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Subject[PATCH] vfs: Convert functionfs to fs_context
From
Date
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Felipe Balbi <balbi@kernel.org>
cc: Michał Nazarewicz <mina86@mina86.com>
cc: linux-usb@vger.kernel.org
---

drivers/usb/gadget/function/f_fs.c | 232 ++++++++++++++++++------------------
1 file changed, 119 insertions(+), 113 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 20413c276c61..1b8061cdf87c 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -17,6 +17,7 @@
#include <linux/blkdev.h>
#include <linux/pagemap.h>
#include <linux/export.h>
+#include <linux/fs_parser.h>
#include <linux/hid.h>
#include <linux/mm.h>
#include <linux/module.h>
@@ -1447,9 +1448,9 @@ struct ffs_sb_fill_data {
struct ffs_data *ffs_data;
};

-static int ffs_sb_fill(struct super_block *sb, void *_data, int silent)
+static int ffs_sb_fill(struct super_block *sb, struct fs_context *fc)
{
- struct ffs_sb_fill_data *data = _data;
+ struct ffs_sb_fill_data *data = fc->fs_private;
struct inode *inode;
struct ffs_data *ffs = data->ffs_data;

@@ -1482,147 +1483,152 @@ static int ffs_sb_fill(struct super_block *sb, void *_data, int silent)
return 0;
}

-static int ffs_fs_parse_opts(struct ffs_sb_fill_data *data, char *opts)
-{
- ENTER();
+enum {
+ Opt_no_disconnect,
+ Opt_rmode,
+ Opt_fmode,
+ Opt_mode,
+ Opt_uid,
+ Opt_gid,
+};

- if (!opts || !*opts)
- return 0;
+static const struct fs_parameter_spec ffs_fs_param_specs[] = {
+ fsparam_bool ("no_disconnect", Opt_no_disconnect),
+ fsparam_u32 ("rmode", Opt_rmode),
+ fsparam_u32 ("fmode", Opt_fmode),
+ fsparam_u32 ("mode", Opt_mode),
+ fsparam_u32 ("uid", Opt_uid),
+ fsparam_u32 ("gid", Opt_gid),
+ {}
+};

- for (;;) {
- unsigned long value;
- char *eq, *comma;
-
- /* Option limit */
- comma = strchr(opts, ',');
- if (comma)
- *comma = 0;
-
- /* Value limit */
- eq = strchr(opts, '=');
- if (unlikely(!eq)) {
- pr_err("'=' missing in %s\n", opts);
- return -EINVAL;
- }
- *eq = 0;
+static const struct fs_parameter_description ffs_fs_fs_parameters = {
+ .name = "kAFS",
+ .specs = ffs_fs_param_specs,
+};

- /* Parse value */
- if (kstrtoul(eq + 1, 0, &value)) {
- pr_err("%s: invalid value: %s\n", opts, eq + 1);
- return -EINVAL;
- }
+static int ffs_fs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+ struct ffs_sb_fill_data *data = fc->fs_private;
+ struct fs_parse_result result;
+ int opt;

- /* Interpret option */
- switch (eq - opts) {
- case 13:
- if (!memcmp(opts, "no_disconnect", 13))
- data->no_disconnect = !!value;
- else
- goto invalid;
- break;
- case 5:
- if (!memcmp(opts, "rmode", 5))
- data->root_mode = (value & 0555) | S_IFDIR;
- else if (!memcmp(opts, "fmode", 5))
- data->perms.mode = (value & 0666) | S_IFREG;
- else
- goto invalid;
- break;
+ ENTER();

- case 4:
- if (!memcmp(opts, "mode", 4)) {
- data->root_mode = (value & 0555) | S_IFDIR;
- data->perms.mode = (value & 0666) | S_IFREG;
- } else {
- goto invalid;
- }
- break;
+ opt = fs_parse(fc, &ffs_fs_fs_parameters, param, &result);
+ if (opt < 0)
+ return opt;

- case 3:
- if (!memcmp(opts, "uid", 3)) {
- data->perms.uid = make_kuid(current_user_ns(), value);
- if (!uid_valid(data->perms.uid)) {
- pr_err("%s: unmapped value: %lu\n", opts, value);
- return -EINVAL;
- }
- } else if (!memcmp(opts, "gid", 3)) {
- data->perms.gid = make_kgid(current_user_ns(), value);
- if (!gid_valid(data->perms.gid)) {
- pr_err("%s: unmapped value: %lu\n", opts, value);
- return -EINVAL;
- }
- } else {
- goto invalid;
- }
- break;
+ switch (opt) {
+ case Opt_no_disconnect:
+ data->no_disconnect = result.boolean;
+ break;
+ case Opt_rmode:
+ data->root_mode = (result.uint_32 & 0555) | S_IFDIR;
+ break;
+ case Opt_fmode:
+ data->perms.mode = (result.uint_32 & 0666) | S_IFREG;
+ break;
+ case Opt_mode:
+ data->root_mode = (result.uint_32 & 0555) | S_IFDIR;
+ data->perms.mode = (result.uint_32 & 0666) | S_IFREG;
+ break;

- default:
-invalid:
- pr_err("%s: invalid option\n", opts);
- return -EINVAL;
- }
+ case Opt_uid:
+ data->perms.uid = make_kuid(current_user_ns(), result.uint_32);
+ if (!uid_valid(data->perms.uid))
+ goto unmapped_value;
+ break;
+ case Opt_gid:
+ data->perms.gid = make_kgid(current_user_ns(), result.uint_32);
+ if (!gid_valid(data->perms.gid))
+ goto unmapped_value;
+ break;

- /* Next iteration */
- if (!comma)
- break;
- opts = comma + 1;
+ default:
+ return -ENOPARAM;
}

return 0;
-}

-/* "mount -t functionfs dev_name /dev/function" ends up here */
+unmapped_value:
+ return invalf(fc, "%s: unmapped value: %u", param->key, result.uint_32);
+}

-static struct dentry *
-ffs_fs_mount(struct file_system_type *t, int flags,
- const char *dev_name, void *opts)
-{
- struct ffs_sb_fill_data data = {
- .perms = {
- .mode = S_IFREG | 0600,
- .uid = GLOBAL_ROOT_UID,
- .gid = GLOBAL_ROOT_GID,
- },
- .root_mode = S_IFDIR | 0500,
- .no_disconnect = false,
- };
- struct dentry *rv;
- int ret;
+/*
+ * Set up the superblock for a mount.
+ */
+static int ffs_fs_get_tree(struct fs_context *fc)
+{
+ struct ffs_sb_fill_data *ctx = fc->fs_private;
void *ffs_dev;
struct ffs_data *ffs;

ENTER();

- ret = ffs_fs_parse_opts(&data, opts);
- if (unlikely(ret < 0))
- return ERR_PTR(ret);
+ if (!fc->source)
+ return invalf(fc, "No source specified");

- ffs = ffs_data_new(dev_name);
+ ffs = ffs_data_new(fc->source);
if (unlikely(!ffs))
- return ERR_PTR(-ENOMEM);
- ffs->file_perms = data.perms;
- ffs->no_disconnect = data.no_disconnect;
+ return -ENOMEM;
+ ffs->file_perms = ctx->perms;
+ ffs->no_disconnect = ctx->no_disconnect;

- ffs->dev_name = kstrdup(dev_name, GFP_KERNEL);
+ ffs->dev_name = kstrdup(fc->source, GFP_KERNEL);
if (unlikely(!ffs->dev_name)) {
ffs_data_put(ffs);
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
}

- ffs_dev = ffs_acquire_dev(dev_name);
+ ffs_dev = ffs_acquire_dev(ffs->dev_name);
if (IS_ERR(ffs_dev)) {
ffs_data_put(ffs);
- return ERR_CAST(ffs_dev);
+ return PTR_ERR(ffs_dev);
}
+
ffs->private_data = ffs_dev;
- data.ffs_data = ffs;
+ ctx->ffs_data = ffs;
+ return vfs_get_super(fc, vfs_get_independent_super, ffs_sb_fill);
+}
+
+static void ffs_fs_free_fc(struct fs_context *fc)
+{
+ struct ffs_sb_fill_data *ctx = fc->fs_private;
+
+ if (ctx) {
+ if (ctx->ffs_data) {
+ ffs_release_dev(ctx->ffs_data);
+ ffs_data_put(ctx->ffs_data);
+ }

- rv = mount_nodev(t, flags, &data, ffs_sb_fill);
- if (IS_ERR(rv) && data.ffs_data) {
- ffs_release_dev(data.ffs_data);
- ffs_data_put(data.ffs_data);
+ kfree(ctx);
}
- return rv;
+}
+
+static const struct fs_context_operations ffs_fs_context_ops = {
+ .free = ffs_fs_free_fc,
+ .parse_param = ffs_fs_parse_param,
+ .get_tree = ffs_fs_get_tree,
+};
+
+static int ffs_fs_init_fs_context(struct fs_context *fc)
+{
+ struct ffs_sb_fill_data *ctx;
+
+ ctx = kzalloc(sizeof(struct ffs_sb_fill_data), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->perms.mode = S_IFREG | 0600;
+ ctx->perms.uid = GLOBAL_ROOT_UID;
+ ctx->perms.gid = GLOBAL_ROOT_GID;
+ ctx->root_mode = S_IFDIR | 0500;
+ ctx->no_disconnect = false;
+
+ fc->fs_private = ctx;
+ fc->ops = &ffs_fs_context_ops;
+ return 0;
}

static void
@@ -1640,7 +1646,7 @@ ffs_fs_kill_sb(struct super_block *sb)
static struct file_system_type ffs_fs_type = {
.owner = THIS_MODULE,
.name = "functionfs",
- .mount = ffs_fs_mount,
+ .init_fs_context = ffs_fs_init_fs_context,
.kill_sb = ffs_fs_kill_sb,
};
MODULE_ALIAS_FS("functionfs");
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