Linux 2.6.33.13

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / staging / pohmelfs / dir.c

/*
 * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/jhash.h>
#include <linux/namei.h>
#include <linux/pagemap.h>

#include "netfs.h"

static int pohmelfs_cmp_hash(struct pohmelfs_name *n, u32 hash)
{
        if (n->hash > hash)
                return -1;
        if (n->hash < hash)
                return 1;

        return 0;
}

static struct pohmelfs_name *pohmelfs_search_hash_unprecise(struct pohmelfs_inode *pi, u32 hash)
{
        struct rb_node *n = pi->hash_root.rb_node;
        struct pohmelfs_name *tmp = NULL;
        int cmp;

        while (n) {
                tmp = rb_entry(n, struct pohmelfs_name, hash_node);

                cmp = pohmelfs_cmp_hash(tmp, hash);
                if (cmp < 0)
                        n = n->rb_left;
                else if (cmp > 0)
                        n = n->rb_right;
                else
                        break;

        }

        return tmp;
}

struct pohmelfs_name *pohmelfs_search_hash(struct pohmelfs_inode *pi, u32 hash)
{
        struct pohmelfs_name *tmp;

        tmp = pohmelfs_search_hash_unprecise(pi, hash);
        if (tmp && (tmp->hash == hash))
                return tmp;

        return NULL;
}

static void __pohmelfs_name_del(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
{
        rb_erase(&node->hash_node, &parent->hash_root);
}

/*
 * Remove name cache entry from its caches and free it.
 */
static void pohmelfs_name_free(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
{
        __pohmelfs_name_del(parent, node);
        list_del(&node->sync_create_entry);
        kfree(node);
}

static struct pohmelfs_name *pohmelfs_insert_hash(struct pohmelfs_inode *pi,
                struct pohmelfs_name *new)
{
        struct rb_node **n = &pi->hash_root.rb_node, *parent = NULL;
        struct pohmelfs_name *ret = NULL, *tmp;
        int cmp;

        while (*n) {
                parent = *n;

                tmp = rb_entry(parent, struct pohmelfs_name, hash_node);

                cmp = pohmelfs_cmp_hash(tmp, new->hash);
                if (cmp < 0)
                        n = &parent->rb_left;
                else if (cmp > 0)
                        n = &parent->rb_right;
                else {
                        ret = tmp;
                        break;
                }
        }

        if (ret) {
                printk("%s: exist: parent: %llu, ino: %llu, hash: %x, len: %u, data: '%s', "
                                           "new: ino: %llu, hash: %x, len: %u, data: '%s'.\n",
                                __func__, pi->ino,
                                ret->ino, ret->hash, ret->len, ret->data,
                                new->ino, new->hash, new->len, new->data);
                ret->ino = new->ino;
                return ret;
        }

        rb_link_node(&new->hash_node, parent, n);
        rb_insert_color(&new->hash_node, &pi->hash_root);

        return NULL;
}

/*
 * Free name cache for given inode.
 */
void pohmelfs_free_names(struct pohmelfs_inode *parent)
{
        struct rb_node *rb_node;
        struct pohmelfs_name *n;

        for (rb_node = rb_first(&parent->hash_root); rb_node;) {
                n = rb_entry(rb_node, struct pohmelfs_name, hash_node);
                rb_node = rb_next(rb_node);

                pohmelfs_name_free(parent, n);
        }
}

static void pohmelfs_fix_offset(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
{
        parent->total_len -= node->len;
}

/*
 * Free name cache entry helper.
 */
void pohmelfs_name_del(struct pohmelfs_inode *parent, struct pohmelfs_name *node)
{
        pohmelfs_fix_offset(parent, node);
        pohmelfs_name_free(parent, node);
}

/*
 * Insert new name cache entry into all hash cache.
 */
static int pohmelfs_insert_name(struct pohmelfs_inode *parent, struct pohmelfs_name *n)
{
        struct pohmelfs_name *name;

        name = pohmelfs_insert_hash(parent, n);
        if (name)
                return -EEXIST;

        parent->total_len += n->len;
        list_add_tail(&n->sync_create_entry, &parent->sync_create_list);

        return 0;
}

/*
 * Allocate new name cache entry.
 */
static struct pohmelfs_name *pohmelfs_name_alloc(unsigned int len)
{
        struct pohmelfs_name *n;

        n = kzalloc(sizeof(struct pohmelfs_name) + len, GFP_KERNEL);
        if (!n)
                return NULL;

        INIT_LIST_HEAD(&n->sync_create_entry);

        n->data = (char *)(n+1);

        return n;
}

/*
 * Add new name entry into directory's cache.
 */
static int pohmelfs_add_dir(struct pohmelfs_sb *psb, struct pohmelfs_inode *parent,
                struct pohmelfs_inode *npi, struct qstr *str, unsigned int mode, int link)
{
        int err = -ENOMEM;
        struct pohmelfs_name *n;

        n = pohmelfs_name_alloc(str->len + 1);
        if (!n)
                goto err_out_exit;

        n->ino = npi->ino;
        n->mode = mode;
        n->len = str->len;
        n->hash = str->hash;
        sprintf(n->data, "%s", str->name);

        mutex_lock(&parent->offset_lock);
        err = pohmelfs_insert_name(parent, n);
        mutex_unlock(&parent->offset_lock);

        if (err) {
                if (err != -EEXIST)
                        goto err_out_free;
                kfree(n);
        }

        return 0;

err_out_free:
        kfree(n);
err_out_exit:
        return err;
}

/*
 * Create new inode for given parameters (name, inode info, parent).
 * This does not create object on the server, it will be synced there during writeback.
 */
struct pohmelfs_inode *pohmelfs_new_inode(struct pohmelfs_sb *psb,
                struct pohmelfs_inode *parent, struct qstr *str,
                struct netfs_inode_info *info, int link)
{
        struct inode *new = NULL;
        struct pohmelfs_inode *npi;
        int err = -EEXIST;

        dprintk("%s: creating inode: parent: %llu, ino: %llu, str: %p.\n",
                        __func__, (parent)?parent->ino:0, info->ino, str);

        err = -ENOMEM;
        new = iget_locked(psb->sb, info->ino);
        if (!new)
                goto err_out_exit;

        npi = POHMELFS_I(new);
        npi->ino = info->ino;
        err = 0;

        if (new->i_state & I_NEW) {
                dprintk("%s: filling VFS inode: %lu/%llu.\n",
                                __func__, new->i_ino, info->ino);
                pohmelfs_fill_inode(new, info);

                if (S_ISDIR(info->mode)) {
                        struct qstr s;

                        s.name = ".";
                        s.len = 1;
                        s.hash = jhash(s.name, s.len, 0);

                        err = pohmelfs_add_dir(psb, npi, npi, &s, info->mode, 0);
                        if (err)
                                goto err_out_put;

                        s.name = "..";
                        s.len = 2;
                        s.hash = jhash(s.name, s.len, 0);

                        err = pohmelfs_add_dir(psb, npi, (parent)?parent:npi, &s,
                                        (parent)?parent->vfs_inode.i_mode:npi->vfs_inode.i_mode, 0);
                        if (err)
                                goto err_out_put;
                }
        }

        if (str) {
                if (parent) {
                        err = pohmelfs_add_dir(psb, parent, npi, str, info->mode, link);

                        dprintk("%s: %s inserted name: '%s', new_offset: %llu, ino: %llu, parent: %llu.\n",
                                        __func__, (err)?"unsuccessfully":"successfully",
                                        str->name, parent->total_len, info->ino, parent->ino);

                        if (err && err != -EEXIST)
                                goto err_out_put;
                }
        }

        if (new->i_state & I_NEW) {
                if (parent)
                        mark_inode_dirty(&parent->vfs_inode);
                mark_inode_dirty(new);
        }

        set_bit(NETFS_INODE_OWNED, &npi->state);
        npi->lock_type = POHMELFS_WRITE_LOCK;
        unlock_new_inode(new);

        return npi;

err_out_put:
        printk("%s: putting inode: %p, npi: %p, error: %d.\n", __func__, new, npi, err);
        iput(new);
err_out_exit:
        return ERR_PTR(err);
}

static int pohmelfs_remote_sync_complete(struct page **pages, unsigned int page_num,
                void *private, int err)
{
        struct pohmelfs_inode *pi = private;
        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);

        dprintk("%s: ino: %llu, err: %d.\n", __func__, pi->ino, err);

        if (err)
                pi->error = err;
        wake_up(&psb->wait);
        pohmelfs_put_inode(pi);

        return err;
}

/*
 * Receive directory content from the server.
 * This should be only done for objects, which were not created locally,
 * and which were not synced previously.
 */
static int pohmelfs_sync_remote_dir(struct pohmelfs_inode *pi)
{
        struct inode *inode = &pi->vfs_inode;
        struct pohmelfs_sb *psb = POHMELFS_SB(inode->i_sb);
        long ret = psb->wait_on_page_timeout;
        int err;

        dprintk("%s: dir: %llu, state: %lx: remote_synced: %d.\n",
                __func__, pi->ino, pi->state, test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state));

        if (test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state))
                return 0;

        if (!igrab(inode)) {
                err = -ENOENT;
                goto err_out_exit;
        }

        err = pohmelfs_meta_command(pi, NETFS_READDIR, NETFS_TRANS_SINGLE_DST,
                        pohmelfs_remote_sync_complete, pi, 0);
        if (err)
                goto err_out_exit;

        pi->error = 0;
        ret = wait_event_interruptible_timeout(psb->wait,
                        test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &pi->state) || pi->error, ret);
        dprintk("%s: awake dir: %llu, ret: %ld, err: %d.\n", __func__, pi->ino, ret, pi->error);
        if (ret <= 0) {
                err = ret;
                if (!err)
                        err = -ETIMEDOUT;
                goto err_out_exit;
        }

        if (pi->error)
                return pi->error;

        return 0;

err_out_exit:
        clear_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);

        return err;
}

static int pohmelfs_dir_open(struct inode *inode, struct file *file)
{
        file->private_data = NULL;
        return 0;
}

/*
 * VFS readdir callback. Syncs directory content from server if needed,
 * and provides direntry info to the userspace.
 */
static int pohmelfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct pohmelfs_inode *pi = POHMELFS_I(inode);
        struct pohmelfs_name *n;
        struct rb_node *rb_node;
        int err = 0, mode;
        u64 len;

        dprintk("%s: parent: %llu, fpos: %llu, hash: %08lx.\n",
                        __func__, pi->ino, (u64)file->f_pos,
                        (unsigned long)file->private_data);
#if 0
        err = pohmelfs_data_lock(pi, 0, ~0, POHMELFS_READ_LOCK);
        if (err)
                return err;
#endif
        err = pohmelfs_sync_remote_dir(pi);
        if (err)
                return err;

        if (file->private_data && (file->private_data == (void *)(unsigned long)file->f_pos))
                return 0;

        mutex_lock(&pi->offset_lock);
        n = pohmelfs_search_hash_unprecise(pi, (unsigned long)file->private_data);

        while (n) {
                mode = (n->mode >> 12) & 15;

                dprintk("%s: offset: %llu, parent ino: %llu, name: '%s', len: %u, ino: %llu, "
                                "mode: %o/%o, fpos: %llu, hash: %08x.\n",
                                __func__, file->f_pos, pi->ino, n->data, n->len,
                                n->ino, n->mode, mode, file->f_pos, n->hash);

                file->private_data = (void *)(unsigned long)n->hash;

                len = n->len;
                err = filldir(dirent, n->data, n->len, file->f_pos, n->ino, mode);

                if (err < 0) {
                        dprintk("%s: err: %d.\n", __func__, err);
                        err = 0;
                        break;
                }

                file->f_pos += len;

                rb_node = rb_next(&n->hash_node);

                if (!rb_node || (rb_node == &n->hash_node)) {
                        file->private_data = (void *)(unsigned long)file->f_pos;
                        break;
                }

                n = rb_entry(rb_node, struct pohmelfs_name, hash_node);
        }
        mutex_unlock(&pi->offset_lock);

        return err;
}

static loff_t pohmelfs_dir_lseek(struct file *file, loff_t offset, int origin)
{
        file->f_pos = offset;
        file->private_data = NULL;
        return offset;
}

const struct file_operations pohmelfs_dir_fops = {
        .open = pohmelfs_dir_open,
        .read = generic_read_dir,
        .llseek = pohmelfs_dir_lseek,
        .readdir = pohmelfs_readdir,
};

/*
 * Lookup single object on server.
 */
static int pohmelfs_lookup_single(struct pohmelfs_inode *parent,
                struct qstr *str, u64 ino)
{
        struct pohmelfs_sb *psb = POHMELFS_SB(parent->vfs_inode.i_sb);
        long ret = msecs_to_jiffies(5000);
        int err;

        set_bit(NETFS_COMMAND_PENDING, &parent->state);
        err = pohmelfs_meta_command_data(parent, parent->ino, NETFS_LOOKUP,
                        (char *)str->name, NETFS_TRANS_SINGLE_DST, NULL, NULL, ino);
        if (err)
                goto err_out_exit;

        err = 0;
        ret = wait_event_interruptible_timeout(psb->wait,
                        !test_bit(NETFS_COMMAND_PENDING, &parent->state), ret);
        if (ret <= 0) {
                err = ret;
                if (!err)
                        err = -ETIMEDOUT;
        }

        if (err)
                goto err_out_exit;

        return 0;

err_out_exit:
        clear_bit(NETFS_COMMAND_PENDING, &parent->state);

        printk("%s: failed: parent: %llu, ino: %llu, name: '%s', err: %d.\n",
                        __func__, parent->ino, ino, str->name, err);

        return err;
}

/*
 * VFS lookup callback.
 * We first try to get inode number from local name cache, if we have one,
 * then inode can be found in inode cache. If there is no inode or no object in
 * local cache, try to lookup it on server. This only should be done for directories,
 * which were not created locally, otherwise remote server does not know about dir at all,
 * so no need to try to know that.
 */
struct dentry *pohmelfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
        struct pohmelfs_inode *parent = POHMELFS_I(dir);
        struct pohmelfs_name *n;
        struct inode *inode = NULL;
        unsigned long ino = 0;
        int err, lock_type = POHMELFS_READ_LOCK, need_lock = 1;
        struct qstr str = dentry->d_name;

        if ((nd->intent.open.flags & O_ACCMODE) > 1)
                lock_type = POHMELFS_WRITE_LOCK;

        if (test_bit(NETFS_INODE_OWNED, &parent->state)) {
                if (lock_type == parent->lock_type)
                        need_lock = 0;
                if ((lock_type == POHMELFS_READ_LOCK) && (parent->lock_type == POHMELFS_WRITE_LOCK))
                        need_lock = 0;
        }

        if ((lock_type == POHMELFS_READ_LOCK) && !test_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state))
                need_lock = 1;

        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);

        mutex_lock(&parent->offset_lock);
        n = pohmelfs_search_hash(parent, str.hash);
        if (n)
                ino = n->ino;
        mutex_unlock(&parent->offset_lock);

        dprintk("%s: start ino: %lu, inode: %p, name: '%s', hash: %x, parent_state: %lx, need_lock: %d.\n",
                        __func__, ino, inode, str.name, str.hash, parent->state, need_lock);

        if (ino) {
                inode = ilookup(dir->i_sb, ino);
                if (inode)
                        goto out;
        }

        dprintk("%s: no inode dir: %p, dir_ino: %llu, name: '%s', len: %u, dir_state: %lx, ino: %lu.\n",
                        __func__, dir, parent->ino,
                        str.name, str.len, parent->state, ino);

        if (!ino) {
                if (!need_lock)
                        goto out;
        }

        err = pohmelfs_data_lock(parent, 0, ~0, lock_type);
        if (err)
                goto out;

        err = pohmelfs_lookup_single(parent, &str, ino);
        if (err)
                goto out;

        if (!ino) {
                mutex_lock(&parent->offset_lock);
                n = pohmelfs_search_hash(parent, str.hash);
                if (n)
                        ino = n->ino;
                mutex_unlock(&parent->offset_lock);
        }

        if (ino) {
                inode = ilookup(dir->i_sb, ino);
                dprintk("%s: second lookup ino: %lu, inode: %p, name: '%s', hash: %x.\n",
                                __func__, ino, inode, str.name, str.hash);
                if (!inode) {
                        dprintk("%s: No inode for ino: %lu, name: '%s', hash: %x.\n",
                                __func__, ino, str.name, str.hash);
                        /* return NULL; */
                        return ERR_PTR(-EACCES);
                }
        } else {
                printk("%s: No inode number : name: '%s', hash: %x.\n",
                        __func__, str.name, str.hash);
        }
out:
        return d_splice_alias(inode, dentry);
}

/*
 * Create new object in local cache. Object will be synced to server
 * during writeback for given inode.
 */
struct pohmelfs_inode *pohmelfs_create_entry_local(struct pohmelfs_sb *psb,
        struct pohmelfs_inode *parent, struct qstr *str, u64 start, int mode)
{
        struct pohmelfs_inode *npi;
        int err = -ENOMEM;
        struct netfs_inode_info info;

        dprintk("%s: name: '%s', mode: %o, start: %llu.\n",
                        __func__, str->name, mode, start);

        info.mode = mode;
        info.ino = start;

        if (!start)
                info.ino = pohmelfs_new_ino(psb);

        info.nlink = S_ISDIR(mode)?2:1;
        info.uid = current_fsuid();
        info.gid = current_fsgid();
        info.size = 0;
        info.blocksize = 512;
        info.blocks = 0;
        info.rdev = 0;
        info.version = 0;

        npi = pohmelfs_new_inode(psb, parent, str, &info, !!start);
        if (IS_ERR(npi)) {
                err = PTR_ERR(npi);
                goto err_out_unlock;
        }

        return npi;

err_out_unlock:
        dprintk("%s: err: %d.\n", __func__, err);
        return ERR_PTR(err);
}

/*
 * Create local object and bind it to dentry.
 */
static int pohmelfs_create_entry(struct inode *dir, struct dentry *dentry, u64 start, int mode)
{
        struct pohmelfs_sb *psb = POHMELFS_SB(dir->i_sb);
        struct pohmelfs_inode *npi, *parent;
        struct qstr str = dentry->d_name;
        int err;

        parent = POHMELFS_I(dir);

        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
        if (err)
                return err;

        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);

        npi = pohmelfs_create_entry_local(psb, parent, &str, start, mode);
        if (IS_ERR(npi))
                return PTR_ERR(npi);

        d_instantiate(dentry, &npi->vfs_inode);

        dprintk("%s: parent: %llu, inode: %llu, name: '%s', parent_nlink: %d, nlink: %d.\n",
                        __func__, parent->ino, npi->ino, dentry->d_name.name,
                        (signed)dir->i_nlink, (signed)npi->vfs_inode.i_nlink);

        return 0;
}

/*
 * VFS create and mkdir callbacks.
 */
static int pohmelfs_create(struct inode *dir, struct dentry *dentry, int mode,
                struct nameidata *nd)
{
        return pohmelfs_create_entry(dir, dentry, 0, mode);
}

static int pohmelfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        int err;

        inode_inc_link_count(dir);
        err = pohmelfs_create_entry(dir, dentry, 0, mode | S_IFDIR);
        if (err)
                inode_dec_link_count(dir);

        return err;
}

static int pohmelfs_remove_entry(struct inode *dir, struct dentry *dentry)
{
        struct pohmelfs_sb *psb = POHMELFS_SB(dir->i_sb);
        struct inode *inode = dentry->d_inode;
        struct pohmelfs_inode *parent = POHMELFS_I(dir), *pi = POHMELFS_I(inode);
        struct pohmelfs_name *n;
        int err = -ENOENT;
        struct qstr str = dentry->d_name;

        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
        if (err)
                return err;

        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);

        dprintk("%s: dir_ino: %llu, inode: %llu, name: '%s', nlink: %d.\n",
                        __func__, parent->ino, pi->ino,
                        str.name, (signed)inode->i_nlink);

        BUG_ON(!inode);

        mutex_lock(&parent->offset_lock);
        n = pohmelfs_search_hash(parent, str.hash);
        if (n) {
                pohmelfs_fix_offset(parent, n);
                if (test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state))
                        pohmelfs_remove_child(pi, n);

                pohmelfs_name_free(parent, n);
                err = 0;
        }
        mutex_unlock(&parent->offset_lock);

        if (!err) {
                psb->avail_size += inode->i_size;

                pohmelfs_inode_del_inode(psb, pi);

                mark_inode_dirty(dir);

                inode->i_ctime = dir->i_ctime;
                if (inode->i_nlink)
                        inode_dec_link_count(inode);
        }

        return err;
}

/*
 * Unlink and rmdir VFS callbacks.
 */
static int pohmelfs_unlink(struct inode *dir, struct dentry *dentry)
{
        return pohmelfs_remove_entry(dir, dentry);
}

static int pohmelfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        int err;
        struct inode *inode = dentry->d_inode;

        dprintk("%s: parent: %llu, inode: %llu, name: '%s', parent_nlink: %d, nlink: %d.\n",
                        __func__, POHMELFS_I(dir)->ino, POHMELFS_I(inode)->ino,
                        dentry->d_name.name, (signed)dir->i_nlink, (signed)inode->i_nlink);

        err = pohmelfs_remove_entry(dir, dentry);
        if (!err) {
                inode_dec_link_count(dir);
                inode_dec_link_count(inode);
        }

        return err;
}

/*
 * Link creation is synchronous.
 * I'm lazy.
 * Earth is somewhat round.
 */
static int pohmelfs_create_link(struct pohmelfs_inode *parent, struct qstr *obj,
                struct pohmelfs_inode *target, struct qstr *tstr)
{
        struct super_block *sb = parent->vfs_inode.i_sb;
        struct pohmelfs_sb *psb = POHMELFS_SB(sb);
        struct netfs_cmd *cmd;
        struct netfs_trans *t;
        void *data;
        int err, parent_len, target_len = 0, cur_len, path_size = 0;

        err = pohmelfs_data_lock(parent, 0, ~0, POHMELFS_WRITE_LOCK);
        if (err)
                return err;

        err = sb->s_op->write_inode(&parent->vfs_inode, 0);
        if (err)
                goto err_out_exit;

        if (tstr)
                target_len = tstr->len;

        parent_len = pohmelfs_path_length(parent);
        if (target)
                target_len += pohmelfs_path_length(target);

        if (parent_len < 0) {
                err = parent_len;
                goto err_out_exit;
        }

        if (target_len < 0) {
                err = target_len;
                goto err_out_exit;
        }

        t = netfs_trans_alloc(psb, parent_len + target_len + obj->len + 2, 0, 0);
        if (!t) {
                err = -ENOMEM;
                goto err_out_exit;
        }
        cur_len = netfs_trans_cur_len(t);

        cmd = netfs_trans_current(t);
        if (IS_ERR(cmd)) {
                err = PTR_ERR(cmd);
                goto err_out_free;
        }

        data = (void *)(cmd + 1);
        cur_len -= sizeof(struct netfs_cmd);

        err = pohmelfs_construct_path_string(parent, data, parent_len);
        if (err > 0) {
                /* Do not place null-byte before the slash */
                path_size = err - 1;
                cur_len -= path_size;

                err = snprintf(data + path_size, cur_len, "/%s|", obj->name);

                path_size += err;
                cur_len -= err;

                cmd->ext = path_size - 1; /* No | symbol */

                if (target) {
                        err = pohmelfs_construct_path_string(target, data + path_size, target_len);
                        if (err > 0) {
                                path_size += err;
                                cur_len -= err;
                        }
                }
        }

        if (err < 0)
                goto err_out_free;

        cmd->start = 0;

        if (!target && tstr) {
                if (tstr->len > cur_len - 1) {
                        err = -ENAMETOOLONG;
                        goto err_out_free;
                }

                err = snprintf(data + path_size, cur_len, "%s", tstr->name) + 1; /* 0-byte */
                path_size += err;
                cur_len -= err;
                cmd->start = 1;
        }

        dprintk("%s: parent: %llu, obj: '%s', target_inode: %llu, target_str: '%s', full: '%s'.\n",
                        __func__, parent->ino, obj->name, (target)?target->ino:0, (tstr)?tstr->name:NULL,
                        (char *)data);

        cmd->cmd = NETFS_LINK;
        cmd->size = path_size;
        cmd->id = parent->ino;

        netfs_convert_cmd(cmd);

        netfs_trans_update(cmd, t, path_size);

        err = netfs_trans_finish(t, psb);
        if (err)
                goto err_out_exit;

        return 0;

err_out_free:
        t->result = err;
        netfs_trans_put(t);
err_out_exit:
        return err;
}

/*
 *  VFS hard and soft link callbacks.
 */
static int pohmelfs_link(struct dentry *old_dentry, struct inode *dir,
        struct dentry *dentry)
{
        struct inode *inode = old_dentry->d_inode;
        struct pohmelfs_inode *pi = POHMELFS_I(inode);
        int err;
        struct qstr str = dentry->d_name;

        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);

        err = inode->i_sb->s_op->write_inode(inode, 0);
        if (err)
                return err;

        err = pohmelfs_create_link(POHMELFS_I(dir), &str, pi, NULL);
        if (err)
                return err;

        return pohmelfs_create_entry(dir, dentry, pi->ino, inode->i_mode);
}

static int pohmelfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
        struct qstr sym_str;
        struct qstr str = dentry->d_name;
        struct inode *inode;
        int err;

        str.hash = jhash(dentry->d_name.name, dentry->d_name.len, 0);

        sym_str.name = symname;
        sym_str.len = strlen(symname);

        err = pohmelfs_create_link(POHMELFS_I(dir), &str, NULL, &sym_str);
        if (err)
                goto err_out_exit;

        err = pohmelfs_create_entry(dir, dentry, 0, S_IFLNK | S_IRWXU | S_IRWXG | S_IRWXO);
        if (err)
                goto err_out_exit;

        inode = dentry->d_inode;

        err = page_symlink(inode, symname, sym_str.len + 1);
        if (err)
                goto err_out_put;

        return 0;

err_out_put:
        iput(inode);
err_out_exit:
        return err;
}

static int pohmelfs_send_rename(struct pohmelfs_inode *pi, struct pohmelfs_inode *parent,
                struct qstr *str)
{
        int path_len, err, total_len = 0, inode_len, parent_len;
        char *path;
        struct netfs_trans *t;
        struct netfs_cmd *cmd;
        struct pohmelfs_sb *psb = POHMELFS_SB(pi->vfs_inode.i_sb);

        parent_len = pohmelfs_path_length(parent);
        inode_len = pohmelfs_path_length(pi);

        if (parent_len < 0 || inode_len < 0)
                return -EINVAL;

        path_len = parent_len + inode_len + str->len + 3;

        t = netfs_trans_alloc(psb, path_len, 0, 0);
        if (!t)
                return -ENOMEM;

        cmd = netfs_trans_current(t);
        path = (char *)(cmd + 1);

        err = pohmelfs_construct_path_string(pi, path, inode_len);
        if (err < 0)
                goto err_out_unlock;

        cmd->ext = err;

        path += err;
        total_len += err;
        path_len -= err;

        *path = '|';
        path++;
        total_len++;
        path_len--;

        err = pohmelfs_construct_path_string(parent, path, parent_len);
        if (err < 0)
                goto err_out_unlock;

        /*
         * Do not place a null-byte before the final slash and the name.
         */
        err--;
        path += err;
        total_len += err;
        path_len -= err;

        err = snprintf(path, path_len - 1, "/%s", str->name);

        total_len += err + 1; /* 0 symbol */
        path_len -= err + 1;

        cmd->cmd = NETFS_RENAME;
        cmd->id = pi->ino;
        cmd->start = parent->ino;
        cmd->size = total_len;

        netfs_convert_cmd(cmd);

        netfs_trans_update(cmd, t, total_len);

        return netfs_trans_finish(t, psb);

err_out_unlock:
        netfs_trans_free(t);
        return err;
}

static int pohmelfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                        struct inode *new_dir, struct dentry *new_dentry)
{
        struct inode *inode = old_dentry->d_inode;
        struct pohmelfs_inode *old_parent, *pi, *new_parent;
        struct qstr str = new_dentry->d_name;
        struct pohmelfs_name *n;
        unsigned int old_hash;
        int err = -ENOENT;

        pi = POHMELFS_I(inode);
        old_parent = POHMELFS_I(old_dir);

        if (new_dir)
                new_dir->i_sb->s_op->write_inode(new_dir, 0);

        old_hash = jhash(old_dentry->d_name.name, old_dentry->d_name.len, 0);
        str.hash = jhash(new_dentry->d_name.name, new_dentry->d_name.len, 0);

        str.len = new_dentry->d_name.len;
        str.name = new_dentry->d_name.name;
        str.hash = jhash(new_dentry->d_name.name, new_dentry->d_name.len, 0);

        if (new_dir) {
                new_parent = POHMELFS_I(new_dir);
                err = -ENOTEMPTY;

                if (S_ISDIR(inode->i_mode) &&
                                new_parent->total_len <= 3)
                        goto err_out_exit;
        } else {
                new_parent = old_parent;
        }

        dprintk("%s: ino: %llu, parent: %llu, name: '%s' -> parent: %llu, name: '%s', i_size: %llu.\n",
                        __func__, pi->ino, old_parent->ino, old_dentry->d_name.name,
                        new_parent->ino, new_dentry->d_name.name, inode->i_size);

        if (test_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state) &&
                        test_bit(NETFS_INODE_OWNED, &pi->state)) {
                err = pohmelfs_send_rename(pi, new_parent, &str);
                if (err)
                        goto err_out_exit;
        }

        n = pohmelfs_name_alloc(str.len + 1);
        if (!n)
                goto err_out_exit;

        mutex_lock(&new_parent->offset_lock);
        n->ino = pi->ino;
        n->mode = inode->i_mode;
        n->len = str.len;
        n->hash = str.hash;
        sprintf(n->data, "%s", str.name);

        err = pohmelfs_insert_name(new_parent, n);
        mutex_unlock(&new_parent->offset_lock);

        if (err)
                goto err_out_exit;

        mutex_lock(&old_parent->offset_lock);
        n = pohmelfs_search_hash(old_parent, old_hash);
        if (n)
                pohmelfs_name_del(old_parent, n);
        mutex_unlock(&old_parent->offset_lock);

        mark_inode_dirty(inode);
        mark_inode_dirty(&new_parent->vfs_inode);

        WARN_ON_ONCE(list_empty(&inode->i_dentry));

        return 0;

err_out_exit:

        clear_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);

        mutex_unlock(&inode->i_mutex);
        return err;
}

/*
 * POHMELFS directory inode operations.
 */
const struct inode_operations pohmelfs_dir_inode_ops = {
        .link           = pohmelfs_link,
        .symlink        = pohmelfs_symlink,
        .unlink         = pohmelfs_unlink,
        .mkdir          = pohmelfs_mkdir,
        .rmdir          = pohmelfs_rmdir,
        .create         = pohmelfs_create,
        .lookup         = pohmelfs_lookup,
        .setattr        = pohmelfs_setattr,
        .rename         = pohmelfs_rename,
};