From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Unfortunately, cgroup is tangled into kernfs infrastructure.
To avoid converting all kernfs-based filesystems at once,
we need to untangle the remount part of things, instead of
having it go through kernfs_sop_remount_fs(). Fortunately,
it's not hard to do.
This commit just gets cgroup/cgroup1 to use fs_context to
deliver options on mount and remount paths. Parsing those
is going to be done in the next commits; for now we do
pretty much what legacy case does.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
kernel/cgroup/cgroup-internal.h | 14 ++++
kernel/cgroup/cgroup-v1.c | 9 +--
kernel/cgroup/cgroup.c | 134 ++++++++++++++++++++++++++++-----------
3 files changed, 116 insertions(+), 41 deletions(-)
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index c9a35f09e4b9..a89cb0ba7a68 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -7,6 +7,7 @@
#include <linux/workqueue.h>
#include <linux/list.h>
#include <linux/refcount.h>
+#include <linux/fs_context.h>
#define TRACE_CGROUP_PATH_LEN 1024
extern spinlock_t trace_cgroup_path_lock;
@@ -36,6 +37,18 @@ extern void __init enable_debug_cgroup(void);
} \
} while (0)
+/*
+ * The cgroup filesystem superblock creation/mount context.
+ */
+struct cgroup_fs_context {
+ char *data;
+};
+
+static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
+{
+ return fc->fs_private;
+}
+
/*
* A cgroup can be associated with multiple css_sets as different tasks may
* belong to different cgroups on different hierarchies. In the other
@@ -255,5 +268,6 @@ void cgroup1_check_for_release(struct cgroup *cgrp);
struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
void *data, unsigned long magic,
struct cgroup_namespace *ns);
+int cgroup1_reconfigure(struct fs_context *ctx);
#endif /* __CGROUP_INTERNAL_H */
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index f94a7229974e..e377e19dd3e6 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -1046,17 +1046,19 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
return 0;
}
-static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
+int cgroup1_reconfigure(struct fs_context *fc)
{
- int ret = 0;
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ int ret = 0;
struct cgroup_sb_opts opts;
u16 added_mask, removed_mask;
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
/* See what subsystems are wanted */
- ret = parse_cgroupfs_options(data, &opts);
+ ret = parse_cgroupfs_options(ctx->data, &opts);
if (ret)
goto out_unlock;
@@ -1106,7 +1108,6 @@ static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
.rename = cgroup1_rename,
.show_options = cgroup1_show_options,
- .remount_fs = cgroup1_remount,
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.show_path = cgroup_show_path,
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 7fd9f22e406d..7f7db5f967e3 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1811,12 +1811,13 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root
return 0;
}
-static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+static int cgroup_reconfigure(struct fs_context *fc)
{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
unsigned int root_flags;
int ret;
- ret = parse_cgroup_root_flags(data, &root_flags);
+ ret = parse_cgroup_root_flags(ctx->data, &root_flags);
if (ret)
return ret;
@@ -2067,21 +2068,98 @@ struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
return dentry;
}
-static struct dentry *cgroup_mount(struct file_system_type *fs_type,
- int flags, const char *unused_dev_name,
- void *data)
+/*
+ * Destroy a cgroup filesystem context.
+ */
+static void cgroup_fs_context_free(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+
+ kfree(ctx);
+}
+
+static int cgroup_parse_monolithic(struct fs_context *fc, void *data)
+{
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+
+ ctx->data = data;
+ if (ctx->data)
+ security_sb_eat_lsm_opts(ctx->data, &fc->security);
+ return 0;
+}
+
+static int cgroup_get_tree(struct fs_context *fc)
{
struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
- struct dentry *dentry;
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ unsigned int root_flags;
+ struct dentry *root;
int ret;
- get_cgroup_ns(ns);
+ /* Check if the caller has permission to mount. */
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ ret = parse_cgroup_root_flags(ctx->data, &root_flags);
+ if (ret)
+ return ret;
+
+ cgrp_dfl_visible = true;
+ cgroup_get_live(&cgrp_dfl_root.cgrp);
+
+ root = cgroup_do_mount(&cgroup2_fs_type, fc->sb_flags, &cgrp_dfl_root,
+ CGROUP2_SUPER_MAGIC, ns);
+ if (IS_ERR(root))
+ return PTR_ERR(root);
+
+ apply_cgroup_root_flags(root_flags);
+ fc->root = root;
+ return 0;
+}
+
+static int cgroup1_get_tree(struct fs_context *fc)
+{
+ struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
+ struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+ struct dentry *root;
/* Check if the caller has permission to mount. */
- if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
- put_cgroup_ns(ns);
- return ERR_PTR(-EPERM);
- }
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ root = cgroup1_mount(&cgroup_fs_type, fc->sb_flags, ctx->data,
+ CGROUP_SUPER_MAGIC, ns);
+ if (IS_ERR(root))
+ return PTR_ERR(root);
+
+ fc->root = root;
+ return 0;
+}
+
+static const struct fs_context_operations cgroup_fs_context_ops = {
+ .free = cgroup_fs_context_free,
+ .parse_monolithic = cgroup_parse_monolithic,
+ .get_tree = cgroup_get_tree,
+ .reconfigure = cgroup_reconfigure,
+};
+
+static const struct fs_context_operations cgroup1_fs_context_ops = {
+ .free = cgroup_fs_context_free,
+ .parse_monolithic = cgroup_parse_monolithic,
+ .get_tree = cgroup1_get_tree,
+ .reconfigure = cgroup1_reconfigure,
+};
+
+/*
+ * Initialise the cgroup filesystem creation/reconfiguration context.
+ */
+static int cgroup_init_fs_context(struct fs_context *fc)
+{
+ struct cgroup_fs_context *ctx;
+
+ ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
/*
* The first time anyone tries to mount a cgroup, enable the list
@@ -2090,29 +2168,12 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (!use_task_css_set_links)
cgroup_enable_task_cg_lists();
- if (fs_type == &cgroup2_fs_type) {
- unsigned int root_flags;
-
- ret = parse_cgroup_root_flags(data, &root_flags);
- if (ret) {
- put_cgroup_ns(ns);
- return ERR_PTR(ret);
- }
-
- cgrp_dfl_visible = true;
- cgroup_get_live(&cgrp_dfl_root.cgrp);
-
- dentry = cgroup_do_mount(&cgroup2_fs_type, flags, &cgrp_dfl_root,
- CGROUP2_SUPER_MAGIC, ns);
- if (!IS_ERR(dentry))
- apply_cgroup_root_flags(root_flags);
- } else {
- dentry = cgroup1_mount(&cgroup_fs_type, flags, data,
- CGROUP_SUPER_MAGIC, ns);
- }
-
- put_cgroup_ns(ns);
- return dentry;
+ fc->fs_private = ctx;
+ if (fc->fs_type == &cgroup2_fs_type)
+ fc->ops = &cgroup_fs_context_ops;
+ else
+ fc->ops = &cgroup1_fs_context_ops;
+ return 0;
}
static void cgroup_kill_sb(struct super_block *sb)
@@ -2136,14 +2197,14 @@ static void cgroup_kill_sb(struct super_block *sb)
struct file_system_type cgroup_fs_type = {
.name = "cgroup",
- .mount = cgroup_mount,
+ .init_fs_context = cgroup_init_fs_context,
.kill_sb = cgroup_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
static struct file_system_type cgroup2_fs_type = {
.name = "cgroup2",
- .mount = cgroup_mount,
+ .init_fs_context = cgroup_init_fs_context,
.kill_sb = cgroup_kill_sb,
.fs_flags = FS_USERNS_MOUNT,
};
@@ -5268,7 +5329,6 @@ int cgroup_rmdir(struct kernfs_node *kn)
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
.show_options = cgroup_show_options,
- .remount_fs = cgroup_remount,
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.show_path = cgroup_show_path,
