// SPDX-License-Identifier: GPL-2.0
#include <linux/ceph/ceph_debug.h>

#include <linux/exportfs.h>
#include <linux/slab.h>
#include <linux/unaligned.h>

#include "super.h"
#include "mds_client.h"
#include "crypto.h"

/*
 * Basic fh
 */
struct ceph_nfs_fh {
        u64 ino;
} __attribute__ ((packed));

/*
 * Larger fh that includes parent ino.
 */
struct ceph_nfs_confh {
        u64 ino, parent_ino;
} __attribute__ ((packed));

/*
 * fh for snapped inode
 */
struct ceph_nfs_snapfh {
        u64 ino;
        u64 snapid;
        u64 parent_ino;
        u32 hash;
} __attribute__ ((packed));

#define BYTES_PER_U32           (sizeof(u32))
#define CEPH_FH_BASIC_SIZE \
        (sizeof(struct ceph_nfs_fh) / BYTES_PER_U32)
#define CEPH_FH_WITH_PARENT_SIZE \
        (sizeof(struct ceph_nfs_confh) / BYTES_PER_U32)
#define CEPH_FH_SNAPPED_INODE_SIZE \
        (sizeof(struct ceph_nfs_snapfh) / BYTES_PER_U32)

static int ceph_encode_snapfh(struct inode *inode, u32 *rawfh, int *max_len,
                              struct inode *parent_inode)
{
        struct ceph_client *cl = ceph_inode_to_client(inode);
        static const int snap_handle_length = CEPH_FH_SNAPPED_INODE_SIZE;
        struct ceph_nfs_snapfh *sfh = (void *)rawfh;
        u64 snapid = ceph_snap(inode);
        int ret;
        bool no_parent = true;

        if (*max_len < snap_handle_length) {
                *max_len = snap_handle_length;
                ret = FILEID_INVALID;
                goto out;
        }

        ret =  -EINVAL;
        if (snapid != CEPH_SNAPDIR) {
                struct inode *dir;
                struct dentry *dentry = d_find_alias(inode);
                if (!dentry)
                        goto out;

                rcu_read_lock();
                dir = d_inode_rcu(dentry->d_parent);
                if (ceph_snap(dir) != CEPH_SNAPDIR) {
                        sfh->parent_ino = ceph_ino(dir);
                        sfh->hash = ceph_dentry_hash(dir, dentry);
                        no_parent = false;
                }
                rcu_read_unlock();
                dput(dentry);
        }

        if (no_parent) {
                if (!S_ISDIR(inode->i_mode))
                        goto out;
                sfh->parent_ino = sfh->ino;
                sfh->hash = 0;
        }
        sfh->ino = ceph_ino(inode);
        sfh->snapid = snapid;

        *max_len = snap_handle_length;
        ret = FILEID_BTRFS_WITH_PARENT;
out:
        doutc(cl, "%p %llx.%llx ret=%d\n", inode, ceph_vinop(inode), ret);
        return ret;
}

static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
                          struct inode *parent_inode)
{
        struct ceph_client *cl = ceph_inode_to_client(inode);
        static const int handle_length = CEPH_FH_BASIC_SIZE;
        static const int connected_handle_length = CEPH_FH_WITH_PARENT_SIZE;
        int type;

        if (ceph_snap(inode) != CEPH_NOSNAP)
                return ceph_encode_snapfh(inode, rawfh, max_len, parent_inode);

        if (parent_inode && (*max_len < connected_handle_length)) {
                *max_len = connected_handle_length;
                return FILEID_INVALID;
        } else if (*max_len < handle_length) {
                *max_len = handle_length;
                return FILEID_INVALID;
        }

        if (parent_inode) {
                struct ceph_nfs_confh *cfh = (void *)rawfh;
                doutc(cl, "%p %llx.%llx with parent %p %llx.%llx\n", inode,
                      ceph_vinop(inode), parent_inode, ceph_vinop(parent_inode));
                cfh->ino = ceph_ino(inode);
                cfh->parent_ino = ceph_ino(parent_inode);
                *max_len = connected_handle_length;
                type = FILEID_INO32_GEN_PARENT;
        } else {
                struct ceph_nfs_fh *fh = (void *)rawfh;
                doutc(cl, "%p %llx.%llx\n", inode, ceph_vinop(inode));
                fh->ino = ceph_ino(inode);
                *max_len = handle_length;
                type = FILEID_INO32_GEN;
        }
        return type;
}

static struct inode *__lookup_inode(struct super_block *sb, u64 ino)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_fs_client(sb)->mdsc;
        struct inode *inode;
        struct ceph_vino vino;
        int err;

        vino.ino = ino;
        vino.snap = CEPH_NOSNAP;

        if (ceph_vino_is_reserved(vino))
                return ERR_PTR(-ESTALE);

        inode = ceph_find_inode(sb, vino);
        if (!inode) {
                struct ceph_mds_request *req;
                int mask;

                req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
                                               USE_ANY_MDS);
                if (IS_ERR(req))
                        return ERR_CAST(req);

                mask = CEPH_STAT_CAP_INODE;
                if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
                        mask |= CEPH_CAP_XATTR_SHARED;
                req->r_args.lookupino.mask = cpu_to_le32(mask);

                req->r_ino1 = vino;
                req->r_num_caps = 1;
                err = ceph_mdsc_do_request(mdsc, NULL, req);
                inode = req->r_target_inode;
                if (inode)
                        ihold(inode);
                ceph_mdsc_put_request(req);
                if (!inode)
                        return err < 0 ? ERR_PTR(err) : ERR_PTR(-ESTALE);
        } else {
                if (ceph_inode_is_shutdown(inode)) {
                        iput(inode);
                        return ERR_PTR(-ESTALE);
                }
        }
        return inode;
}

struct inode *ceph_lookup_inode(struct super_block *sb, u64 ino)
{
        struct inode *inode = __lookup_inode(sb, ino);
        if (IS_ERR(inode))
                return inode;
        if (inode->i_nlink == 0) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }
        return inode;
}

static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
{
        struct inode *inode = __lookup_inode(sb, ino);
        struct ceph_inode_info *ci = ceph_inode(inode);
        int err;

        if (IS_ERR(inode))
                return ERR_CAST(inode);
        /* We need LINK caps to reliably check i_nlink */
        err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
        if (err) {
                iput(inode);
                return ERR_PTR(err);
        }
        /* -ESTALE if inode as been unlinked and no file is open */
        if ((inode->i_nlink == 0) && !__ceph_is_file_opened(ci)) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }
        return d_obtain_alias(inode);
}

static struct dentry *__snapfh_to_dentry(struct super_block *sb,
                                          struct ceph_nfs_snapfh *sfh,
                                          bool want_parent)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_fs_client(sb)->mdsc;
        struct ceph_client *cl = mdsc->fsc->client;
        struct ceph_mds_request *req;
        struct inode *inode;
        struct ceph_vino vino;
        int mask;
        int err;
        bool unlinked = false;

        if (want_parent) {
                vino.ino = sfh->parent_ino;
                if (sfh->snapid == CEPH_SNAPDIR)
                        vino.snap = CEPH_NOSNAP;
                else if (sfh->ino == sfh->parent_ino)
                        vino.snap = CEPH_SNAPDIR;
                else
                        vino.snap = sfh->snapid;
        } else {
                vino.ino = sfh->ino;
                vino.snap = sfh->snapid;
        }

        if (ceph_vino_is_reserved(vino))
                return ERR_PTR(-ESTALE);

        inode = ceph_find_inode(sb, vino);
        if (inode) {
                if (ceph_inode_is_shutdown(inode)) {
                        iput(inode);
                        return ERR_PTR(-ESTALE);
                }
                return d_obtain_alias(inode);
        }

        req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
                                       USE_ANY_MDS);
        if (IS_ERR(req))
                return ERR_CAST(req);

        mask = CEPH_STAT_CAP_INODE;
        if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
                mask |= CEPH_CAP_XATTR_SHARED;
        req->r_args.lookupino.mask = cpu_to_le32(mask);
        if (vino.snap < CEPH_NOSNAP) {
                req->r_args.lookupino.snapid = cpu_to_le64(vino.snap);
                if (!want_parent && sfh->ino != sfh->parent_ino) {
                        req->r_args.lookupino.parent =
                                        cpu_to_le64(sfh->parent_ino);
                        req->r_args.lookupino.hash =
                                        cpu_to_le32(sfh->hash);
                }
        }

        req->r_ino1 = vino;
        req->r_num_caps = 1;
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        inode = req->r_target_inode;
        if (inode) {
                if (vino.snap == CEPH_SNAPDIR) {
                        if (inode->i_nlink == 0)
                                unlinked = true;
                        inode = ceph_get_snapdir(inode);
                } else if (ceph_snap(inode) == vino.snap) {
                        ihold(inode);
                } else {
                        /* mds does not support lookup snapped inode */
                        inode = ERR_PTR(-EOPNOTSUPP);
                }
        } else {
                inode = ERR_PTR(-ESTALE);
        }
        ceph_mdsc_put_request(req);

        if (want_parent) {
                doutc(cl, "%llx.%llx\n err=%d\n", vino.ino, vino.snap, err);
        } else {
                doutc(cl, "%llx.%llx parent %llx hash %x err=%d", vino.ino,
                      vino.snap, sfh->parent_ino, sfh->hash, err);
        }
        /* see comments in ceph_get_parent() */
        return unlinked ? d_obtain_root(inode) : d_obtain_alias(inode);
}

/*
 * convert regular fh to dentry
 */
static struct dentry *ceph_fh_to_dentry(struct super_block *sb,
                                        struct fid *fid,
                                        int fh_len, int fh_type)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
        struct ceph_nfs_fh *fh = (void *)fid->raw;

        if (fh_type == FILEID_BTRFS_WITH_PARENT) {
                struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
                return __snapfh_to_dentry(sb, sfh, false);
        }

        if (fh_type != FILEID_INO32_GEN  &&
            fh_type != FILEID_INO32_GEN_PARENT)
                return NULL;
        if (fh_len < sizeof(*fh) / BYTES_PER_U32)
                return NULL;

        doutc(fsc->client, "%llx\n", fh->ino);
        return __fh_to_dentry(sb, fh->ino);
}

static struct dentry *__get_parent(struct super_block *sb,
                                   struct dentry *child, u64 ino)
{
        struct ceph_mds_client *mdsc = ceph_sb_to_fs_client(sb)->mdsc;
        struct ceph_mds_request *req;
        struct inode *inode;
        int mask;
        int err;

        req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPPARENT,
                                       USE_ANY_MDS);
        if (IS_ERR(req))
                return ERR_CAST(req);

        if (child) {
                req->r_inode = d_inode(child);
                ihold(d_inode(child));
        } else {
                req->r_ino1 = (struct ceph_vino) {
                        .ino = ino,
                        .snap = CEPH_NOSNAP,
                };
        }

        mask = CEPH_STAT_CAP_INODE;
        if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
                mask |= CEPH_CAP_XATTR_SHARED;
        req->r_args.getattr.mask = cpu_to_le32(mask);

        req->r_num_caps = 1;
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        if (err) {
                ceph_mdsc_put_request(req);
                return ERR_PTR(err);
        }

        inode = req->r_target_inode;
        if (inode)
                ihold(inode);
        ceph_mdsc_put_request(req);
        if (!inode)
                return ERR_PTR(-ENOENT);

        return d_obtain_alias(inode);
}

static struct dentry *ceph_get_parent(struct dentry *child)
{
        struct inode *inode = d_inode(child);
        struct ceph_client *cl = ceph_inode_to_client(inode);
        struct dentry *dn;

        if (ceph_snap(inode) != CEPH_NOSNAP) {
                struct inode* dir;
                bool unlinked = false;
                /* do not support non-directory */
                if (!d_is_dir(child)) {
                        dn = ERR_PTR(-EINVAL);
                        goto out;
                }
                dir = __lookup_inode(inode->i_sb, ceph_ino(inode));
                if (IS_ERR(dir)) {
                        dn = ERR_CAST(dir);
                        goto out;
                }
                /* There can be multiple paths to access snapped inode.
                 * For simplicity, treat snapdir of head inode as parent */
                if (ceph_snap(inode) != CEPH_SNAPDIR) {
                        struct inode *snapdir = ceph_get_snapdir(dir);
                        if (dir->i_nlink == 0)
                                unlinked = true;
                        iput(dir);
                        if (IS_ERR(snapdir)) {
                                dn = ERR_CAST(snapdir);
                                goto out;
                        }
                        dir = snapdir;
                }
                /* If directory has already been deleted, further get_parent
                 * will fail. Do not mark snapdir dentry as disconnected,
                 * this prevents exportfs from doing further get_parent. */
                if (unlinked)
                        dn = d_obtain_root(dir);
                else
                        dn = d_obtain_alias(dir);
        } else {
                dn = __get_parent(child->d_sb, child, 0);
        }
out:
        doutc(cl, "child %p %p %llx.%llx err=%ld\n", child, inode,
              ceph_vinop(inode), (long)PTR_ERR_OR_ZERO(dn));
        return dn;
}

/*
 * convert regular fh to parent
 */
static struct dentry *ceph_fh_to_parent(struct super_block *sb,
                                        struct fid *fid,
                                        int fh_len, int fh_type)
{
        struct ceph_fs_client *fsc = ceph_sb_to_fs_client(sb);
        struct ceph_nfs_confh *cfh = (void *)fid->raw;
        struct dentry *dentry;

        if (fh_type == FILEID_BTRFS_WITH_PARENT) {
                struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
                return __snapfh_to_dentry(sb, sfh, true);
        }

        if (fh_type != FILEID_INO32_GEN_PARENT)
                return NULL;
        if (fh_len < sizeof(*cfh) / BYTES_PER_U32)
                return NULL;

        doutc(fsc->client, "%llx\n", cfh->parent_ino);
        dentry = __get_parent(sb, NULL, cfh->ino);
        if (unlikely(dentry == ERR_PTR(-ENOENT)))
                dentry = __fh_to_dentry(sb, cfh->parent_ino);
        return dentry;
}

static int __get_snap_name(struct dentry *parent, char *name,
                           struct dentry *child)
{
        struct inode *inode = d_inode(child);
        struct inode *dir = d_inode(parent);
        struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
        struct ceph_mds_request *req = NULL;
        char *last_name = NULL;
        unsigned next_offset = 2;
        int err = -EINVAL;

        if (ceph_ino(inode) != ceph_ino(dir))
                goto out;
        if (ceph_snap(inode) == CEPH_SNAPDIR) {
                if (ceph_snap(dir) == CEPH_NOSNAP) {
                        /*
                         * .get_name() from struct export_operations
                         * assumes that its 'name' parameter is pointing
                         * to a NAME_MAX+1 sized buffer
                         */
                        strscpy(name, fsc->mount_options->snapdir_name,
                                NAME_MAX + 1);
                        err = 0;
                }
                goto out;
        }
        if (ceph_snap(dir) != CEPH_SNAPDIR)
                goto out;

        while (1) {
                struct ceph_mds_reply_info_parsed *rinfo;
                struct ceph_mds_reply_dir_entry *rde;
                int i;

                req = ceph_mdsc_create_request(fsc->mdsc, CEPH_MDS_OP_LSSNAP,
                                               USE_AUTH_MDS);
                if (IS_ERR(req)) {
                        err = PTR_ERR(req);
                        req = NULL;
                        goto out;
                }
                err = ceph_alloc_readdir_reply_buffer(req, inode);
                if (err)
                        goto out;

                req->r_direct_mode = USE_AUTH_MDS;
                req->r_readdir_offset = next_offset;
                req->r_args.readdir.flags =
                                cpu_to_le16(CEPH_READDIR_REPLY_BITFLAGS);
                if (last_name) {
                        req->r_path2 = last_name;
                        last_name = NULL;
                }

                req->r_inode = dir;
                ihold(dir);
                req->r_dentry = dget(parent);

                inode_lock(dir);
                err = ceph_mdsc_do_request(fsc->mdsc, NULL, req);
                inode_unlock(dir);

                if (err < 0)
                        goto out;

                rinfo = &req->r_reply_info;
                for (i = 0; i < rinfo->dir_nr; i++) {
                        rde = rinfo->dir_entries + i;
                        BUG_ON(!rde->inode.in);
                        if (ceph_snap(inode) ==
                            le64_to_cpu(rde->inode.in->snapid)) {
                                memcpy(name, rde->name, rde->name_len);
                                name[rde->name_len] = '\0';
                                err = 0;
                                goto out;
                        }
                }

                if (rinfo->dir_end)
                        break;

                BUG_ON(rinfo->dir_nr <= 0);
                rde = rinfo->dir_entries + (rinfo->dir_nr - 1);
                next_offset += rinfo->dir_nr;
                last_name = kstrndup(rde->name, rde->name_len, GFP_KERNEL);
                if (!last_name) {
                        err = -ENOMEM;
                        goto out;
                }

                ceph_mdsc_put_request(req);
                req = NULL;
        }
        err = -ENOENT;
out:
        if (req)
                ceph_mdsc_put_request(req);
        kfree(last_name);
        doutc(fsc->client, "child dentry %p %p %llx.%llx err=%d\n", child,
              inode, ceph_vinop(inode), err);
        return err;
}

static int ceph_get_name(struct dentry *parent, char *name,
                         struct dentry *child)
{
        struct ceph_mds_client *mdsc;
        struct ceph_mds_request *req;
        struct inode *dir = d_inode(parent);
        struct inode *inode = d_inode(child);
        struct ceph_mds_reply_info_parsed *rinfo;
        int err;

        if (ceph_snap(inode) != CEPH_NOSNAP)
                return __get_snap_name(parent, name, child);

        mdsc = ceph_inode_to_fs_client(inode)->mdsc;
        req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPNAME,
                                       USE_ANY_MDS);
        if (IS_ERR(req))
                return PTR_ERR(req);

        inode_lock(dir);
        req->r_inode = inode;
        ihold(inode);
        req->r_ino2 = ceph_vino(d_inode(parent));
        req->r_parent = dir;
        ihold(dir);
        set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
        req->r_num_caps = 2;
        err = ceph_mdsc_do_request(mdsc, NULL, req);
        inode_unlock(dir);

        if (err)
                goto out;

        rinfo = &req->r_reply_info;
        if (!IS_ENCRYPTED(dir)) {
                memcpy(name, rinfo->dname, rinfo->dname_len);
                name[rinfo->dname_len] = 0;
        } else {
                struct fscrypt_str oname = FSTR_INIT(NULL, 0);
                struct ceph_fname fname = { .dir        = dir,
                                            .name       = rinfo->dname,
                                            .ctext      = rinfo->altname,
                                            .name_len   = rinfo->dname_len,
                                            .ctext_len  = rinfo->altname_len };

                err = ceph_fname_alloc_buffer(dir, &oname);
                if (err < 0)
                        goto out;

                err = ceph_fname_to_usr(&fname, NULL, &oname, NULL);
                if (!err) {
                        memcpy(name, oname.name, oname.len);
                        name[oname.len] = 0;
                }
                ceph_fname_free_buffer(dir, &oname);
        }
out:
        doutc(mdsc->fsc->client, "child dentry %p %p %llx.%llx err %d %s%s\n",
              child, inode, ceph_vinop(inode), err, err ? "" : "name ",
              err ? "" : name);
        ceph_mdsc_put_request(req);
        return err;
}

const struct export_operations ceph_export_ops = {
        .encode_fh = ceph_encode_fh,
        .fh_to_dentry = ceph_fh_to_dentry,
        .fh_to_parent = ceph_fh_to_parent,
        .get_parent = ceph_get_parent,
        .get_name = ceph_get_name,
};