/*

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/pagemap.h>

#include <linux/slab.h>

#include <linux/file.h>

#include <linux/seq_file.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/parser.h>

#include <linux/statfs.h>

#include <linux/random.h>

#include <linux/sched.h>

#include <linux/exportfs.h>

MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");

MODULE_DESCRIPTION("Filesystem in Userspace");

MODULE_LICENSE("GPL");

static struct kmem_cache *fuse_inode_cachep;

struct list_head fuse_conn_list;

DEFINE_MUTEX(fuse_mutex);

static int set_global_limit(const char *val, struct kernel_param *kp);

unsigned max_user_bgreq;

module_param_call(max_user_bgreq, set_global_limit, param_get_uint,

&max_user_bgreq, 0644);

__MODULE_PARM_TYPE(max_user_bgreq, "uint");

MODULE_PARM_DESC(max_user_bgreq,

"Global limit for the maximum number of backgrounded requests an "

"unprivileged user can set");

unsigned max_user_congthresh;

module_param_call(max_user_congthresh, set_global_limit, param_get_uint,

&max_user_congthresh, 0644);

__MODULE_PARM_TYPE(max_user_congthresh, "uint");

MODULE_PARM_DESC(max_user_congthresh,

"Global limit for the maximum congestion threshold an "

"unprivileged user can set");

#define FUSE_SUPER_MAGIC 0x65735546

#define FUSE_DEFAULT_BLKSIZE 512

/** Maximum number of outstanding background requests */

#define FUSE_DEFAULT_MAX_BACKGROUND 12

/** Congestion starts at 75% of maximum */

#define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)

struct fuse_mount_data {

int fd;

unsigned rootmode;

kuid_t user_id;

kgid_t group_id;

unsigned fd_present:1;

unsigned rootmode_present:1;

unsigned user_id_present:1;

unsigned group_id_present:1;

unsigned flags;

unsigned max_read;

unsigned blksize;

};

struct fuse_forget_link *fuse_alloc_forget(void)

{

return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);

}

static struct inode *fuse_alloc_inode(struct super_block *sb)

{

struct inode *inode;

struct fuse_inode *fi;

inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);

if (!inode)

return NULL;

fi = get_fuse_inode(inode);

fi->i_time = 0;

fi->nodeid = 0;

fi->nlookup = 0;

fi->attr_version = 0;

fi->writectr = 0;

fi->orig_ino = 0;

fi->state = 0;

INIT_LIST_HEAD(&fi->write_files);

INIT_LIST_HEAD(&fi->queued_writes);

INIT_LIST_HEAD(&fi->writepages);

init_waitqueue_head(&fi->page_waitq);

fi->forget = fuse_alloc_forget();

if (!fi->forget) {

kmem_cache_free(fuse_inode_cachep, inode);

return NULL;

}

return inode;

}

static void fuse_i_callback(struct rcu_head *head)

{

struct inode *inode = container_of(head, struct inode, i_rcu);

kmem_cache_free(fuse_inode_cachep, inode);

}

static void fuse_destroy_inode(struct inode *inode)

{

struct fuse_inode *fi = get_fuse_inode(inode);

BUG_ON(!list_empty(&fi->write_files));

BUG_ON(!list_empty(&fi->queued_writes));

kfree(fi->forget);

call_rcu(&inode->i_rcu, fuse_i_callback);

}

static void fuse_evict_inode(struct inode *inode)

{

truncate_inode_pages_final(&inode->i_data);

clear_inode(inode);

if (inode->i_sb->s_flags & MS_ACTIVE) {

struct fuse_conn *fc = get_fuse_conn(inode);

struct fuse_inode *fi = get_fuse_inode(inode);

fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);

fi->forget = NULL;

}

}

static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)

{

sync_filesystem(sb);

if (*flags & MS_MANDLOCK)

return -EINVAL;

return 0;

}

/*

* ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down

* so that it will fit.

*/

static ino_t fuse_squash_ino(u64 ino64)

{

ino_t ino = (ino_t) ino64;

if (sizeof(ino_t) < sizeof(u64))

ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;

return ino;

}

void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,

u64 attr_valid)

{

struct fuse_conn *fc = get_fuse_conn(inode);

struct fuse_inode *fi = get_fuse_inode(inode);

fi->attr_version = ++fc->attr_version;

fi->i_time = attr_valid;

inode->i_ino = fuse_squash_ino(attr->ino);

inode->i_mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777);

set_nlink(inode, attr->nlink);

inode->i_uid = make_kuid(&init_user_ns, attr->uid);

inode->i_gid = make_kgid(&init_user_ns, attr->gid);

inode->i_blocks = attr->blocks;

inode->i_atime.tv_sec = attr->atime;

inode->i_atime.tv_nsec = attr->atimensec;

/* mtime from server may be stale due to local buffered write */

if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {

inode->i_mtime.tv_sec = attr->mtime;

inode->i_mtime.tv_nsec = attr->mtimensec;

inode->i_ctime.tv_sec = attr->ctime;

inode->i_ctime.tv_nsec = attr->ctimensec;

}

if (attr->blksize != 0)

inode->i_blkbits = ilog2(attr->blksize);

else

inode->i_blkbits = inode->i_sb->s_blocksize_bits;

/*

* Don't set the sticky bit in i_mode, unless we want the VFS

* to check permissions. This prevents failures due to the

* check in may_delete().

*/

fi->orig_i_mode = inode->i_mode;

if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))

inode->i_mode &= ~S_ISVTX;

fi->orig_ino = attr->ino;

}

void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,

u64 attr_valid, u64 attr_version)

{

struct fuse_conn *fc = get_fuse_conn(inode);

struct fuse_inode *fi = get_fuse_inode(inode);

bool is_wb = fc->writeback_cache;

loff_t oldsize;

struct timespec old_mtime;

spin_lock(&fc->lock);

if ((attr_version != 0 && fi->attr_version > attr_version) ||

test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {

spin_unlock(&fc->lock);

return;

}

old_mtime = inode->i_mtime;

fuse_change_attributes_common(inode, attr, attr_valid);

oldsize = inode->i_size;

/*

* In case of writeback_cache enabled, the cached writes beyond EOF

* extend local i_size without keeping userspace server in sync. So,

* attr->size coming from server can be stale. We cannot trust it.

*/

if (!is_wb || !S_ISREG(inode->i_mode))

i_size_write(inode, attr->size);

spin_unlock(&fc->lock);

if (!is_wb && S_ISREG(inode->i_mode)) {

bool inval = false;

if (oldsize != attr->size) {

truncate_pagecache(inode, attr->size);

inval = true;

} else if (fc->auto_inval_data) {

struct timespec new_mtime = {

.tv_sec = attr->mtime,

.tv_nsec = attr->mtimensec,

};

/*

* Auto inval mode also checks and invalidates if mtime

* has changed.

*/

if (!timespec_equal(&old_mtime, &new_mtime))

inval = true;

}

if (inval)

invalidate_inode_pages2(inode->i_mapping);

}

}

static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)

{

inode->i_mode = attr->mode & S_IFMT;

inode->i_size = attr->size;

inode->i_mtime.tv_sec = attr->mtime;

inode->i_mtime.tv_nsec = attr->mtimensec;

inode->i_ctime.tv_sec = attr->ctime;

inode->i_ctime.tv_nsec = attr->ctimensec;

if (S_ISREG(inode->i_mode)) {

fuse_init_common(inode);

fuse_init_file_inode(inode);

} else if (S_ISDIR(inode->i_mode))

fuse_init_dir(inode);

else if (S_ISLNK(inode->i_mode))

fuse_init_symlink(inode);

else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||

S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {

fuse_init_common(inode);

init_special_inode(inode, inode->i_mode,

new_decode_dev(attr->rdev));

} else

BUG();

}

int fuse_inode_eq(struct inode *inode, void *_nodeidp)

{

u64 nodeid = *(u64 *) _nodeidp;

if (get_node_id(inode) == nodeid)

return 1;

else

return 0;

}

static int fuse_inode_set(struct inode *inode, void *_nodeidp)

{

u64 nodeid = *(u64 *) _nodeidp;

get_fuse_inode(inode)->nodeid = nodeid;

return 0;

}

struct inode *fuse_iget(struct super_block *sb, u64 nodeid,

int generation, struct fuse_attr *attr,

u64 attr_valid, u64 attr_version)

{

struct inode *inode;

struct fuse_inode *fi;

struct fuse_conn *fc = get_fuse_conn_super(sb);

retry:

inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);

if (!inode)

return NULL;

if ((inode->i_state & I_NEW)) {

inode->i_flags |= S_NOATIME;

if (!fc->writeback_cache || !S_ISREG(attr->mode))

inode->i_flags |= S_NOCMTIME;

inode->i_generation = generation;

fuse_init_inode(inode, attr);

unlock_new_inode(inode);

} else if ((inode->i_mode ^ attr->mode) & S_IFMT) {

/* Inode has changed type, any I/O on the old should fail */

make_bad_inode(inode);

iput(inode);

goto retry;

}

fi = get_fuse_inode(inode);

spin_lock(&fc->lock);

fi->nlookup++;

spin_unlock(&fc->lock);

fuse_change_attributes(inode, attr, attr_valid, attr_version);

return inode;

}

int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,

loff_t offset, loff_t len)

{

struct inode *inode;

pgoff_t pg_start;

pgoff_t pg_end;

inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);

if (!inode)

return -ENOENT;

fuse_invalidate_attr(inode);

if (offset >= 0) {

pg_start = offset >> PAGE_CACHE_SHIFT;

if (len <= 0)

pg_end = -1;

else

pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;

invalidate_inode_pages2_range(inode->i_mapping,

pg_start, pg_end);

}

iput(inode);

return 0;

}

static void fuse_umount_begin(struct super_block *sb)

{

fuse_abort_conn(get_fuse_conn_super(sb));

}

static void fuse_send_destroy(struct fuse_conn *fc)

{

struct fuse_req *req = fc->destroy_req;

if (req && fc->conn_init) {

fc->destroy_req = NULL;

req->in.h.opcode = FUSE_DESTROY;

req->force = 1;

req->background = 0;

fuse_request_send(fc, req);

fuse_put_request(fc, req);

}

}

static void fuse_bdi_destroy(struct fuse_conn *fc)

{

if (fc->bdi_initialized)

bdi_destroy(&fc->bdi);

}

static void fuse_put_super(struct super_block *sb)

{

struct fuse_conn *fc = get_fuse_conn_super(sb);

fuse_send_destroy(fc);

fuse_abort_conn(fc);

mutex_lock(&fuse_mutex);

list_del(&fc->entry);

fuse_ctl_remove_conn(fc);

mutex_unlock(&fuse_mutex);

fuse_bdi_destroy(fc);

fuse_conn_put(fc);

}

static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)

{

stbuf->f_type = FUSE_SUPER_MAGIC;

stbuf->f_bsize = attr->bsize;

stbuf->f_frsize = attr->frsize;

stbuf->f_blocks = attr->blocks;

stbuf->f_bfree = attr->bfree;

stbuf->f_bavail = attr->bavail;

stbuf->f_files = attr->files;

stbuf->f_ffree = attr->ffree;

stbuf->f_namelen = attr->namelen;

/* fsid is left zero */

}

static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)

{

struct super_block *sb = dentry->d_sb;

struct fuse_conn *fc = get_fuse_conn_super(sb);

FUSE_ARGS(args);

struct fuse_statfs_out outarg;

int err;

if (!fuse_allow_current_process(fc)) {

buf->f_type = FUSE_SUPER_MAGIC;

return 0;

}

memset(&outarg, 0, sizeof(outarg));

args.in.numargs = 0;

args.in.h.opcode = FUSE_STATFS;

args.in.h.nodeid = get_node_id(dentry->d_inode);

args.out.numargs = 1;

args.out.args[0].size = sizeof(outarg);

args.out.args[0].value = &outarg;

err = fuse_simple_request(fc, &args);

if (!err)

convert_fuse_statfs(buf, &outarg.st);

return err;

}

enum {

OPT_FD,

OPT_ROOTMODE,

OPT_USER_ID,

OPT_GROUP_ID,

OPT_DEFAULT_PERMISSIONS,

OPT_ALLOW_OTHER,

OPT_MAX_READ,

OPT_BLKSIZE,

OPT_ERR

};

static const match_table_t tokens = {

{OPT_FD, "fd=%u"},

{OPT_ROOTMODE, "rootmode=%o"},

{OPT_USER_ID, "user_id=%u"},

{OPT_GROUP_ID, "group_id=%u"},

{OPT_DEFAULT_PERMISSIONS, "default_permissions"},

{OPT_ALLOW_OTHER, "allow_other"},

{OPT_MAX_READ, "max_read=%u"},

{OPT_BLKSIZE, "blksize=%u"},

{OPT_ERR, NULL}

};

static int fuse_match_uint(substring_t *s, unsigned int *res)

{

int err = -ENOMEM;

char *buf = match_strdup(s);

if (buf) {

err = kstrtouint(buf, 10, res);

kfree(buf);

}

return err;

}

static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)

{

char *p;

memset(d, 0, sizeof(struct fuse_mount_data));

d->max_read = ~0;

d->blksize = FUSE_DEFAULT_BLKSIZE;

while ((p = strsep(&opt, ",")) != NULL) {

int token;

int value;

unsigned uv;

substring_t args[MAX_OPT_ARGS];

if (!*p)

continue;

token = match_token(p, tokens, args);

switch (token) {

case OPT_FD:

if (match_int(&args[0], &value))

return 0;

d->fd = value;

d->fd_present = 1;

break;

case OPT_ROOTMODE:

if (match_octal(&args[0], &value))

return 0;

if (!fuse_valid_type(value))

return 0;

d->rootmode = value;

d->rootmode_present = 1;

break;

case OPT_USER_ID:

if (fuse_match_uint(&args[0], &uv))

return 0;

d->user_id = make_kuid(current_user_ns(), uv);

if (!uid_valid(d->user_id))

return 0;

d->user_id_present = 1;

break;

case OPT_GROUP_ID:

if (fuse_match_uint(&args[0], &uv))

return 0;

d->group_id = make_kgid(current_user_ns(), uv);

if (!gid_valid(d->group_id))

return 0;

d->group_id_present = 1;

break;

case OPT_DEFAULT_PERMISSIONS:

d->flags |= FUSE_DEFAULT_PERMISSIONS;

break;

case OPT_ALLOW_OTHER:

d->flags |= FUSE_ALLOW_OTHER;

break;

case OPT_MAX_READ:

if (match_int(&args[0], &value))

return 0;

d->max_read = value;

break;

case OPT_BLKSIZE:

if (!is_bdev || match_int(&args[0], &value))

return 0;

d->blksize = value;

break;

default:

return 0;

}

}

if (!d->fd_present || !d->rootmode_present ||

!d->user_id_present || !d->group_id_present)

return 0;

return 1;

}

static int fuse_show_options(struct seq_file *m, struct dentry *root)

{

struct super_block *sb = root->d_sb;

struct fuse_conn *fc = get_fuse_conn_super(sb);

seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));

seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));

if (fc->flags & FUSE_DEFAULT_PERMISSIONS)

seq_puts(m, ",default_permissions");

if (fc->flags & FUSE_ALLOW_OTHER)

seq_puts(m, ",allow_other");

if (fc->max_read != ~0)

seq_printf(m, ",max_read=%u", fc->max_read);

if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)

seq_printf(m, ",blksize=%lu", sb->s_blocksize);

return 0;

}

void fuse_conn_init(struct fuse_conn *fc)

{

memset(fc, 0, sizeof(*fc));

spin_lock_init(&fc->lock);

init_rwsem(&fc->killsb);

atomic_set(&fc->count, 1);

init_waitqueue_head(&fc->waitq);

init_waitqueue_head(&fc->blocked_waitq);

init_waitqueue_head(&fc->reserved_req_waitq);

INIT_LIST_HEAD(&fc->pending);

INIT_LIST_HEAD(&fc->processing);

INIT_LIST_HEAD(&fc->io);

INIT_LIST_HEAD(&fc->interrupts);

INIT_LIST_HEAD(&fc->bg_queue);

INIT_LIST_HEAD(&fc->entry);

fc->forget_list_tail = &fc->forget_list_head;

atomic_set(&fc->num_waiting, 0);

fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;

fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;

fc->khctr = 0;

fc->polled_files = RB_ROOT;

fc->reqctr = 0;

fc->blocked = 0;

fc->initialized = 0;

fc->attr_version = 1;

get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));

}

EXPORT_SYMBOL_GPL(fuse_conn_init);

void fuse_conn_put(struct fuse_conn *fc)

{

if (atomic_dec_and_test(&fc->count)) {

if (fc->destroy_req)

fuse_request_free(fc->destroy_req);

fc->release(fc);

}

}

EXPORT_SYMBOL_GPL(fuse_conn_put);

struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)

{

atomic_inc(&fc->count);

return fc;

}

EXPORT_SYMBOL_GPL(fuse_conn_get);

static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)

{

struct fuse_attr attr;

memset(&attr, 0, sizeof(attr));

attr.mode = mode;

attr.ino = FUSE_ROOT_ID;

attr.nlink = 1;

return fuse_iget(sb, 1, 0, &attr, 0, 0);

}

struct fuse_inode_handle {

u64 nodeid;

u32 generation;

};

static struct dentry *fuse_get_dentry(struct super_block *sb,

struct fuse_inode_handle *handle)

{

struct fuse_conn *fc = get_fuse_conn_super(sb);

struct inode *inode;

struct dentry *entry;

int err = -ESTALE;

if (handle->nodeid == 0)

goto out_err;

inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);

if (!inode) {

struct fuse_entry_out outarg;

struct qstr name;

if (!fc->export_support)

goto out_err;

name.len = 1;

name.name = ".";

err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,

&inode);

if (err && err != -ENOENT)

goto out_err;

if (err || !inode) {

err = -ESTALE;

goto out_err;

}

err = -EIO;

if (get_node_id(inode) != handle->nodeid)

goto out_iput;

}

err = -ESTALE;

if (inode->i_generation != handle->generation)

goto out_iput;

entry = d_obtain_alias(inode);

if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)

fuse_invalidate_entry_cache(entry);

return entry;

out_iput:

iput(inode);

out_err:

return ERR_PTR(err);

}

static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,

struct inode *parent)

{

int len = parent ? 6 : 3;

u64 nodeid;

u32 generation;

if (*max_len < len) {

*max_len = len;

return FILEID_INVALID;

}

nodeid = get_fuse_inode(inode)->nodeid;

generation = inode->i_generation;

fh[0] = (u32)(nodeid >> 32);

fh[1] = (u32)(nodeid & 0xffffffff);

fh[2] = generation;

if (parent) {

nodeid = get_fuse_inode(parent)->nodeid;

generation = parent->i_generation;

fh[3] = (u32)(nodeid >> 32);

fh[4] = (u32)(nodeid & 0xffffffff);

fh[5] = generation;

}

*max_len = len;

return parent ? 0x82 : 0x81;

}

static struct dentry *fuse_fh_to_dentry(struct super_block *sb,

struct fid *fid, int fh_len, int fh_type)

{

struct fuse_inode_handle handle;

if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)

return NULL;

handle.nodeid = (u64) fid->raw[0] << 32;

handle.nodeid |= (u64) fid->raw[1];

handle.generation = fid->raw[2];

return fuse_get_dentry(sb, &handle);

}

static struct dentry *fuse_fh_to_parent(struct super_block *sb,

struct fid *fid, int fh_len, int fh_type)

{

struct fuse_inode_handle parent;

if (fh_type != 0x82 || fh_len < 6)

return NULL;

parent.nodeid = (u64) fid->raw[3] << 32;

parent.nodeid |= (u64) fid->raw[4];

parent.generation = fid->raw[5];

return fuse_get_dentry(sb, &parent);

}

static struct dentry *fuse_get_parent(struct dentry *child)

{

struct inode *child_inode = child->d_inode;

struct fuse_conn *fc = get_fuse_conn(child_inode);

struct inode *inode;

struct dentry *parent;

struct fuse_entry_out outarg;

struct qstr name;

int err;

if (!fc->export_support)

return ERR_PTR(-ESTALE);

name.len = 2;

name.name = "..";

err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),

&name, &outarg, &inode);

if (err) {

if (err == -ENOENT)

return ERR_PTR(-ESTALE);

return ERR_PTR(err);

}

parent = d_obtain_alias(inode);

if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)

fuse_invalidate_entry_cache(parent);

return parent;

}

static const struct export_operations fuse_export_operations = {

.fh_to_dentry = fuse_fh_to_dentry,

.fh_to_parent = fuse_fh_to_parent,

.encode_fh = fuse_encode_fh,

.get_parent = fuse_get_parent,

};

static const struct super_operations fuse_super_operations = {

.alloc_inode = fuse_alloc_inode,

.destroy_inode = fuse_destroy_inode,

.evict_inode = fuse_evict_inode,

.write_inode = fuse_write_inode,

.drop_inode = generic_delete_inode,

.remount_fs = fuse_remount_fs,

.put_super = fuse_put_super,

.umount_begin = fuse_umount_begin,

.statfs = fuse_statfs,

.show_options = fuse_show_options,

};

static void sanitize_global_limit(unsigned *limit)

{

if (*limit == 0)

*limit = ((totalram_pages << PAGE_SHIFT) >> 13) /

sizeof(struct fuse_req);

if (*limit >= 1 << 16)

*limit = (1 << 16) - 1;

}

static int set_global_limit(const char *val, struct kernel_param *kp)

{

int rv;

rv = param_set_uint(val, kp);

if (rv)

return rv;

sanitize_global_limit((unsigned *)kp->arg);

return 0;

}

static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)

{

int cap_sys_admin = capable(CAP_SYS_ADMIN);

if (arg->minor < 13)

return;

sanitize_global_limit(&max_user_bgreq);

sanitize_global_limit(&max_user_congthresh);

if (arg->max_background) {

fc->max_background = arg->max_background;

if (!cap_sys_admin && fc->max_background > max_user_bgreq)

fc->max_background = max_user_bgreq;

}

if (arg->congestion_threshold) {

fc->congestion_threshold = arg->congestion_threshold;

if (!cap_sys_admin &&

fc->congestion_threshold > max_user_congthresh)

fc->congestion_threshold = max_user_congthresh;

}

}

static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)

{

struct fuse_init_out *arg = &req->misc.init_out;

if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)

fc->conn_error = 1;

else {

unsigned long ra_pages;

process_init_limits(fc, arg);

if (arg->minor >= 6) {

ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;

if (arg->flags & FUSE_ASYNC_READ)

fc->async_read = 1;

if (!(arg->flags & FUSE_POSIX_LOCKS))

fc->no_lock = 1;

if (arg->minor >= 17) {

if (!(arg->flags & FUSE_FLOCK_LOCKS))

fc->no_flock = 1;

} else {

if (!(arg->flags & FUSE_POSIX_LOCKS))

fc->no_flock = 1;

}

if (arg->flags & FUSE_ATOMIC_O_TRUNC)

fc->atomic_o_trunc = 1;

if (arg->minor >= 9) {

/* LOOKUP has dependency on proto version */

if (arg->flags & FUSE_EXPORT_SUPPORT)

fc->export_support = 1;

}

if (arg->flags & FUSE_BIG_WRITES)

fc->big_writes = 1;

if (arg->flags & FUSE_DONT_MASK)

fc->dont_mask = 1;

if (arg->flags & FUSE_AUTO_INVAL_DATA)

fc->auto_inval_data = 1;

if (arg->flags & FUSE_DO_READDIRPLUS) {

fc->do_readdirplus = 1;

if (arg->flags & FUSE_READDIRPLUS_AUTO)

fc->readdirplus_auto = 1;

}

if (arg->flags & FUSE_ASYNC_DIO)

fc->async_dio = 1;

if (arg->flags & FUSE_WRITEBACK_CACHE)

fc->writeback_cache = 1;

if (arg->time_gran && arg->time_gran <= 1000000000)

fc->sb->s_time_gran = arg->time_gran;

} else {

ra_pages = fc->max_read / PAGE_CACHE_SIZE;

fc->no_lock = 1;

fc->no_flock = 1;

}

fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);

fc->minor = arg->minor;

fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;

fc->max_write = max_t(unsigned, 4096, fc->max_write);

fc->conn_init = 1;

}

fuse_set_initialized(fc);

wake_up_all(&fc->blocked_waitq);

}

static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)

{

struct fuse_init_in *arg = &req->misc.init_in;

arg->major = FUSE_KERNEL_VERSION;

arg->minor = FUSE_KERNEL_MINOR_VERSION;

arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;

arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |

FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |

FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |

FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |

FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |

FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT;

req->in.h.opcode = FUSE_INIT;

req->in.numargs = 1;

req->in.args[0].size = sizeof(*arg);

req->in.args[0].value = arg;

req->out.numargs = 1;

/* Variable length argument used for backward compatibility

with interface version < 7.5. Rest of init_out is zeroed

by do_get_request(), so a short reply is not a problem */

req->out.argvar = 1;

req->out.args[0].size = sizeof(struct fuse_init_out);

req->out.args[0].value = &req->misc.init_out;

req->end = process_init_reply;

fuse_request_send_background(fc, req);

}

static void fuse_free_conn(struct fuse_conn *fc)

{

kfree_rcu(fc, rcu);

}

static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)

{

int err;

fc->bdi.name = "fuse";

fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;

/* fuse does it's own writeback accounting */

fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;

err = bdi_init(&fc->bdi);

if (err)

return err;

fc->bdi_initialized = 1;

if (sb->s_bdev) {

err = bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",

MAJOR(fc->dev), MINOR(fc->dev));

} else {

err = bdi_register_dev(&fc->bdi, fc->dev);

}

if (err)

return err;

/*

* For a single fuse filesystem use max 1% of dirty +

* writeback threshold.

*

* This gives about 1M of write buffer for memory maps on a

* machine with 1G and 10% dirty_ratio, which should be more

* than enough.

*

* Privileged users can raise it by writing to

*

* /sys/class/bdi/<bdi>/max_ratio

*/

bdi_set_max_ratio(&fc->bdi, 1);

return 0;

}

static int fuse_fill_super(struct super_block *sb, void *data, int silent)

{

struct fuse_conn *fc;

struct inode *root;

struct fuse_mount_data d;

struct file *file;

struct dentry *root_dentry;

struct fuse_req *init_req;

int err;

int is_bdev = sb->s_bdev != NULL;

err = -EINVAL;

if (sb->s_flags & MS_MANDLOCK)

goto err;

sb->s_flags &= ~(MS_NOSEC | MS_I_VERSION);

if (!parse_fuse_opt(data, &d, is_bdev))

goto err;

if (is_bdev) {

#ifdef CONFIG_BLOCK

err = -EINVAL;