/*	$NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $	*/

/*-
 * Copyright (c) 2005 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
 * 2005 program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Efficient memory file system.
 *
 * tmpfs is a file system that uses virtual memory to store file data and
 * metadata efficiently. It does not follow the structure of an on-disk
 * file system because it simply does not need to. Instead, it uses
 * memory-specific data structures and algorithms to automatically
 * allocate and release resources.
 */

#include <sys/conf.h>
#include <sys/param.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/sysctl.h>

#include <vm/vm.h>
#include <vm/vm_object.h>
#include <vm/vm_param.h>

#if 0
#include <vfs/tmpfs/tmpfs.h>
#endif
#include "tmpfs.h"
#include <vfs/tmpfs/tmpfs_vnops.h>
#include <vfs/tmpfs/tmpfs_mount.h>

/*
 * Default permission for root node
 */
#define TMPFS_DEFAULT_ROOT_MODE	(S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)

MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures");

/* --------------------------------------------------------------------- */

static int	tmpfs_mount(struct mount *, char *, caddr_t, struct ucred *);
static int	tmpfs_unmount(struct mount *, int);
static int	tmpfs_root(struct mount *, struct vnode **);
static int	tmpfs_fhtovp(struct mount *, struct vnode *, struct fid *, struct vnode **);
static int	tmpfs_statfs(struct mount *, struct statfs *, struct ucred *cred);

/* --------------------------------------------------------------------- */

void
tmpfs_node_init(struct tmpfs_node *node)
{
	node->tn_blksize = PAGE_SIZE;	/* start small */
	lockinit(&node->tn_interlock, "tmpfs node interlock", 0, LK_CANRECURSE);
	node->tn_gen = karc4random();
}

void
tmpfs_node_uninit(struct tmpfs_node *node)
{
	node->tn_type = VNON;
	node->tn_vpstate = TMPFS_VNODE_DOOMED;
	lockuninit(&node->tn_interlock);
}

static int
tmpfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
{
	struct tmpfs_mount *tmp;
	struct tmpfs_node *root;
	struct tmpfs_mount_info args;
	vm_pindex_t pages;
	vm_pindex_t pages_limit;
	ino_t nodes;
	u_int64_t	maxfsize;
	int error;
	/* Size counters. */
	ino_t	nodes_max;
	off_t	size_max;
	size_t	maxfsize_max;
	size_t	size;

	/* Root node attributes. */
	uid_t	root_uid = cred->cr_uid;
	gid_t	root_gid = cred->cr_gid;
	mode_t	root_mode = (VREAD | VWRITE);

	if (mp->mnt_flag & MNT_UPDATE) {
		/* XXX: There is no support yet to update file system
		 * settings.  Should be added. */

		return EOPNOTSUPP;
	}

	/*
	 * mount info
	 */
	bzero(&args, sizeof(args));
	size_max  = 0;
	nodes_max = 0;
	maxfsize_max = 0;

	if (path) {
		if (data) {
			error = copyin(data, &args, sizeof(args));
			if (error)
				return (error);
		}
		size_max = args.ta_size_max;
		nodes_max = args.ta_nodes_max;
		maxfsize_max = args.ta_maxfsize_max;
		root_uid = args.ta_root_uid;
		root_gid = args.ta_root_gid;
		root_mode = args.ta_root_mode;
	}

	/*
	 * If mount by non-root, then verify that user has necessary
	 * permissions on the device.
	 */
	if (cred->cr_uid != 0) {
		root_mode = VREAD;
		if ((mp->mnt_flag & MNT_RDONLY) == 0)
			root_mode |= VWRITE;
	}

	pages_limit = vm_swap_max + vmstats.v_page_count / 2;

	if (size_max == 0) {
		pages = pages_limit / 2;
	} else if (size_max < PAGE_SIZE) {
		pages = 1;
	} else if (OFF_TO_IDX(size_max) > pages_limit) {
		/*
		 * do not force pages = pages_limit for this case, otherwise
		 * we might not honor tmpfs size requests from /etc/fstab
		 * during boot because they are mounted prior to swap being
		 * turned on.
		 */
		pages = OFF_TO_IDX(size_max);
	} else {
		pages = OFF_TO_IDX(size_max);
	}

	if (nodes_max == 0)
		nodes = 3 + pages * PAGE_SIZE / 1024;
	else if (nodes_max < 3)
		nodes = 3;
	else if (nodes_max > pages)
		nodes = pages;
	else
		nodes = nodes_max;

	maxfsize = 0x7FFFFFFFFFFFFFFFLLU - TMPFS_BLKSIZE;
	if (maxfsize_max != 0 && maxfsize > maxfsize_max)
		maxfsize = maxfsize_max;

	/* Allocate the tmpfs mount structure and fill it. */
	tmp = kmalloc(sizeof(*tmp), M_TMPFSMNT, M_WAITOK | M_ZERO);

	tmp->tm_mount = mp;
	tmp->tm_nodes_max = nodes;
	tmp->tm_nodes_inuse = 0;
	tmp->tm_maxfilesize = maxfsize;
	LIST_INIT(&tmp->tm_nodes_used);

	tmp->tm_pages_max = pages;
	tmp->tm_pages_used = 0;

	kmalloc_create_obj(&tmp->tm_node_zone, "tmpfs node",
			sizeof(struct tmpfs_node));
	kmalloc_create_obj(&tmp->tm_dirent_zone, "tmpfs dirent",
			sizeof(struct tmpfs_dirent));
	kmalloc_create(&tmp->tm_name_zone, "tmpfs name zone");

	kmalloc_obj_raise_limit(tmp->tm_node_zone,
				sizeof(struct tmpfs_node) * tmp->tm_nodes_max);

	tmp->tm_ino = TMPFS_ROOTINO;

	/* Allocate the root node. */
	error = tmpfs_alloc_node(tmp, VDIR, root_uid, root_gid,
				 root_mode & ALLPERMS, NULL,
				 VNOVAL, VNOVAL, &root);

	/*
	 * We are backed by swap, set snocache chflags flag so we
	 * don't trip over swapcache.
	 */
	root->tn_flags = SF_NOCACHE;

	if (error != 0 || root == NULL) {
	    kmalloc_destroy(&tmp->tm_name_zone);
	    kmalloc_destroy(&tmp->tm_dirent_zone_obj);
	    kmalloc_destroy(&tmp->tm_node_zone_obj);
	    kfree(tmp, M_TMPFSMNT);
	    return error;
	}
	KASSERT(root->tn_id == TMPFS_ROOTINO,
		("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id));

	atomic_add_int(&root->tn_links, 1);	/* keep around */
	tmp->tm_root = root;

	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_ALL_MPSAFE;
	mp->mnt_kern_flag |= MNTK_NOMSYNC;
	mp->mnt_kern_flag |= MNTK_THR_SYNC;	/* new vsyncscan semantics */
	mp->mnt_kern_flag |= MNTK_QUICKHALT;	/* no teardown needed on halt */
	mp->mnt_data = (qaddr_t)tmp;
	mp->mnt_iosize_max = MAXBSIZE;
	vfs_getnewfsid(mp);

	vfs_add_vnodeops(mp, &tmpfs_vnode_vops, &mp->mnt_vn_norm_ops);
	vfs_add_vnodeops(mp, &tmpfs_fifo_vops, &mp->mnt_vn_fifo_ops);

	copystr("tmpfs", mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &size);
	bzero(mp->mnt_stat.f_mntfromname +size, MNAMELEN - size);
	bzero(mp->mnt_stat.f_mntonname, sizeof(mp->mnt_stat.f_mntonname));
	copyinstr(path, mp->mnt_stat.f_mntonname,
		  sizeof(mp->mnt_stat.f_mntonname) -1,
		  &size);

	tmpfs_statfs(mp, &mp->mnt_stat, cred);

	return 0;
}

/* --------------------------------------------------------------------- */

/* ARGSUSED2 */
static int
tmpfs_unmount(struct mount *mp, int mntflags)
{
	int error;
	int flags = 0;
	struct tmpfs_mount *tmp;
	struct tmpfs_node *node;
	struct vnode *vp;
	int isok;

	tmp = VFS_TO_TMPFS(mp);
	TMPFS_LOCK(tmp);

	/* Handle forced unmounts. */
	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;

	/*
	 * Finalize all pending I/O.  In the case of tmpfs we want
	 * to throw all the data away so clean out the buffer cache
	 * and vm objects before calling vflush().
	 */
	LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
		/*
		 * tn_links is mnt_token protected
		 */
		atomic_add_int(&node->tn_links, 1);
		TMPFS_NODE_LOCK(node);

		while (node->tn_type == VREG && node->tn_vnode) {
			vp = node->tn_vnode;
			vhold(vp);
			TMPFS_NODE_UNLOCK(node);
			lwkt_yield();

			/*
			 * vx_get/vx_put and tmpfs_truncate may block,
			 * releasing the tmpfs mountpoint token.
			 *
			 * Make sure the lock order is correct.
			 */
			vx_get(vp);		/* held vnode */
			TMPFS_NODE_LOCK(node);
			if (node->tn_vnode == vp) {
				tmpfs_truncate(vp, 0);
				isok = 1;
			} else {
				isok = 0;
			}
			TMPFS_NODE_UNLOCK(node);
			vx_put(vp);
			vdrop(vp);
			TMPFS_NODE_LOCK(node);
			if (isok)
				break;
			/* retry */
		}

		TMPFS_NODE_UNLOCK(node);
		atomic_add_int(&node->tn_links, -1);
	}

	/*
	 * Flush all vnodes on the unmount.
	 *
	 * If we fail to flush, we cannot unmount, but all the nodes have
	 * already been truncated. Erroring out is the best we can do.
	 */
	error = vflush(mp, 0, flags);
	if (error != 0) {
		TMPFS_UNLOCK(tmp);
		return (error);
	}

	/*
	 * First pass get rid of all the directory entries and
	 * vnode associations.  This will also destroy the
	 * directory topology and should drop all link counts
	 * to 0 except for the root.
	 *
	 * No vnodes should remain after the vflush above.
	 */
	LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
		lwkt_yield();

		atomic_add_int(&node->tn_links, 1);
		TMPFS_NODE_LOCK(node);
		if (node->tn_type == VDIR) {
			struct tmpfs_dirent *de;

			while ((de = RB_ROOT(&node->tn_dir.tn_dirtree)) != NULL)			{
				tmpfs_dir_detach_locked(node, de);
				tmpfs_free_dirent(tmp, de);
			}
		}
		KKASSERT(node->tn_vnode == NULL);

		TMPFS_NODE_UNLOCK(node);
		atomic_add_int(&node->tn_links, -1);
	}

	/*
	 * Allow the root node to be destroyed by dropping the link count
	 * we bumped in the mount code.
	 */
	KKASSERT(tmp->tm_root);
	TMPFS_NODE_LOCK(tmp->tm_root);
	atomic_add_int(&tmp->tm_root->tn_links, -1);
	TMPFS_NODE_UNLOCK(tmp->tm_root);

	/*
	 * At this point all nodes, including the root node, should have a
	 * link count of 0.  The root is not necessarily going to be last.
	 */
	while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) {
		if (node->tn_links) {
			panic("tmpfs: Dangling nodes during umount (%p)!\n",
			      node);
		}

		TMPFS_NODE_LOCK(node);
		tmpfs_free_node(tmp, node);
		/* eats lock */
		lwkt_yield();
	}
	KKASSERT(tmp->tm_root == NULL);

	kmalloc_destroy(&tmp->tm_name_zone);
	kmalloc_destroy(&tmp->tm_dirent_zone_obj);
	kmalloc_destroy(&tmp->tm_node_zone_obj);

	tmp->tm_node_zone_obj = NULL;
	tmp->tm_dirent_zone_obj = NULL;

	KKASSERT(tmp->tm_pages_used == 0);
	KKASSERT(tmp->tm_nodes_inuse == 0);

	TMPFS_UNLOCK(tmp);

	/* Throw away the tmpfs_mount structure. */
	kfree(tmp, M_TMPFSMNT);
	mp->mnt_data = NULL;

	mp->mnt_flag &= ~MNT_LOCAL;
	return 0;
}

/* --------------------------------------------------------------------- */

static int
tmpfs_root(struct mount *mp, struct vnode **vpp)
{
	struct tmpfs_mount *tmp;
	int error;

	tmp = VFS_TO_TMPFS(mp);
	if (tmp->tm_root == NULL) {
		kprintf("tmpfs_root: called without root node %p\n", mp);
		print_backtrace(-1);
		*vpp = NULL;
		error = EINVAL;
	} else {
		error = tmpfs_alloc_vp(mp, NULL, tmp->tm_root,
				       LK_EXCLUSIVE, vpp);
		(*vpp)->v_flag |= VROOT;
		(*vpp)->v_type = VDIR;
	}
	return error;
}

/* --------------------------------------------------------------------- */

static int
tmpfs_fhtovp(struct mount *mp, struct vnode *rootvp, struct fid *fhp,
	     struct vnode **vpp)
{
	boolean_t found;
	struct tmpfs_fid *tfhp;
	struct tmpfs_mount *tmp;
	struct tmpfs_node *node;
	int rc;

	tmp = VFS_TO_TMPFS(mp);

	tfhp = (struct tmpfs_fid *) fhp;
	if (tfhp->tf_len != sizeof(struct tmpfs_fid))
		return EINVAL;

	rc = EINVAL;
	found = FALSE;

	TMPFS_LOCK(tmp);
	LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) {
		if (node->tn_id == tfhp->tf_id &&
		    node->tn_gen == tfhp->tf_gen) {
			found = TRUE;
			break;
		}
	}

	if (found)
		rc = tmpfs_alloc_vp(mp, NULL, node, LK_EXCLUSIVE, vpp);

	TMPFS_UNLOCK(tmp);

	return (rc);
}

/* --------------------------------------------------------------------- */

/* ARGSUSED2 */
static int
tmpfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
{
	fsfilcnt_t freenodes;
	struct tmpfs_mount *tmp;

	tmp = VFS_TO_TMPFS(mp);

	/* TMPFS_LOCK(tmp); not really needed */

	sbp->f_iosize = PAGE_SIZE;
	sbp->f_bsize = PAGE_SIZE;

	sbp->f_blocks = tmp->tm_pages_max;
	sbp->f_bavail = tmp->tm_pages_max - tmp->tm_pages_used;
	sbp->f_bfree = sbp->f_bavail;

	freenodes = tmp->tm_nodes_max - tmp->tm_nodes_inuse;

	sbp->f_files = freenodes + tmp->tm_nodes_inuse;
	sbp->f_ffree = freenodes;
	sbp->f_owner = tmp->tm_root->tn_uid;

	/* TMPFS_UNLOCK(tmp); */

	return 0;
}

/* --------------------------------------------------------------------- */

static int
tmpfs_vptofh(struct vnode *vp, struct fid *fhp)
{
	struct tmpfs_node *node;
	struct tmpfs_fid tfh;
	node = VP_TO_TMPFS_NODE(vp);
	memset(&tfh, 0, sizeof(tfh));
	tfh.tf_len = sizeof(struct tmpfs_fid);
	tfh.tf_gen = node->tn_gen;
	tfh.tf_id = node->tn_id;
	memcpy(fhp, &tfh, sizeof(tfh));
	return (0);
}

/* --------------------------------------------------------------------- */

static int
tmpfs_checkexp(struct mount *mp, struct sockaddr *nam, int *exflagsp,
	       struct ucred **credanonp)
{
	struct tmpfs_mount *tmp;
	struct netcred *nc;

	tmp = (struct tmpfs_mount *) mp->mnt_data;
	nc = vfs_export_lookup(mp, &tmp->tm_export, nam);
	if (nc == NULL)
		return (EACCES);

	*exflagsp = nc->netc_exflags;
	*credanonp = &nc->netc_anon;

	return (0);
}

/* --------------------------------------------------------------------- */

/*
 * tmpfs vfs operations.
 */

static struct vfsops tmpfs_vfsops = {
	.vfs_flags =			0,
	.vfs_mount =			tmpfs_mount,
	.vfs_unmount =			tmpfs_unmount,
	.vfs_root =			tmpfs_root,
	.vfs_statfs =			tmpfs_statfs,
	.vfs_fhtovp =			tmpfs_fhtovp,
	.vfs_vptofh =			tmpfs_vptofh, 
	.vfs_checkexp =			tmpfs_checkexp,
};

VFS_SET(tmpfs_vfsops, tmpfs, VFCF_MPSAFE);
MODULE_VERSION(tmpfs, 1);