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401 lines
8.9 KiB
401 lines
8.9 KiB
/* |
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FUSE: Filesystem in Userspace |
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Copyright (C) 2001-2008 Miklos Szeredi <[email protected]> |
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This program can be distributed under the terms of the GNU GPL. |
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See the file COPYING. |
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*/ |
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#include "fuse_i.h" |
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#include <linux/init.h> |
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#include <linux/module.h> |
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#include <linux/fs_context.h> |
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#define FUSE_CTL_SUPER_MAGIC 0x65735543 |
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/* |
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* This is non-NULL when the single instance of the control filesystem |
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* exists. Protected by fuse_mutex |
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*/ |
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static struct super_block *fuse_control_sb; |
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static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file) |
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{ |
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struct fuse_conn *fc; |
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mutex_lock(&fuse_mutex); |
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fc = file_inode(file)->i_private; |
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if (fc) |
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fc = fuse_conn_get(fc); |
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mutex_unlock(&fuse_mutex); |
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return fc; |
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} |
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static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file); |
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if (fc) { |
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if (fc->abort_err) |
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fc->aborted = true; |
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fuse_abort_conn(fc); |
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fuse_conn_put(fc); |
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} |
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return count; |
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} |
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static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf, |
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size_t len, loff_t *ppos) |
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{ |
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char tmp[32]; |
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size_t size; |
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if (!*ppos) { |
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long value; |
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file); |
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if (!fc) |
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return 0; |
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value = atomic_read(&fc->num_waiting); |
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file->private_data = (void *)value; |
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fuse_conn_put(fc); |
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} |
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size = sprintf(tmp, "%ld\n", (long)file->private_data); |
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return simple_read_from_buffer(buf, len, ppos, tmp, size); |
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} |
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static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf, |
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size_t len, loff_t *ppos, unsigned val) |
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{ |
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char tmp[32]; |
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size_t size = sprintf(tmp, "%u\n", val); |
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return simple_read_from_buffer(buf, len, ppos, tmp, size); |
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} |
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static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos, unsigned *val, |
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unsigned global_limit) |
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{ |
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unsigned long t; |
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unsigned limit = (1 << 16) - 1; |
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int err; |
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if (*ppos) |
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return -EINVAL; |
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err = kstrtoul_from_user(buf, count, 0, &t); |
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if (err) |
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return err; |
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if (!capable(CAP_SYS_ADMIN)) |
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limit = min(limit, global_limit); |
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if (t > limit) |
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return -EINVAL; |
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*val = t; |
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return count; |
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} |
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static ssize_t fuse_conn_max_background_read(struct file *file, |
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char __user *buf, size_t len, |
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loff_t *ppos) |
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{ |
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struct fuse_conn *fc; |
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unsigned val; |
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fc = fuse_ctl_file_conn_get(file); |
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if (!fc) |
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return 0; |
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val = READ_ONCE(fc->max_background); |
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fuse_conn_put(fc); |
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return fuse_conn_limit_read(file, buf, len, ppos, val); |
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} |
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static ssize_t fuse_conn_max_background_write(struct file *file, |
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const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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unsigned val; |
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ssize_t ret; |
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ret = fuse_conn_limit_write(file, buf, count, ppos, &val, |
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max_user_bgreq); |
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if (ret > 0) { |
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struct fuse_conn *fc = fuse_ctl_file_conn_get(file); |
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if (fc) { |
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spin_lock(&fc->bg_lock); |
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fc->max_background = val; |
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fc->blocked = fc->num_background >= fc->max_background; |
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if (!fc->blocked) |
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wake_up(&fc->blocked_waitq); |
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spin_unlock(&fc->bg_lock); |
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fuse_conn_put(fc); |
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} |
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} |
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return ret; |
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} |
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static ssize_t fuse_conn_congestion_threshold_read(struct file *file, |
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char __user *buf, size_t len, |
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loff_t *ppos) |
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{ |
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struct fuse_conn *fc; |
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unsigned val; |
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fc = fuse_ctl_file_conn_get(file); |
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if (!fc) |
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return 0; |
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val = READ_ONCE(fc->congestion_threshold); |
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fuse_conn_put(fc); |
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return fuse_conn_limit_read(file, buf, len, ppos, val); |
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} |
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static ssize_t fuse_conn_congestion_threshold_write(struct file *file, |
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const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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unsigned val; |
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struct fuse_conn *fc; |
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struct fuse_mount *fm; |
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ssize_t ret; |
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ret = fuse_conn_limit_write(file, buf, count, ppos, &val, |
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max_user_congthresh); |
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if (ret <= 0) |
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goto out; |
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fc = fuse_ctl_file_conn_get(file); |
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if (!fc) |
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goto out; |
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down_read(&fc->killsb); |
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spin_lock(&fc->bg_lock); |
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fc->congestion_threshold = val; |
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/* |
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* Get any fuse_mount belonging to this fuse_conn; s_bdi is |
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* shared between all of them |
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*/ |
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if (!list_empty(&fc->mounts)) { |
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fm = list_first_entry(&fc->mounts, struct fuse_mount, fc_entry); |
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if (fc->num_background < fc->congestion_threshold) { |
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clear_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); |
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clear_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); |
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} else { |
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set_bdi_congested(fm->sb->s_bdi, BLK_RW_SYNC); |
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set_bdi_congested(fm->sb->s_bdi, BLK_RW_ASYNC); |
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} |
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} |
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spin_unlock(&fc->bg_lock); |
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up_read(&fc->killsb); |
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fuse_conn_put(fc); |
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out: |
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return ret; |
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} |
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static const struct file_operations fuse_ctl_abort_ops = { |
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.open = nonseekable_open, |
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.write = fuse_conn_abort_write, |
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.llseek = no_llseek, |
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}; |
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static const struct file_operations fuse_ctl_waiting_ops = { |
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.open = nonseekable_open, |
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.read = fuse_conn_waiting_read, |
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.llseek = no_llseek, |
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}; |
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static const struct file_operations fuse_conn_max_background_ops = { |
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.open = nonseekable_open, |
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.read = fuse_conn_max_background_read, |
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.write = fuse_conn_max_background_write, |
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.llseek = no_llseek, |
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}; |
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static const struct file_operations fuse_conn_congestion_threshold_ops = { |
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.open = nonseekable_open, |
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.read = fuse_conn_congestion_threshold_read, |
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.write = fuse_conn_congestion_threshold_write, |
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.llseek = no_llseek, |
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}; |
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static struct dentry *fuse_ctl_add_dentry(struct dentry *parent, |
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struct fuse_conn *fc, |
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const char *name, |
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int mode, int nlink, |
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const struct inode_operations *iop, |
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const struct file_operations *fop) |
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{ |
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struct dentry *dentry; |
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struct inode *inode; |
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BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES); |
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dentry = d_alloc_name(parent, name); |
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if (!dentry) |
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return NULL; |
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inode = new_inode(fuse_control_sb); |
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if (!inode) { |
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dput(dentry); |
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return NULL; |
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} |
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inode->i_ino = get_next_ino(); |
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inode->i_mode = mode; |
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inode->i_uid = fc->user_id; |
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inode->i_gid = fc->group_id; |
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inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
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/* setting ->i_op to NULL is not allowed */ |
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if (iop) |
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inode->i_op = iop; |
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inode->i_fop = fop; |
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set_nlink(inode, nlink); |
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inode->i_private = fc; |
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d_add(dentry, inode); |
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fc->ctl_dentry[fc->ctl_ndents++] = dentry; |
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return dentry; |
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} |
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/* |
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* Add a connection to the control filesystem (if it exists). Caller |
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* must hold fuse_mutex |
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*/ |
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int fuse_ctl_add_conn(struct fuse_conn *fc) |
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{ |
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struct dentry *parent; |
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char name[32]; |
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if (!fuse_control_sb) |
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return 0; |
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parent = fuse_control_sb->s_root; |
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inc_nlink(d_inode(parent)); |
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sprintf(name, "%u", fc->dev); |
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parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2, |
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&simple_dir_inode_operations, |
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&simple_dir_operations); |
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if (!parent) |
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goto err; |
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if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1, |
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NULL, &fuse_ctl_waiting_ops) || |
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!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1, |
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NULL, &fuse_ctl_abort_ops) || |
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!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600, |
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1, NULL, &fuse_conn_max_background_ops) || |
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!fuse_ctl_add_dentry(parent, fc, "congestion_threshold", |
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S_IFREG | 0600, 1, NULL, |
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&fuse_conn_congestion_threshold_ops)) |
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goto err; |
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return 0; |
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err: |
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fuse_ctl_remove_conn(fc); |
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return -ENOMEM; |
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} |
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/* |
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* Remove a connection from the control filesystem (if it exists). |
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* Caller must hold fuse_mutex |
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*/ |
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void fuse_ctl_remove_conn(struct fuse_conn *fc) |
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{ |
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int i; |
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if (!fuse_control_sb) |
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return; |
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for (i = fc->ctl_ndents - 1; i >= 0; i--) { |
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struct dentry *dentry = fc->ctl_dentry[i]; |
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d_inode(dentry)->i_private = NULL; |
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if (!i) { |
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/* Get rid of submounts: */ |
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d_invalidate(dentry); |
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} |
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dput(dentry); |
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} |
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drop_nlink(d_inode(fuse_control_sb->s_root)); |
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} |
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static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fctx) |
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{ |
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static const struct tree_descr empty_descr = {""}; |
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struct fuse_conn *fc; |
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int err; |
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err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr); |
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if (err) |
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return err; |
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mutex_lock(&fuse_mutex); |
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BUG_ON(fuse_control_sb); |
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fuse_control_sb = sb; |
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list_for_each_entry(fc, &fuse_conn_list, entry) { |
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err = fuse_ctl_add_conn(fc); |
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if (err) { |
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fuse_control_sb = NULL; |
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mutex_unlock(&fuse_mutex); |
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return err; |
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} |
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} |
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mutex_unlock(&fuse_mutex); |
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return 0; |
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} |
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static int fuse_ctl_get_tree(struct fs_context *fc) |
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{ |
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return get_tree_single(fc, fuse_ctl_fill_super); |
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} |
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static const struct fs_context_operations fuse_ctl_context_ops = { |
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.get_tree = fuse_ctl_get_tree, |
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}; |
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static int fuse_ctl_init_fs_context(struct fs_context *fc) |
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{ |
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fc->ops = &fuse_ctl_context_ops; |
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return 0; |
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} |
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static void fuse_ctl_kill_sb(struct super_block *sb) |
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{ |
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struct fuse_conn *fc; |
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mutex_lock(&fuse_mutex); |
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fuse_control_sb = NULL; |
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list_for_each_entry(fc, &fuse_conn_list, entry) |
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fc->ctl_ndents = 0; |
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mutex_unlock(&fuse_mutex); |
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kill_litter_super(sb); |
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} |
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static struct file_system_type fuse_ctl_fs_type = { |
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.owner = THIS_MODULE, |
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.name = "fusectl", |
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.init_fs_context = fuse_ctl_init_fs_context, |
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.kill_sb = fuse_ctl_kill_sb, |
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}; |
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MODULE_ALIAS_FS("fusectl"); |
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int __init fuse_ctl_init(void) |
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{ |
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return register_filesystem(&fuse_ctl_fs_type); |
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} |
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void __exit fuse_ctl_cleanup(void) |
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{ |
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unregister_filesystem(&fuse_ctl_fs_type); |
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}
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