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Subject[PATCH 19/38] vfs: Convert binderfs to fs_context
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Date
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christian Brauner <christian@brauner.io>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cc: "Arve Hjønnevåg" <arve@android.com>
cc: Todd Kjos <tkjos@android.com>
cc: Martijn Coenen <maco@android.com>
cc: Joel Fernandes <joel@joelfernandes.org>
cc: devel@driverdev.osuosl.org
---

drivers/android/binderfs.c | 173 ++++++++++++++++++++++++--------------------
1 file changed, 96 insertions(+), 77 deletions(-)

diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index e773f45d19d9..0a16ecc9594f 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -18,7 +18,8 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/mount.h>
-#include <linux/parser.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
#include <linux/radix-tree.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
@@ -48,22 +49,18 @@ static dev_t binderfs_dev;
static DEFINE_MUTEX(binderfs_minors_mutex);
static DEFINE_IDA(binderfs_minors);

-/**
- * binderfs_mount_opts - mount options for binderfs
- * @max: maximum number of allocatable binderfs binder devices
- */
-struct binderfs_mount_opts {
- int max;
-};
-
enum {
Opt_max,
- Opt_err
};

-static const match_table_t tokens = {
- { Opt_max, "max=%d" },
- { Opt_err, NULL }
+static const struct fs_parameter_spec binderfs_param_specs[] = {
+ fsparam_s32 ("max", Opt_max),
+ {}
+};
+
+static const struct fs_parameter_description binderfs_fs_parameters = {
+ .name = "binderfs",
+ .specs = binderfs_param_specs,
};

/**
@@ -75,7 +72,7 @@ static const match_table_t tokens = {
* created.
* @root_gid: gid that needs to be used when a new binder device is
* created.
- * @mount_opts: The mount options in use.
+ * @max: Maximum number of allocatable binderfs binder devices.
* @device_count: The current number of allocated binder devices.
*/
struct binderfs_info {
@@ -83,7 +80,7 @@ struct binderfs_info {
struct dentry *control_dentry;
kuid_t root_uid;
kgid_t root_gid;
- struct binderfs_mount_opts mount_opts;
+ int max;
int device_count;
};

@@ -138,7 +135,7 @@ static int binderfs_binder_device_create(struct inode *ref_inode,

/* Reserve new minor number for the new device. */
mutex_lock(&binderfs_minors_mutex);
- if (++info->device_count <= info->mount_opts.max)
+ if (++info->device_count <= info->max)
minor = ida_alloc_max(&binderfs_minors,
use_reserve ? BINDERFS_MAX_MINOR :
BINDERFS_MAX_MINOR_CAPPED,
@@ -285,46 +282,36 @@ static void binderfs_evict_inode(struct inode *inode)
}

/**
- * binderfs_parse_mount_opts - parse binderfs mount options
- * @data: options to set (can be NULL in which case defaults are used)
+ * binderfs_parse_param - parse a binderfs mount option
+ * @fc: The context to be configured
+ * @param: The parameter to apply
*/
-static int binderfs_parse_mount_opts(char *data,
- struct binderfs_mount_opts *opts)
+static int binderfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
- char *p;
- opts->max = BINDERFS_MAX_MINOR;
-
- while ((p = strsep(&data, ",")) != NULL) {
- substring_t args[MAX_OPT_ARGS];
- int token;
- int max_devices;
-
- if (!*p)
- continue;
-
- token = match_token(p, tokens, args);
- switch (token) {
- case Opt_max:
- if (match_int(&args[0], &max_devices) ||
- (max_devices < 0 ||
- (max_devices > BINDERFS_MAX_MINOR)))
- return -EINVAL;
-
- opts->max = max_devices;
- break;
- default:
- pr_err("Invalid mount options\n");
- return -EINVAL;
- }
+ struct fs_parse_result result;
+ struct binderfs_info *info = fc->s_fs_info;
+ int opt;
+
+ opt = fs_parse(fc, &binderfs_fs_parameters, param, &result);
+ if (opt < 0)
+ return opt;
+
+ switch (opt) {
+ case Opt_max:
+ info->max = result.int_32;
+ break;
}

return 0;
}

-static int binderfs_remount(struct super_block *sb, int *flags, char *data)
+static int binderfs_reconfigure(struct fs_context *fc)
{
- struct binderfs_info *info = sb->s_fs_info;
- return binderfs_parse_mount_opts(data, &info->mount_opts);
+ struct binderfs_info *info = fc->root->d_sb->s_fs_info;
+ struct binderfs_info *cfg = fc->s_fs_info;
+
+ info->max = cfg->max;
+ return 0;
}

static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
@@ -332,15 +319,14 @@ static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
struct binderfs_info *info;

info = root->d_sb->s_fs_info;
- if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
- seq_printf(seq, ",max=%d", info->mount_opts.max);
+ if (info->max <= BINDERFS_MAX_MINOR)
+ seq_printf(seq, ",max=%d", info->max);

return 0;
}

static const struct super_operations binderfs_super_ops = {
.evict_inode = binderfs_evict_inode,
- .remount_fs = binderfs_remount,
.show_options = binderfs_show_mount_opts,
.statfs = simple_statfs,
};
@@ -462,10 +448,8 @@ static const struct inode_operations binderfs_dir_inode_operations = {
.unlink = binderfs_unlink,
};

-static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
+static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
- int ret;
- struct binderfs_info *info;
struct inode *inode = NULL;

sb->s_blocksize = PAGE_SIZE;
@@ -488,24 +472,6 @@ static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_op = &binderfs_super_ops;
sb->s_time_gran = 1;

- sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
- if (!sb->s_fs_info)
- return -ENOMEM;
- info = sb->s_fs_info;
-
- info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
-
- ret = binderfs_parse_mount_opts(data, &info->mount_opts);
- if (ret)
- return ret;
-
- info->root_gid = make_kgid(sb->s_user_ns, 0);
- if (!gid_valid(info->root_gid))
- info->root_gid = GLOBAL_ROOT_GID;
- info->root_uid = make_kuid(sb->s_user_ns, 0);
- if (!uid_valid(info->root_uid))
- info->root_uid = GLOBAL_ROOT_UID;
-
inode = new_inode(sb);
if (!inode)
return -ENOMEM;
@@ -524,11 +490,63 @@ static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
return binderfs_binder_ctl_create(sb);
}

-static struct dentry *binderfs_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name,
- void *data)
+static int binderfs_get_tree(struct fs_context *fc)
+{
+ if (!ns_capable(fc->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ return vfs_get_super(fc, vfs_get_independent_super, binderfs_fill_super);
+}
+
+static void binderfs_free_fc(struct fs_context *fc)
+{
+ struct binderfs_info *info = fc->s_fs_info;
+
+ if (info) {
+ struct ipc_namespace *ipc_ns = fc->s_fs_info;
+ put_ipc_ns(ipc_ns);
+ kfree(info);
+ }
+}
+
+static const struct fs_context_operations binderfs_context_ops = {
+ .free = binderfs_free_fc,
+ .parse_param = binderfs_parse_param,
+ .get_tree = binderfs_get_tree,
+ .reconfigure = binderfs_reconfigure,
+};
+
+static int binderfs_init_fs_context(struct fs_context *fc)
{
- return mount_nodev(fs_type, flags, data, binderfs_fill_super);
+ struct binderfs_info *info;
+ struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
+ struct user_namespace *user_ns = ipc_ns->user_ns;
+
+ info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ switch (fc->purpose) {
+ case FS_CONTEXT_FOR_MOUNT:
+ put_user_ns(fc->user_ns);
+ fc->user_ns = get_user_ns(user_ns);
+ info->ipc_ns = get_ipc_ns(ipc_ns);
+
+ info->root_gid = make_kgid(user_ns, 0);
+ if (!gid_valid(info->root_gid))
+ info->root_gid = GLOBAL_ROOT_GID;
+ info->root_uid = make_kuid(user_ns, 0);
+ if (!uid_valid(info->root_uid))
+ info->root_uid = GLOBAL_ROOT_UID;
+ break;
+
+ default:
+ break;
+ }
+
+ fc->s_fs_info = info;
+ fc->ops = &binderfs_context_ops;
+ return 0;
}

static void binderfs_kill_super(struct super_block *sb)
@@ -545,7 +563,8 @@ static void binderfs_kill_super(struct super_block *sb)

static struct file_system_type binder_fs_type = {
.name = "binder",
- .mount = binderfs_mount,
+ .init_fs_context = binderfs_init_fs_context,
+ .parameters = &binderfs_fs_parameters,
.kill_sb = binderfs_kill_super,
.fs_flags = FS_USERNS_MOUNT,
};
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