From 90129625d9203a917fc1d3e4768976ba90d71b44 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 5 Jan 2019 00:38:03 -0500 Subject: cgroup: start switching to fs_context 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 --- kernel/cgroup/cgroup-internal.h | 14 +++++ kernel/cgroup/cgroup-v1.c | 9 +-- kernel/cgroup/cgroup.c | 134 +++++++++++++++++++++++++++++----------- 3 files changed, 116 insertions(+), 41 deletions(-) (limited to 'kernel/cgroup') 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 #include #include +#include #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, -- cgit