Documentation/filesystems/files.txt: remove rcuref_inc_lf() reverences

[linux-2.6/mini2440.git] / fs / gfs2 / dir.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

/*
 * Implements Extendible Hashing as described in:
 *   "Extendible Hashing" by Fagin, et al in
 *     __ACM Trans. on Database Systems__, Sept 1979.
 *
 *
 * Here's the layout of dirents which is essentially the same as that of ext2
 * within a single block. The field de_name_len is the number of bytes
 * actually required for the name (no null terminator). The field de_rec_len
 * is the number of bytes allocated to the dirent. The offset of the next
 * dirent in the block is (dirent + dirent->de_rec_len). When a dirent is
 * deleted, the preceding dirent inherits its allocated space, ie
 * prev->de_rec_len += deleted->de_rec_len. Since the next dirent is obtained
 * by adding de_rec_len to the current dirent, this essentially causes the
 * deleted dirent to get jumped over when iterating through all the dirents.
 *
 * When deleting the first dirent in a block, there is no previous dirent so
 * the field de_ino is set to zero to designate it as deleted. When allocating
 * a dirent, gfs2_dirent_alloc iterates through the dirents in a block. If the
 * first dirent has (de_ino == 0) and de_rec_len is large enough, this first
 * dirent is allocated. Otherwise it must go through all the 'used' dirents
 * searching for one in which the amount of total space minus the amount of
 * used space will provide enough space for the new dirent.
 *
 * There are two types of blocks in which dirents reside. In a stuffed dinode,
 * the dirents begin at offset sizeof(struct gfs2_dinode) from the beginning of
 * the block.  In leaves, they begin at offset sizeof(struct gfs2_leaf) from the
 * beginning of the leaf block. The dirents reside in leaves when
 *
 * dip->i_di.di_flags & GFS2_DIF_EXHASH is true
 *
 * Otherwise, the dirents are "linear", within a single stuffed dinode block.
 *
 * When the dirents are in leaves, the actual contents of the directory file are
 * used as an array of 64-bit block pointers pointing to the leaf blocks. The
 * dirents are NOT in the directory file itself. There can be more than one
 * block pointer in the array that points to the same leaf. In fact, when a
 * directory is first converted from linear to exhash, all of the pointers
 * point to the same leaf.
 *
 * When a leaf is completely full, the size of the hash table can be
 * doubled unless it is already at the maximum size which is hard coded into
 * GFS2_DIR_MAX_DEPTH. After that, leaves are chained together in a linked list,
 * but never before the maximum hash table size has been reached.
 */

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/buffer_head.h>
#include <linux/sort.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/vmalloc.h>
#include <linux/lm_interface.h>

#include "gfs2.h"
#include "incore.h"
#include "dir.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"
#include "bmap.h"
#include "util.h"

#define IS_LEAF     1 /* Hashed (leaf) directory */
#define IS_DINODE   2 /* Linear (stuffed dinode block) directory */

#define gfs2_disk_hash2offset(h) (((u64)(h)) >> 1)
#define gfs2_dir_offset2hash(p) ((u32)(((u64)(p)) << 1))

typedef int (*leaf_call_t) (struct gfs2_inode *dip, u32 index, u32 len,
                            u64 leaf_no, void *data);
typedef int (*gfs2_dscan_t)(const struct gfs2_dirent *dent,
                            const struct qstr *name, void *opaque);


int gfs2_dir_get_new_buffer(struct gfs2_inode *ip, u64 block,
                            struct buffer_head **bhp)
{
        struct buffer_head *bh;

        bh = gfs2_meta_new(ip->i_gl, block);
        gfs2_trans_add_bh(ip->i_gl, bh, 1);
        gfs2_metatype_set(bh, GFS2_METATYPE_JD, GFS2_FORMAT_JD);
        gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header));
        *bhp = bh;
        return 0;
}

static int gfs2_dir_get_existing_buffer(struct gfs2_inode *ip, u64 block,
                                        struct buffer_head **bhp)
{
        struct buffer_head *bh;
        int error;

        error = gfs2_meta_read(ip->i_gl, block, DIO_WAIT, &bh);
        if (error)
                return error;
        if (gfs2_metatype_check(GFS2_SB(&ip->i_inode), bh, GFS2_METATYPE_JD)) {
                brelse(bh);
                return -EIO;
        }
        *bhp = bh;
        return 0;
}

static int gfs2_dir_write_stuffed(struct gfs2_inode *ip, const char *buf,
                                  unsigned int offset, unsigned int size)
{
        struct buffer_head *dibh;
        int error;

        error = gfs2_meta_inode_buffer(ip, &dibh);
        if (error)
                return error;

        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
        memcpy(dibh->b_data + offset + sizeof(struct gfs2_dinode), buf, size);
        if (ip->i_di.di_size < offset + size)
                ip->i_di.di_size = offset + size;
        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
        gfs2_dinode_out(ip, dibh->b_data);

        brelse(dibh);

        return size;
}



/**
 * gfs2_dir_write_data - Write directory information to the inode
 * @ip: The GFS2 inode
 * @buf: The buffer containing information to be written
 * @offset: The file offset to start writing at
 * @size: The amount of data to write
 *
 * Returns: The number of bytes correctly written or error code
 */
static int gfs2_dir_write_data(struct gfs2_inode *ip, const char *buf,
                               u64 offset, unsigned int size)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct buffer_head *dibh;
        u64 lblock, dblock;
        u32 extlen = 0;
        unsigned int o;
        int copied = 0;
        int error = 0;

        if (!size)
                return 0;

        if (gfs2_is_stuffed(ip) &&
            offset + size <= sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
                return gfs2_dir_write_stuffed(ip, buf, (unsigned int)offset,
                                              size);

        if (gfs2_assert_warn(sdp, gfs2_is_jdata(ip)))
                return -EINVAL;

        if (gfs2_is_stuffed(ip)) {
                error = gfs2_unstuff_dinode(ip, NULL);
                if (error)
                        return error;
        }

        lblock = offset;
        o = do_div(lblock, sdp->sd_jbsize) + sizeof(struct gfs2_meta_header);

        while (copied < size) {
                unsigned int amount;
                struct buffer_head *bh;
                int new = 0;

                amount = size - copied;
                if (amount > sdp->sd_sb.sb_bsize - o)
                        amount = sdp->sd_sb.sb_bsize - o;

                if (!extlen) {
                        new = 1;
                        error = gfs2_extent_map(&ip->i_inode, lblock, &new,
                                                &dblock, &extlen);
                        if (error)
                                goto fail;
                        error = -EIO;
                        if (gfs2_assert_withdraw(sdp, dblock))
                                goto fail;
                }

                if (amount == sdp->sd_jbsize || new)
                        error = gfs2_dir_get_new_buffer(ip, dblock, &bh);
                else
                        error = gfs2_dir_get_existing_buffer(ip, dblock, &bh);

                if (error)
                        goto fail;

                gfs2_trans_add_bh(ip->i_gl, bh, 1);
                memcpy(bh->b_data + o, buf, amount);
                brelse(bh);

                buf += amount;
                copied += amount;
                lblock++;
                dblock++;
                extlen--;

                o = sizeof(struct gfs2_meta_header);
        }

out:
        error = gfs2_meta_inode_buffer(ip, &dibh);
        if (error)
                return error;

        if (ip->i_di.di_size < offset + copied)
                ip->i_di.di_size = offset + copied;
        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;

        gfs2_trans_add_bh(ip->i_gl, dibh, 1);
        gfs2_dinode_out(ip, dibh->b_data);
        brelse(dibh);

        return copied;
fail:
        if (copied)
                goto out;
        return error;
}

static int gfs2_dir_read_stuffed(struct gfs2_inode *ip, char *buf,
                                 u64 offset, unsigned int size)
{
        struct buffer_head *dibh;
        int error;

        error = gfs2_meta_inode_buffer(ip, &dibh);
        if (!error) {
                offset += sizeof(struct gfs2_dinode);
                memcpy(buf, dibh->b_data + offset, size);
                brelse(dibh);
        }

        return (error) ? error : size;
}


/**
 * gfs2_dir_read_data - Read a data from a directory inode
 * @ip: The GFS2 Inode
 * @buf: The buffer to place result into
 * @offset: File offset to begin jdata_readng from
 * @size: Amount of data to transfer
 *
 * Returns: The amount of data actually copied or the error
 */
static int gfs2_dir_read_data(struct gfs2_inode *ip, char *buf, u64 offset,
                              unsigned int size, unsigned ra)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        u64 lblock, dblock;
        u32 extlen = 0;
        unsigned int o;
        int copied = 0;
        int error = 0;

        if (offset >= ip->i_di.di_size)
                return 0;

        if (offset + size > ip->i_di.di_size)
                size = ip->i_di.di_size - offset;

        if (!size)
                return 0;

        if (gfs2_is_stuffed(ip))
                return gfs2_dir_read_stuffed(ip, buf, offset, size);

        if (gfs2_assert_warn(sdp, gfs2_is_jdata(ip)))
                return -EINVAL;

        lblock = offset;
        o = do_div(lblock, sdp->sd_jbsize) + sizeof(struct gfs2_meta_header);

        while (copied < size) {
                unsigned int amount;
                struct buffer_head *bh;
                int new;

                amount = size - copied;
                if (amount > sdp->sd_sb.sb_bsize - o)
                        amount = sdp->sd_sb.sb_bsize - o;

                if (!extlen) {
                        new = 0;
                        error = gfs2_extent_map(&ip->i_inode, lblock, &new,
                                                &dblock, &extlen);
                        if (error || !dblock)
                                goto fail;
                        BUG_ON(extlen < 1);
                        if (!ra)
                                extlen = 1;
                        bh = gfs2_meta_ra(ip->i_gl, dblock, extlen);
                } else {
                        error = gfs2_meta_read(ip->i_gl, dblock, DIO_WAIT, &bh);
                        if (error)
                                goto fail;
                }
                error = gfs2_metatype_check(sdp, bh, GFS2_METATYPE_JD);
                if (error) {
                        brelse(bh);
                        goto fail;
                }
                dblock++;
                extlen--;
                memcpy(buf, bh->b_data + o, amount);
                brelse(bh);
                buf += amount;
                copied += amount;
                lblock++;
                o = sizeof(struct gfs2_meta_header);
        }

        return copied;
fail:
        return (copied) ? copied : error;
}

static inline int gfs2_dirent_sentinel(const struct gfs2_dirent *dent)
{
        return dent->de_inum.no_addr == 0 || dent->de_inum.no_formal_ino == 0;
}

static inline int __gfs2_dirent_find(const struct gfs2_dirent *dent,
                                     const struct qstr *name, int ret)
{
        if (!gfs2_dirent_sentinel(dent) &&
            be32_to_cpu(dent->de_hash) == name->hash &&
            be16_to_cpu(dent->de_name_len) == name->len &&
            memcmp(dent+1, name->name, name->len) == 0)
                return ret;
        return 0;
}

static int gfs2_dirent_find(const struct gfs2_dirent *dent,
                            const struct qstr *name,
                            void *opaque)
{
        return __gfs2_dirent_find(dent, name, 1);
}

static int gfs2_dirent_prev(const struct gfs2_dirent *dent,
                            const struct qstr *name,
                            void *opaque)
{
        return __gfs2_dirent_find(dent, name, 2);
}

/*
 * name->name holds ptr to start of block.
 * name->len holds size of block.
 */
static int gfs2_dirent_last(const struct gfs2_dirent *dent,
                            const struct qstr *name,
                            void *opaque)
{
        const char *start = name->name;
        const char *end = (const char *)dent + be16_to_cpu(dent->de_rec_len);
        if (name->len == (end - start))
                return 1;
        return 0;
}

static int gfs2_dirent_find_space(const struct gfs2_dirent *dent,
                                  const struct qstr *name,
                                  void *opaque)
{
        unsigned required = GFS2_DIRENT_SIZE(name->len);
        unsigned actual = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
        unsigned totlen = be16_to_cpu(dent->de_rec_len);

        if (gfs2_dirent_sentinel(dent))
                actual = GFS2_DIRENT_SIZE(0);
        if (totlen - actual >= required)
                return 1;
        return 0;
}

struct dirent_gather {
        const struct gfs2_dirent **pdent;
        unsigned offset;
};

static int gfs2_dirent_gather(const struct gfs2_dirent *dent,
                              const struct qstr *name,
                              void *opaque)
{
        struct dirent_gather *g = opaque;
        if (!gfs2_dirent_sentinel(dent)) {
                g->pdent[g->offset++] = dent;
        }
        return 0;
}

/*
 * Other possible things to check:
 * - Inode located within filesystem size (and on valid block)
 * - Valid directory entry type
 * Not sure how heavy-weight we want to make this... could also check
 * hash is correct for example, but that would take a lot of extra time.
 * For now the most important thing is to check that the various sizes
 * are correct.
 */
static int gfs2_check_dirent(struct gfs2_dirent *dent, unsigned int offset,
                             unsigned int size, unsigned int len, int first)
{
        const char *msg = "gfs2_dirent too small";
        if (unlikely(size < sizeof(struct gfs2_dirent)))
                goto error;
        msg = "gfs2_dirent misaligned";
        if (unlikely(offset & 0x7))
                goto error;
        msg = "gfs2_dirent points beyond end of block";
        if (unlikely(offset + size > len))
                goto error;
        msg = "zero inode number";
        if (unlikely(!first && gfs2_dirent_sentinel(dent)))
                goto error;
        msg = "name length is greater than space in dirent";
        if (!gfs2_dirent_sentinel(dent) &&
            unlikely(sizeof(struct gfs2_dirent)+be16_to_cpu(dent->de_name_len) >
                     size))
                goto error;
        return 0;
error:
        printk(KERN_WARNING "gfs2_check_dirent: %s (%s)\n", msg,
               first ? "first in block" : "not first in block");
        return -EIO;
}

static int gfs2_dirent_offset(const void *buf)
{
        const struct gfs2_meta_header *h = buf;
        int offset;

        BUG_ON(buf == NULL);

        switch(be32_to_cpu(h->mh_type)) {
        case GFS2_METATYPE_LF:
                offset = sizeof(struct gfs2_leaf);
                break;
        case GFS2_METATYPE_DI:
                offset = sizeof(struct gfs2_dinode);
                break;
        default:
                goto wrong_type;
        }
        return offset;
wrong_type:
        printk(KERN_WARNING "gfs2_scan_dirent: wrong block type %u\n",
               be32_to_cpu(h->mh_type));
        return -1;
}

static struct gfs2_dirent *gfs2_dirent_scan(struct inode *inode, void *buf,
                                            unsigned int len, gfs2_dscan_t scan,
                                            const struct qstr *name,
                                            void *opaque)
{
        struct gfs2_dirent *dent, *prev;
        unsigned offset;
        unsigned size;
        int ret = 0;

        ret = gfs2_dirent_offset(buf);
        if (ret < 0)
                goto consist_inode;

        offset = ret;
        prev = NULL;
        dent = buf + offset;
        size = be16_to_cpu(dent->de_rec_len);
        if (gfs2_check_dirent(dent, offset, size, len, 1))
                goto consist_inode;
        do {
                ret = scan(dent, name, opaque);
                if (ret)
                        break;
                offset += size;
                if (offset == len)
                        break;
                prev = dent;
                dent = buf + offset;
                size = be16_to_cpu(dent->de_rec_len);
                if (gfs2_check_dirent(dent, offset, size, len, 0))
                        goto consist_inode;
        } while(1);

        switch(ret) {
        case 0:
                return NULL;
        case 1:
                return dent;
        case 2:
                return prev ? prev : dent;
        default:
                BUG_ON(ret > 0);
                return ERR_PTR(ret);
        }

consist_inode:
        gfs2_consist_inode(GFS2_I(inode));
        return ERR_PTR(-EIO);
}


/**
 * dirent_first - Return the first dirent
 * @dip: the directory
 * @bh: The buffer
 * @dent: Pointer to list of dirents
 *
 * return first dirent whether bh points to leaf or stuffed dinode
 *
 * Returns: IS_LEAF, IS_DINODE, or -errno
 */

static int dirent_first(struct gfs2_inode *dip, struct buffer_head *bh,
                        struct gfs2_dirent **dent)
{
        struct gfs2_meta_header *h = (struct gfs2_meta_header *)bh->b_data;

        if (be32_to_cpu(h->mh_type) == GFS2_METATYPE_LF) {
                if (gfs2_meta_check(GFS2_SB(&dip->i_inode), bh))
                        return -EIO;
                *dent = (struct gfs2_dirent *)(bh->b_data +
                                               sizeof(struct gfs2_leaf));
                return IS_LEAF;
        } else {
                if (gfs2_metatype_check(GFS2_SB(&dip->i_inode), bh, GFS2_METATYPE_DI))
                        return -EIO;
                *dent = (struct gfs2_dirent *)(bh->b_data +
                                               sizeof(struct gfs2_dinode));
                return IS_DINODE;
        }
}

static int dirent_check_reclen(struct gfs2_inode *dip,
                               const struct gfs2_dirent *d, const void *end_p)
{
        const void *ptr = d;
        u16 rec_len = be16_to_cpu(d->de_rec_len);

        if (unlikely(rec_len < sizeof(struct gfs2_dirent)))
                goto broken;
        ptr += rec_len;
        if (ptr < end_p)
                return rec_len;
        if (ptr == end_p)
                return -ENOENT;
broken:
        gfs2_consist_inode(dip);
        return -EIO;
}

/**
 * dirent_next - Next dirent
 * @dip: the directory
 * @bh: The buffer
 * @dent: Pointer to list of dirents
 *
 * Returns: 0 on success, error code otherwise
 */

static int dirent_next(struct gfs2_inode *dip, struct buffer_head *bh,
                       struct gfs2_dirent **dent)
{
        struct gfs2_dirent *cur = *dent, *tmp;
        char *bh_end = bh->b_data + bh->b_size;
        int ret;

        ret = dirent_check_reclen(dip, cur, bh_end);
        if (ret < 0)
                return ret;

        tmp = (void *)cur + ret;
        ret = dirent_check_reclen(dip, tmp, bh_end);
        if (ret == -EIO)
                return ret;

        /* Only the first dent could ever have de_inum.no_addr == 0 */
        if (gfs2_dirent_sentinel(tmp)) {
                gfs2_consist_inode(dip);
                return -EIO;
        }

        *dent = tmp;
        return 0;
}

/**
 * dirent_del - Delete a dirent
 * @dip: The GFS2 inode
 * @bh: The buffer
 * @prev: The previous dirent
 * @cur: The current dirent
 *
 */

static void dirent_del(struct gfs2_inode *dip, struct buffer_head *bh,
                       struct gfs2_dirent *prev, struct gfs2_dirent *cur)
{
        u16 cur_rec_len, prev_rec_len;

        if (gfs2_dirent_sentinel(cur)) {
                gfs2_consist_inode(dip);
                return;
        }

        gfs2_trans_add_bh(dip->i_gl, bh, 1);

        /* If there is no prev entry, this is the first entry in the block.
           The de_rec_len is already as big as it needs to be.  Just zero
           out the inode number and return.  */

        if (!prev) {
                cur->de_inum.no_addr = 0;
                cur->de_inum.no_formal_ino = 0;
                return;
        }

        /*  Combine this dentry with the previous one.  */

        prev_rec_len = be16_to_cpu(prev->de_rec_len);
        cur_rec_len = be16_to_cpu(cur->de_rec_len);

        if ((char *)prev + prev_rec_len != (char *)cur)
                gfs2_consist_inode(dip);
        if ((char *)cur + cur_rec_len > bh->b_data + bh->b_size)
                gfs2_consist_inode(dip);

        prev_rec_len += cur_rec_len;
        prev->de_rec_len = cpu_to_be16(prev_rec_len);
}

/*
 * Takes a dent from which to grab space as an argument. Returns the
 * newly created dent.
 */
static struct gfs2_dirent *gfs2_init_dirent(struct inode *inode,
                                            struct gfs2_dirent *dent,
                                            const struct qstr *name,
                                            struct buffer_head *bh)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_dirent *ndent;
        unsigned offset = 0, totlen;

        if (!gfs2_dirent_sentinel(dent))
                offset = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
        totlen = be16_to_cpu(dent->de_rec_len);
        BUG_ON(offset + name->len > totlen);
        gfs2_trans_add_bh(ip->i_gl, bh, 1);
        ndent = (struct gfs2_dirent *)((char *)dent + offset);
        dent->de_rec_len = cpu_to_be16(offset);
        gfs2_qstr2dirent(name, totlen - offset, ndent);
        return ndent;
}

static struct gfs2_dirent *gfs2_dirent_alloc(struct inode *inode,
                                             struct buffer_head *bh,
                                             const struct qstr *name)
{
        struct gfs2_dirent *dent;
        dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
                                gfs2_dirent_find_space, name, NULL);
        if (!dent || IS_ERR(dent))
                return dent;
        return gfs2_init_dirent(inode, dent, name, bh);
}

static int get_leaf(struct gfs2_inode *dip, u64 leaf_no,
                    struct buffer_head **bhp)
{
        int error;

        error = gfs2_meta_read(dip->i_gl, leaf_no, DIO_WAIT, bhp);
        if (!error && gfs2_metatype_check(GFS2_SB(&dip->i_inode), *bhp, GFS2_METATYPE_LF)) {
                /* printk(KERN_INFO "block num=%llu\n", leaf_no); */
                error = -EIO;
        }

        return error;
}

/**
 * get_leaf_nr - Get a leaf number associated with the index
 * @dip: The GFS2 inode
 * @index:
 * @leaf_out:
 *
 * Returns: 0 on success, error code otherwise
 */

static int get_leaf_nr(struct gfs2_inode *dip, u32 index,
                       u64 *leaf_out)
{
        __be64 leaf_no;
        int error;

        error = gfs2_dir_read_data(dip, (char *)&leaf_no,
                                    index * sizeof(__be64),
                                    sizeof(__be64), 0);
        if (error != sizeof(u64))
                return (error < 0) ? error : -EIO;

        *leaf_out = be64_to_cpu(leaf_no);

        return 0;
}

static int get_first_leaf(struct gfs2_inode *dip, u32 index,
                          struct buffer_head **bh_out)
{
        u64 leaf_no;
        int error;

        error = get_leaf_nr(dip, index, &leaf_no);
        if (!error)
                error = get_leaf(dip, leaf_no, bh_out);

        return error;
}

static struct gfs2_dirent *gfs2_dirent_search(struct inode *inode,
                                              const struct qstr *name,
                                              gfs2_dscan_t scan,
                                              struct buffer_head **pbh)
{
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        struct gfs2_inode *ip = GFS2_I(inode);
        int error;

        if (ip->i_di.di_flags & GFS2_DIF_EXHASH) {
                struct gfs2_leaf *leaf;
                unsigned hsize = 1 << ip->i_di.di_depth;
                unsigned index;
                u64 ln;
                if (hsize * sizeof(u64) != ip->i_di.di_size) {
                        gfs2_consist_inode(ip);
                        return ERR_PTR(-EIO);
                }

                index = name->hash >> (32 - ip->i_di.di_depth);
                error = get_first_leaf(ip, index, &bh);
                if (error)
                        return ERR_PTR(error);
                do {
                        dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
                                                scan, name, NULL);
                        if (dent)
                                goto got_dent;
                        leaf = (struct gfs2_leaf *)bh->b_data;
                        ln = be64_to_cpu(leaf->lf_next);
                        brelse(bh);
                        if (!ln)
                                break;

                        error = get_leaf(ip, ln, &bh);
                } while(!error);

                return error ? ERR_PTR(error) : NULL;
        }


        error = gfs2_meta_inode_buffer(ip, &bh);
        if (error)
                return ERR_PTR(error);
        dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size, scan, name, NULL);
got_dent:
        if (unlikely(dent == NULL || IS_ERR(dent))) {
                brelse(bh);
                bh = NULL;
        }
        *pbh = bh;
        return dent;
}

static struct gfs2_leaf *new_leaf(struct inode *inode, struct buffer_head **pbh, u16 depth)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        u64 bn = gfs2_alloc_meta(ip);
        struct buffer_head *bh = gfs2_meta_new(ip->i_gl, bn);
        struct gfs2_leaf *leaf;
        struct gfs2_dirent *dent;
        struct qstr name = { .name = "", .len = 0, .hash = 0 };
        if (!bh)
                return NULL;

        gfs2_trans_add_bh(ip->i_gl, bh, 1);
        gfs2_metatype_set(bh, GFS2_METATYPE_LF, GFS2_FORMAT_LF);
        leaf = (struct gfs2_leaf *)bh->b_data;
        leaf->lf_depth = cpu_to_be16(depth);
        leaf->lf_entries = 0;
        leaf->lf_dirent_format = cpu_to_be32(GFS2_FORMAT_DE);
        leaf->lf_next = 0;
        memset(leaf->lf_reserved, 0, sizeof(leaf->lf_reserved));
        dent = (struct gfs2_dirent *)(leaf+1);
        gfs2_qstr2dirent(&name, bh->b_size - sizeof(struct gfs2_leaf), dent);
        *pbh = bh;
        return leaf;
}

/**
 * dir_make_exhash - Convert a stuffed directory into an ExHash directory
 * @dip: The GFS2 inode
 *
 * Returns: 0 on success, error code otherwise
 */

static int dir_make_exhash(struct inode *inode)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct gfs2_dirent *dent;
        struct qstr args;
        struct buffer_head *bh, *dibh;
        struct gfs2_leaf *leaf;
        int y;
        u32 x;
        __be64 *lp;
        u64 bn;
        int error;

        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (error)
                return error;

        /*  Turn over a new leaf  */

        leaf = new_leaf(inode, &bh, 0);
        if (!leaf)
                return -ENOSPC;
        bn = bh->b_blocknr;

        gfs2_assert(sdp, dip->i_di.di_entries < (1 << 16));
        leaf->lf_entries = cpu_to_be16(dip->i_di.di_entries);

        /*  Copy dirents  */

        gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_leaf), dibh,
                             sizeof(struct gfs2_dinode));

        /*  Find last entry  */

        x = 0;
        args.len = bh->b_size - sizeof(struct gfs2_dinode) +
                   sizeof(struct gfs2_leaf);
        args.name = bh->b_data;
        dent = gfs2_dirent_scan(&dip->i_inode, bh->b_data, bh->b_size,
                                gfs2_dirent_last, &args, NULL);
        if (!dent) {
                brelse(bh);
                brelse(dibh);
                return -EIO;
        }
        if (IS_ERR(dent)) {
                brelse(bh);
                brelse(dibh);
                return PTR_ERR(dent);
        }

        /*  Adjust the last dirent's record length
           (Remember that dent still points to the last entry.)  */

        dent->de_rec_len = cpu_to_be16(be16_to_cpu(dent->de_rec_len) +
                sizeof(struct gfs2_dinode) -
                sizeof(struct gfs2_leaf));

        brelse(bh);

        /*  We're done with the new leaf block, now setup the new
            hash table.  */

        gfs2_trans_add_bh(dip->i_gl, dibh, 1);
        gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));

        lp = (__be64 *)(dibh->b_data + sizeof(struct gfs2_dinode));

        for (x = sdp->sd_hash_ptrs; x--; lp++)
                *lp = cpu_to_be64(bn);

        dip->i_di.di_size = sdp->sd_sb.sb_bsize / 2;
        dip->i_di.di_blocks++;
        gfs2_set_inode_blocks(&dip->i_inode);
        dip->i_di.di_flags |= GFS2_DIF_EXHASH;

        for (x = sdp->sd_hash_ptrs, y = -1; x; x >>= 1, y++) ;
        dip->i_di.di_depth = y;

        gfs2_dinode_out(dip, dibh->b_data);

        brelse(dibh);

        return 0;
}

/**
 * dir_split_leaf - Split a leaf block into two
 * @dip: The GFS2 inode
 * @index:
 * @leaf_no:
 *
 * Returns: 0 on success, error code on failure
 */

static int dir_split_leaf(struct inode *inode, const struct qstr *name)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        struct buffer_head *nbh, *obh, *dibh;
        struct gfs2_leaf *nleaf, *oleaf;
        struct gfs2_dirent *dent = NULL, *prev = NULL, *next = NULL, *new;
        u32 start, len, half_len, divider;
        u64 bn, leaf_no;
        __be64 *lp;
        u32 index;
        int x, moved = 0;
        int error;

        index = name->hash >> (32 - dip->i_di.di_depth);
        error = get_leaf_nr(dip, index, &leaf_no);
        if (error)
                return error;

        /*  Get the old leaf block  */
        error = get_leaf(dip, leaf_no, &obh);
        if (error)
                return error;

        oleaf = (struct gfs2_leaf *)obh->b_data;
        if (dip->i_di.di_depth == be16_to_cpu(oleaf->lf_depth)) {
                brelse(obh);
                return 1; /* can't split */
        }

        gfs2_trans_add_bh(dip->i_gl, obh, 1);

        nleaf = new_leaf(inode, &nbh, be16_to_cpu(oleaf->lf_depth) + 1);
        if (!nleaf) {
                brelse(obh);
                return -ENOSPC;
        }
        bn = nbh->b_blocknr;

        /*  Compute the start and len of leaf pointers in the hash table.  */
        len = 1 << (dip->i_di.di_depth - be16_to_cpu(oleaf->lf_depth));
        half_len = len >> 1;
        if (!half_len) {
                printk(KERN_WARNING "di_depth %u lf_depth %u index %u\n", dip->i_di.di_depth, be16_to_cpu(oleaf->lf_depth), index);
                gfs2_consist_inode(dip);
                error = -EIO;
                goto fail_brelse;
        }

        start = (index & ~(len - 1));

        /* Change the pointers.
           Don't bother distinguishing stuffed from non-stuffed.
           This code is complicated enough already. */
        lp = kmalloc(half_len * sizeof(__be64), GFP_NOFS | __GFP_NOFAIL);
        /*  Change the pointers  */
        for (x = 0; x < half_len; x++)
                lp[x] = cpu_to_be64(bn);

        error = gfs2_dir_write_data(dip, (char *)lp, start * sizeof(u64),
                                    half_len * sizeof(u64));
        if (error != half_len * sizeof(u64)) {
                if (error >= 0)
                        error = -EIO;
                goto fail_lpfree;
        }

        kfree(lp);

        /*  Compute the divider  */
        divider = (start + half_len) << (32 - dip->i_di.di_depth);

        /*  Copy the entries  */
        dirent_first(dip, obh, &dent);

        do {
                next = dent;
                if (dirent_next(dip, obh, &next))
                        next = NULL;

                if (!gfs2_dirent_sentinel(dent) &&
                    be32_to_cpu(dent->de_hash) < divider) {
                        struct qstr str;
                        str.name = (char*)(dent+1);
                        str.len = be16_to_cpu(dent->de_name_len);
                        str.hash = be32_to_cpu(dent->de_hash);
                        new = gfs2_dirent_alloc(inode, nbh, &str);
                        if (IS_ERR(new)) {
                                error = PTR_ERR(new);
                                break;
                        }

                        new->de_inum = dent->de_inum; /* No endian worries */
                        new->de_type = dent->de_type; /* No endian worries */
                        nleaf->lf_entries = cpu_to_be16(be16_to_cpu(nleaf->lf_entries)+1);

                        dirent_del(dip, obh, prev, dent);

                        if (!oleaf->lf_entries)
                                gfs2_consist_inode(dip);
                        oleaf->lf_entries = cpu_to_be16(be16_to_cpu(oleaf->lf_entries)-1);

                        if (!prev)
                                prev = dent;

                        moved = 1;
                } else {
                        prev = dent;
                }
                dent = next;
        } while (dent);

        oleaf->lf_depth = nleaf->lf_depth;

        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (!gfs2_assert_withdraw(GFS2_SB(&dip->i_inode), !error)) {
                gfs2_trans_add_bh(dip->i_gl, dibh, 1);
                dip->i_di.di_blocks++;
                gfs2_set_inode_blocks(&dip->i_inode);
                gfs2_dinode_out(dip, dibh->b_data);
                brelse(dibh);
        }

        brelse(obh);
        brelse(nbh);

        return error;

fail_lpfree:
        kfree(lp);

fail_brelse:
        brelse(obh);
        brelse(nbh);
        return error;
}

/**
 * dir_double_exhash - Double size of ExHash table
 * @dip: The GFS2 dinode
 *
 * Returns: 0 on success, error code on failure
 */

static int dir_double_exhash(struct gfs2_inode *dip)
{
        struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
        struct buffer_head *dibh;
        u32 hsize;
        u64 *buf;
        u64 *from, *to;
        u64 block;
        int x;
        int error = 0;

        hsize = 1 << dip->i_di.di_depth;
        if (hsize * sizeof(u64) != dip->i_di.di_size) {
                gfs2_consist_inode(dip);
                return -EIO;
        }

        /*  Allocate both the "from" and "to" buffers in one big chunk  */

        buf = kcalloc(3, sdp->sd_hash_bsize, GFP_KERNEL | __GFP_NOFAIL);

        for (block = dip->i_di.di_size >> sdp->sd_hash_bsize_shift; block--;) {
                error = gfs2_dir_read_data(dip, (char *)buf,
                                            block * sdp->sd_hash_bsize,
                                            sdp->sd_hash_bsize, 1);
                if (error != sdp->sd_hash_bsize) {
                        if (error >= 0)
                                error = -EIO;
                        goto fail;
                }

                from = buf;
                to = (u64 *)((char *)buf + sdp->sd_hash_bsize);

                for (x = sdp->sd_hash_ptrs; x--; from++) {
                        *to++ = *from;  /*  No endianess worries  */
                        *to++ = *from;
                }

                error = gfs2_dir_write_data(dip,
                                             (char *)buf + sdp->sd_hash_bsize,
                                             block * sdp->sd_sb.sb_bsize,
                                             sdp->sd_sb.sb_bsize);
                if (error != sdp->sd_sb.sb_bsize) {
                        if (error >= 0)
                                error = -EIO;
                        goto fail;
                }
        }

        kfree(buf);

        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (!gfs2_assert_withdraw(sdp, !error)) {
                dip->i_di.di_depth++;
                gfs2_dinode_out(dip, dibh->b_data);
                brelse(dibh);
        }

        return error;

fail:
        kfree(buf);
        return error;
}

/**
 * compare_dents - compare directory entries by hash value
 * @a: first dent
 * @b: second dent
 *
 * When comparing the hash entries of @a to @b:
 *   gt: returns 1
 *   lt: returns -1
 *   eq: returns 0
 */

static int compare_dents(const void *a, const void *b)
{
        const struct gfs2_dirent *dent_a, *dent_b;
        u32 hash_a, hash_b;
        int ret = 0;

        dent_a = *(const struct gfs2_dirent **)a;
        hash_a = be32_to_cpu(dent_a->de_hash);

        dent_b = *(const struct gfs2_dirent **)b;
        hash_b = be32_to_cpu(dent_b->de_hash);

        if (hash_a > hash_b)
                ret = 1;
        else if (hash_a < hash_b)
                ret = -1;
        else {
                unsigned int len_a = be16_to_cpu(dent_a->de_name_len);
                unsigned int len_b = be16_to_cpu(dent_b->de_name_len);

                if (len_a > len_b)
                        ret = 1;
                else if (len_a < len_b)
                        ret = -1;
                else
                        ret = memcmp(dent_a + 1, dent_b + 1, len_a);
        }

        return ret;
}

/**
 * do_filldir_main - read out directory entries
 * @dip: The GFS2 inode
 * @offset: The offset in the file to read from
 * @opaque: opaque data to pass to filldir
 * @filldir: The function to pass entries to
 * @darr: an array of struct gfs2_dirent pointers to read
 * @entries: the number of entries in darr
 * @copied: pointer to int that's non-zero if a entry has been copied out
 *
 * Jump through some hoops to make sure that if there are hash collsions,
 * they are read out at the beginning of a buffer.  We want to minimize
 * the possibility that they will fall into different readdir buffers or
 * that someone will want to seek to that location.
 *
 * Returns: errno, >0 on exception from filldir
 */

static int do_filldir_main(struct gfs2_inode *dip, u64 *offset,
                           void *opaque, filldir_t filldir,
                           const struct gfs2_dirent **darr, u32 entries,
                           int *copied)
{
        const struct gfs2_dirent *dent, *dent_next;
        u64 off, off_next;
        unsigned int x, y;
        int run = 0;
        int error = 0;

        sort(darr, entries, sizeof(struct gfs2_dirent *), compare_dents, NULL);

        dent_next = darr[0];
        off_next = be32_to_cpu(dent_next->de_hash);
        off_next = gfs2_disk_hash2offset(off_next);

        for (x = 0, y = 1; x < entries; x++, y++) {
                dent = dent_next;
                off = off_next;

                if (y < entries) {
                        dent_next = darr[y];
                        off_next = be32_to_cpu(dent_next->de_hash);
                        off_next = gfs2_disk_hash2offset(off_next);

                        if (off < *offset)
                                continue;
                        *offset = off;

                        if (off_next == off) {
                                if (*copied && !run)
                                        return 1;
                                run = 1;
                        } else
                                run = 0;
                } else {
                        if (off < *offset)
                                continue;
                        *offset = off;
                }

                error = filldir(opaque, (const char *)(dent + 1),
                                be16_to_cpu(dent->de_name_len),
                                off, be64_to_cpu(dent->de_inum.no_addr),
                                be16_to_cpu(dent->de_type));
                if (error)
                        return 1;

                *copied = 1;
        }

        /* Increment the *offset by one, so the next time we come into the
           do_filldir fxn, we get the next entry instead of the last one in the
           current leaf */

        (*offset)++;

        return 0;
}

static int gfs2_dir_read_leaf(struct inode *inode, u64 *offset, void *opaque,
                              filldir_t filldir, int *copied, unsigned *depth,
                              u64 leaf_no)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct buffer_head *bh;
        struct gfs2_leaf *lf;
        unsigned entries = 0, entries2 = 0;
        unsigned leaves = 0;
        const struct gfs2_dirent **darr, *dent;
        struct dirent_gather g;
        struct buffer_head **larr;
        int leaf = 0;
        int error, i;
        u64 lfn = leaf_no;

        do {
                error = get_leaf(ip, lfn, &bh);
                if (error)
                        goto out;
                lf = (struct gfs2_leaf *)bh->b_data;
                if (leaves == 0)
                        *depth = be16_to_cpu(lf->lf_depth);
                entries += be16_to_cpu(lf->lf_entries);
                leaves++;
                lfn = be64_to_cpu(lf->lf_next);
                brelse(bh);
        } while(lfn);

        if (!entries)
                return 0;

        error = -ENOMEM;
        /*
         * The extra 99 entries are not normally used, but are a buffer
         * zone in case the number of entries in the leaf is corrupt.
         * 99 is the maximum number of entries that can fit in a single
         * leaf block.
         */
        larr = vmalloc((leaves + entries + 99) * sizeof(void *));
        if (!larr)
                goto out;
        darr = (const struct gfs2_dirent **)(larr + leaves);
        g.pdent = darr;
        g.offset = 0;
        lfn = leaf_no;

        do {
                error = get_leaf(ip, lfn, &bh);
                if (error)
                        goto out_kfree;
                lf = (struct gfs2_leaf *)bh->b_data;
                lfn = be64_to_cpu(lf->lf_next);
                if (lf->lf_entries) {
                        entries2 += be16_to_cpu(lf->lf_entries);
                        dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
                                                gfs2_dirent_gather, NULL, &g);
                        error = PTR_ERR(dent);
                        if (IS_ERR(dent))
                                goto out_kfree;
                        if (entries2 != g.offset) {
                                fs_warn(sdp, "Number of entries corrupt in dir "
                                                "leaf %llu, entries2 (%u) != "
                                                "g.offset (%u)\n",
                                        (unsigned long long)bh->b_blocknr,
                                        entries2, g.offset);
                                        
                                error = -EIO;
                                goto out_kfree;
                        }
                        error = 0;
                        larr[leaf++] = bh;
                } else {
                        brelse(bh);
                }
        } while(lfn);

        BUG_ON(entries2 != entries);
        error = do_filldir_main(ip, offset, opaque, filldir, darr,
                                entries, copied);
out_kfree:
        for(i = 0; i < leaf; i++)
                brelse(larr[i]);
        vfree(larr);
out:
        return error;
}

/**
 * dir_e_read - Reads the entries from a directory into a filldir buffer
 * @dip: dinode pointer
 * @offset: the hash of the last entry read shifted to the right once
 * @opaque: buffer for the filldir function to fill
 * @filldir: points to the filldir function to use
 *
 * Returns: errno
 */

static int dir_e_read(struct inode *inode, u64 *offset, void *opaque,
                      filldir_t filldir)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        u32 hsize, len = 0;
        u32 ht_offset, lp_offset, ht_offset_cur = -1;
        u32 hash, index;
        __be64 *lp;
        int copied = 0;
        int error = 0;
        unsigned depth = 0;

        hsize = 1 << dip->i_di.di_depth;
        if (hsize * sizeof(u64) != dip->i_di.di_size) {
                gfs2_consist_inode(dip);
                return -EIO;
        }

        hash = gfs2_dir_offset2hash(*offset);
        index = hash >> (32 - dip->i_di.di_depth);

        lp = kmalloc(sdp->sd_hash_bsize, GFP_KERNEL);
        if (!lp)
                return -ENOMEM;

        while (index < hsize) {
                lp_offset = index & (sdp->sd_hash_ptrs - 1);
                ht_offset = index - lp_offset;

                if (ht_offset_cur != ht_offset) {
                        error = gfs2_dir_read_data(dip, (char *)lp,
                                                ht_offset * sizeof(__be64),
                                                sdp->sd_hash_bsize, 1);
                        if (error != sdp->sd_hash_bsize) {
                                if (error >= 0)
                                        error = -EIO;
                                goto out;
                        }
                        ht_offset_cur = ht_offset;
                }

                error = gfs2_dir_read_leaf(inode, offset, opaque, filldir,
                                           &copied, &depth,
                                           be64_to_cpu(lp[lp_offset]));
                if (error)
                        break;

                len = 1 << (dip->i_di.di_depth - depth);
                index = (index & ~(len - 1)) + len;
        }

out:
        kfree(lp);
        if (error > 0)
                error = 0;
        return error;
}

int gfs2_dir_read(struct inode *inode, u64 *offset, void *opaque,
                  filldir_t filldir)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct dirent_gather g;
        const struct gfs2_dirent **darr, *dent;
        struct buffer_head *dibh;
        int copied = 0;
        int error;

        if (!dip->i_di.di_entries)
                return 0;

        if (dip->i_di.di_flags & GFS2_DIF_EXHASH)
                return dir_e_read(inode, offset, opaque, filldir);

        if (!gfs2_is_stuffed(dip)) {
                gfs2_consist_inode(dip);
                return -EIO;
        }

        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (error)
                return error;

        error = -ENOMEM;
        /* 96 is max number of dirents which can be stuffed into an inode */
        darr = kmalloc(96 * sizeof(struct gfs2_dirent *), GFP_KERNEL);
        if (darr) {
                g.pdent = darr;
                g.offset = 0;
                dent = gfs2_dirent_scan(inode, dibh->b_data, dibh->b_size,
                                        gfs2_dirent_gather, NULL, &g);
                if (IS_ERR(dent)) {
                        error = PTR_ERR(dent);
                        goto out;
                }
                if (dip->i_di.di_entries != g.offset) {
                        fs_warn(sdp, "Number of entries corrupt in dir %llu, "
                                "ip->i_di.di_entries (%u) != g.offset (%u)\n",
                                (unsigned long long)dip->i_no_addr,
                                dip->i_di.di_entries,
                                g.offset);
                        error = -EIO;
                        goto out;
                }
                error = do_filldir_main(dip, offset, opaque, filldir, darr,
                                        dip->i_di.di_entries, &copied);
out:
                kfree(darr);
        }

        if (error > 0)
                error = 0;

        brelse(dibh);

        return error;
}

/**
 * gfs2_dir_search - Search a directory
 * @dip: The GFS2 inode
 * @filename:
 * @inode:
 *
 * This routine searches a directory for a file or another directory.
 * Assumes a glock is held on dip.
 *
 * Returns: errno
 */

struct inode *gfs2_dir_search(struct inode *dir, const struct qstr *name)
{
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        struct inode *inode;

        dent = gfs2_dirent_search(dir, name, gfs2_dirent_find, &bh);
        if (dent) {
                if (IS_ERR(dent))
                        return ERR_PTR(PTR_ERR(dent));
                inode = gfs2_inode_lookup(dir->i_sb, 
                                be16_to_cpu(dent->de_type),
                                be64_to_cpu(dent->de_inum.no_addr),
                                be64_to_cpu(dent->de_inum.no_formal_ino), 0);
                brelse(bh);
                return inode;
        }
        return ERR_PTR(-ENOENT);
}

int gfs2_dir_check(struct inode *dir, const struct qstr *name,
                   const struct gfs2_inode *ip)
{
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        int ret = -ENOENT;

        dent = gfs2_dirent_search(dir, name, gfs2_dirent_find, &bh);
        if (dent) {
                if (IS_ERR(dent))
                        return PTR_ERR(dent);
                if (ip) {
                        if (be64_to_cpu(dent->de_inum.no_addr) != ip->i_no_addr)
                                goto out;
                        if (be64_to_cpu(dent->de_inum.no_formal_ino) !=
                            ip->i_no_formal_ino)
                                goto out;
                        if (unlikely(IF2DT(ip->i_inode.i_mode) !=
                            be16_to_cpu(dent->de_type))) {
                                gfs2_consist_inode(GFS2_I(dir));
                                ret = -EIO;
                                goto out;
                        }
                }
                ret = 0;
out:
                brelse(bh);
        }
        return ret;
}

static int dir_new_leaf(struct inode *inode, const struct qstr *name)
{
        struct buffer_head *bh, *obh;
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_leaf *leaf, *oleaf;
        int error;
        u32 index;
        u64 bn;

        index = name->hash >> (32 - ip->i_di.di_depth);
        error = get_first_leaf(ip, index, &obh);
        if (error)
                return error;
        do {
                oleaf = (struct gfs2_leaf *)obh->b_data;
                bn = be64_to_cpu(oleaf->lf_next);
                if (!bn)
                        break;
                brelse(obh);
                error = get_leaf(ip, bn, &obh);
                if (error)
                        return error;
        } while(1);

        gfs2_trans_add_bh(ip->i_gl, obh, 1);

        leaf = new_leaf(inode, &bh, be16_to_cpu(oleaf->lf_depth));
        if (!leaf) {
                brelse(obh);
                return -ENOSPC;
        }
        oleaf->lf_next = cpu_to_be64(bh->b_blocknr);
        brelse(bh);
        brelse(obh);

        error = gfs2_meta_inode_buffer(ip, &bh);
        if (error)
                return error;
        gfs2_trans_add_bh(ip->i_gl, bh, 1);
        ip->i_di.di_blocks++;
        gfs2_set_inode_blocks(&ip->i_inode);
        gfs2_dinode_out(ip, bh->b_data);
        brelse(bh);
        return 0;
}

/**
 * gfs2_dir_add - Add new filename into directory
 * @dip: The GFS2 inode
 * @filename: The new name
 * @inode: The inode number of the entry
 * @type: The type of the entry
 *
 * Returns: 0 on success, error code on failure
 */

int gfs2_dir_add(struct inode *inode, const struct qstr *name,
                 const struct gfs2_inode *nip, unsigned type)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        struct gfs2_leaf *leaf;
        int error;

        while(1) {
                dent = gfs2_dirent_search(inode, name, gfs2_dirent_find_space,
                                          &bh);
                if (dent) {
                        if (IS_ERR(dent))
                                return PTR_ERR(dent);
                        dent = gfs2_init_dirent(inode, dent, name, bh);
                        gfs2_inum_out(nip, dent);
                        dent->de_type = cpu_to_be16(type);
                        if (ip->i_di.di_flags & GFS2_DIF_EXHASH) {
                                leaf = (struct gfs2_leaf *)bh->b_data;
                                leaf->lf_entries = cpu_to_be16(be16_to_cpu(leaf->lf_entries) + 1);
                        }
                        brelse(bh);
                        error = gfs2_meta_inode_buffer(ip, &bh);
                        if (error)
                                break;
                        gfs2_trans_add_bh(ip->i_gl, bh, 1);
                        ip->i_di.di_entries++;
                        ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
                        gfs2_dinode_out(ip, bh->b_data);
                        brelse(bh);
                        error = 0;
                        break;
                }
                if (!(ip->i_di.di_flags & GFS2_DIF_EXHASH)) {
                        error = dir_make_exhash(inode);
                        if (error)
                                break;
                        continue;
                }
                error = dir_split_leaf(inode, name);
                if (error == 0)
                        continue;
                if (error < 0)
                        break;
                if (ip->i_di.di_depth < GFS2_DIR_MAX_DEPTH) {
                        error = dir_double_exhash(ip);
                        if (error)
                                break;
                        error = dir_split_leaf(inode, name);
                        if (error < 0)
                                break;
                        if (error == 0)
                                continue;
                }
                error = dir_new_leaf(inode, name);
                if (!error)
                        continue;
                error = -ENOSPC;
                break;
        }
        return error;
}


/**
 * gfs2_dir_del - Delete a directory entry
 * @dip: The GFS2 inode
 * @filename: The filename
 *
 * Returns: 0 on success, error code on failure
 */

int gfs2_dir_del(struct gfs2_inode *dip, const struct qstr *name)
{
        struct gfs2_dirent *dent, *prev = NULL;
        struct buffer_head *bh;
        int error;

        /* Returns _either_ the entry (if its first in block) or the
           previous entry otherwise */
        dent = gfs2_dirent_search(&dip->i_inode, name, gfs2_dirent_prev, &bh);
        if (!dent) {
                gfs2_consist_inode(dip);
                return -EIO;
        }
        if (IS_ERR(dent)) {
                gfs2_consist_inode(dip);
                return PTR_ERR(dent);
        }
        /* If not first in block, adjust pointers accordingly */
        if (gfs2_dirent_find(dent, name, NULL) == 0) {
                prev = dent;
                dent = (struct gfs2_dirent *)((char *)dent + be16_to_cpu(prev->de_rec_len));
        }

        dirent_del(dip, bh, prev, dent);
        if (dip->i_di.di_flags & GFS2_DIF_EXHASH) {
                struct gfs2_leaf *leaf = (struct gfs2_leaf *)bh->b_data;
                u16 entries = be16_to_cpu(leaf->lf_entries);
                if (!entries)
                        gfs2_consist_inode(dip);
                leaf->lf_entries = cpu_to_be16(--entries);
        }
        brelse(bh);

        error = gfs2_meta_inode_buffer(dip, &bh);
        if (error)
                return error;

        if (!dip->i_di.di_entries)
                gfs2_consist_inode(dip);
        gfs2_trans_add_bh(dip->i_gl, bh, 1);
        dip->i_di.di_entries--;
        dip->i_inode.i_mtime = dip->i_inode.i_ctime = CURRENT_TIME;
        gfs2_dinode_out(dip, bh->b_data);
        brelse(bh);
        mark_inode_dirty(&dip->i_inode);

        return error;
}

/**
 * gfs2_dir_mvino - Change inode number of directory entry
 * @dip: The GFS2 inode
 * @filename:
 * @new_inode:
 *
 * This routine changes the inode number of a directory entry.  It's used
 * by rename to change ".." when a directory is moved.
 * Assumes a glock is held on dvp.
 *
 * Returns: errno
 */

int gfs2_dir_mvino(struct gfs2_inode *dip, const struct qstr *filename,
                   const struct gfs2_inode *nip, unsigned int new_type)
{
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        int error;

        dent = gfs2_dirent_search(&dip->i_inode, filename, gfs2_dirent_find, &bh);
        if (!dent) {
                gfs2_consist_inode(dip);
                return -EIO;
        }
        if (IS_ERR(dent))
                return PTR_ERR(dent);

        gfs2_trans_add_bh(dip->i_gl, bh, 1);
        gfs2_inum_out(nip, dent);
        dent->de_type = cpu_to_be16(new_type);

        if (dip->i_di.di_flags & GFS2_DIF_EXHASH) {
                brelse(bh);
                error = gfs2_meta_inode_buffer(dip, &bh);
                if (error)
                        return error;
                gfs2_trans_add_bh(dip->i_gl, bh, 1);
        }

        dip->i_inode.i_mtime = dip->i_inode.i_ctime = CURRENT_TIME;
        gfs2_dinode_out(dip, bh->b_data);
        brelse(bh);
        return 0;
}

/**
 * foreach_leaf - call a function for each leaf in a directory
 * @dip: the directory
 * @lc: the function to call for each each
 * @data: private data to pass to it
 *
 * Returns: errno
 */

static int foreach_leaf(struct gfs2_inode *dip, leaf_call_t lc, void *data)
{
        struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
        struct buffer_head *bh;
        struct gfs2_leaf *leaf;
        u32 hsize, len;
        u32 ht_offset, lp_offset, ht_offset_cur = -1;
        u32 index = 0;
        __be64 *lp;
        u64 leaf_no;
        int error = 0;

        hsize = 1 << dip->i_di.di_depth;
        if (hsize * sizeof(u64) != dip->i_di.di_size) {
                gfs2_consist_inode(dip);
                return -EIO;
        }

        lp = kmalloc(sdp->sd_hash_bsize, GFP_KERNEL);
        if (!lp)
                return -ENOMEM;

        while (index < hsize) {
                lp_offset = index & (sdp->sd_hash_ptrs - 1);
                ht_offset = index - lp_offset;

                if (ht_offset_cur != ht_offset) {
                        error = gfs2_dir_read_data(dip, (char *)lp,
                                                ht_offset * sizeof(__be64),
                                                sdp->sd_hash_bsize, 1);
                        if (error != sdp->sd_hash_bsize) {
                                if (error >= 0)
                                        error = -EIO;
                                goto out;
                        }
                        ht_offset_cur = ht_offset;
                }

                leaf_no = be64_to_cpu(lp[lp_offset]);
                if (leaf_no) {
                        error = get_leaf(dip, leaf_no, &bh);
                        if (error)
                                goto out;
                        leaf = (struct gfs2_leaf *)bh->b_data;
                        len = 1 << (dip->i_di.di_depth - be16_to_cpu(leaf->lf_depth));
                        brelse(bh);

                        error = lc(dip, index, len, leaf_no, data);
                        if (error)
                                goto out;

                        index = (index & ~(len - 1)) + len;
                } else
                        index++;
        }

        if (index != hsize) {
                gfs2_consist_inode(dip);
                error = -EIO;
        }

out:
        kfree(lp);

        return error;
}

/**
 * leaf_dealloc - Deallocate a directory leaf
 * @dip: the directory
 * @index: the hash table offset in the directory
 * @len: the number of pointers to this leaf
 * @leaf_no: the leaf number
 * @data: not used
 *
 * Returns: errno
 */

static int leaf_dealloc(struct gfs2_inode *dip, u32 index, u32 len,
                        u64 leaf_no, void *data)
{
        struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
        struct gfs2_leaf *tmp_leaf;
        struct gfs2_rgrp_list rlist;
        struct buffer_head *bh, *dibh;
        u64 blk, nblk;
        unsigned int rg_blocks = 0, l_blocks = 0;
        char *ht;
        unsigned int x, size = len * sizeof(u64);
        int error;

        memset(&rlist, 0, sizeof(struct gfs2_rgrp_list));

        ht = kzalloc(size, GFP_KERNEL);
        if (!ht)
                return -ENOMEM;

        gfs2_alloc_get(dip);

        error = gfs2_quota_hold(dip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
        if (error)
                goto out;

        error = gfs2_rindex_hold(sdp, &dip->i_alloc.al_ri_gh);
        if (error)
                goto out_qs;

        /*  Count the number of leaves  */

        for (blk = leaf_no; blk; blk = nblk) {
                error = get_leaf(dip, blk, &bh);
                if (error)
                        goto out_rlist;
                tmp_leaf = (struct gfs2_leaf *)bh->b_data;
                nblk = be64_to_cpu(tmp_leaf->lf_next);
                brelse(bh);

                gfs2_rlist_add(sdp, &rlist, blk);
                l_blocks++;
        }

        gfs2_rlist_alloc(&rlist, LM_ST_EXCLUSIVE, 0);

        for (x = 0; x < rlist.rl_rgrps; x++) {
                struct gfs2_rgrpd *rgd;
                rgd = rlist.rl_ghs[x].gh_gl->gl_object;
                rg_blocks += rgd->rd_length;
        }

        error = gfs2_glock_nq_m(rlist.rl_rgrps, rlist.rl_ghs);
        if (error)
                goto out_rlist;

        error = gfs2_trans_begin(sdp,
                        rg_blocks + (DIV_ROUND_UP(size, sdp->sd_jbsize) + 1) +
                        RES_DINODE + RES_STATFS + RES_QUOTA, l_blocks);
        if (error)
                goto out_rg_gunlock;

        for (blk = leaf_no; blk; blk = nblk) {
                error = get_leaf(dip, blk, &bh);
                if (error)
                        goto out_end_trans;
                tmp_leaf = (struct gfs2_leaf *)bh->b_data;
                nblk = be64_to_cpu(tmp_leaf->lf_next);
                brelse(bh);

                gfs2_free_meta(dip, blk, 1);

                if (!dip->i_di.di_blocks)
                        gfs2_consist_inode(dip);
                dip->i_di.di_blocks--;
                gfs2_set_inode_blocks(&dip->i_inode);
        }

        error = gfs2_dir_write_data(dip, ht, index * sizeof(u64), size);
        if (error != size) {
                if (error >= 0)
                        error = -EIO;
                goto out_end_trans;
        }

        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (error)
                goto out_end_trans;

        gfs2_trans_add_bh(dip->i_gl, dibh, 1);
        gfs2_dinode_out(dip, dibh->b_data);
        brelse(dibh);

out_end_trans:
        gfs2_trans_end(sdp);
out_rg_gunlock:
        gfs2_glock_dq_m(rlist.rl_rgrps, rlist.rl_ghs);
out_rlist:
        gfs2_rlist_free(&rlist);
        gfs2_glock_dq_uninit(&dip->i_alloc.al_ri_gh);
out_qs:
        gfs2_quota_unhold(dip);
out:
        gfs2_alloc_put(dip);
        kfree(ht);
        return error;
}

/**
 * gfs2_dir_exhash_dealloc - free all the leaf blocks in a directory
 * @dip: the directory
 *
 * Dealloc all on-disk directory leaves to FREEMETA state
 * Change on-disk inode type to "regular file"
 *
 * Returns: errno
 */

int gfs2_dir_exhash_dealloc(struct gfs2_inode *dip)
{
        struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
        struct buffer_head *bh;
        int error;

        /* Dealloc on-disk leaves to FREEMETA state */
        error = foreach_leaf(dip, leaf_dealloc, NULL);
        if (error)
                return error;

        /* Make this a regular file in case we crash.
           (We don't want to free these blocks a second time.)  */

        error = gfs2_trans_begin(sdp, RES_DINODE, 0);
        if (error)
                return error;

        error = gfs2_meta_inode_buffer(dip, &bh);
        if (!error) {
                gfs2_trans_add_bh(dip->i_gl, bh, 1);
                ((struct gfs2_dinode *)bh->b_data)->di_mode =
                                                cpu_to_be32(S_IFREG);
                brelse(bh);
        }

        gfs2_trans_end(sdp);

        return error;
}

/**
 * gfs2_diradd_alloc_required - find if adding entry will require an allocation
 * @ip: the file being written to
 * @filname: the filename that's going to be added
 *
 * Returns: 1 if alloc required, 0 if not, -ve on error
 */

int gfs2_diradd_alloc_required(struct inode *inode, const struct qstr *name)
{
        struct gfs2_dirent *dent;
        struct buffer_head *bh;

        dent = gfs2_dirent_search(inode, name, gfs2_dirent_find_space, &bh);
        if (!dent) {
                return 1;
        }
        if (IS_ERR(dent))
                return PTR_ERR(dent);
        brelse(bh);
        return 0;
}