// SPDX-License-Identifier: GPL-2.0
/*
 * (C) 2001 Clemson University and The University of Chicago
 *
 * See COPYING in top-level directory.
 */

/*
 *  Implementation of dentry (directory cache) functions.
 */

#include "protocol.h"
#include "orangefs-kernel.h"

/* Returns 1 if dentry can still be trusted, else 0. */
static int orangefs_revalidate_lookup(struct inode *parent_inode, const struct qstr *name,
                                      struct dentry *dentry)
{
        struct orangefs_inode_s *parent = ORANGEFS_I(parent_inode);
        struct inode *inode = dentry->d_inode;
        struct orangefs_kernel_op_s *new_op;
        int ret = 0;
        int err = 0;

        gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: attempting lookup.\n", __func__);

        new_op = op_alloc(ORANGEFS_VFS_OP_LOOKUP);
        if (!new_op)
                return -ENOMEM;

        new_op->upcall.req.lookup.sym_follow = ORANGEFS_LOOKUP_LINK_NO_FOLLOW;
        new_op->upcall.req.lookup.parent_refn = parent->refn;
        /* op_alloc() leaves ->upcall zeroed */
        memcpy(new_op->upcall.req.lookup.d_name, name->name,
                        min(name->len, ORANGEFS_NAME_MAX - 1));

        gossip_debug(GOSSIP_DCACHE_DEBUG,
                     "%s:%s:%d interrupt flag [%d]\n",
                     __FILE__,
                     __func__,
                     __LINE__,
                     get_interruptible_flag(parent_inode));

        err = service_operation(new_op, "orangefs_lookup",
                        get_interruptible_flag(parent_inode));

        /* Positive dentry: reject if error or not the same inode. */
        if (inode) {
                if (err) {
                        gossip_debug(GOSSIP_DCACHE_DEBUG,
                            "%s:%s:%d lookup failure.\n",
                            __FILE__, __func__, __LINE__);
                        goto out_drop;
                }
                if (!match_handle(new_op->downcall.resp.lookup.refn.khandle,
                    inode)) {
                        gossip_debug(GOSSIP_DCACHE_DEBUG,
                            "%s:%s:%d no match.\n",
                            __FILE__, __func__, __LINE__);
                        goto out_drop;
                }

        /* Negative dentry: reject if success or error other than ENOENT. */
        } else {
                gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: negative dentry.\n",
                    __func__);
                if (!err || err != -ENOENT) {
                        if (new_op->downcall.status != 0)
                                gossip_debug(GOSSIP_DCACHE_DEBUG,
                                    "%s:%s:%d lookup failure.\n",
                                    __FILE__, __func__, __LINE__);
                        goto out_drop;
                }
        }

        orangefs_set_timeout(dentry);
        ret = 1;
out_release_op:
        op_release(new_op);
        return ret;
out_drop:
        gossip_debug(GOSSIP_DCACHE_DEBUG, "%s:%s:%d revalidate failed\n",
            __FILE__, __func__, __LINE__);
        goto out_release_op;
}

/*
 * Verify that dentry is valid.
 *
 * Should return 1 if dentry can still be trusted, else 0.
 */
static int orangefs_d_revalidate(struct inode *dir, const struct qstr *name,
                                 struct dentry *dentry, unsigned int flags)
{
        int ret;
        unsigned long time = (unsigned long) dentry->d_fsdata;

        if (time_before(jiffies, time))
                return 1;

        if (flags & LOOKUP_RCU)
                return -ECHILD;

        gossip_debug(GOSSIP_DCACHE_DEBUG, "%s: called on dentry %p.\n",
                     __func__, dentry);

        /* skip root handle lookups. */
        if (dentry->d_inode && is_root_handle(dentry->d_inode))
                return 1;

        /*
         * If this passes, the positive dentry still exists or the negative
         * dentry still does not exist.
         */
        if (!orangefs_revalidate_lookup(dir, name, dentry))
                return 0;

        /* We do not need to continue with negative dentries. */
        if (!dentry->d_inode) {
                gossip_debug(GOSSIP_DCACHE_DEBUG,
                    "%s: negative dentry or positive dentry and inode valid.\n",
                    __func__);
                return 1;
        }

        /* Now we must perform a getattr to validate the inode contents. */

        ret = orangefs_inode_check_changed(dentry->d_inode);
        if (ret < 0) {
                gossip_debug(GOSSIP_DCACHE_DEBUG, "%s:%s:%d getattr failure.\n",
                    __FILE__, __func__, __LINE__);
                return 0;
        }
        return !ret;
}

const struct dentry_operations orangefs_dentry_operations = {
        .d_revalidate = orangefs_d_revalidate,
};