/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *   Portions Copyright (C) Christoph Hellwig, 2001-2002
 *
 *   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.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/ctype.h>
#include <linux/quotaops.h>
#include <linux/exportfs.h>
#include "jfs_incore.h"
#include "jfs_superblock.h"
#include "jfs_inode.h"
#include "jfs_dinode.h"
#include "jfs_dmap.h"
#include "jfs_unicode.h"
#include "jfs_metapage.h"
#include "jfs_xattr.h"
#include "jfs_acl.h"
#include "jfs_debug.h"

/*
 * forward references
 */
const struct dentry_operations jfs_ci_dentry_operations;

static s64 commitZeroLink(tid_t, struct inode *);

/*
 * NAME:        free_ea_wmap(inode)
 *
 * FUNCTION:    free uncommitted extended attributes from working map
 *
 */
static inline void free_ea_wmap(struct inode *inode)
{
        dxd_t *ea = &JFS_IP(inode)->ea;

        if (ea->flag & DXD_EXTENT) {
                /* free EA pages from cache */
                invalidate_dxd_metapages(inode, *ea);
                dbFree(inode, addressDXD(ea), lengthDXD(ea));
        }
        ea->flag = 0;
}

/*
 * NAME:        jfs_create(dip, dentry, mode)
 *
 * FUNCTION:    create a regular file in the parent directory <dip>
 *              with name = <from dentry> and mode = <mode>
 *
 * PARAMETER:   dip     - parent directory vnode
 *              dentry  - dentry of new file
 *              mode    - create mode (rwxrwxrwx).
 *              nd- nd struct
 *
 * RETURN:      Errors from subroutines
 *
 */
static int jfs_create(struct inode *dip, struct dentry *dentry, umode_t mode,
                bool excl)
{
        int rc = 0;
        tid_t tid;              /* transaction id */
        struct inode *ip = NULL;        /* child directory inode */
        ino_t ino;
        struct component_name dname;    /* child directory name */
        struct btstack btstack;
        struct inode *iplist[2];
        struct tblock *tblk;

        jfs_info("jfs_create: dip:0x%p name:%pd", dip, dentry);

        rc = dquot_initialize(dip);
        if (rc)
                goto out1;

        /*
         * search parent directory for entry/freespace
         * (dtSearch() returns parent directory page pinned)
         */
        if ((rc = get_UCSname(&dname, dentry)))
                goto out1;

        /*
         * Either iAlloc() or txBegin() may block.  Deadlock can occur if we
         * block there while holding dtree page, so we allocate the inode &
         * begin the transaction before we search the directory.
         */
        ip = ialloc(dip, mode);
        if (IS_ERR(ip)) {
                rc = PTR_ERR(ip);
                goto out2;
        }

        tid = txBegin(dip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dip)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        rc = jfs_init_acl(tid, ip, dip);
        if (rc)
                goto out3;

        rc = jfs_init_security(tid, ip, dip, &dentry->d_name);
        if (rc) {
                txAbort(tid, 0);
                goto out3;
        }

        if ((rc = dtSearch(dip, &dname, &ino, &btstack, JFS_CREATE))) {
                jfs_err("jfs_create: dtSearch returned %d", rc);
                txAbort(tid, 0);
                goto out3;
        }

        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_CREATE;
        tblk->ino = ip->i_ino;
        tblk->u.ixpxd = JFS_IP(ip)->ixpxd;

        iplist[0] = dip;
        iplist[1] = ip;

        /*
         * initialize the child XAD tree root in-line in inode
         */
        xtInitRoot(tid, ip);

        /*
         * create entry in parent directory for child directory
         * (dtInsert() releases parent directory page)
         */
        ino = ip->i_ino;
        if ((rc = dtInsert(tid, dip, &dname, &ino, &btstack))) {
                if (rc == -EIO) {
                        jfs_err("jfs_create: dtInsert returned -EIO");
                        txAbort(tid, 1);        /* Marks Filesystem dirty */
                } else
                        txAbort(tid, 0);        /* Filesystem full */
                goto out3;
        }

        ip->i_op = &jfs_file_inode_operations;
        ip->i_fop = &jfs_file_operations;
        ip->i_mapping->a_ops = &jfs_aops;

        mark_inode_dirty(ip);

        dip->i_ctime = dip->i_mtime = CURRENT_TIME;

        mark_inode_dirty(dip);

        rc = txCommit(tid, 2, &iplist[0], 0);

      out3:
        txEnd(tid);
        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dip)->commit_mutex);
        if (rc) {
                free_ea_wmap(ip);
                clear_nlink(ip);
                unlock_new_inode(ip);
                iput(ip);
        } else {
                unlock_new_inode(ip);
                d_instantiate(dentry, ip);
        }

      out2:
        free_UCSname(&dname);

      out1:

        jfs_info("jfs_create: rc:%d", rc);
        return rc;
}


/*
 * NAME:        jfs_mkdir(dip, dentry, mode)
 *
 * FUNCTION:    create a child directory in the parent directory <dip>
 *              with name = <from dentry> and mode = <mode>
 *
 * PARAMETER:   dip     - parent directory vnode
 *              dentry  - dentry of child directory
 *              mode    - create mode (rwxrwxrwx).
 *
 * RETURN:      Errors from subroutines
 *
 * note:
 * EACCESS: user needs search+write permission on the parent directory
 */
static int jfs_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
{
        int rc = 0;
        tid_t tid;              /* transaction id */
        struct inode *ip = NULL;        /* child directory inode */
        ino_t ino;
        struct component_name dname;    /* child directory name */
        struct btstack btstack;
        struct inode *iplist[2];
        struct tblock *tblk;

        jfs_info("jfs_mkdir: dip:0x%p name:%pd", dip, dentry);

        rc = dquot_initialize(dip);
        if (rc)
                goto out1;

        /*
         * search parent directory for entry/freespace
         * (dtSearch() returns parent directory page pinned)
         */
        if ((rc = get_UCSname(&dname, dentry)))
                goto out1;

        /*
         * Either iAlloc() or txBegin() may block.  Deadlock can occur if we
         * block there while holding dtree page, so we allocate the inode &
         * begin the transaction before we search the directory.
         */
        ip = ialloc(dip, S_IFDIR | mode);
        if (IS_ERR(ip)) {
                rc = PTR_ERR(ip);
                goto out2;
        }

        tid = txBegin(dip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dip)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        rc = jfs_init_acl(tid, ip, dip);
        if (rc)
                goto out3;

        rc = jfs_init_security(tid, ip, dip, &dentry->d_name);
        if (rc) {
                txAbort(tid, 0);
                goto out3;
        }

        if ((rc = dtSearch(dip, &dname, &ino, &btstack, JFS_CREATE))) {
                jfs_err("jfs_mkdir: dtSearch returned %d", rc);
                txAbort(tid, 0);
                goto out3;
        }

        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_CREATE;
        tblk->ino = ip->i_ino;
        tblk->u.ixpxd = JFS_IP(ip)->ixpxd;

        iplist[0] = dip;
        iplist[1] = ip;

        /*
         * initialize the child directory in-line in inode
         */
        dtInitRoot(tid, ip, dip->i_ino);

        /*
         * create entry in parent directory for child directory
         * (dtInsert() releases parent directory page)
         */
        ino = ip->i_ino;
        if ((rc = dtInsert(tid, dip, &dname, &ino, &btstack))) {
                if (rc == -EIO) {
                        jfs_err("jfs_mkdir: dtInsert returned -EIO");
                        txAbort(tid, 1);        /* Marks Filesystem dirty */
                } else
                        txAbort(tid, 0);        /* Filesystem full */
                goto out3;
        }

        set_nlink(ip, 2);       /* for '.' */
        ip->i_op = &jfs_dir_inode_operations;
        ip->i_fop = &jfs_dir_operations;

        mark_inode_dirty(ip);

        /* update parent directory inode */
        inc_nlink(dip);         /* for '..' from child directory */
        dip->i_ctime = dip->i_mtime = CURRENT_TIME;
        mark_inode_dirty(dip);

        rc = txCommit(tid, 2, &iplist[0], 0);

      out3:
        txEnd(tid);
        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dip)->commit_mutex);
        if (rc) {
                free_ea_wmap(ip);
                clear_nlink(ip);
                unlock_new_inode(ip);
                iput(ip);
        } else {
                unlock_new_inode(ip);
                d_instantiate(dentry, ip);
        }

      out2:
        free_UCSname(&dname);


      out1:

        jfs_info("jfs_mkdir: rc:%d", rc);
        return rc;
}

/*
 * NAME:        jfs_rmdir(dip, dentry)
 *
 * FUNCTION:    remove a link to child directory
 *
 * PARAMETER:   dip     - parent inode
 *              dentry  - child directory dentry
 *
 * RETURN:      -EINVAL - if name is . or ..
 *              -EINVAL - if . or .. exist but are invalid.
 *              errors from subroutines
 *
 * note:
 * if other threads have the directory open when the last link
 * is removed, the "." and ".." entries, if present, are removed before
 * rmdir() returns and no new entries may be created in the directory,
 * but the directory is not removed until the last reference to
 * the directory is released (cf.unlink() of regular file).
 */
static int jfs_rmdir(struct inode *dip, struct dentry *dentry)
{
        int rc;
        tid_t tid;              /* transaction id */
        struct inode *ip = d_inode(dentry);
        ino_t ino;
        struct component_name dname;
        struct inode *iplist[2];
        struct tblock *tblk;

        jfs_info("jfs_rmdir: dip:0x%p name:%pd", dip, dentry);

        /* Init inode for quota operations. */
        rc = dquot_initialize(dip);
        if (rc)
                goto out;
        rc = dquot_initialize(ip);
        if (rc)
                goto out;

        /* directory must be empty to be removed */
        if (!dtEmpty(ip)) {
                rc = -ENOTEMPTY;
                goto out;
        }

        if ((rc = get_UCSname(&dname, dentry))) {
                goto out;
        }

        tid = txBegin(dip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dip)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        iplist[0] = dip;
        iplist[1] = ip;

        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_DELETE;
        tblk->u.ip = ip;

        /*
         * delete the entry of target directory from parent directory
         */
        ino = ip->i_ino;
        if ((rc = dtDelete(tid, dip, &dname, &ino, JFS_REMOVE))) {
                jfs_err("jfs_rmdir: dtDelete returned %d", rc);
                if (rc == -EIO)
                        txAbort(tid, 1);
                txEnd(tid);
                mutex_unlock(&JFS_IP(ip)->commit_mutex);
                mutex_unlock(&JFS_IP(dip)->commit_mutex);

                goto out2;
        }

        /* update parent directory's link count corresponding
         * to ".." entry of the target directory deleted
         */
        dip->i_ctime = dip->i_mtime = CURRENT_TIME;
        inode_dec_link_count(dip);

        /*
         * OS/2 could have created EA and/or ACL
         */
        /* free EA from both persistent and working map */
        if (JFS_IP(ip)->ea.flag & DXD_EXTENT) {
                /* free EA pages */
                txEA(tid, ip, &JFS_IP(ip)->ea, NULL);
        }
        JFS_IP(ip)->ea.flag = 0;

        /* free ACL from both persistent and working map */
        if (JFS_IP(ip)->acl.flag & DXD_EXTENT) {
                /* free ACL pages */
                txEA(tid, ip, &JFS_IP(ip)->acl, NULL);
        }
        JFS_IP(ip)->acl.flag = 0;

        /* mark the target directory as deleted */
        clear_nlink(ip);
        mark_inode_dirty(ip);

        rc = txCommit(tid, 2, &iplist[0], 0);

        txEnd(tid);

        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dip)->commit_mutex);

        /*
         * Truncating the directory index table is not guaranteed.  It
         * may need to be done iteratively
         */
        if (test_cflag(COMMIT_Stale, dip)) {
                if (dip->i_size > 1)
                        jfs_truncate_nolock(dip, 0);

                clear_cflag(COMMIT_Stale, dip);
        }

      out2:
        free_UCSname(&dname);

      out:
        jfs_info("jfs_rmdir: rc:%d", rc);
        return rc;
}

/*
 * NAME:        jfs_unlink(dip, dentry)
 *
 * FUNCTION:    remove a link to object <vp> named by <name>
 *              from parent directory <dvp>
 *
 * PARAMETER:   dip     - inode of parent directory
 *              dentry  - dentry of object to be removed
 *
 * RETURN:      errors from subroutines
 *
 * note:
 * temporary file: if one or more processes have the file open
 * when the last link is removed, the link will be removed before
 * unlink() returns, but the removal of the file contents will be
 * postponed until all references to the files are closed.
 *
 * JFS does NOT support unlink() on directories.
 *
 */
static int jfs_unlink(struct inode *dip, struct dentry *dentry)
{
        int rc;
        tid_t tid;              /* transaction id */
        struct inode *ip = d_inode(dentry);
        ino_t ino;
        struct component_name dname;    /* object name */
        struct inode *iplist[2];
        struct tblock *tblk;
        s64 new_size = 0;
        int commit_flag;

        jfs_info("jfs_unlink: dip:0x%p name:%pd", dip, dentry);

        /* Init inode for quota operations. */
        rc = dquot_initialize(dip);
        if (rc)
                goto out;
        rc = dquot_initialize(ip);
        if (rc)
                goto out;

        if ((rc = get_UCSname(&dname, dentry)))
                goto out;

        IWRITE_LOCK(ip, RDWRLOCK_NORMAL);

        tid = txBegin(dip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dip)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        iplist[0] = dip;
        iplist[1] = ip;

        /*
         * delete the entry of target file from parent directory
         */
        ino = ip->i_ino;
        if ((rc = dtDelete(tid, dip, &dname, &ino, JFS_REMOVE))) {
                jfs_err("jfs_unlink: dtDelete returned %d", rc);
                if (rc == -EIO)
                        txAbort(tid, 1);        /* Marks FS Dirty */
                txEnd(tid);
                mutex_unlock(&JFS_IP(ip)->commit_mutex);
                mutex_unlock(&JFS_IP(dip)->commit_mutex);
                IWRITE_UNLOCK(ip);
                goto out1;
        }

        ASSERT(ip->i_nlink);

        ip->i_ctime = dip->i_ctime = dip->i_mtime = CURRENT_TIME;
        mark_inode_dirty(dip);

        /* update target's inode */
        inode_dec_link_count(ip);

        /*
         *      commit zero link count object
         */
        if (ip->i_nlink == 0) {
                assert(!test_cflag(COMMIT_Nolink, ip));
                /* free block resources */
                if ((new_size = commitZeroLink(tid, ip)) < 0) {
                        txAbort(tid, 1);        /* Marks FS Dirty */
                        txEnd(tid);
                        mutex_unlock(&JFS_IP(ip)->commit_mutex);
                        mutex_unlock(&JFS_IP(dip)->commit_mutex);
                        IWRITE_UNLOCK(ip);
                        rc = new_size;
                        goto out1;
                }
                tblk = tid_to_tblock(tid);
                tblk->xflag |= COMMIT_DELETE;
                tblk->u.ip = ip;
        }

        /*
         * Incomplete truncate of file data can
         * result in timing problems unless we synchronously commit the
         * transaction.
         */
        if (new_size)
                commit_flag = COMMIT_SYNC;
        else
                commit_flag = 0;

        /*
         * If xtTruncate was incomplete, commit synchronously to avoid
         * timing complications
         */
        rc = txCommit(tid, 2, &iplist[0], commit_flag);

        txEnd(tid);

        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dip)->commit_mutex);

        while (new_size && (rc == 0)) {
                tid = txBegin(dip->i_sb, 0);
                mutex_lock(&JFS_IP(ip)->commit_mutex);
                new_size = xtTruncate_pmap(tid, ip, new_size);
                if (new_size < 0) {
                        txAbort(tid, 1);        /* Marks FS Dirty */
                        rc = new_size;
                } else
                        rc = txCommit(tid, 2, &iplist[0], COMMIT_SYNC);
                txEnd(tid);
                mutex_unlock(&JFS_IP(ip)->commit_mutex);
        }

        if (ip->i_nlink == 0)
                set_cflag(COMMIT_Nolink, ip);

        IWRITE_UNLOCK(ip);

        /*
         * Truncating the directory index table is not guaranteed.  It
         * may need to be done iteratively
         */
        if (test_cflag(COMMIT_Stale, dip)) {
                if (dip->i_size > 1)
                        jfs_truncate_nolock(dip, 0);

                clear_cflag(COMMIT_Stale, dip);
        }

      out1:
        free_UCSname(&dname);
      out:
        jfs_info("jfs_unlink: rc:%d", rc);
        return rc;
}

/*
 * NAME:        commitZeroLink()
 *
 * FUNCTION:    for non-directory, called by jfs_remove(),
 *              truncate a regular file, directory or symbolic
 *              link to zero length. return 0 if type is not
 *              one of these.
 *
 *              if the file is currently associated with a VM segment
 *              only permanent disk and inode map resources are freed,
 *              and neither the inode nor indirect blocks are modified
 *              so that the resources can be later freed in the work
 *              map by ctrunc1.
 *              if there is no VM segment on entry, the resources are
 *              freed in both work and permanent map.
 *              (? for temporary file - memory object is cached even
 *              after no reference:
 *              reference count > 0 -   )
 *
 * PARAMETERS:  cd      - pointer to commit data structure.
 *                        current inode is the one to truncate.
 *
 * RETURN:      Errors from subroutines
 */
static s64 commitZeroLink(tid_t tid, struct inode *ip)
{
        int filetype;
        struct tblock *tblk;

        jfs_info("commitZeroLink: tid = %d, ip = 0x%p", tid, ip);

        filetype = ip->i_mode & S_IFMT;
        switch (filetype) {
        case S_IFREG:
                break;
        case S_IFLNK:
                /* fast symbolic link */
                if (ip->i_size < IDATASIZE) {
                        ip->i_size = 0;
                        return 0;
                }
                break;
        default:
                assert(filetype != S_IFDIR);
                return 0;
        }

        set_cflag(COMMIT_Freewmap, ip);

        /* mark transaction of block map update type */
        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_PMAP;

        /*
         * free EA
         */
        if (JFS_IP(ip)->ea.flag & DXD_EXTENT)
                /* acquire maplock on EA to be freed from block map */
                txEA(tid, ip, &JFS_IP(ip)->ea, NULL);

        /*
         * free ACL
         */
        if (JFS_IP(ip)->acl.flag & DXD_EXTENT)
                /* acquire maplock on EA to be freed from block map */
                txEA(tid, ip, &JFS_IP(ip)->acl, NULL);

        /*
         * free xtree/data (truncate to zero length):
         * free xtree/data pages from cache if COMMIT_PWMAP,
         * free xtree/data blocks from persistent block map, and
         * free xtree/data blocks from working block map if COMMIT_PWMAP;
         */
        if (ip->i_size)
                return xtTruncate_pmap(tid, ip, 0);

        return 0;
}


/*
 * NAME:        jfs_free_zero_link()
 *
 * FUNCTION:    for non-directory, called by iClose(),
 *              free resources of a file from cache and WORKING map
 *              for a file previously committed with zero link count
 *              while associated with a pager object,
 *
 * PARAMETER:   ip      - pointer to inode of file.
 */
void jfs_free_zero_link(struct inode *ip)
{
        int type;

        jfs_info("jfs_free_zero_link: ip = 0x%p", ip);

        /* return if not reg or symbolic link or if size is
         * already ok.
         */
        type = ip->i_mode & S_IFMT;

        switch (type) {
        case S_IFREG:
                break;
        case S_IFLNK:
                /* if its contained in inode nothing to do */
                if (ip->i_size < IDATASIZE)
                        return;
                break;
        default:
                return;
        }

        /*
         * free EA
         */
        if (JFS_IP(ip)->ea.flag & DXD_EXTENT) {
                s64 xaddr = addressDXD(&JFS_IP(ip)->ea);
                int xlen = lengthDXD(&JFS_IP(ip)->ea);
                struct maplock maplock; /* maplock for COMMIT_WMAP */
                struct pxd_lock *pxdlock;       /* maplock for COMMIT_WMAP */

                /* free EA pages from cache */
                invalidate_dxd_metapages(ip, JFS_IP(ip)->ea);

                /* free EA extent from working block map */
                maplock.index = 1;
                pxdlock = (struct pxd_lock *) & maplock;
                pxdlock->flag = mlckFREEPXD;
                PXDaddress(&pxdlock->pxd, xaddr);
                PXDlength(&pxdlock->pxd, xlen);
                txFreeMap(ip, pxdlock, NULL, COMMIT_WMAP);
        }

        /*
         * free ACL
         */
        if (JFS_IP(ip)->acl.flag & DXD_EXTENT) {
                s64 xaddr = addressDXD(&JFS_IP(ip)->acl);
                int xlen = lengthDXD(&JFS_IP(ip)->acl);
                struct maplock maplock; /* maplock for COMMIT_WMAP */
                struct pxd_lock *pxdlock;       /* maplock for COMMIT_WMAP */

                invalidate_dxd_metapages(ip, JFS_IP(ip)->acl);

                /* free ACL extent from working block map */
                maplock.index = 1;
                pxdlock = (struct pxd_lock *) & maplock;
                pxdlock->flag = mlckFREEPXD;
                PXDaddress(&pxdlock->pxd, xaddr);
                PXDlength(&pxdlock->pxd, xlen);
                txFreeMap(ip, pxdlock, NULL, COMMIT_WMAP);
        }

        /*
         * free xtree/data (truncate to zero length):
         * free xtree/data pages from cache, and
         * free xtree/data blocks from working block map;
         */
        if (ip->i_size)
                xtTruncate(0, ip, 0, COMMIT_WMAP);
}

/*
 * NAME:        jfs_link(vp, dvp, name, crp)
 *
 * FUNCTION:    create a link to <vp> by the name = <name>
 *              in the parent directory <dvp>
 *
 * PARAMETER:   vp      - target object
 *              dvp     - parent directory of new link
 *              name    - name of new link to target object
 *              crp     - credential
 *
 * RETURN:      Errors from subroutines
 *
 * note:
 * JFS does NOT support link() on directories (to prevent circular
 * path in the directory hierarchy);
 * EPERM: the target object is a directory, and either the caller
 * does not have appropriate privileges or the implementation prohibits
 * using link() on directories [XPG4.2].
 *
 * JFS does NOT support links between file systems:
 * EXDEV: target object and new link are on different file systems and
 * implementation does not support links between file systems [XPG4.2].
 */
static int jfs_link(struct dentry *old_dentry,
             struct inode *dir, struct dentry *dentry)
{
        int rc;
        tid_t tid;
        struct inode *ip = d_inode(old_dentry);
        ino_t ino;
        struct component_name dname;
        struct btstack btstack;
        struct inode *iplist[2];

        jfs_info("jfs_link: %pd %pd", old_dentry, dentry);

        rc = dquot_initialize(dir);
        if (rc)
                goto out;

        tid = txBegin(ip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dir)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        /*
         * scan parent directory for entry/freespace
         */
        if ((rc = get_UCSname(&dname, dentry)))
                goto out_tx;

        if ((rc = dtSearch(dir, &dname, &ino, &btstack, JFS_CREATE)))
                goto free_dname;

        /*
         * create entry for new link in parent directory
         */
        ino = ip->i_ino;
        if ((rc = dtInsert(tid, dir, &dname, &ino, &btstack)))
                goto free_dname;

        /* update object inode */
        inc_nlink(ip);          /* for new link */
        ip->i_ctime = CURRENT_TIME;
        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
        mark_inode_dirty(dir);
        ihold(ip);

        iplist[0] = ip;
        iplist[1] = dir;
        rc = txCommit(tid, 2, &iplist[0], 0);

        if (rc) {
                drop_nlink(ip); /* never instantiated */
                iput(ip);
        } else
                d_instantiate(dentry, ip);

      free_dname:
        free_UCSname(&dname);

      out_tx:
        txEnd(tid);

        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dir)->commit_mutex);

      out:
        jfs_info("jfs_link: rc:%d", rc);
        return rc;
}

/*
 * NAME:        jfs_symlink(dip, dentry, name)
 *
 * FUNCTION:    creates a symbolic link to <symlink> by name <name>
 *                      in directory <dip>
 *
 * PARAMETER:   dip     - parent directory vnode
 *              dentry  - dentry of symbolic link
 *              name    - the path name of the existing object
 *                        that will be the source of the link
 *
 * RETURN:      errors from subroutines
 *
 * note:
 * ENAMETOOLONG: pathname resolution of a symbolic link produced
 * an intermediate result whose length exceeds PATH_MAX [XPG4.2]
*/

static int jfs_symlink(struct inode *dip, struct dentry *dentry,
                const char *name)
{
        int rc;
        tid_t tid;
        ino_t ino = 0;
        struct component_name dname;
        int ssize;              /* source pathname size */
        struct btstack btstack;
        struct inode *ip = d_inode(dentry);
        s64 xlen = 0;
        int bmask = 0, xsize;
        s64 xaddr;
        struct metapage *mp;
        struct super_block *sb;
        struct tblock *tblk;

        struct inode *iplist[2];

        jfs_info("jfs_symlink: dip:0x%p name:%s", dip, name);

        rc = dquot_initialize(dip);
        if (rc)
                goto out1;

        ssize = strlen(name) + 1;

        /*
         * search parent directory for entry/freespace
         * (dtSearch() returns parent directory page pinned)
         */

        if ((rc = get_UCSname(&dname, dentry)))
                goto out1;

        /*
         * allocate on-disk/in-memory inode for symbolic link:
         * (iAlloc() returns new, locked inode)
         */
        ip = ialloc(dip, S_IFLNK | 0777);
        if (IS_ERR(ip)) {
                rc = PTR_ERR(ip);
                goto out2;
        }

        tid = txBegin(dip->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dip)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        rc = jfs_init_security(tid, ip, dip, &dentry->d_name);
        if (rc)
                goto out3;

        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_CREATE;
        tblk->ino = ip->i_ino;
        tblk->u.ixpxd = JFS_IP(ip)->ixpxd;

        /* fix symlink access permission
         * (dir_create() ANDs in the u.u_cmask,
         * but symlinks really need to be 777 access)
         */
        ip->i_mode |= 0777;

        /*
         * write symbolic link target path name
         */
        xtInitRoot(tid, ip);

        /*
         * write source path name inline in on-disk inode (fast symbolic link)
         */

        if (ssize <= IDATASIZE) {
                ip->i_op = &jfs_fast_symlink_inode_operations;

                ip->i_link = JFS_IP(ip)->i_inline;
                memcpy(ip->i_link, name, ssize);
                ip->i_size = ssize - 1;

                /*
                 * if symlink is > 128 bytes, we don't have the space to
                 * store inline extended attributes
                 */
                if (ssize > sizeof (JFS_IP(ip)->i_inline))
                        JFS_IP(ip)->mode2 &= ~INLINEEA;

                jfs_info("jfs_symlink: fast symlink added  ssize:%d name:%s ",
                         ssize, name);
        }
        /*
         * write source path name in a single extent
         */
        else {
                jfs_info("jfs_symlink: allocate extent ip:0x%p", ip);

                ip->i_op = &jfs_symlink_inode_operations;
                inode_nohighmem(ip);
                ip->i_mapping->a_ops = &jfs_aops;

                /*
                 * even though the data of symlink object (source
                 * path name) is treated as non-journaled user data,
                 * it is read/written thru buffer cache for performance.
                 */
                sb = ip->i_sb;
                bmask = JFS_SBI(sb)->bsize - 1;
                xsize = (ssize + bmask) & ~bmask;
                xaddr = 0;
                xlen = xsize >> JFS_SBI(sb)->l2bsize;
                if ((rc = xtInsert(tid, ip, 0, 0, xlen, &xaddr, 0))) {
                        txAbort(tid, 0);

                        goto out3;
                }
                ip->i_size = ssize - 1;
                while (ssize) {
                        /* This is kind of silly since PATH_MAX == 4K */
                        int copy_size = min(ssize, PSIZE);

                        mp = get_metapage(ip, xaddr, PSIZE, 1);

                        if (mp == NULL) {
                                xtTruncate(tid, ip, 0, COMMIT_PWMAP);
                                rc = -EIO;
                                txAbort(tid, 0);
                                goto out3;
                        }
                        memcpy(mp->data, name, copy_size);
                        flush_metapage(mp);
                        ssize -= copy_size;
                        name += copy_size;
                        xaddr += JFS_SBI(sb)->nbperpage;
                }
        }

        /*
         * create entry for symbolic link in parent directory
         */
        rc = dtSearch(dip, &dname, &ino, &btstack, JFS_CREATE);
        if (rc == 0) {
                ino = ip->i_ino;
                rc = dtInsert(tid, dip, &dname, &ino, &btstack);
        }
        if (rc) {
                if (xlen)
                        xtTruncate(tid, ip, 0, COMMIT_PWMAP);
                txAbort(tid, 0);
                /* discard new inode */
                goto out3;
        }

        mark_inode_dirty(ip);

        dip->i_ctime = dip->i_mtime = CURRENT_TIME;
        mark_inode_dirty(dip);
        /*
         * commit update of parent directory and link object
         */

        iplist[0] = dip;
        iplist[1] = ip;
        rc = txCommit(tid, 2, &iplist[0], 0);

      out3:
        txEnd(tid);
        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dip)->commit_mutex);
        if (rc) {
                free_ea_wmap(ip);
                clear_nlink(ip);
                unlock_new_inode(ip);
                iput(ip);
        } else {
                unlock_new_inode(ip);
                d_instantiate(dentry, ip);
        }

      out2:
        free_UCSname(&dname);

      out1:
        jfs_info("jfs_symlink: rc:%d", rc);
        return rc;
}


/*
 * NAME:        jfs_rename
 *
 * FUNCTION:    rename a file or directory
 */
static int jfs_rename(struct inode *old_dir, struct dentry *old_dentry,
               struct inode *new_dir, struct dentry *new_dentry)
{
        struct btstack btstack;
        ino_t ino;
        struct component_name new_dname;
        struct inode *new_ip;
        struct component_name old_dname;
        struct inode *old_ip;
        int rc;
        tid_t tid;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct lv *lv;
        int ipcount;
        struct inode *iplist[4];
        struct tblock *tblk;
        s64 new_size = 0;
        int commit_flag;


        jfs_info("jfs_rename: %pd %pd", old_dentry, new_dentry);

        rc = dquot_initialize(old_dir);
        if (rc)
                goto out1;
        rc = dquot_initialize(new_dir);
        if (rc)
                goto out1;

        old_ip = d_inode(old_dentry);
        new_ip = d_inode(new_dentry);

        if ((rc = get_UCSname(&old_dname, old_dentry)))
                goto out1;

        if ((rc = get_UCSname(&new_dname, new_dentry)))
                goto out2;

        /*
         * Make sure source inode number is what we think it is
         */
        rc = dtSearch(old_dir, &old_dname, &ino, &btstack, JFS_LOOKUP);
        if (rc || (ino != old_ip->i_ino)) {
                rc = -ENOENT;
                goto out3;
        }

        /*
         * Make sure dest inode number (if any) is what we think it is
         */
        rc = dtSearch(new_dir, &new_dname, &ino, &btstack, JFS_LOOKUP);
        if (!rc) {
                if ((!new_ip) || (ino != new_ip->i_ino)) {
                        rc = -ESTALE;
                        goto out3;
                }
        } else if (rc != -ENOENT)
                goto out3;
        else if (new_ip) {
                /* no entry exists, but one was expected */
                rc = -ESTALE;
                goto out3;
        }

        if (S_ISDIR(old_ip->i_mode)) {
                if (new_ip) {
                        if (!dtEmpty(new_ip)) {
                                rc = -ENOTEMPTY;
                                goto out3;
                        }
                }
        } else if (new_ip) {
                IWRITE_LOCK(new_ip, RDWRLOCK_NORMAL);
                /* Init inode for quota operations. */
                rc = dquot_initialize(new_ip);
                if (rc)
                        goto out_unlock;
        }

        /*
         * The real work starts here
         */
        tid = txBegin(new_dir->i_sb, 0);

        /*
         * How do we know the locking is safe from deadlocks?
         * The vfs does the hard part for us.  Any time we are taking nested
         * commit_mutexes, the vfs already has i_mutex held on the parent.
         * Here, the vfs has already taken i_mutex on both old_dir and new_dir.
         */
        mutex_lock_nested(&JFS_IP(new_dir)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(old_ip)->commit_mutex, COMMIT_MUTEX_CHILD);
        if (old_dir != new_dir)
                mutex_lock_nested(&JFS_IP(old_dir)->commit_mutex,
                                  COMMIT_MUTEX_SECOND_PARENT);

        if (new_ip) {
                mutex_lock_nested(&JFS_IP(new_ip)->commit_mutex,
                                  COMMIT_MUTEX_VICTIM);
                /*
                 * Change existing directory entry to new inode number
                 */
                ino = new_ip->i_ino;
                rc = dtModify(tid, new_dir, &new_dname, &ino,
                              old_ip->i_ino, JFS_RENAME);
                if (rc)
                        goto out_tx;
                drop_nlink(new_ip);
                if (S_ISDIR(new_ip->i_mode)) {
                        drop_nlink(new_ip);
                        if (new_ip->i_nlink) {
                                mutex_unlock(&JFS_IP(new_ip)->commit_mutex);
                                if (old_dir != new_dir)
                                        mutex_unlock(&JFS_IP(old_dir)->commit_mutex);
                                mutex_unlock(&JFS_IP(old_ip)->commit_mutex);
                                mutex_unlock(&JFS_IP(new_dir)->commit_mutex);
                                if (!S_ISDIR(old_ip->i_mode) && new_ip)
                                        IWRITE_UNLOCK(new_ip);
                                jfs_error(new_ip->i_sb,
                                          "new_ip->i_nlink != 0\n");
                                return -EIO;
                        }
                        tblk = tid_to_tblock(tid);
                        tblk->xflag |= COMMIT_DELETE;
                        tblk->u.ip = new_ip;
                } else if (new_ip->i_nlink == 0) {
                        assert(!test_cflag(COMMIT_Nolink, new_ip));
                        /* free block resources */
                        if ((new_size = commitZeroLink(tid, new_ip)) < 0) {
                                txAbort(tid, 1);        /* Marks FS Dirty */
                                rc = new_size;
                                goto out_tx;
                        }
                        tblk = tid_to_tblock(tid);
                        tblk->xflag |= COMMIT_DELETE;
                        tblk->u.ip = new_ip;
                } else {
                        new_ip->i_ctime = CURRENT_TIME;
                        mark_inode_dirty(new_ip);
                }
        } else {
                /*
                 * Add new directory entry
                 */
                rc = dtSearch(new_dir, &new_dname, &ino, &btstack,
                              JFS_CREATE);
                if (rc) {
                        jfs_err("jfs_rename didn't expect dtSearch to fail w/rc = %d",
                                rc);
                        goto out_tx;
                }

                ino = old_ip->i_ino;
                rc = dtInsert(tid, new_dir, &new_dname, &ino, &btstack);
                if (rc) {
                        if (rc == -EIO)
                                jfs_err("jfs_rename: dtInsert returned -EIO");
                        goto out_tx;
                }
                if (S_ISDIR(old_ip->i_mode))
                        inc_nlink(new_dir);
        }
        /*
         * Remove old directory entry
         */

        ino = old_ip->i_ino;
        rc = dtDelete(tid, old_dir, &old_dname, &ino, JFS_REMOVE);
        if (rc) {
                jfs_err("jfs_rename did not expect dtDelete to return rc = %d",
                        rc);
                txAbort(tid, 1);        /* Marks Filesystem dirty */
                goto out_tx;
        }
        if (S_ISDIR(old_ip->i_mode)) {
                drop_nlink(old_dir);
                if (old_dir != new_dir) {
                        /*
                         * Change inode number of parent for moved directory
                         */

                        JFS_IP(old_ip)->i_dtroot.header.idotdot =
                                cpu_to_le32(new_dir->i_ino);

                        /* Linelock header of dtree */
                        tlck = txLock(tid, old_ip,
                                    (struct metapage *) &JFS_IP(old_ip)->bxflag,
                                      tlckDTREE | tlckBTROOT | tlckRELINK);
                        dtlck = (struct dt_lock *) & tlck->lock;
                        ASSERT(dtlck->index == 0);
                        lv = & dtlck->lv[0];
                        lv->offset = 0;
                        lv->length = 1;
                        dtlck->index++;
                }
        }

        /*
         * Update ctime on changed/moved inodes & mark dirty
         */
        old_ip->i_ctime = CURRENT_TIME;
        mark_inode_dirty(old_ip);

        new_dir->i_ctime = new_dir->i_mtime = current_fs_time(new_dir->i_sb);
        mark_inode_dirty(new_dir);

        /* Build list of inodes modified by this transaction */
        ipcount = 0;
        iplist[ipcount++] = old_ip;
        if (new_ip)
                iplist[ipcount++] = new_ip;
        iplist[ipcount++] = old_dir;

        if (old_dir != new_dir) {
                iplist[ipcount++] = new_dir;
                old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
                mark_inode_dirty(old_dir);
        }

        /*
         * Incomplete truncate of file data can
         * result in timing problems unless we synchronously commit the
         * transaction.
         */
        if (new_size)
                commit_flag = COMMIT_SYNC;
        else
                commit_flag = 0;

        rc = txCommit(tid, ipcount, iplist, commit_flag);

      out_tx:
        txEnd(tid);
        if (new_ip)
                mutex_unlock(&JFS_IP(new_ip)->commit_mutex);
        if (old_dir != new_dir)
                mutex_unlock(&JFS_IP(old_dir)->commit_mutex);
        mutex_unlock(&JFS_IP(old_ip)->commit_mutex);
        mutex_unlock(&JFS_IP(new_dir)->commit_mutex);

        while (new_size && (rc == 0)) {
                tid = txBegin(new_ip->i_sb, 0);
                mutex_lock(&JFS_IP(new_ip)->commit_mutex);
                new_size = xtTruncate_pmap(tid, new_ip, new_size);
                if (new_size < 0) {
                        txAbort(tid, 1);
                        rc = new_size;
                } else
                        rc = txCommit(tid, 1, &new_ip, COMMIT_SYNC);
                txEnd(tid);
                mutex_unlock(&JFS_IP(new_ip)->commit_mutex);
        }
        if (new_ip && (new_ip->i_nlink == 0))
                set_cflag(COMMIT_Nolink, new_ip);
        /*
         * Truncating the directory index table is not guaranteed.  It
         * may need to be done iteratively
         */
        if (test_cflag(COMMIT_Stale, old_dir)) {
                if (old_dir->i_size > 1)
                        jfs_truncate_nolock(old_dir, 0);

                clear_cflag(COMMIT_Stale, old_dir);
        }
      out_unlock:
        if (new_ip && !S_ISDIR(new_ip->i_mode))
                IWRITE_UNLOCK(new_ip);
      out3:
        free_UCSname(&new_dname);
      out2:
        free_UCSname(&old_dname);
      out1:
        jfs_info("jfs_rename: returning %d", rc);
        return rc;
}


/*
 * NAME:        jfs_mknod
 *
 * FUNCTION:    Create a special file (device)
 */
static int jfs_mknod(struct inode *dir, struct dentry *dentry,
                umode_t mode, dev_t rdev)
{
        struct jfs_inode_info *jfs_ip;
        struct btstack btstack;
        struct component_name dname;
        ino_t ino;
        struct inode *ip;
        struct inode *iplist[2];
        int rc;
        tid_t tid;
        struct tblock *tblk;

        jfs_info("jfs_mknod: %pd", dentry);

        rc = dquot_initialize(dir);
        if (rc)
                goto out;

        if ((rc = get_UCSname(&dname, dentry)))
                goto out;

        ip = ialloc(dir, mode);
        if (IS_ERR(ip)) {
                rc = PTR_ERR(ip);
                goto out1;
        }
        jfs_ip = JFS_IP(ip);

        tid = txBegin(dir->i_sb, 0);

        mutex_lock_nested(&JFS_IP(dir)->commit_mutex, COMMIT_MUTEX_PARENT);
        mutex_lock_nested(&JFS_IP(ip)->commit_mutex, COMMIT_MUTEX_CHILD);

        rc = jfs_init_acl(tid, ip, dir);
        if (rc)
                goto out3;

        rc = jfs_init_security(tid, ip, dir, &dentry->d_name);
        if (rc) {
                txAbort(tid, 0);
                goto out3;
        }

        if ((rc = dtSearch(dir, &dname, &ino, &btstack, JFS_CREATE))) {
                txAbort(tid, 0);
                goto out3;
        }

        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_CREATE;
        tblk->ino = ip->i_ino;
        tblk->u.ixpxd = JFS_IP(ip)->ixpxd;

        ino = ip->i_ino;
        if ((rc = dtInsert(tid, dir, &dname, &ino, &btstack))) {
                txAbort(tid, 0);
                goto out3;
        }

        ip->i_op = &jfs_file_inode_operations;
        jfs_ip->dev = new_encode_dev(rdev);
        init_special_inode(ip, ip->i_mode, rdev);

        mark_inode_dirty(ip);

        dir->i_ctime = dir->i_mtime = CURRENT_TIME;

        mark_inode_dirty(dir);

        iplist[0] = dir;
        iplist[1] = ip;
        rc = txCommit(tid, 2, iplist, 0);

      out3:
        txEnd(tid);
        mutex_unlock(&JFS_IP(ip)->commit_mutex);
        mutex_unlock(&JFS_IP(dir)->commit_mutex);
        if (rc) {
                free_ea_wmap(ip);
                clear_nlink(ip);
                unlock_new_inode(ip);
                iput(ip);
        } else {
                unlock_new_inode(ip);
                d_instantiate(dentry, ip);
        }

      out1:
        free_UCSname(&dname);

      out:
        jfs_info("jfs_mknod: returning %d", rc);
        return rc;
}

static struct dentry *jfs_lookup(struct inode *dip, struct dentry *dentry, unsigned int flags)
{
        struct btstack btstack;
        ino_t inum;
        struct inode *ip;
        struct component_name key;
        int rc;

        jfs_info("jfs_lookup: name = %pd", dentry);

        if ((rc = get_UCSname(&key, dentry)))
                return ERR_PTR(rc);
        rc = dtSearch(dip, &key, &inum, &btstack, JFS_LOOKUP);
        free_UCSname(&key);
        if (rc == -ENOENT) {
                ip = NULL;
        } else if (rc) {
                jfs_err("jfs_lookup: dtSearch returned %d", rc);
                ip = ERR_PTR(rc);
        } else {
                ip = jfs_iget(dip->i_sb, inum);
                if (IS_ERR(ip))
                        jfs_err("jfs_lookup: iget failed on inum %d", (uint)inum);
        }

        return d_splice_alias(ip, dentry);
}

static struct inode *jfs_nfs_get_inode(struct super_block *sb,
                u64 ino, u32 generation)
{
        struct inode *inode;

        if (ino == 0)
                return ERR_PTR(-ESTALE);
        inode = jfs_iget(sb, ino);
        if (IS_ERR(inode))
                return ERR_CAST(inode);

        if (generation && inode->i_generation != generation) {
                iput(inode);
                return ERR_PTR(-ESTALE);
        }

        return inode;
}

struct dentry *jfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                                    jfs_nfs_get_inode);
}

struct dentry *jfs_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                                    jfs_nfs_get_inode);
}

struct dentry *jfs_get_parent(struct dentry *dentry)
{
        unsigned long parent_ino;

        parent_ino =
                le32_to_cpu(JFS_IP(d_inode(dentry))->i_dtroot.header.idotdot);

        return d_obtain_alias(jfs_iget(dentry->d_sb, parent_ino));
}

const struct inode_operations jfs_dir_inode_operations = {
        .create         = jfs_create,
        .lookup         = jfs_lookup,
        .link           = jfs_link,
        .unlink         = jfs_unlink,
        .symlink        = jfs_symlink,
        .mkdir          = jfs_mkdir,
        .rmdir          = jfs_rmdir,
        .mknod          = jfs_mknod,
        .rename         = jfs_rename,
        .setxattr       = generic_setxattr,
        .getxattr       = generic_getxattr,
        .listxattr      = jfs_listxattr,
        .removexattr    = generic_removexattr,
        .setattr        = jfs_setattr,
#ifdef CONFIG_JFS_POSIX_ACL
        .get_acl        = jfs_get_acl,
        .set_acl        = jfs_set_acl,
#endif
};

const struct file_operations jfs_dir_operations = {
        .read           = generic_read_dir,
        .iterate        = jfs_readdir,
        .fsync          = jfs_fsync,
        .unlocked_ioctl = jfs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = jfs_compat_ioctl,
#endif
        .llseek         = generic_file_llseek,
};

static int jfs_ci_hash(const struct dentry *dir, struct qstr *this)
{
        unsigned long hash;
        int i;

        hash = init_name_hash(dir);
        for (i=0; i < this->len; i++)
                hash = partial_name_hash(tolower(this->name[i]), hash);
        this->hash = end_name_hash(hash);

        return 0;
}

static int jfs_ci_compare(const struct dentry *dentry,
                unsigned int len, const char *str, const struct qstr *name)
{
        int i, result = 1;

        if (len != name->len)
                goto out;
        for (i=0; i < len; i++) {
                if (tolower(str[i]) != tolower(name->name[i]))
                        goto out;
        }
        result = 0;
out:
        return result;
}

static int jfs_ci_revalidate(struct dentry *dentry, unsigned int flags)
{
        /*
         * This is not negative dentry. Always valid.
         *
         * Note, rename() to existing directory entry will have ->d_inode,
         * and will use existing name which isn't specified name by user.
         *
         * We may be able to drop this positive dentry here. But dropping
         * positive dentry isn't good idea. So it's unsupported like
         * rename("filename", "FILENAME") for now.
         */
        if (d_really_is_positive(dentry))
                return 1;

        /*
         * This may be nfsd (or something), anyway, we can't see the
         * intent of this. So, since this can be for creation, drop it.
         */
        if (!flags)
                return 0;

        /*
         * Drop the negative dentry, in order to make sure to use the
         * case sensitive name which is specified by user if this is
         * for creation.
         */
        if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
                return 0;
        return 1;
}

const struct dentry_operations jfs_ci_dentry_operations =
{
        .d_hash = jfs_ci_hash,
        .d_compare = jfs_ci_compare,
        .d_revalidate = jfs_ci_revalidate,
};