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. 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
