// SPDX-License-Identifier: GPL-2.0+
/*
 * NILFS pathname lookup operations.
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Modified for NILFS by Amagai Yoshiji and Ryusuke Konishi.
 */
/*
 *  linux/fs/ext2/namei.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/namei.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

#include <linux/pagemap.h>
#include "nilfs.h"
#include "export.h"

#define NILFS_FID_SIZE_NON_CONNECTABLE \
        (offsetof(struct nilfs_fid, parent_gen) / 4)
#define NILFS_FID_SIZE_CONNECTABLE      (sizeof(struct nilfs_fid) / 4)

static inline int nilfs_add_nondir(struct dentry *dentry, struct inode *inode)
{
        int err = nilfs_add_link(dentry, inode);

        if (!err) {
                d_instantiate_new(dentry, inode);
                return 0;
        }
        inode_dec_link_count(inode);
        unlock_new_inode(inode);
        iput(inode);
        return err;
}

/*
 * Methods themselves.
 */

static struct dentry *
nilfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
        struct inode *inode;
        ino_t ino;
        int res;

        if (dentry->d_name.len > NILFS_NAME_LEN)
                return ERR_PTR(-ENAMETOOLONG);

        res = nilfs_inode_by_name(dir, &dentry->d_name, &ino);
        if (res) {
                if (res != -ENOENT)
                        return ERR_PTR(res);
                inode = NULL;
        } else {
                inode = nilfs_iget(dir->i_sb, NILFS_I(dir)->i_root, ino);
                if (inode == ERR_PTR(-ESTALE)) {
                        nilfs_error(dir->i_sb,
                                        "deleted inode referenced: %lu", ino);
                        return ERR_PTR(-EIO);
                }
        }

        return d_splice_alias(inode, dentry);
}

/*
 * By the time this is called, we already have created
 * the directory cache entry for the new file, but it
 * is so far negative - it has no inode.
 *
 * If the create succeeds, we fill in the inode information
 * with d_instantiate().
 */
static int nilfs_create(struct mnt_idmap *idmap, struct inode *dir,
                        struct dentry *dentry, umode_t mode, bool excl)
{
        struct inode *inode;
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
        if (err)
                return err;
        inode = nilfs_new_inode(dir, mode);
        err = PTR_ERR(inode);
        if (!IS_ERR(inode)) {
                inode->i_op = &nilfs_file_inode_operations;
                inode->i_fop = &nilfs_file_operations;
                inode->i_mapping->a_ops = &nilfs_aops;
                nilfs_mark_inode_dirty(inode);
                err = nilfs_add_nondir(dentry, inode);
        }
        if (!err)
                err = nilfs_transaction_commit(dir->i_sb);
        else
                nilfs_transaction_abort(dir->i_sb);

        return err;
}

static int
nilfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
            struct dentry *dentry, umode_t mode, dev_t rdev)
{
        struct inode *inode;
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
        if (err)
                return err;
        inode = nilfs_new_inode(dir, mode);
        err = PTR_ERR(inode);
        if (!IS_ERR(inode)) {
                init_special_inode(inode, inode->i_mode, rdev);
                nilfs_mark_inode_dirty(inode);
                err = nilfs_add_nondir(dentry, inode);
        }
        if (!err)
                err = nilfs_transaction_commit(dir->i_sb);
        else
                nilfs_transaction_abort(dir->i_sb);

        return err;
}

static int nilfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
                         struct dentry *dentry, const char *symname)
{
        struct nilfs_transaction_info ti;
        struct super_block *sb = dir->i_sb;
        unsigned int l = strlen(symname) + 1;
        struct inode *inode;
        int err;

        if (l > sb->s_blocksize)
                return -ENAMETOOLONG;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
        if (err)
                return err;

        inode = nilfs_new_inode(dir, S_IFLNK | 0777);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                goto out;

        /* slow symlink */
        inode->i_op = &nilfs_symlink_inode_operations;
        inode_nohighmem(inode);
        mapping_set_gfp_mask(inode->i_mapping,
                             mapping_gfp_constraint(inode->i_mapping,
                                                    ~__GFP_FS));
        inode->i_mapping->a_ops = &nilfs_aops;
        err = page_symlink(inode, symname, l);
        if (err)
                goto out_fail;

        /* mark_inode_dirty(inode); */
        /* page_symlink() do this */

        err = nilfs_add_nondir(dentry, inode);
out:
        if (!err)
                err = nilfs_transaction_commit(dir->i_sb);
        else
                nilfs_transaction_abort(dir->i_sb);

        return err;

out_fail:
        drop_nlink(inode);
        nilfs_mark_inode_dirty(inode);
        unlock_new_inode(inode);
        iput(inode);
        goto out;
}

static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
                      struct dentry *dentry)
{
        struct inode *inode = d_inode(old_dentry);
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
        if (err)
                return err;

        inode_set_ctime_current(inode);
        inode_inc_link_count(inode);
        ihold(inode);

        err = nilfs_add_link(dentry, inode);
        if (!err) {
                d_instantiate(dentry, inode);
                err = nilfs_transaction_commit(dir->i_sb);
        } else {
                inode_dec_link_count(inode);
                iput(inode);
                nilfs_transaction_abort(dir->i_sb);
        }

        return err;
}

static struct dentry *nilfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
                                  struct dentry *dentry, umode_t mode)
{
        struct inode *inode;
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
        if (err)
                return ERR_PTR(err);

        inc_nlink(dir);

        inode = nilfs_new_inode(dir, S_IFDIR | mode);
        err = PTR_ERR(inode);
        if (IS_ERR(inode))
                goto out_dir;

        inode->i_op = &nilfs_dir_inode_operations;
        inode->i_fop = &nilfs_dir_operations;
        inode->i_mapping->a_ops = &nilfs_aops;

        inc_nlink(inode);

        err = nilfs_make_empty(inode, dir);
        if (err)
                goto out_fail;

        err = nilfs_add_link(dentry, inode);
        if (err)
                goto out_fail;

        nilfs_mark_inode_dirty(inode);
        d_instantiate_new(dentry, inode);
out:
        if (!err)
                err = nilfs_transaction_commit(dir->i_sb);
        else
                nilfs_transaction_abort(dir->i_sb);

        return ERR_PTR(err);

out_fail:
        drop_nlink(inode);
        drop_nlink(inode);
        nilfs_mark_inode_dirty(inode);
        unlock_new_inode(inode);
        iput(inode);
out_dir:
        drop_nlink(dir);
        nilfs_mark_inode_dirty(dir);
        goto out;
}

static int nilfs_do_unlink(struct inode *dir, struct dentry *dentry)
{
        struct inode *inode;
        struct nilfs_dir_entry *de;
        struct folio *folio;
        int err;

        de = nilfs_find_entry(dir, &dentry->d_name, &folio);
        if (IS_ERR(de)) {
                err = PTR_ERR(de);
                goto out;
        }

        inode = d_inode(dentry);
        err = -EIO;
        if (le64_to_cpu(de->inode) != inode->i_ino)
                goto out;

        if (!inode->i_nlink) {
                nilfs_warn(inode->i_sb,
                           "deleting nonexistent file (ino=%lu), %d",
                           inode->i_ino, inode->i_nlink);
                set_nlink(inode, 1);
        }
        err = nilfs_delete_entry(de, folio);
        folio_release_kmap(folio, de);
        if (err)
                goto out;

        inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
        drop_nlink(inode);
        err = 0;
out:
        return err;
}

static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
{
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
        if (err)
                return err;

        err = nilfs_do_unlink(dir, dentry);

        if (!err) {
                nilfs_mark_inode_dirty(dir);
                nilfs_mark_inode_dirty(d_inode(dentry));
                err = nilfs_transaction_commit(dir->i_sb);
        } else
                nilfs_transaction_abort(dir->i_sb);

        return err;
}

static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        struct inode *inode = d_inode(dentry);
        struct nilfs_transaction_info ti;
        int err;

        err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
        if (err)
                return err;

        err = -ENOTEMPTY;
        if (nilfs_empty_dir(inode)) {
                err = nilfs_do_unlink(dir, dentry);
                if (!err) {
                        inode->i_size = 0;
                        drop_nlink(inode);
                        nilfs_mark_inode_dirty(inode);
                        drop_nlink(dir);
                        nilfs_mark_inode_dirty(dir);
                }
        }
        if (!err)
                err = nilfs_transaction_commit(dir->i_sb);
        else
                nilfs_transaction_abort(dir->i_sb);

        return err;
}

static int nilfs_rename(struct mnt_idmap *idmap,
                        struct inode *old_dir, struct dentry *old_dentry,
                        struct inode *new_dir, struct dentry *new_dentry,
                        unsigned int flags)
{
        struct inode *old_inode = d_inode(old_dentry);
        struct inode *new_inode = d_inode(new_dentry);
        struct folio *dir_folio = NULL;
        struct nilfs_dir_entry *dir_de = NULL;
        struct folio *old_folio;
        struct nilfs_dir_entry *old_de;
        struct nilfs_transaction_info ti;
        bool old_is_dir = S_ISDIR(old_inode->i_mode);
        int err;

        if (flags & ~RENAME_NOREPLACE)
                return -EINVAL;

        err = nilfs_transaction_begin(old_dir->i_sb, &ti, 1);
        if (unlikely(err))
                return err;

        old_de = nilfs_find_entry(old_dir, &old_dentry->d_name, &old_folio);
        if (IS_ERR(old_de)) {
                err = PTR_ERR(old_de);
                goto out;
        }

        if (old_is_dir && old_dir != new_dir) {
                err = -EIO;
                dir_de = nilfs_dotdot(old_inode, &dir_folio);
                if (!dir_de)
                        goto out_old;
        }

        if (new_inode) {
                struct folio *new_folio;
                struct nilfs_dir_entry *new_de;

                err = -ENOTEMPTY;
                if (old_is_dir && !nilfs_empty_dir(new_inode))
                        goto out_dir;

                new_de = nilfs_find_entry(new_dir, &new_dentry->d_name,
                                          &new_folio);
                if (IS_ERR(new_de)) {
                        err = PTR_ERR(new_de);
                        goto out_dir;
                }
                err = nilfs_set_link(new_dir, new_de, new_folio, old_inode);
                folio_release_kmap(new_folio, new_de);
                if (unlikely(err))
                        goto out_dir;
                nilfs_mark_inode_dirty(new_dir);
                inode_set_ctime_current(new_inode);
                if (old_is_dir)
                        drop_nlink(new_inode);
                drop_nlink(new_inode);
                nilfs_mark_inode_dirty(new_inode);
        } else {
                err = nilfs_add_link(new_dentry, old_inode);
                if (err)
                        goto out_dir;
                if (old_is_dir) {
                        inc_nlink(new_dir);
                        nilfs_mark_inode_dirty(new_dir);
                }
        }

        /*
         * Like most other Unix systems, set the ctime for inodes on a
         * rename.
         */
        inode_set_ctime_current(old_inode);

        err = nilfs_delete_entry(old_de, old_folio);
        if (likely(!err)) {
                if (old_is_dir) {
                        if (old_dir != new_dir)
                                err = nilfs_set_link(old_inode, dir_de,
                                                     dir_folio, new_dir);
                        drop_nlink(old_dir);
                }
                nilfs_mark_inode_dirty(old_dir);
        }
        nilfs_mark_inode_dirty(old_inode);

out_dir:
        if (dir_de)
                folio_release_kmap(dir_folio, dir_de);
out_old:
        folio_release_kmap(old_folio, old_de);
out:
        if (likely(!err))
                err = nilfs_transaction_commit(old_dir->i_sb);
        else
                nilfs_transaction_abort(old_dir->i_sb);
        return err;
}

/*
 * Export operations
 */
static struct dentry *nilfs_get_parent(struct dentry *child)
{
        ino_t ino;
        int res;
        struct nilfs_root *root;

        res = nilfs_inode_by_name(d_inode(child), &dotdot_name, &ino);
        if (res)
                return ERR_PTR(res);

        root = NILFS_I(d_inode(child))->i_root;

        return d_obtain_alias(nilfs_iget(child->d_sb, root, ino));
}

static struct dentry *nilfs_get_dentry(struct super_block *sb, u64 cno,
                                       u64 ino, u32 gen)
{
        struct nilfs_root *root;
        struct inode *inode;

        if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO)
                return ERR_PTR(-ESTALE);

        root = nilfs_lookup_root(sb->s_fs_info, cno);
        if (!root)
                return ERR_PTR(-ESTALE);

        inode = nilfs_iget(sb, root, ino);
        nilfs_put_root(root);

        if (IS_ERR(inode))
                return ERR_CAST(inode);
        if (gen && inode->i_generation != gen) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }
        return d_obtain_alias(inode);
}

static struct dentry *nilfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
                                         int fh_len, int fh_type)
{
        struct nilfs_fid *fid = (struct nilfs_fid *)fh;

        if (fh_len < NILFS_FID_SIZE_NON_CONNECTABLE ||
            (fh_type != FILEID_NILFS_WITH_PARENT &&
             fh_type != FILEID_NILFS_WITHOUT_PARENT))
                return NULL;

        return nilfs_get_dentry(sb, fid->cno, fid->ino, fid->gen);
}

static struct dentry *nilfs_fh_to_parent(struct super_block *sb, struct fid *fh,
                                         int fh_len, int fh_type)
{
        struct nilfs_fid *fid = (struct nilfs_fid *)fh;

        if (fh_len < NILFS_FID_SIZE_CONNECTABLE ||
            fh_type != FILEID_NILFS_WITH_PARENT)
                return NULL;

        return nilfs_get_dentry(sb, fid->cno, fid->parent_ino, fid->parent_gen);
}

static int nilfs_encode_fh(struct inode *inode, __u32 *fh, int *lenp,
                           struct inode *parent)
{
        struct nilfs_fid *fid = (struct nilfs_fid *)fh;
        struct nilfs_root *root = NILFS_I(inode)->i_root;
        int type;

        if (parent && *lenp < NILFS_FID_SIZE_CONNECTABLE) {
                *lenp = NILFS_FID_SIZE_CONNECTABLE;
                return FILEID_INVALID;
        }
        if (*lenp < NILFS_FID_SIZE_NON_CONNECTABLE) {
                *lenp = NILFS_FID_SIZE_NON_CONNECTABLE;
                return FILEID_INVALID;
        }

        fid->cno = root->cno;
        fid->ino = inode->i_ino;
        fid->gen = inode->i_generation;

        if (parent) {
                fid->parent_ino = parent->i_ino;
                fid->parent_gen = parent->i_generation;
                type = FILEID_NILFS_WITH_PARENT;
                *lenp = NILFS_FID_SIZE_CONNECTABLE;
        } else {
                type = FILEID_NILFS_WITHOUT_PARENT;
                *lenp = NILFS_FID_SIZE_NON_CONNECTABLE;
        }

        return type;
}

const struct inode_operations nilfs_dir_inode_operations = {
        .create         = nilfs_create,
        .lookup         = nilfs_lookup,
        .link           = nilfs_link,
        .unlink         = nilfs_unlink,
        .symlink        = nilfs_symlink,
        .mkdir          = nilfs_mkdir,
        .rmdir          = nilfs_rmdir,
        .mknod          = nilfs_mknod,
        .rename         = nilfs_rename,
        .setattr        = nilfs_setattr,
        .permission     = nilfs_permission,
        .fiemap         = nilfs_fiemap,
        .fileattr_get   = nilfs_fileattr_get,
        .fileattr_set   = nilfs_fileattr_set,
};

const struct inode_operations nilfs_special_inode_operations = {
        .setattr        = nilfs_setattr,
        .permission     = nilfs_permission,
};

const struct inode_operations nilfs_symlink_inode_operations = {
        .get_link       = page_get_link,
        .permission     = nilfs_permission,
};

const struct export_operations nilfs_export_ops = {
        .encode_fh = nilfs_encode_fh,
        .fh_to_dentry = nilfs_fh_to_dentry,
        .fh_to_parent = nilfs_fh_to_parent,
        .get_parent = nilfs_get_parent,
};