/*
 * 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_diskflags & 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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/bio.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 MAX_RA_BLOCKS 32 /* max read-ahead blocks */

#define gfs2_disk_hash2offset(h) (((u64)(h)) >> 1)
#define gfs2_dir_offset2hash(p) ((u32)(((u64)(p)) << 1))
#define GFS2_HASH_INDEX_MASK 0xffffc000
#define GFS2_USE_HASH_FLAG 0x2000

struct qstr gfs2_qdot __read_mostly;
struct qstr gfs2_qdotdot __read_mostly;

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_meta(ip->i_gl, bh);
        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, 0, &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_meta(ip->i_gl, dibh);
        memcpy(dibh->b_data + offset + sizeof(struct gfs2_dinode), buf, size);
        if (ip->i_inode.i_size < offset + size)
                i_size_write(&ip->i_inode, offset + size);
        ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
        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;
        bool new = false;

        if (!size)
                return 0;

        if (gfs2_is_stuffed(ip) && offset + size <= gfs2_max_stuffed_size(ip))
                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);
                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;

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

                if (!extlen) {
                        extlen = 1;
                        error = gfs2_alloc_extent(&ip->i_inode, lblock, &dblock,
                                                  &extlen, &new);
                        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_meta(ip->i_gl, bh);
                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_inode.i_size < offset + copied)
                i_size_write(&ip->i_inode, offset + copied);
        ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);

        gfs2_trans_add_meta(ip->i_gl, dibh);
        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, __be64 *buf,
                                 unsigned int size)
{
        struct buffer_head *dibh;
        int error;

        error = gfs2_meta_inode_buffer(ip, &dibh);
        if (!error) {
                memcpy(buf, dibh->b_data + sizeof(struct gfs2_dinode), 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
 * @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, __be64 *buf,
                              unsigned int size)
{
        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 (gfs2_is_stuffed(ip))
                return gfs2_dir_read_stuffed(ip, buf, size);

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

        lblock = 0;
        o = do_div(lblock, sdp->sd_jbsize) + sizeof(struct gfs2_meta_header);

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

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

                if (!extlen) {
                        extlen = 32;
                        error = gfs2_get_extent(&ip->i_inode, lblock,
                                                &dblock, &extlen);
                        if (error || !dblock)
                                goto fail;
                        BUG_ON(extlen < 1);
                        bh = gfs2_meta_ra(ip->i_gl, dblock, extlen);
                } else {
                        error = gfs2_meta_read(ip->i_gl, dblock, DIO_WAIT, 0, &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/sizeof(__be64));
                copied += amount;
                lblock++;
                o = sizeof(struct gfs2_meta_header);
        }

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

/**
 * gfs2_dir_get_hash_table - Get pointer to the dir hash table
 * @ip: The inode in question
 *
 * Returns: The hash table or an error
 */

static __be64 *gfs2_dir_get_hash_table(struct gfs2_inode *ip)
{
        struct inode *inode = &ip->i_inode;
        int ret;
        u32 hsize;
        __be64 *hc;

        BUG_ON(!(ip->i_diskflags & GFS2_DIF_EXHASH));

        hc = ip->i_hash_cache;
        if (hc)
                return hc;

        hsize = BIT(ip->i_depth);
        hsize *= sizeof(__be64);
        if (hsize != i_size_read(&ip->i_inode)) {
                gfs2_consist_inode(ip);
                return ERR_PTR(-EIO);
        }

        hc = kmalloc(hsize, GFP_NOFS | __GFP_NOWARN);
        if (hc == NULL)
                hc = __vmalloc(hsize, GFP_NOFS, PAGE_KERNEL);

        if (hc == NULL)
                return ERR_PTR(-ENOMEM);

        ret = gfs2_dir_read_data(ip, hc, hsize);
        if (ret < 0) {
                kvfree(hc);
                return ERR_PTR(ret);
        }

        spin_lock(&inode->i_lock);
        if (likely(!ip->i_hash_cache)) {
                ip->i_hash_cache = hc;
                hc = NULL;
        }
        spin_unlock(&inode->i_lock);
        kvfree(hc);

        return ip->i_hash_cache;
}

/**
 * gfs2_dir_hash_inval - Invalidate dir hash
 * @ip: The directory inode
 *
 * Must be called with an exclusive glock, or during glock invalidation.
 */
void gfs2_dir_hash_inval(struct gfs2_inode *ip)
{
        __be64 *hc;

        spin_lock(&ip->i_inode.i_lock);
        hc = ip->i_hash_cache;
        ip->i_hash_cache = NULL;
        spin_unlock(&ip->i_inode.i_lock);

        kvfree(hc);
}

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;
}

/* Look for the dirent that contains the offset specified in data. Once we
 * find that dirent, there must be space available there for the new dirent */
static int gfs2_dirent_find_offset(const struct gfs2_dirent *dent,
                                  const struct qstr *name,
                                  void *ptr)
{
        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 (ptr < (void *)dent || ptr >= (void *)dent + totlen)
                return 0;
        if (gfs2_dirent_sentinel(dent))
                actual = 0;
        if (ptr < (void *)dent + actual)
                return -1;
        if ((void *)dent + totlen >= ptr + required)
                return 1;
        return -1;
}

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 = 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_sbd *sdp,
                             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:
        fs_warn(sdp, "%s: %s (%s)\n",
                __func__, msg, first ? "first in block" : "not first in block");
        return -EIO;
}

static int gfs2_dirent_offset(struct gfs2_sbd *sdp, 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:
        fs_warn(sdp, "%s: wrong block type %u\n", __func__,
                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(GFS2_SB(inode), 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(GFS2_SB(inode), 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(GFS2_SB(inode), 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);
}

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_meta(dip->i_gl, bh);

        /* 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);
}


static struct gfs2_dirent *do_init_dirent(struct inode *inode,
                                          struct gfs2_dirent *dent,
                                          const struct qstr *name,
                                          struct buffer_head *bh,
                                          unsigned offset)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_dirent *ndent;
        unsigned totlen;

        totlen = be16_to_cpu(dent->de_rec_len);
        BUG_ON(offset + name->len > totlen);
        gfs2_trans_add_meta(ip->i_gl, bh);
        ndent = (struct gfs2_dirent *)((char *)dent + offset);
        dent->de_rec_len = cpu_to_be16(offset);
        gfs2_qstr2dirent(name, totlen - offset, ndent);
        return ndent;
}


/*
 * 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)
{
        unsigned offset = 0;

        if (!gfs2_dirent_sentinel(dent))
                offset = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
        return do_init_dirent(inode, dent, name, bh, offset);
}

static struct gfs2_dirent *gfs2_dirent_split_alloc(struct inode *inode,
                                                   struct buffer_head *bh,
                                                   const struct qstr *name,
                                                   void *ptr)
{
        struct gfs2_dirent *dent;
        dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
                                gfs2_dirent_find_offset, name, ptr);
        if (IS_ERR_OR_NULL(dent))
                return dent;
        return do_init_dirent(inode, dent, name, bh,
                              (unsigned)(ptr - (void *)dent));
}

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, 0, bhp);
        if (!error && gfs2_metatype_check(GFS2_SB(&dip->i_inode), *bhp, GFS2_METATYPE_LF)) {
                /* pr_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: hash table index of the targeted leaf
 * @leaf_out: Resulting leaf block number
 *
 * Returns: 0 on success, error code otherwise
 */

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

        hash = gfs2_dir_get_hash_table(dip);
        error = PTR_ERR_OR_ZERO(hash);

        if (!error)
                *leaf_out = be64_to_cpu(*(hash + index));

        return error;
}

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_diskflags & GFS2_DIF_EXHASH) {
                struct gfs2_leaf *leaf;
                unsigned int hsize = BIT(ip->i_depth);
                unsigned int index;
                u64 ln;
                if (hsize * sizeof(u64) != i_size_read(inode)) {
                        gfs2_consist_inode(ip);
                        return ERR_PTR(-EIO);
                }

                index = name->hash >> (32 - ip->i_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 (IS_ERR_OR_NULL(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);
        unsigned int n = 1;
        u64 bn;
        int error;
        struct buffer_head *bh;
        struct gfs2_leaf *leaf;
        struct gfs2_dirent *dent;
        struct timespec64 tv = current_time(inode);

        error = gfs2_alloc_blocks(ip, &bn, &n, 0, NULL);
        if (error)
                return NULL;
        bh = gfs2_meta_new(ip->i_gl, bn);
        if (!bh)
                return NULL;

        gfs2_trans_remove_revoke(GFS2_SB(inode), bn, 1);
        gfs2_trans_add_meta(ip->i_gl, bh);
        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;
        leaf->lf_inode = cpu_to_be64(ip->i_no_addr);
        leaf->lf_dist = cpu_to_be32(1);
        leaf->lf_nsec = cpu_to_be32(tv.tv_nsec);
        leaf->lf_sec = cpu_to_be64(tv.tv_sec);
        memset(leaf->lf_reserved2, 0, sizeof(leaf->lf_reserved2));
        dent = (struct gfs2_dirent *)(leaf+1);
        gfs2_qstr2dirent(&empty_name, bh->b_size - sizeof(struct gfs2_leaf), dent);
        *pbh = bh;
        return leaf;
}

/**
 * dir_make_exhash - Convert a stuffed directory into an ExHash directory
 * @inode: The directory inode to be converted to exhash
 *
 * 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_entries < BIT(16));
        leaf->lf_entries = cpu_to_be16(dip->i_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_meta(dip->i_gl, dibh);
        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);

        i_size_write(inode, sdp->sd_sb.sb_bsize / 2);
        gfs2_add_inode_blocks(&dip->i_inode, 1);
        dip->i_diskflags |= GFS2_DIF_EXHASH;

        for (x = sdp->sd_hash_ptrs, y = -1; x; x >>= 1, y++) ;
        dip->i_depth = y;

        gfs2_dinode_out(dip, dibh->b_data);

        brelse(dibh);

        return 0;
}

/**
 * dir_split_leaf - Split a leaf block into two
 * @inode: The directory inode to be split
 * @name: name of the dirent we're trying to insert
 *

 * 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;
        int error;

        index = name->hash >> (32 - dip->i_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_depth == be16_to_cpu(oleaf->lf_depth)) {
                brelse(obh);
                return 1; /* can't split */
        }

        gfs2_trans_add_meta(dip->i_gl, obh);

        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 = BIT(dip->i_depth - be16_to_cpu(oleaf->lf_depth));
        half_len = len >> 1;
        if (!half_len) {
                fs_warn(GFS2_SB(inode), "i_depth %u lf_depth %u index %u\n",
                        dip->i_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_array(half_len, sizeof(__be64), GFP_NOFS);
        if (!lp) {
                error = -ENOMEM;
                goto fail_brelse;
        }

        /*  Change the pointers  */
        for (x = 0; x < half_len; x++)
                lp[x] = cpu_to_be64(bn);

        gfs2_dir_hash_inval(dip);

        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_depth);

        /*  Copy the entries  */
        dent = (struct gfs2_dirent *)(obh->b_data + sizeof(struct gfs2_leaf));

        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;
                        void *ptr = ((char *)dent - obh->b_data) + nbh->b_data;
                        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_split_alloc(inode, nbh, &str, ptr);
                        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 */
                        be16_add_cpu(&nleaf->lf_entries, 1);

                        dirent_del(dip, obh, prev, dent);

                        if (!oleaf->lf_entries)
                                gfs2_consist_inode(dip);
                        be16_add_cpu(&oleaf->lf_entries, -1);

                        if (!prev)
                                prev = dent;
                } 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_meta(dip->i_gl, dibh);
                gfs2_add_inode_blocks(&dip->i_inode, 1);
                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 buffer_head *dibh;
        u32 hsize;
        u32 hsize_bytes;
        __be64 *hc;
        __be64 *hc2, *h;
        int x;
        int error = 0;

        hsize = BIT(dip->i_depth);
        hsize_bytes = hsize * sizeof(__be64);

        hc = gfs2_dir_get_hash_table(dip);
        if (IS_ERR(hc))
                return PTR_ERR(hc);

        hc2 = kmalloc_array(hsize_bytes, 2, GFP_NOFS | __GFP_NOWARN);
        if (hc2 == NULL)
                hc2 = __vmalloc(hsize_bytes * 2, GFP_NOFS, PAGE_KERNEL);

        if (!hc2)
                return -ENOMEM;

        h = hc2;
        error = gfs2_meta_inode_buffer(dip, &dibh);
        if (error)
                goto out_kfree;

        for (x = 0; x < hsize; x++) {
                *h++ = *hc;
                *h++ = *hc;
                hc++;
        }

        error = gfs2_dir_write_data(dip, (char *)hc2, 0, hsize_bytes * 2);
        if (error != (hsize_bytes * 2))
                goto fail;

        gfs2_dir_hash_inval(dip);
        dip->i_hash_cache = hc2;
        dip->i_depth++;
        gfs2_dinode_out(dip, dibh->b_data);
        brelse(dibh);
        return 0;

fail:
        /* Replace original hash table & size */
        gfs2_dir_write_data(dip, (char *)hc, 0, hsize_bytes);
        i_size_write(&dip->i_inode, hsize_bytes);
        gfs2_dinode_out(dip, dibh->b_data);
        brelse(dibh);
out_kfree:
        kvfree(hc2);
        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 = dent_a->de_cookie;

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

        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
 * @ctx: what to feed the entries to
 * @darr: an array of struct gfs2_dirent pointers to read
 * @entries: the number of entries in darr
 * @sort_start: index of the directory array to start our sort
 * @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 if the actor tells you to stop
 */

static int do_filldir_main(struct gfs2_inode *dip, struct dir_context *ctx,
                           struct gfs2_dirent **darr, u32 entries,
                           u32 sort_start, int *copied)
{
        const struct gfs2_dirent *dent, *dent_next;
        u64 off, off_next;
        unsigned int x, y;
        int run = 0;

        if (sort_start < entries)
                sort(&darr[sort_start], entries - sort_start,
                     sizeof(struct gfs2_dirent *), compare_dents, NULL);

        dent_next = darr[0];
        off_next = dent_next->de_cookie;

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

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

                        if (off < ctx->pos)
                                continue;
                        ctx->pos = off;

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

                if (!dir_emit(ctx, (const char *)(dent + 1),
                                be16_to_cpu(dent->de_name_len),
                                be64_to_cpu(dent->de_inum.no_addr),
                                be16_to_cpu(dent->de_type)))
                        return 1;

                *copied = 1;
        }

        /* Increment the ctx->pos 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 */

        ctx->pos++;

        return 0;
}

static void *gfs2_alloc_sort_buffer(unsigned size)
{
        void *ptr = NULL;

        if (size < KMALLOC_MAX_SIZE)
                ptr = kmalloc(size, GFP_NOFS | __GFP_NOWARN);
        if (!ptr)
                ptr = __vmalloc(size, GFP_NOFS, PAGE_KERNEL);
        return ptr;
}


static int gfs2_set_cookies(struct gfs2_sbd *sdp, struct buffer_head *bh,
                            unsigned leaf_nr, struct gfs2_dirent **darr,
                            unsigned entries)
{
        int sort_id = -1;
        int i;
        
        for (i = 0; i < entries; i++) {
                unsigned offset;

                darr[i]->de_cookie = be32_to_cpu(darr[i]->de_hash);
                darr[i]->de_cookie = gfs2_disk_hash2offset(darr[i]->de_cookie);

                if (!sdp->sd_args.ar_loccookie)
                        continue;
                offset = (char *)(darr[i]) -
                        (bh->b_data + gfs2_dirent_offset(sdp, bh->b_data));
                offset /= GFS2_MIN_DIRENT_SIZE;
                offset += leaf_nr * sdp->sd_max_dents_per_leaf;
                if (offset >= GFS2_USE_HASH_FLAG ||
                    leaf_nr >= GFS2_USE_HASH_FLAG) {
                        darr[i]->de_cookie |= GFS2_USE_HASH_FLAG;
                        if (sort_id < 0)
                                sort_id = i;
                        continue;
                }
                darr[i]->de_cookie &= GFS2_HASH_INDEX_MASK;
                darr[i]->de_cookie |= offset;
        }
        return sort_id;
}       


static int gfs2_dir_read_leaf(struct inode *inode, struct dir_context *ctx,
                              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, leaf = 0, offset, sort_offset;
        struct gfs2_dirent **darr, *dent;
        struct dirent_gather g;
        struct buffer_head **larr;
        int error, i, need_sort = 0, sort_id;
        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 (*depth < GFS2_DIR_MAX_DEPTH || !sdp->sd_args.ar_loccookie) {
                need_sort = 1;
                sort_offset = 0;
        }

        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 = gfs2_alloc_sort_buffer((leaves + entries + 99) * sizeof(void *));
        if (!larr)
                goto out;
        darr = (struct gfs2_dirent **)(larr + leaves);
        g.pdent = (const struct gfs2_dirent **)darr;
        g.offset = 0;
        lfn = leaf_no;

        do {
                error = get_leaf(ip, lfn, &bh);
                if (error)
                        goto out_free;
                lf = (struct gfs2_leaf *)bh->b_data;
                lfn = be64_to_cpu(lf->lf_next);
                if (lf->lf_entries) {
                        offset = g.offset;
                        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_free;
                        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);
                                gfs2_consist_inode(ip);
                                error = -EIO;
                                goto out_free;
                        }
                        error = 0;
                        sort_id = gfs2_set_cookies(sdp, bh, leaf, &darr[offset],
                                                   be16_to_cpu(lf->lf_entries));
                        if (!need_sort && sort_id >= 0) {
                                need_sort = 1;
                                sort_offset = offset + sort_id;
                        }
                        larr[leaf++] = bh;
                } else {
                        larr[leaf++] = NULL;
                        brelse(bh);
                }
        } while(lfn);

        BUG_ON(entries2 != entries);
        error = do_filldir_main(ip, ctx, darr, entries, need_sort ?
                                sort_offset : entries, copied);
out_free:
        for(i = 0; i < leaf; i++)
                if (larr[i])
                        brelse(larr[i]);
        kvfree(larr);
out:
        return error;
}

/**
 * gfs2_dir_readahead - Issue read-ahead requests for leaf blocks.
 * @inode: the directory inode
 * @hsize: hash table size
 * @index: index into the hash table
 * @f_ra: read-ahead parameters
 *
 * Note: we can't calculate each index like dir_e_read can because we don't
 * have the leaf, and therefore we don't have the depth, and therefore we
 * don't have the length. So we have to just read enough ahead to make up
 * for the loss of information.
 */
static void gfs2_dir_readahead(struct inode *inode, unsigned hsize, u32 index,
                               struct file_ra_state *f_ra)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_glock *gl = ip->i_gl;
        struct buffer_head *bh;
        u64 blocknr = 0, last;
        unsigned count;

        /* First check if we've already read-ahead for the whole range. */
        if (index + MAX_RA_BLOCKS < f_ra->start)
                return;

        f_ra->start = max((pgoff_t)index, f_ra->start);
        for (count = 0; count < MAX_RA_BLOCKS; count++) {
                if (f_ra->start >= hsize) /* if exceeded the hash table */
                        break;

                last = blocknr;
                blocknr = be64_to_cpu(ip->i_hash_cache[f_ra->start]);
                f_ra->start++;
                if (blocknr == last)
                        continue;

                bh = gfs2_getbuf(gl, blocknr, 1);
                if (trylock_buffer(bh)) {
                        if (buffer_uptodate(bh)) {
                                unlock_buffer(bh);
                                brelse(bh);
                                continue;
                        }
                        bh->b_end_io = end_buffer_read_sync;
                        submit_bh(REQ_OP_READ,
                                  REQ_RAHEAD | REQ_META | REQ_PRIO,
                                  bh);
                        continue;
                }
                brelse(bh);
        }
}

/**
 * dir_e_read - Reads the entries from a directory into a filldir buffer
 * @inode: the directory inode
 * @ctx: actor to feed the entries to
 * @f_ra: read-ahead parameters
 *
 * Returns: errno
 */

static int dir_e_read(struct inode *inode, struct dir_context *ctx,
                      struct file_ra_state *f_ra)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        u32 hsize, len = 0;
        u32 hash, index;
        __be64 *lp;
        int copied = 0;
        int error = 0;
        unsigned depth = 0;

        hsize = BIT(dip->i_depth);
        hash = gfs2_dir_offset2hash(ctx->pos);
        index = hash >> (32 - dip->i_depth);

        if (dip->i_hash_cache == NULL)
                f_ra->start = 0;
        lp = gfs2_dir_get_hash_table(dip);
        if (IS_ERR(lp))
                return PTR_ERR(lp);

        gfs2_dir_readahead(inode, hsize, index, f_ra);

        while (index < hsize) {
                error = gfs2_dir_read_leaf(inode, ctx,
                                           &copied, &depth,
                                           be64_to_cpu(lp[index]));
                if (error)
                        break;

                len = BIT(dip->i_depth - depth);
                index = (index & ~(len - 1)) + len;
        }

        if (error > 0)
                error = 0;
        return error;
}

int gfs2_dir_read(struct inode *inode, struct dir_context *ctx,
                  struct file_ra_state *f_ra)
{
        struct gfs2_inode *dip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct dirent_gather g;
        struct gfs2_dirent **darr, *dent;
        struct buffer_head *dibh;
        int copied = 0;
        int error;

        if (!dip->i_entries)
                return 0;

        if (dip->i_diskflags & GFS2_DIF_EXHASH)
                return dir_e_read(inode, ctx, f_ra);

        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_array(96, sizeof(struct gfs2_dirent *), GFP_NOFS);
        if (darr) {
                g.pdent = (const struct gfs2_dirent **)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_entries != g.offset) {
                        fs_warn(sdp, "Number of entries corrupt in dir %llu, "
                                "ip->i_entries (%u) != g.offset (%u)\n",
                                (unsigned long long)dip->i_no_addr,
                                dip->i_entries,
                                g.offset);
                        gfs2_consist_inode(dip);
                        error = -EIO;
                        goto out;
                }
                gfs2_set_cookies(sdp, dibh, 0, darr, dip->i_entries);
                error = do_filldir_main(dip, ctx, darr,
                                        dip->i_entries, 0, &copied);
out:
                kfree(darr);
        }

        if (error > 0)
                error = 0;

        brelse(dibh);

        return error;
}

/**
 * gfs2_dir_search - Search a directory
 * @dir: The GFS2 directory inode
 * @name: The name we are looking up
 * @fail_on_exist: Fail if the name exists rather than looking it up
 *
 * 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,
                              bool fail_on_exist)
{
        struct buffer_head *bh;
        struct gfs2_dirent *dent;
        u64 addr, formal_ino;
        u16 dtype;

        dent = gfs2_dirent_search(dir, name, gfs2_dirent_find, &bh);
        if (dent) {
                struct inode *inode;
                u16 rahead;

                if (IS_ERR(dent))
                        return ERR_CAST(dent);
                dtype = be16_to_cpu(dent->de_type);
                rahead = be16_to_cpu(dent->de_rahead);
                addr = be64_to_cpu(dent->de_inum.no_addr);
                formal_ino = be64_to_cpu(dent->de_inum.no_formal_ino);
                brelse(bh);
                if (fail_on_exist)
                        return ERR_PTR(-EEXIST);
                inode = gfs2_inode_lookup(dir->i_sb, dtype, addr, formal_ino,
                                          GFS2_BLKST_FREE /* ignore */);
                if (!IS_ERR(inode))
                        GFS2_I(inode)->i_rahead = rahead;
                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;
}

/**
 * dir_new_leaf - Add a new leaf onto hash chain
 * @inode: The directory
 * @name: The name we are adding
 *
 * This adds a new dir leaf onto an existing leaf when there is not
 * enough space to add a new dir entry. This is a last resort after
 * we've expanded the hash table to max size and also split existing
 * leaf blocks, so it will only occur for very large directories.
 *
 * The dist parameter is set to 1 for leaf blocks directly attached
 * to the hash table, 2 for one layer of indirection, 3 for two layers
 * etc. We are thus able to tell the difference between an old leaf
 * with dist set to zero (i.e. "don't know") and a new one where we
 * set this information for debug/fsck purposes.
 *
 * Returns: 0 on success, or -ve on error
 */

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;
        u32 dist = 1;
        int error;
        u32 index;
        u64 bn;

        index = name->hash >> (32 - ip->i_depth);
        error = get_first_leaf(ip, index, &obh);
        if (error)
                return error;
        do {
                dist++;
                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_meta(ip->i_gl, obh);

        leaf = new_leaf(inode, &bh, be16_to_cpu(oleaf->lf_depth));
        if (!leaf) {
                brelse(obh);
                return -ENOSPC;
        }
        leaf->lf_dist = cpu_to_be32(dist);
        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_meta(ip->i_gl, bh);
        gfs2_add_inode_blocks(&ip->i_inode, 1);
        gfs2_dinode_out(ip, bh->b_data);
        brelse(bh);
        return 0;
}

static u16 gfs2_inode_ra_len(const struct gfs2_inode *ip)
{
        u64 where = ip->i_no_addr + 1;
        if (ip->i_eattr == where)
                return 1;
        return 0;
}

/**
 * gfs2_dir_add - Add new filename into directory
 * @inode: The directory inode
 * @name: The new name
 * @nip: The GFS2 inode to be linked in to the directory
 * @da: The directory addition info
 *
 * If the call to gfs2_diradd_alloc_required resulted in there being
 * no need to allocate any new directory blocks, then it will contain
 * a pointer to the directory entry and the bh in which it resides. We
 * can use that without having to repeat the search. If there was no
 * free space, then we must now create more space.
 *
 * Returns: 0 on success, error code on failure
 */

int gfs2_dir_add(struct inode *inode, const struct qstr *name,
                 const struct gfs2_inode *nip, struct gfs2_diradd *da)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct buffer_head *bh = da->bh;
        struct gfs2_dirent *dent = da->dent;
        struct timespec64 tv;
        struct gfs2_leaf *leaf;
        int error;

        while(1) {
                if (da->bh == NULL) {
                        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(IF2DT(nip->i_inode.i_mode));
                        dent->de_rahead = cpu_to_be16(gfs2_inode_ra_len(nip));
                        tv = current_time(&ip->i_inode);
                        if (ip->i_diskflags & GFS2_DIF_EXHASH) {
                                leaf = (struct gfs2_leaf *)bh->b_data;
                                be16_add_cpu(&leaf->lf_entries, 1);
                                leaf->lf_nsec = cpu_to_be32(tv.tv_nsec);
                                leaf->lf_sec = cpu_to_be64(tv.tv_sec);
                        }
                        da->dent = NULL;
                        da->bh = NULL;
                        brelse(bh);
                        ip->i_entries++;
                        ip->i_inode.i_mtime = ip->i_inode.i_ctime = tv;
                        if (S_ISDIR(nip->i_inode.i_mode))
                                inc_nlink(&ip->i_inode);
                        mark_inode_dirty(inode);
                        error = 0;
                        break;
                }
                if (!(ip->i_diskflags & 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_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
 * @dentry: The directory entry we want to delete
 *
 * Returns: 0 on success, error code on failure
 */

int gfs2_dir_del(struct gfs2_inode *dip, const struct dentry *dentry)
{
        const struct qstr *name = &dentry->d_name;
        struct gfs2_dirent *dent, *prev = NULL;
        struct buffer_head *bh;
        struct timespec64 tv = current_time(&dip->i_inode);

        /* 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_diskflags & 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);
                leaf->lf_nsec = cpu_to_be32(tv.tv_nsec);
                leaf->lf_sec = cpu_to_be64(tv.tv_sec);
        }
        brelse(bh);

        if (!dip->i_entries)
                gfs2_consist_inode(dip);
        dip->i_entries--;
        dip->i_inode.i_mtime = dip->i_inode.i_ctime = tv;
        if (d_is_dir(dentry))
                drop_nlink(&dip->i_inode);
        mark_inode_dirty(&dip->i_inode);

        return 0;
}

/**
 * gfs2_dir_mvino - Change inode number of directory entry
 * @dip: The GFS2 directory inode
 * @filename: the filename to be moved
 * @nip: the new GFS2 inode
 * @new_type: the de_type of the new dirent
 *
 * 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;

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

        dip->i_inode.i_mtime = dip->i_inode.i_ctime = current_time(&dip->i_inode);
        mark_inode_dirty_sync(&dip->i_inode);
        return 0;
}

/**
 * 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
 * @leaf_bh: buffer_head for the starting leaf
 * @last_dealloc: 1 if this is the final dealloc for the leaf, else 0
 *
 * Returns: errno
 */

static int leaf_dealloc(struct gfs2_inode *dip, u32 index, u32 len,
                        u64 leaf_no, struct buffer_head *leaf_bh,
                        int last_dealloc)
{
        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;

        error = gfs2_rindex_update(sdp);
        if (error)
                return error;

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

        ht = kzalloc(size, GFP_NOFS | __GFP_NOWARN);
        if (ht == NULL)

                ht = __vmalloc(size, GFP_NOFS | __GFP_NOWARN | __GFP_ZERO,
                               PAGE_KERNEL);
        if (!ht)
                return -ENOMEM;

        error = gfs2_quota_hold(dip, NO_UID_QUOTA_CHANGE, NO_GID_QUOTA_CHANGE);
        if (error)
                goto out;

        /*  Count the number of leaves  */
        bh = leaf_bh;

        for (blk = leaf_no; blk; blk = nblk) {
                if (blk != leaf_no) {
                        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);
                if (blk != leaf_no)
                        brelse(bh);

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

        gfs2_rlist_alloc(&rlist);

        for (x = 0; x < rlist.rl_rgrps; x++) {
                struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(rlist.rl_ghs[x].gh_gl);

                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;

        bh = leaf_bh;

        for (blk = leaf_no; blk; blk = nblk) {
                struct gfs2_rgrpd *rgd;

                if (blk != leaf_no) {
                        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);
                if (blk != leaf_no)
                        brelse(bh);

                rgd = gfs2_blk2rgrpd(sdp, blk, true);
                gfs2_free_meta(dip, rgd, blk, 1);
                gfs2_add_inode_blocks(&dip->i_inode, -1);
        }

        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_meta(dip->i_gl, dibh);
        /* On the last dealloc, make this a regular file in case we crash.
           (We don't want to free these blocks a second time.)  */
        if (last_dealloc)
                dip->i_inode.i_mode = S_IFREG;
        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_quota_unhold(dip);
out:
        kvfree(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 buffer_head *bh;
        struct gfs2_leaf *leaf;
        u32 hsize, len;
        u32 index = 0, next_index;
        __be64 *lp;
        u64 leaf_no;
        int error = 0, last;

        hsize = BIT(dip->i_depth);

        lp = gfs2_dir_get_hash_table(dip);
        if (IS_ERR(lp))
                return PTR_ERR(lp);

        while (index < hsize) {
                leaf_no = be64_to_cpu(lp[index]);
                if (leaf_no) {
                        error = get_leaf(dip, leaf_no, &bh);
                        if (error)
                                goto out;
                        leaf = (struct gfs2_leaf *)bh->b_data;
                        len = BIT(dip->i_depth - be16_to_cpu(leaf->lf_depth));

                        next_index = (index & ~(len - 1)) + len;
                        last = ((next_index >= hsize) ? 1 : 0);
                        error = leaf_dealloc(dip, index, len, leaf_no, bh,
                                             last);
                        brelse(bh);
                        if (error)
                                goto out;
                        index = next_index;
                } else
                        index++;
        }

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

out:

        return error;
}

/**
 * gfs2_diradd_alloc_required - find if adding entry will require an allocation
 * @inode: the directory inode being written to
 * @name: the filename that's going to be added
 * @da: The structure to return dir alloc info
 *
 * Returns: 0 if ok, -ve on error
 */

int gfs2_diradd_alloc_required(struct inode *inode, const struct qstr *name,
                               struct gfs2_diradd *da)
{
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        const unsigned int extra = sizeof(struct gfs2_dinode) - sizeof(struct gfs2_leaf);
        struct gfs2_dirent *dent;
        struct buffer_head *bh;

        da->nr_blocks = 0;
        da->bh = NULL;
        da->dent = NULL;

        dent = gfs2_dirent_search(inode, name, gfs2_dirent_find_space, &bh);
        if (!dent) {
                da->nr_blocks = sdp->sd_max_dirres;
                if (!(ip->i_diskflags & GFS2_DIF_EXHASH) &&
                    (GFS2_DIRENT_SIZE(name->len) < extra))
                        da->nr_blocks = 1;
                return 0;
        }
        if (IS_ERR(dent))
                return PTR_ERR(dent);

        if (da->save_loc) {
                da->bh = bh;
                da->dent = dent;
        } else {
                brelse(bh);
        }
        return 0;
}