v4.19.13 snapshot.
diff --git a/fs/fuse/control.c b/fs/fuse/control.c
new file mode 100644
index 0000000..0b69465
--- /dev/null
+++ b/fs/fuse/control.c
@@ -0,0 +1,361 @@
+/*
+ FUSE: Filesystem in Userspace
+ Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
+
+ This program can be distributed under the terms of the GNU GPL.
+ See the file COPYING.
+*/
+
+#include "fuse_i.h"
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+#define FUSE_CTL_SUPER_MAGIC 0x65735543
+
+/*
+ * This is non-NULL when the single instance of the control filesystem
+ * exists. Protected by fuse_mutex
+ */
+static struct super_block *fuse_control_sb;
+
+static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
+{
+ struct fuse_conn *fc;
+ mutex_lock(&fuse_mutex);
+ fc = file_inode(file)->i_private;
+ if (fc)
+ fc = fuse_conn_get(fc);
+ mutex_unlock(&fuse_mutex);
+ return fc;
+}
+
+static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
+ if (fc) {
+ fuse_abort_conn(fc, true);
+ fuse_conn_put(fc);
+ }
+ return count;
+}
+
+static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ char tmp[32];
+ size_t size;
+
+ if (!*ppos) {
+ long value;
+ struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
+ if (!fc)
+ return 0;
+
+ value = atomic_read(&fc->num_waiting);
+ file->private_data = (void *)value;
+ fuse_conn_put(fc);
+ }
+ size = sprintf(tmp, "%ld\n", (long)file->private_data);
+ return simple_read_from_buffer(buf, len, ppos, tmp, size);
+}
+
+static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
+ size_t len, loff_t *ppos, unsigned val)
+{
+ char tmp[32];
+ size_t size = sprintf(tmp, "%u\n", val);
+
+ return simple_read_from_buffer(buf, len, ppos, tmp, size);
+}
+
+static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos, unsigned *val,
+ unsigned global_limit)
+{
+ unsigned long t;
+ unsigned limit = (1 << 16) - 1;
+ int err;
+
+ if (*ppos)
+ return -EINVAL;
+
+ err = kstrtoul_from_user(buf, count, 0, &t);
+ if (err)
+ return err;
+
+ if (!capable(CAP_SYS_ADMIN))
+ limit = min(limit, global_limit);
+
+ if (t > limit)
+ return -EINVAL;
+
+ *val = t;
+
+ return count;
+}
+
+static ssize_t fuse_conn_max_background_read(struct file *file,
+ char __user *buf, size_t len,
+ loff_t *ppos)
+{
+ struct fuse_conn *fc;
+ unsigned val;
+
+ fc = fuse_ctl_file_conn_get(file);
+ if (!fc)
+ return 0;
+
+ val = fc->max_background;
+ fuse_conn_put(fc);
+
+ return fuse_conn_limit_read(file, buf, len, ppos, val);
+}
+
+static ssize_t fuse_conn_max_background_write(struct file *file,
+ const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ unsigned uninitialized_var(val);
+ ssize_t ret;
+
+ ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
+ max_user_bgreq);
+ if (ret > 0) {
+ struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
+ if (fc) {
+ fc->max_background = val;
+ fuse_conn_put(fc);
+ }
+ }
+
+ return ret;
+}
+
+static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
+ char __user *buf, size_t len,
+ loff_t *ppos)
+{
+ struct fuse_conn *fc;
+ unsigned val;
+
+ fc = fuse_ctl_file_conn_get(file);
+ if (!fc)
+ return 0;
+
+ val = fc->congestion_threshold;
+ fuse_conn_put(fc);
+
+ return fuse_conn_limit_read(file, buf, len, ppos, val);
+}
+
+static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
+ const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ unsigned uninitialized_var(val);
+ ssize_t ret;
+
+ ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
+ max_user_congthresh);
+ if (ret > 0) {
+ struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
+ if (fc) {
+ fc->congestion_threshold = val;
+ fuse_conn_put(fc);
+ }
+ }
+
+ return ret;
+}
+
+static const struct file_operations fuse_ctl_abort_ops = {
+ .open = nonseekable_open,
+ .write = fuse_conn_abort_write,
+ .llseek = no_llseek,
+};
+
+static const struct file_operations fuse_ctl_waiting_ops = {
+ .open = nonseekable_open,
+ .read = fuse_conn_waiting_read,
+ .llseek = no_llseek,
+};
+
+static const struct file_operations fuse_conn_max_background_ops = {
+ .open = nonseekable_open,
+ .read = fuse_conn_max_background_read,
+ .write = fuse_conn_max_background_write,
+ .llseek = no_llseek,
+};
+
+static const struct file_operations fuse_conn_congestion_threshold_ops = {
+ .open = nonseekable_open,
+ .read = fuse_conn_congestion_threshold_read,
+ .write = fuse_conn_congestion_threshold_write,
+ .llseek = no_llseek,
+};
+
+static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
+ struct fuse_conn *fc,
+ const char *name,
+ int mode, int nlink,
+ const struct inode_operations *iop,
+ const struct file_operations *fop)
+{
+ struct dentry *dentry;
+ struct inode *inode;
+
+ BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
+ dentry = d_alloc_name(parent, name);
+ if (!dentry)
+ return NULL;
+
+ inode = new_inode(fuse_control_sb);
+ if (!inode) {
+ dput(dentry);
+ return NULL;
+ }
+
+ inode->i_ino = get_next_ino();
+ inode->i_mode = mode;
+ inode->i_uid = fc->user_id;
+ inode->i_gid = fc->group_id;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+ /* setting ->i_op to NULL is not allowed */
+ if (iop)
+ inode->i_op = iop;
+ inode->i_fop = fop;
+ set_nlink(inode, nlink);
+ inode->i_private = fc;
+ d_add(dentry, inode);
+
+ fc->ctl_dentry[fc->ctl_ndents++] = dentry;
+
+ return dentry;
+}
+
+/*
+ * Add a connection to the control filesystem (if it exists). Caller
+ * must hold fuse_mutex
+ */
+int fuse_ctl_add_conn(struct fuse_conn *fc)
+{
+ struct dentry *parent;
+ char name[32];
+
+ if (!fuse_control_sb)
+ return 0;
+
+ parent = fuse_control_sb->s_root;
+ inc_nlink(d_inode(parent));
+ sprintf(name, "%u", fc->dev);
+ parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
+ &simple_dir_inode_operations,
+ &simple_dir_operations);
+ if (!parent)
+ goto err;
+
+ if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
+ NULL, &fuse_ctl_waiting_ops) ||
+ !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
+ NULL, &fuse_ctl_abort_ops) ||
+ !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
+ 1, NULL, &fuse_conn_max_background_ops) ||
+ !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
+ S_IFREG | 0600, 1, NULL,
+ &fuse_conn_congestion_threshold_ops))
+ goto err;
+
+ return 0;
+
+ err:
+ fuse_ctl_remove_conn(fc);
+ return -ENOMEM;
+}
+
+/*
+ * Remove a connection from the control filesystem (if it exists).
+ * Caller must hold fuse_mutex
+ */
+void fuse_ctl_remove_conn(struct fuse_conn *fc)
+{
+ int i;
+
+ if (!fuse_control_sb)
+ return;
+
+ for (i = fc->ctl_ndents - 1; i >= 0; i--) {
+ struct dentry *dentry = fc->ctl_dentry[i];
+ d_inode(dentry)->i_private = NULL;
+ if (!i) {
+ /* Get rid of submounts: */
+ d_invalidate(dentry);
+ }
+ dput(dentry);
+ }
+ drop_nlink(d_inode(fuse_control_sb->s_root));
+}
+
+static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
+{
+ static const struct tree_descr empty_descr = {""};
+ struct fuse_conn *fc;
+ int err;
+
+ err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
+ if (err)
+ return err;
+
+ mutex_lock(&fuse_mutex);
+ BUG_ON(fuse_control_sb);
+ fuse_control_sb = sb;
+ list_for_each_entry(fc, &fuse_conn_list, entry) {
+ err = fuse_ctl_add_conn(fc);
+ if (err) {
+ fuse_control_sb = NULL;
+ mutex_unlock(&fuse_mutex);
+ return err;
+ }
+ }
+ mutex_unlock(&fuse_mutex);
+
+ return 0;
+}
+
+static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *raw_data)
+{
+ return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
+}
+
+static void fuse_ctl_kill_sb(struct super_block *sb)
+{
+ struct fuse_conn *fc;
+
+ mutex_lock(&fuse_mutex);
+ fuse_control_sb = NULL;
+ list_for_each_entry(fc, &fuse_conn_list, entry)
+ fc->ctl_ndents = 0;
+ mutex_unlock(&fuse_mutex);
+
+ kill_litter_super(sb);
+}
+
+static struct file_system_type fuse_ctl_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "fusectl",
+ .mount = fuse_ctl_mount,
+ .kill_sb = fuse_ctl_kill_sb,
+};
+MODULE_ALIAS_FS("fusectl");
+
+int __init fuse_ctl_init(void)
+{
+ return register_filesystem(&fuse_ctl_fs_type);
+}
+
+void __exit fuse_ctl_cleanup(void)
+{
+ unregister_filesystem(&fuse_ctl_fs_type);
+}