front so
default_groups are no good for this.
Example:
$ echo 3 > /cfg/..../mass_storage/luns
causes
/cfg/....../mass_storage/lun0
/cfg/....../mass_storage/lun1
/cfg/....../mass_storage/lun2
to be created. Yet
$ mkdir /cfg/..../mass_storage/<any name>
should not be allowed.
With create_group exported it is very easily achieved: make_group and make_item
are set to NULL in mass_storage's config_group, yet the kernel can
create_groups at will.
I kindly ask for comments. In particular, I would like to discuss
if this is the right approach. A counterpart to remove config groups
is also required. It is not implemented in this patch, though. What are
your opinions?
Andrzej Pietrasiewicz (1):
fs: configfs: allow other kernel parts to programmatically create
config groups
fs/configfs/dir.c | 5 +++--
include/linux/configfs.h | 2 ++
2 files changed, 5 insertions(+), 2 deletions(-)
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