KAMEZAWA Hiroyuki wrote: > From: KAMEZAWA Hiroyuki <[email protected]> > > cgroup's subsys has "readonly" files, but default permission is always > rw-r--r--. This allows to create r--r--r-- file to subsys. > (The user can do chmod on this read-only file. But this behavior is not > different from current pseudo file systems as /proc.) > > Reason: > When I wrote tools for maintain cgroup, I can't find which file is > writable intarfece or not via cgroup file systems. (finally, I did > dirty approach.) > IMHO, showing "this file is read-only" in explicit way is useful > for user-land (tools). In other story, a file whose name sounds read-only > may have "trigger" operation and support reseting. In this case, > "writable" is informative. >
I once planed to do so. I think there's one trial issue, that some files are read-only in top-cgroup, but read-write in sub-dirs, like cpuset.cpus and cpuset.mems. But for those files, they must have a write function, so I think it's still valid to mask them as read-write even they are in top-cgroup. Unless Paul has different option towards this: Acked-by: Li Zefan <[email protected]> > > Signed-off-by: KAMEZAWA Hiroyuki <[email protected]> > --- > include/linux/cgroup.h | 2 ++ > kernel/cgroup.c | 5 ++++- > 2 files changed, 6 insertions(+), 1 deletion(-) > > Index: mmotm-2.6.29-Feb24/include/linux/cgroup.h > =================================================================== > --- mmotm-2.6.29-Feb24.orig/include/linux/cgroup.h > +++ mmotm-2.6.29-Feb24/include/linux/cgroup.h > @@ -258,6 +258,8 @@ struct cftype { > */ > char name[MAX_CFTYPE_NAME]; > int private; > + /* if not 0, mode is set to mode, otherwise 0644 */ > + int mode; > > /* > * If non-zero, defines the maximum length of string that can > Index: mmotm-2.6.29-Feb24/kernel/cgroup.c > =================================================================== > --- mmotm-2.6.29-Feb24.orig/kernel/cgroup.c > +++ mmotm-2.6.29-Feb24/kernel/cgroup.c > @@ -1767,7 +1767,10 @@ int cgroup_add_file(struct cgroup *cgrp, > BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); > dentry = lookup_one_len(name, dir, strlen(name)); > if (!IS_ERR(dentry)) { > - error = cgroup_create_file(dentry, 0644 | S_IFREG, > + int mode = 0644; > + if (cft->mode) > + mode = cft->mode; > + error = cgroup_create_file(dentry, mode | S_IFREG, > cgrp->root->sb); > if (!error) > dentry->d_fsdata = (void *)cft; > _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
