// SPDX-License-Identifier: GPL-2.0-only
/*
 * This file contians vfs dentry ops for the 9P2000 protocol.
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"

/**
 * v9fs_cached_dentry_delete - called when dentry refcount equals 0
 * @dentry:  dentry in question
 *
 */
static int v9fs_cached_dentry_delete(const struct dentry *dentry)
{
        p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
                 dentry, dentry);

        /* Don't cache negative dentries */
        if (d_really_is_negative(dentry))
                return 1;
        return 0;
}

/**
 * v9fs_dentry_release - called when dentry is going to be freed
 * @dentry:  dentry that is being release
 *
 */

static void v9fs_dentry_release(struct dentry *dentry)
{
        struct hlist_node *p, *n;
        struct hlist_head head;

        p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p)\n",
                 dentry, dentry);

        spin_lock(&dentry->d_lock);
        hlist_move_list((struct hlist_head *)&dentry->d_fsdata, &head);
        spin_unlock(&dentry->d_lock);

        hlist_for_each_safe(p, n, &head)
                p9_fid_put(hlist_entry(p, struct p9_fid, dlist));
}

static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
{
        struct p9_fid *fid;
        struct inode *inode;
        struct v9fs_inode *v9inode;

        if (flags & LOOKUP_RCU)
                return -ECHILD;

        inode = d_inode(dentry);
        if (!inode)
                goto out_valid;

        v9inode = V9FS_I(inode);
        if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
                int retval;
                struct v9fs_session_info *v9ses;

                fid = v9fs_fid_lookup(dentry);
                if (IS_ERR(fid)) {
                        p9_debug(
                                P9_DEBUG_VFS,
                                "v9fs_fid_lookup: dentry = %pd (%p), got error %pe\n",
                                dentry, dentry, fid);
                        return PTR_ERR(fid);
                }

                v9ses = v9fs_inode2v9ses(inode);
                if (v9fs_proto_dotl(v9ses))
                        retval = v9fs_refresh_inode_dotl(fid, inode);
                else
                        retval = v9fs_refresh_inode(fid, inode);
                p9_fid_put(fid);

                if (retval == -ENOENT) {
                        p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to ENOENT\n",
                                 dentry, dentry);
                        return 0;
                }
                if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
                        p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to type change\n",
                                 dentry, dentry);
                        return 0;
                }
                if (retval < 0) {
                        p9_debug(P9_DEBUG_VFS,
                                "refresh inode: dentry = %pd (%p), got error %pe\n",
                                dentry, dentry, ERR_PTR(retval));
                        return retval;
                }
        }
out_valid:
        p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
        return 1;
}

static int v9fs_lookup_revalidate(struct inode *dir, const struct qstr *name,
                                  struct dentry *dentry, unsigned int flags)
{
        return __v9fs_lookup_revalidate(dentry, flags);
}

static bool v9fs_dentry_unalias_trylock(const struct dentry *dentry)
{
        struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
        return down_write_trylock(&v9ses->rename_sem);
}

static void v9fs_dentry_unalias_unlock(const struct dentry *dentry)
{
        struct v9fs_session_info *v9ses = v9fs_dentry2v9ses(dentry);
        up_write(&v9ses->rename_sem);
}

const struct dentry_operations v9fs_cached_dentry_operations = {
        .d_revalidate = v9fs_lookup_revalidate,
        .d_weak_revalidate = __v9fs_lookup_revalidate,
        .d_delete = v9fs_cached_dentry_delete,
        .d_release = v9fs_dentry_release,
        .d_unalias_trylock = v9fs_dentry_unalias_trylock,
        .d_unalias_unlock = v9fs_dentry_unalias_unlock,
};

const struct dentry_operations v9fs_dentry_operations = {
        .d_release = v9fs_dentry_release,
        .d_unalias_trylock = v9fs_dentry_unalias_trylock,
        .d_unalias_unlock = v9fs_dentry_unalias_unlock,
};