Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755422AbZGBCaF (ORCPT ); Wed, 1 Jul 2009 22:30:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753094AbZGBC34 (ORCPT ); Wed, 1 Jul 2009 22:29:56 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:51360 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752632AbZGBC3z (ORCPT ); Wed, 1 Jul 2009 22:29:55 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 2 Jul 2009 11:28:14 +0900 From: KAMEZAWA Hiroyuki To: Paul Menage Cc: lizf@cn.fujitsu.com, balbir@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, containers@lists.linux-foundation.org Subject: Re: [PATCH 1/9] [RFC] Support named cgroups hierarchies Message-Id: <20090702112814.ddf0c280.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090702021057.14469.37548.stgit@menage.mtv.corp.google.com> References: <20090702020624.14469.47066.stgit@menage.mtv.corp.google.com> <20090702021057.14469.37548.stgit@menage.mtv.corp.google.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10443 Lines: 352 On Wed, 01 Jul 2009 19:10:58 -0700 Paul Menage wrote: > [RFC] Support named cgroups hierarchies > > To simplify referring to cgroup hierarchies in mount statements, and > to allow disambiguation in the presence of empty hierarchies and > multiply-bindable subsystems (see later patches in series) this patch > adds support for naming a new cgroup hierarchy via the "name=" mount > option > > A pre-existing hierarchy may be specified by either name or by > subsystems; a hierarchy's name cannot be changed by a remount > operation. > > Example usage: > > # To create a hierarchy called "foo" containing the "cpu" subsystem > mount -t cgroup -oname=foo,cpu cgroup /mnt/cgroup1 > > # To mount the "foo" hierarchy on a second location > mount -t cgroup -oname=foo cgroup /mnt/cgroup2 > > Open issues: > > - should the specification be via a name= option as in this patch, or > should we simply use the "device name" as passed to the mount() > system call? Using the device name is more conceptually clean and > consistent with the filesystem API; however, given that the device > name is currently ignored by cgroups, this would lead to a > user-visible behaviour change. > IMHO, name= option is good because people think device name for pseudo file system has no meanings. I think just leaving it as "no meaning" is better. > Signed-off-by: Paul Menage > > --- > > kernel/cgroup.c | 136 ++++++++++++++++++++++++++++++++++++------------------- > 1 files changed, 88 insertions(+), 48 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index ea255fe..940f28d 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -59,6 +59,8 @@ static struct cgroup_subsys *subsys[] = { > #include > }; > > +#define MAX_CGROUP_ROOT_NAMELEN 64 > + I don't like long names but....isn't this too short ? How about NAME_MAX ? > /* > * A cgroupfs_root represents the root of a cgroup hierarchy, > * and may be associated with a superblock to form an active > @@ -93,6 +95,9 @@ struct cgroupfs_root { > > /* The path to use for release notifications. */ > char release_agent_path[PATH_MAX]; > + > + /* The name for this hierarchy - may be empty */ > + char name[MAX_CGROUP_ROOT_NAMELEN]; > }; > If you don't want to make cgroupfs_root bigger, cgroupfs_root { ...... /* this must be the bottom of struct */ char name[0]; } Is a choice. BTW, reading a patch, any kind of charactors are allowed ? Thanks, -Kame > /* > @@ -828,6 +833,8 @@ static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) > seq_puts(seq, ",noprefix"); > if (strlen(root->release_agent_path)) > seq_printf(seq, ",release_agent=%s", root->release_agent_path); > + if (strlen(root->name)) > + seq_printf(seq, ",name=%s", root->name); > mutex_unlock(&cgroup_mutex); > return 0; > } > @@ -836,12 +843,15 @@ struct cgroup_sb_opts { > unsigned long subsys_bits; > unsigned long flags; > char *release_agent; > + char *name; > + /* A flag indicating that a root was created from this options block */ > + bool created_root; > }; > > /* Convert a hierarchy specifier into a bitmask of subsystems and > * flags. */ > static int parse_cgroupfs_options(char *data, > - struct cgroup_sb_opts *opts) > + struct cgroup_sb_opts *opts) > { > char *token, *o = data ?: "all"; > unsigned long mask = (unsigned long)-1; > @@ -850,9 +860,7 @@ static int parse_cgroupfs_options(char *data, > mask = ~(1UL << cpuset_subsys_id); > #endif > > - opts->subsys_bits = 0; > - opts->flags = 0; > - opts->release_agent = NULL; > + memset(opts, 0, sizeof(*opts)); > > while ((token = strsep(&o, ",")) != NULL) { > if (!*token) > @@ -872,11 +880,19 @@ static int parse_cgroupfs_options(char *data, > /* Specifying two release agents is forbidden */ > if (opts->release_agent) > return -EINVAL; > - opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL); > + opts->release_agent = > + kstrndup(token + 14, PATH_MAX, GFP_KERNEL); > if (!opts->release_agent) > return -ENOMEM; > - strncpy(opts->release_agent, token + 14, PATH_MAX - 1); > - opts->release_agent[PATH_MAX - 1] = 0; > + } else if (!strncmp(token, "name=", 5)) { > + /* Specifying two names is forbidden */ > + if (opts->name) > + return -EINVAL; > + opts->name = kstrndup(token + 5, > + MAX_CGROUP_ROOT_NAMELEN, > + GFP_KERNEL); > + if (!opts->name) > + return -ENOMEM; > } else { > struct cgroup_subsys *ss; > int i; > @@ -903,7 +919,7 @@ static int parse_cgroupfs_options(char *data, > return -EINVAL; > > /* We can't have an empty hierarchy */ > - if (!opts->subsys_bits) > + if (!opts->subsys_bits && !opts->name) > return -EINVAL; > > return 0; > @@ -931,6 +947,12 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) > goto out_unlock; > } > > + /* Don't allow name to change at remount */ > + if (opts.name && strcmp(opts.name, root->name)) { > + ret = -EINVAL; > + goto out_unlock; > + } > + > ret = rebind_subsystems(root, opts.subsys_bits); > if (ret) > goto out_unlock; > @@ -942,6 +964,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) > strcpy(root->release_agent_path, opts.release_agent); > out_unlock: > kfree(opts.release_agent); > + kfree(opts.name); > mutex_unlock(&cgroup_mutex); > mutex_unlock(&cgrp->dentry->d_inode->i_mutex); > unlock_kernel(); > @@ -963,6 +986,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) > INIT_LIST_HEAD(&cgrp->release_list); > init_rwsem(&cgrp->pids_mutex); > } > + > static void init_cgroup_root(struct cgroupfs_root *root) > { > struct cgroup *cgrp = &root->top_cgroup; > @@ -976,28 +1000,56 @@ static void init_cgroup_root(struct cgroupfs_root *root) > > static int cgroup_test_super(struct super_block *sb, void *data) > { > - struct cgroupfs_root *new = data; > + struct cgroup_sb_opts *new = data; > struct cgroupfs_root *root = sb->s_fs_info; > > - /* First check subsystems */ > - if (new->subsys_bits != root->subsys_bits) > - return 0; > + /* If we asked for a name then it must match */ > + if (new->name && strcmp(new->name, root->name)) > + return 0; > > - /* Next check flags */ > - if (new->flags != root->flags) > + /* If we asked for subsystems then they must match */ > + if (new->subsys_bits && new->subsys_bits != root->subsys_bits) > return 0; > > return 1; > } > > +static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) > +{ > + struct cgroupfs_root *root; > + > + if (!opts->subsys_bits) > + return ERR_PTR(-EINVAL); > + > + root = kzalloc(sizeof(*root), GFP_KERNEL); > + if (!root) > + return ERR_PTR(-ENOMEM); > + > + init_cgroup_root(root); > + root->subsys_bits = opts->subsys_bits; > + root->flags = opts->flags; > + if (opts->release_agent) > + strcpy(root->release_agent_path, opts->release_agent); > + if (opts->name) > + strcpy(root->name, opts->name); > + opts->created_root = true; > + return root; > +} > + > static int cgroup_set_super(struct super_block *sb, void *data) > { > int ret; > - struct cgroupfs_root *root = data; > + struct cgroup_sb_opts *opts = data; > + struct cgroupfs_root *root; > > + root = cgroup_root_from_opts(opts); > + if (IS_ERR(root)) > + return PTR_ERR(root); > ret = set_anon_super(sb, NULL); > - if (ret) > + if (ret) { > + kfree(root); > return ret; > + } > > sb->s_fs_info = root; > root->sb = sb; > @@ -1039,44 +1091,23 @@ static int cgroup_get_sb(struct file_system_type *fs_type, > struct cgroup_sb_opts opts; > int ret = 0; > struct super_block *sb; > - struct cgroupfs_root *root; > - struct list_head tmp_cg_links; > > /* First find the desired set of subsystems */ > ret = parse_cgroupfs_options(data, &opts); > - if (ret) { > - kfree(opts.release_agent); > - return ret; > - } > - > - root = kzalloc(sizeof(*root), GFP_KERNEL); > - if (!root) { > - kfree(opts.release_agent); > - return -ENOMEM; > - } > - > - init_cgroup_root(root); > - root->subsys_bits = opts.subsys_bits; > - root->flags = opts.flags; > - if (opts.release_agent) { > - strcpy(root->release_agent_path, opts.release_agent); > - kfree(opts.release_agent); > - } > + if (ret) > + goto out_err; > > - sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root); > + sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); > > if (IS_ERR(sb)) { > - kfree(root); > - return PTR_ERR(sb); > + ret = PTR_ERR(sb); > + goto out_err; > } > > - if (sb->s_fs_info != root) { > - /* Reusing an existing superblock */ > - BUG_ON(sb->s_root == NULL); > - kfree(root); > - root = NULL; > - } else { > + if (opts.created_root) { > /* New superblock */ > + struct cgroupfs_root *root = sb->s_fs_info; > + struct list_head tmp_cg_links; > struct cgroup *root_cgrp = &root->top_cgroup; > struct inode *inode; > int i; > @@ -1109,7 +1140,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type, > if (ret == -EBUSY) { > mutex_unlock(&cgroup_mutex); > mutex_unlock(&inode->i_mutex); > - goto free_cg_links; > + free_cg_links(&tmp_cg_links); > + goto drop_new_super; > } > > /* EBUSY should be the only error here */ > @@ -1146,12 +1178,17 @@ static int cgroup_get_sb(struct file_system_type *fs_type, > } > > simple_set_mnt(mnt, sb); > + kfree(opts.release_agent); > + kfree(opts.name); > return 0; > > - free_cg_links: > - free_cg_links(&tmp_cg_links); > drop_new_super: > deactivate_locked_super(sb); > + > + out_err: > + kfree(opts.release_agent); > + kfree(opts.name); > + > return ret; > } > > @@ -2923,6 +2960,9 @@ static int proc_cgroup_show(struct seq_file *m, void *v) > seq_printf(m, "%lu:", root->subsys_bits); > for_each_subsys(root, ss) > seq_printf(m, "%s%s", count++ ? "," : "", ss->name); > + if (strlen(root->name)) > + seq_printf(m, "%sname=%s", > + count ? "," : "", root->name); > seq_putc(m, ':'); > get_first_subsys(&root->top_cgroup, NULL, &subsys_id); > cgrp = task_cgroup(tsk, subsys_id); > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/