/*      $OpenBSD: tmpfs_vfsops.c,v 1.21 2025/11/21 09:49:33 mvs Exp $   */
/*      $NetBSD: tmpfs_vfsops.c,v 1.52 2011/09/27 01:10:43 christos Exp $       */

/*
 * Copyright (c) 2005, 2006, 2007 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 NetBSD's virtual memory sub-system
 * (the well-known UVM) to store file data and metadata in an efficient
 * way.  This means that 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/param.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/malloc.h>

#include <tmpfs/tmpfs.h>

/* MODULE(MODULE_CLASS_VFS, tmpfs, NULL); */

extern uint64_t tmpfs_bytes_limit;
extern uint64_t tmpfs_bytes_used;

struct pool     tmpfs_dirent_pool;
struct pool     tmpfs_node_pool;

int     tmpfs_mount(struct mount *, const char *, void *, struct nameidata *,
            struct proc *);
int     tmpfs_start(struct mount *, int, struct proc *);
int     tmpfs_unmount(struct mount *, int, struct proc *);
int     tmpfs_root(struct mount *, struct vnode **);
int     tmpfs_vget(struct mount *, ino_t, struct vnode **);
int     tmpfs_fhtovp(struct mount *, struct fid *, struct vnode **);
int     tmpfs_vptofh(struct vnode *, struct fid *);
int     tmpfs_statfs(struct mount *, struct statfs *, struct proc *);
int     tmpfs_sync(struct mount *, int, int, struct ucred *, struct proc *);
int     tmpfs_init(struct vfsconf *);
int     tmpfs_mount_update(struct mount *);

int
tmpfs_init(struct vfsconf *vfsp)
{
        tmpfs_bytes_limit = ((uint64_t)(uvmexp.npages / 2) << PAGE_SHIFT);

        pool_init(&tmpfs_dirent_pool, sizeof(tmpfs_dirent_t), 0, IPL_NONE,
            PR_WAITOK, "tmpfs_dirent", NULL);
        pool_init(&tmpfs_node_pool, sizeof(tmpfs_node_t), 0, IPL_NONE,
            PR_WAITOK, "tmpfs_node", NULL);

        return 0;
}

int
tmpfs_mount_update(struct mount *mp)
{
        tmpfs_mount_t *tmp;
        struct vnode *rootvp;
        int error;

        if ((mp->mnt_flag & MNT_RDONLY) == 0)
                return EOPNOTSUPP;

        /* ro->rw transition: nothing to do? */
        if (mp->mnt_flag & MNT_WANTRDWR)
                return 0;

        tmp = mp->mnt_data;
        rootvp = tmp->tm_root->tn_vnode;

        /* Lock root to prevent lookups. */
        error = vn_lock(rootvp, LK_EXCLUSIVE | LK_RETRY);
        if (error)
                return error;

        /* Lock mount point to prevent nodes from being added/removed. */
        rw_enter_write(&tmp->tm_lock);

        /* Flush files opened for writing; skip rootvp. */
        error = vflush(mp, rootvp, WRITECLOSE);

        rw_exit_write(&tmp->tm_lock);
        VOP_UNLOCK(rootvp);

        return error;
}

int
tmpfs_mount(struct mount *mp, const char *path, void *data,
    struct nameidata *ndp, struct proc *p)
{
        struct tmpfs_args *args = data;
        tmpfs_mount_t *tmp;
        tmpfs_node_t *root;
        uint64_t memlimit = 0;
        uint64_t nodes;
        int error;

        if (mp->mnt_flag & MNT_UPDATE)
                return (tmpfs_mount_update(mp));

        if (args->ta_root_uid == VNOVAL || args->ta_root_gid == VNOVAL ||
            args->ta_root_mode == VNOVAL)
                return EINVAL;

        /* Get the memory usage limit for this file-system. */
        if (args->ta_size_max) {
                memlimit = roundup(args->ta_size_max, PAGE_SIZE);

                if ((tmpfs_bytes_limit - tmpfs_bytes_used) < memlimit)
                        return EINVAL; /* historic error */
                tmpfs_bytes_used += memlimit;
        }

        if (args->ta_nodes_max <= 3) {
                nodes = 3 + ((memlimit ?  memlimit : UINT64_MAX) / 1024);
        } else {
                nodes = args->ta_nodes_max;
        }
        nodes = MIN(nodes, INT_MAX);
        KASSERT(nodes >= 3);

        /* Allocate the tmpfs mount structure and fill it. */
        tmp = malloc(sizeof(tmpfs_mount_t), M_MISCFSMNT, M_WAITOK);

        tmp->tm_nodes_max = (ino_t)nodes;
        tmp->tm_nodes_cnt = 0;
        tmp->tm_highest_inode = 1;
        LIST_INIT(&tmp->tm_nodes);

        rw_init(&tmp->tm_lock, "tmplk");
        tmpfs_mntmem_init(tmp, memlimit);

        /* Allocate the root node. */
        error = tmpfs_alloc_node(tmp, VDIR, args->ta_root_uid,
            args->ta_root_gid, args->ta_root_mode & ALLPERMS, NULL,
            VNOVAL, &root);
        KASSERT(error == 0 && root != NULL);

        /*
         * Parent of the root inode is itself.  Also, root inode has no
         * directory entry (i.e. is never attached), thus hold an extra
         * reference (link) for it.
         */
        root->tn_links++;
        root->tn_spec.tn_dir.tn_parent = root;
        tmp->tm_root = root;

        mp->mnt_data = tmp;
        mp->mnt_flag |= MNT_LOCAL;
        mp->mnt_stat.f_namemax = TMPFS_MAXNAMLEN;
        vfs_getnewfsid(mp);

        mp->mnt_stat.mount_info.tmpfs_args = *args;

        bzero(&mp->mnt_stat.f_mntonname, sizeof(mp->mnt_stat.f_mntonname));
        bzero(&mp->mnt_stat.f_mntfromname, sizeof(mp->mnt_stat.f_mntfromname));
        bzero(&mp->mnt_stat.f_mntfromspec, sizeof(mp->mnt_stat.f_mntfromspec));

        strlcpy(mp->mnt_stat.f_mntonname, path,
            sizeof(mp->mnt_stat.f_mntonname) - 1);
        strlcpy(mp->mnt_stat.f_mntfromname, "tmpfs",
            sizeof(mp->mnt_stat.f_mntfromname) - 1);
        strlcpy(mp->mnt_stat.f_mntfromspec, "tmpfs",
            sizeof(mp->mnt_stat.f_mntfromspec) - 1);

        return error;
}

int
tmpfs_start(struct mount *mp, int flags, struct proc *p)
{
        return 0;
}

int
tmpfs_unmount(struct mount *mp, int mntflags, struct proc *p)
{
        tmpfs_mount_t *tmp = VFS_TO_TMPFS(mp);
        tmpfs_node_t *node, *cnode;
        int error, flags = 0;

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

        /* Finalize all pending I/O. */
        error = vflush(mp, NULL, flags);
        if (error != 0)
                return error;

        /*
         * First round, detach and destroy all directory entries.
         * Also, clear the pointers to the vnodes - they are gone.
         */
        LIST_FOREACH(node, &tmp->tm_nodes, tn_entries) {
                tmpfs_dirent_t *de;

                node->tn_vnode = NULL;
                if (node->tn_type != VDIR) {
                        continue;
                }
                while ((de = TAILQ_FIRST(&node->tn_spec.tn_dir.tn_dir)) != NULL) {
                        cnode = de->td_node;
                        if (cnode)
                                cnode->tn_vnode = NULL;
                        tmpfs_dir_detach(node, de);
                        tmpfs_free_dirent(tmp, de);
                }
        }

        /* Second round, destroy all inodes. */
        while ((node = LIST_FIRST(&tmp->tm_nodes)) != NULL) {
                tmpfs_free_node(tmp, node);
        }

        if (tmp->tm_mem_limit)
                tmpfs_bytes_used -= tmp->tm_mem_limit;

        /* Throw away the tmpfs_mount structure. */
        tmpfs_mntmem_destroy(tmp);
        /* mutex_destroy(&tmp->tm_lock); */
        /* kmem_free(tmp, sizeof(*tmp)); */
        free(tmp, M_MISCFSMNT, sizeof(tmpfs_mount_t));
        mp->mnt_data = NULL;

        return 0;
}

int
tmpfs_root(struct mount *mp, struct vnode **vpp)
{
        tmpfs_node_t *node = VFS_TO_TMPFS(mp)->tm_root;

        rw_enter_write(&node->tn_nlock);
        return tmpfs_vnode_get(mp, node, vpp);
}

int
tmpfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp)
{

        printf("tmpfs_vget called; need for it unknown yet\n");
        return EOPNOTSUPP;
}

int
tmpfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
{
        tmpfs_mount_t *tmp = VFS_TO_TMPFS(mp);
        tmpfs_node_t *node;
        tmpfs_fid_t tfh;

        if (fhp->fid_len != sizeof(tmpfs_fid_t)) {
                return EINVAL;
        }
        memcpy(&tfh, fhp, sizeof(tmpfs_fid_t));

        rw_enter_write(&tmp->tm_lock);
        LIST_FOREACH(node, &tmp->tm_nodes, tn_entries) {
                if (node->tn_id != tfh.tf_id) {
                        continue;
                }
                if (TMPFS_NODE_GEN(node) != tfh.tf_gen) {
                        continue;
                }
                rw_enter_write(&node->tn_nlock);
                break;
        }
        rw_exit_write(&tmp->tm_lock);

        /* Will release the tn_nlock. */
        return node ? tmpfs_vnode_get(mp, node, vpp) : ESTALE;
}

int
tmpfs_vptofh(struct vnode *vp, struct fid *fhp)
{
        tmpfs_fid_t tfh;
        tmpfs_node_t *node;

        node = VP_TO_TMPFS_NODE(vp);

        memset(&tfh, 0, sizeof(tfh));
        tfh.tf_len = sizeof(tmpfs_fid_t);
        tfh.tf_gen = TMPFS_NODE_GEN(node);
        tfh.tf_id = node->tn_id;
        memcpy(fhp, &tfh, sizeof(tfh));

        return 0;
}

int
tmpfs_statfs(struct mount *mp, struct statfs *sbp, struct proc *p)
{
        tmpfs_mount_t *tmp;
        fsfilcnt_t freenodes;
        uint64_t avail;

        tmp = VFS_TO_TMPFS(mp);

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

        rw_enter_read(&tmp->tm_acc_lock);
        avail = tmpfs_pages_avail(tmp);
        sbp->f_blocks = tmpfs_pages_total(tmp);
        sbp->f_bfree = avail;
        sbp->f_bavail = avail & INT64_MAX; /* f_bavail is int64_t */

        freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_cnt,
            avail * PAGE_SIZE / sizeof(tmpfs_node_t));

        sbp->f_files = tmp->tm_nodes_cnt + freenodes;
        sbp->f_ffree = freenodes;
        sbp->f_favail = freenodes & INT64_MAX; /* f_favail is int64_t */
        rw_exit_read(&tmp->tm_acc_lock);

        copy_statfs_info(sbp, mp);

        return 0;
}

int
tmpfs_sync(struct mount *mp, int waitfor, int stall, struct ucred *cred,
    struct proc *p)
{

        return 0;
}

/*
 * tmpfs vfs operations.
 */

const struct vfsops tmpfs_vfsops = {
        .vfs_mount      = tmpfs_mount,
        .vfs_start      = tmpfs_start,
        .vfs_unmount    = tmpfs_unmount,
        .vfs_root       = tmpfs_root,
        .vfs_quotactl   = (void *)eopnotsupp,
        .vfs_statfs     = tmpfs_statfs,
        .vfs_sync       = tmpfs_sync,
        .vfs_vget       = tmpfs_vget,
        .vfs_fhtovp     = tmpfs_fhtovp,
        .vfs_vptofh     = tmpfs_vptofh,
        .vfs_init       = tmpfs_init,
        .vfs_sysctl     = (void *)eopnotsupp,
        .vfs_checkexp   = (void *)eopnotsupp,
};