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Subject[RFC PATCH 3/8] vfs: Convert tracefs to fs_context
From
Date
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

fs/tracefs/inode.c | 180 ++++++++++++++++++++++++----------------------------
1 file changed, 83 insertions(+), 97 deletions(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 7098c49f3693..7ba64f38931f 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -16,12 +16,13 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/tracefs.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
-#include <linux/parser.h>
#include <linux/magic.h>
#include <linux/slab.h>

@@ -138,73 +139,62 @@ static struct inode *tracefs_get_inode(struct super_block *sb)
return inode;
}

-struct tracefs_mount_opts {
+struct tracefs_fs_info {
kuid_t uid;
kgid_t gid;
umode_t mode;
};

enum {
- Opt_uid,
Opt_gid,
Opt_mode,
- Opt_err
+ Opt_uid,
};

-static const match_table_t tokens = {
- {Opt_uid, "uid=%u"},
- {Opt_gid, "gid=%u"},
- {Opt_mode, "mode=%o"},
- {Opt_err, NULL}
+static const struct fs_parameter_spec tracefs_param_specs[] = {
+ fsparam_u32 ("gid", Opt_gid),
+ fsparam_u32oct ("mode", Opt_mode),
+ fsparam_u32 ("uid", Opt_uid),
+ {}
};

-struct tracefs_fs_info {
- struct tracefs_mount_opts mount_opts;
+static const struct fs_parameter_description tracefs_fs_parameters = {
+ .name = "tracefs",
+ .specs = tracefs_param_specs,
};

-static int tracefs_parse_options(char *data, struct tracefs_mount_opts *opts)
+static int tracefs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
- substring_t args[MAX_OPT_ARGS];
- int option;
- int token;
+ struct tracefs_fs_info *opts = fc->s_fs_info;
+ struct fs_parse_result result;
kuid_t uid;
kgid_t gid;
- char *p;
-
- opts->mode = TRACEFS_DEFAULT_MODE;
-
- while ((p = strsep(&data, ",")) != NULL) {
- if (!*p)
- continue;
-
- token = match_token(p, tokens, args);
- switch (token) {
- case Opt_uid:
- if (match_int(&args[0], &option))
- return -EINVAL;
- uid = make_kuid(current_user_ns(), option);
- if (!uid_valid(uid))
- return -EINVAL;
- opts->uid = uid;
- break;
- case Opt_gid:
- if (match_int(&args[0], &option))
- return -EINVAL;
- gid = make_kgid(current_user_ns(), option);
- if (!gid_valid(gid))
- return -EINVAL;
- opts->gid = gid;
- break;
- case Opt_mode:
- if (match_octal(&args[0], &option))
- return -EINVAL;
- opts->mode = option & S_IALLUGO;
- break;
+ int opt;
+
+ opt = fs_parse(fc, &tracefs_fs_parameters, param, &result);
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_uid:
+ uid = make_kuid(current_user_ns(), result.uint_32);
+ if (!uid_valid(uid))
+ return invalf(fc, "Unknown uid");
+ opts->uid = uid;
+ break;
+ case Opt_gid:
+ gid = make_kgid(current_user_ns(), result.uint_32);
+ if (!gid_valid(gid))
+ return invalf(fc, "Unknown gid");
+ opts->gid = gid;
+ break;
+ case Opt_mode:
+ opts->mode = result.uint_32 & S_IALLUGO;
+ break;
/*
* We might like to report bad mount options here;
* but traditionally tracefs has ignored all mount options
*/
- }
}

return 0;
@@ -214,100 +204,96 @@ static int tracefs_apply_options(struct super_block *sb)
{
struct tracefs_fs_info *fsi = sb->s_fs_info;
struct inode *inode = sb->s_root->d_inode;
- struct tracefs_mount_opts *opts = &fsi->mount_opts;

inode->i_mode &= ~S_IALLUGO;
- inode->i_mode |= opts->mode;
+ inode->i_mode |= fsi->mode;

- inode->i_uid = opts->uid;
- inode->i_gid = opts->gid;
+ inode->i_uid = fsi->uid;
+ inode->i_gid = fsi->gid;

return 0;
}

-static int tracefs_remount(struct super_block *sb, int *flags, char *data)
+static int tracefs_reconfigure(struct fs_context *fc)
{
- int err;
- struct tracefs_fs_info *fsi = sb->s_fs_info;
+ struct super_block *sb = fc->root->d_sb;

sync_filesystem(sb);
- err = tracefs_parse_options(data, &fsi->mount_opts);
- if (err)
- goto fail;
-
- tracefs_apply_options(sb);
-
-fail:
- return err;
+ return tracefs_apply_options(sb);
}

static int tracefs_show_options(struct seq_file *m, struct dentry *root)
{
struct tracefs_fs_info *fsi = root->d_sb->s_fs_info;
- struct tracefs_mount_opts *opts = &fsi->mount_opts;

- if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+ if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
seq_printf(m, ",uid=%u",
- from_kuid_munged(&init_user_ns, opts->uid));
- if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+ from_kuid_munged(&init_user_ns, fsi->uid));
+ if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
seq_printf(m, ",gid=%u",
- from_kgid_munged(&init_user_ns, opts->gid));
- if (opts->mode != TRACEFS_DEFAULT_MODE)
- seq_printf(m, ",mode=%o", opts->mode);
+ from_kgid_munged(&init_user_ns, fsi->gid));
+ if (fsi->mode != TRACEFS_DEFAULT_MODE)
+ seq_printf(m, ",mode=%o", fsi->mode);

return 0;
}

static const struct super_operations tracefs_super_operations = {
.statfs = simple_statfs,
- .remount_fs = tracefs_remount,
.show_options = tracefs_show_options,
};

-static int trace_fill_super(struct super_block *sb, void *data, int silent)
+static int tracefs_fill_super(struct super_block *sb, struct fs_context *fc)
{
static const struct tree_descr trace_files[] = {{""}};
- struct tracefs_fs_info *fsi;
int err;

- fsi = kzalloc(sizeof(struct tracefs_fs_info), GFP_KERNEL);
- sb->s_fs_info = fsi;
- if (!fsi) {
- err = -ENOMEM;
- goto fail;
- }
-
- err = tracefs_parse_options(data, &fsi->mount_opts);
+ err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files);
if (err)
- goto fail;
-
- err = simple_fill_super(sb, TRACEFS_MAGIC, trace_files);
- if (err)
- goto fail;
+ return err;

sb->s_op = &tracefs_super_operations;
+ return tracefs_apply_options(sb);
+}

- tracefs_apply_options(sb);
-
- return 0;
+static int tracefs_get_tree(struct fs_context *fc)
+{
+ return vfs_get_super(fc, vfs_get_single_reconf_super,
+ tracefs_fill_super);
+}

-fail:
- kfree(fsi);
- sb->s_fs_info = NULL;
- return err;
+static void tracefs_free_fc(struct fs_context *fc)
+{
+ kfree(fc->s_fs_info);
}

-static struct dentry *trace_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data)
+static const struct fs_context_operations tracefs_context_ops = {
+ .free = tracefs_free_fc,
+ .parse_param = tracefs_parse_param,
+ .get_tree = tracefs_get_tree,
+ .reconfigure = tracefs_reconfigure,
+};
+
+static int tracefs_init_fs_context(struct fs_context *fc)
{
- return mount_single(fs_type, flags, data, trace_fill_super);
+ struct tracefs_fs_info *fsi;
+
+ fsi = kzalloc(sizeof(struct tracefs_fs_info), GFP_KERNEL);
+ if (!fsi)
+ return -ENOMEM;
+
+ fsi->mode = TRACEFS_DEFAULT_MODE;
+
+ fc->s_fs_info = fsi;
+ fc->ops = &tracefs_context_ops;
+ return 0;
}

static struct file_system_type trace_fs_type = {
.owner = THIS_MODULE,
.name = "tracefs",
- .mount = trace_mount,
+ .init_fs_context = tracefs_init_fs_context,
+ .parameters = &tracefs_fs_parameters,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("tracefs");
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