[PATCH 36/43] cpuset: Use fs_context
From: David Howells <dhowells@redhat.com>
Date: 2019-02-19 16:33:34
Also in:
linux-fsdevel
Subsystem:
control group (cgroup), control group - cpuset, the rest · Maintainers:
Tejun Heo, Johannes Weiner, Michal Koutný, Waiman Long, Linus Torvalds
Make the cpuset filesystem use the filesystem context. This is potentially tricky as the cpuset fs is almost an alias for the cgroup filesystem, but with some special parameters. This can, however, be handled by setting up an appropriate cgroup filesystem and returning the root directory of that as the root dir of this one. Signed-off-by: David Howells <dhowells@redhat.com> cc: Tejun Heo <tj@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- kernel/cgroup/cpuset.c | 56 ++++++++++++++++++++++++++++++++++++------------ 1 file changed, 42 insertions(+), 14 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 479743db6c37..9758b03834ac 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c@@ -39,6 +39,7 @@ #include <linux/memory.h> #include <linux/export.h> #include <linux/mount.h> +#include <linux/fs_context.h> #include <linux/namei.h> #include <linux/pagemap.h> #include <linux/proc_fs.h>
@@ -372,25 +373,52 @@ static inline bool is_in_v2_mode(void) * users. If someone tries to mount the "cpuset" filesystem, we * silently switch it to mount "cgroup" instead */ -static struct dentry *cpuset_mount(struct file_system_type *fs_type, - int flags, const char *unused_dev_name, void *data) -{ - struct file_system_type *cgroup_fs = get_fs_type("cgroup"); - struct dentry *ret = ERR_PTR(-ENODEV); - if (cgroup_fs) { - char mountopts[] = - "cpuset,noprefix," - "release_agent=/sbin/cpuset_release_agent"; - ret = cgroup_fs->mount(cgroup_fs, flags, - unused_dev_name, mountopts); - put_filesystem(cgroup_fs); +static int cpuset_get_tree(struct fs_context *fc) +{ + struct file_system_type *cgroup_fs; + struct fs_context *new_fc; + int ret; + + cgroup_fs = get_fs_type("cgroup"); + if (!cgroup_fs) + return -ENODEV; + + new_fc = fs_context_for_mount(cgroup_fs, fc->sb_flags); + if (IS_ERR(new_fc)) { + ret = PTR_ERR(new_fc); + } else { + static const char agent_path[] = "/sbin/cpuset_release_agent"; + ret = vfs_parse_fs_string(new_fc, "cpuset", NULL, 0); + if (!ret) + ret = vfs_parse_fs_string(new_fc, "noprefix", NULL, 0); + if (!ret) + ret = vfs_parse_fs_string(new_fc, "release_agent", + agent_path, sizeof(agent_path) - 1); + if (!ret) + ret = vfs_get_tree(new_fc); + if (!ret) { /* steal the result */ + fc->root = new_fc->root; + new_fc->root = NULL; + } + put_fs_context(new_fc); } + put_filesystem(cgroup_fs); return ret; } +static const struct fs_context_operations cpuset_fs_context_ops = { + .get_tree = cpuset_get_tree, +}; + +static int cpuset_init_fs_context(struct fs_context *fc) +{ + fc->ops = &cpuset_fs_context_ops; + return 0; +} + static struct file_system_type cpuset_fs_type = { - .name = "cpuset", - .mount = cpuset_mount, + .name = "cpuset", + .init_fs_context = cpuset_init_fs_context, }; /*