path: root/fs/fuse/dir.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2005  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/file.h>
#include <linux/gfp.h>
#include <linux/sched.h>
#include <linux/namei.h>

/*
 * FUSE caches dentries and attributes with separate timeout.  The
 * time in jiffies until the dentry/attributes are valid is stored in
 * dentry->d_time and fuse_inode->i_time respectively.
 */

/*
 * Calculate the time in jiffies until a dentry/attributes are valid
 */
static unsigned long time_to_jiffies(unsigned long sec, unsigned long nsec)
{
	struct timespec ts = {sec, nsec};
	return jiffies + timespec_to_jiffies(&ts);
}

/*
 * Set dentry and possibly attribute timeouts from the lookup/mk*
 * replies
 */
static void fuse_change_timeout(struct dentry *entry, struct fuse_entry_out *o)
{
	entry->d_time = time_to_jiffies(o->entry_valid, o->entry_valid_nsec);
	if (entry->d_inode)
		get_fuse_inode(entry->d_inode)->i_time =
			time_to_jiffies(o->attr_valid, o->attr_valid_nsec);
}

/*
 * Mark the attributes as stale, so that at the next call to
 * ->getattr() they will be fetched from userspace
 */
void fuse_invalidate_attr(struct inode *inode)
{
	get_fuse_inode(inode)->i_time = jiffies - 1;
}

/*
 * Just mark the entry as stale, so that a next attempt to look it up
 * will result in a new lookup call to userspace
 *
 * This is called when a dentry is about to become negative and the
 * timeout is unknown (unlink, rmdir, rename and in some cases
 * lookup)
 */
static void fuse_invalidate_entry_cache(struct dentry *entry)
{
	entry->d_time = jiffies - 1;
}

/*
 * Same as fuse_invalidate_entry_cache(), but also try to remove the
 * dentry from the hash
 */
static void fuse_invalidate_entry(struct dentry *entry)
{
	d_invalidate(entry);
	fuse_invalidate_entry_cache(entry);
}

static void fuse_lookup_init(struct fuse_req *req, struct inode *dir,
			     struct dentry *entry,
			     struct fuse_entry_out *outarg)
{
	req->in.h.opcode = FUSE_LOOKUP;
	req->in.h.nodeid = get_node_id(dir);
	req->inode = dir;
	req->in.numargs = 1;
	req->in.args[0].size = entry->d_name.len + 1;
	req->in.args[0].value = entry->d_name.name;
	req->out.numargs = 1;
	req->out.args[0].size = sizeof(struct fuse_entry_out);
	req->out.args[0].value = outarg;
}

/*
 * Check whether the dentry is still valid
 *
 * If the entry validity timeout has expired and the dentry is
 * positive, try to redo the lookup.  If the lookup results in a
 * different inode, then let the VFS invalidate the dentry and redo
 * the lookup once more.  If the lookup results in the same inode,
 * then refresh the attributes, timeouts and mark the dentry valid.
 */
static int fuse_dentry_revalidate(struct dentry *entry, struct nameidata *nd)
{
	struct inode *inode = entry->d_inode;

	if (inode && is_bad_inode(inode))
		return 0;
	else if (time_after(jiffies, entry->d_time)) {
		int err;
		struct fuse_entry_out outarg;
		struct fuse_conn *fc;
		struct fuse_req *req;

		/* Doesn't hurt to "reset" the validity timeout */
		fuse_invalidate_entry_cache(entry);

		/* For negative dentries, always do a fresh lookup */
		if (!inode)
			return 0;

		fc = get_fuse_conn(inode);
		req = fuse_get_req(fc);
		if (IS_ERR(req))
			return 0;

		fuse_lookup_init(req, entry->d_parent->d_inode, entry, &outarg);
		request_send(fc, req);
		err = req->out.h.error;
		/* Zero nodeid is same as -ENOENT */
		if (!err && !outarg.nodeid)
			err = -ENOENT;
		if (!err) {
			struct fuse_inode *fi = get_fuse_inode(inode);
			if (outarg.nodeid != get_node_id(inode)) {
				fuse_send_forget(fc, req, outarg.nodeid, 1);
				return 0;
			}
			fi->nlookup ++;
		}
		fuse_put_request(fc, req);
		if (err || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
			return 0;

		fuse_change_attributes(inode, &outarg.attr);
		fuse_change_timeout(entry, &outarg);
	}
	return 1;
}

/*
 * Check if there's already a hashed alias of this directory inode.
 * If yes, then lookup and mkdir must not create a new alias.
 */
static int dir_alias(struct inode *inode)
{
	if (S_ISDIR(inode->i_mode)) {
		struct dentry *alias = d_find_alias(inode);
		if (alias) {
			dput(alias);
			return 1;
		}
	}
	return 0;
}

static int invalid_nodeid(u64 nodeid)
{
	return !nodeid || nodeid == FUSE_ROOT_ID;
}

static struct dentry_operations fuse_dentry_operations = {
	.d_revalidate	= fuse_dentry_revalidate,
};

static int valid_mode(int m)
{
	return S_ISREG(m) || S_ISDIR(m) || S_ISLNK(m) || S_ISCHR(m) ||
		S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m);
}

static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
				  struct nameidata *nd)
{
	int err;
	struct fuse_entry_out outarg;
	struct inode *inode = NULL;
	struct fuse_conn *fc = get_fuse_conn(dir);
	struct fuse_req *req;

	if (entry->d_name.len > FUSE_NAME_MAX)
		return ERR_PTR(-ENAMETOOLONG);

	req = fuse_get_req(fc);
	if (IS_ERR(req))
		return ERR_PTR(PTR_ERR(req));

	fuse_lookup_init(req, dir, entry, &o