writeback: fix periodic superblock dirty inode flushing

[linux-2.6] / fs / ocfs2 / dir.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dir.c
 *
 * Creates, reads, walks and deletes directory-nodes
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 *  Portions of this code from linux/fs/ext3/dir.c
 *
 *  Copyright (C) 1992, 1993, 1994, 1995
 *  Remy Card (card@masi.ibp.fr)
 *  Laboratoire MASI - Institut Blaise pascal
 *  Universite Pierre et Marie Curie (Paris VI)
 *
 *   from
 *
 *   linux/fs/minix/dir.c
 *
 *   Copyright (C) 1991, 1992 Linux Torvalds
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>

#define MLOG_MASK_PREFIX ML_NAMEI
#include <cluster/masklog.h>

#include "ocfs2.h"

#include "alloc.h"
#include "dir.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "file.h"
#include "inode.h"
#include "journal.h"
#include "namei.h"
#include "suballoc.h"
#include "super.h"
#include "uptodate.h"

#include "buffer_head_io.h"

#define NAMEI_RA_CHUNKS  2
#define NAMEI_RA_BLOCKS  4
#define NAMEI_RA_SIZE        (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
#define NAMEI_RA_INDEX(c,b)  (((c) * NAMEI_RA_BLOCKS) + (b))

static unsigned char ocfs2_filetype_table[] = {
        DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
};

static int ocfs2_extend_dir(struct ocfs2_super *osb,
                            struct inode *dir,
                            struct buffer_head *parent_fe_bh,
                            unsigned int blocks_wanted,
                            struct buffer_head **new_de_bh);
static int ocfs2_do_extend_dir(struct super_block *sb,
                               handle_t *handle,
                               struct inode *dir,
                               struct buffer_head *parent_fe_bh,
                               struct ocfs2_alloc_context *data_ac,
                               struct ocfs2_alloc_context *meta_ac,
                               struct buffer_head **new_bh);

/*
 * bh passed here can be an inode block or a dir data block, depending
 * on the inode inline data flag.
 */
static int ocfs2_check_dir_entry(struct inode * dir,
                                 struct ocfs2_dir_entry * de,
                                 struct buffer_head * bh,
                                 unsigned long offset)
{
        const char *error_msg = NULL;
        const int rlen = le16_to_cpu(de->rec_len);

        if (rlen < OCFS2_DIR_REC_LEN(1))
                error_msg = "rec_len is smaller than minimal";
        else if (rlen % 4 != 0)
                error_msg = "rec_len % 4 != 0";
        else if (rlen < OCFS2_DIR_REC_LEN(de->name_len))
                error_msg = "rec_len is too small for name_len";
        else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
                error_msg = "directory entry across blocks";

        if (error_msg != NULL)
                mlog(ML_ERROR, "bad entry in directory #%llu: %s - "
                     "offset=%lu, inode=%llu, rec_len=%d, name_len=%d\n",
                     (unsigned long long)OCFS2_I(dir)->ip_blkno, error_msg,
                     offset, (unsigned long long)le64_to_cpu(de->inode), rlen,
                     de->name_len);
        return error_msg == NULL ? 1 : 0;
}

static inline int ocfs2_match(int len,
                              const char * const name,
                              struct ocfs2_dir_entry *de)
{
        if (len != de->name_len)
                return 0;
        if (!de->inode)
                return 0;
        return !memcmp(name, de->name, len);
}

/*
 * Returns 0 if not found, -1 on failure, and 1 on success
 */
static int inline ocfs2_search_dirblock(struct buffer_head *bh,
                                        struct inode *dir,
                                        const char *name, int namelen,
                                        unsigned long offset,
                                        char *first_de,
                                        unsigned int bytes,
                                        struct ocfs2_dir_entry **res_dir)
{
        struct ocfs2_dir_entry *de;
        char *dlimit, *de_buf;
        int de_len;
        int ret = 0;

        mlog_entry_void();

        de_buf = first_de;
        dlimit = de_buf + bytes;

        while (de_buf < dlimit) {
                /* this code is executed quadratically often */
                /* do minimal checking `by hand' */

                de = (struct ocfs2_dir_entry *) de_buf;

                if (de_buf + namelen <= dlimit &&
                    ocfs2_match(namelen, name, de)) {
                        /* found a match - just to be sure, do a full check */
                        if (!ocfs2_check_dir_entry(dir, de, bh, offset)) {
                                ret = -1;
                                goto bail;
                        }
                        *res_dir = de;
                        ret = 1;
                        goto bail;
                }

                /* prevent looping on a bad block */
                de_len = le16_to_cpu(de->rec_len);
                if (de_len <= 0) {
                        ret = -1;
                        goto bail;
                }

                de_buf += de_len;
                offset += de_len;
        }

bail:
        mlog_exit(ret);
        return ret;
}

static struct buffer_head *ocfs2_find_entry_id(const char *name,
                                               int namelen,
                                               struct inode *dir,
                                               struct ocfs2_dir_entry **res_dir)
{
        int ret, found;
        struct buffer_head *di_bh = NULL;
        struct ocfs2_dinode *di;
        struct ocfs2_inline_data *data;

        ret = ocfs2_read_block(OCFS2_SB(dir->i_sb), OCFS2_I(dir)->ip_blkno,
                               &di_bh, OCFS2_BH_CACHED, dir);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        di = (struct ocfs2_dinode *)di_bh->b_data;
        data = &di->id2.i_data;

        found = ocfs2_search_dirblock(di_bh, dir, name, namelen, 0,
                                      data->id_data, i_size_read(dir), res_dir);
        if (found == 1)
                return di_bh;

        brelse(di_bh);
out:
        return NULL;
}

struct buffer_head *ocfs2_find_entry_el(const char *name, int namelen,
                                        struct inode *dir,
                                        struct ocfs2_dir_entry **res_dir)
{
        struct super_block *sb;
        struct buffer_head *bh_use[NAMEI_RA_SIZE];
        struct buffer_head *bh, *ret = NULL;
        unsigned long start, block, b;
        int ra_max = 0;         /* Number of bh's in the readahead
                                   buffer, bh_use[] */
        int ra_ptr = 0;         /* Current index into readahead
                                   buffer */
        int num = 0;
        int nblocks, i, err;

        mlog_entry_void();

        sb = dir->i_sb;

        nblocks = i_size_read(dir) >> sb->s_blocksize_bits;
        start = OCFS2_I(dir)->ip_dir_start_lookup;
        if (start >= nblocks)
                start = 0;
        block = start;

restart:
        do {
                /*
                 * We deal with the read-ahead logic here.
                 */
                if (ra_ptr >= ra_max) {
                        /* Refill the readahead buffer */
                        ra_ptr = 0;
                        b = block;
                        for (ra_max = 0; ra_max < NAMEI_RA_SIZE; ra_max++) {
                                /*
                                 * Terminate if we reach the end of the
                                 * directory and must wrap, or if our
                                 * search has finished at this block.
                                 */
                                if (b >= nblocks || (num && block == start)) {
                                        bh_use[ra_max] = NULL;
                                        break;
                                }
                                num++;

                                bh = ocfs2_bread(dir, b++, &err, 1);
                                bh_use[ra_max] = bh;
                        }
                }
                if ((bh = bh_use[ra_ptr++]) == NULL)
                        goto next;
                wait_on_buffer(bh);
                if (!buffer_uptodate(bh)) {
                        /* read error, skip block & hope for the best */
                        ocfs2_error(dir->i_sb, "reading directory %llu, "
                                    "offset %lu\n",
                                    (unsigned long long)OCFS2_I(dir)->ip_blkno,
                                    block);
                        brelse(bh);
                        goto next;
                }
                i = ocfs2_search_dirblock(bh, dir, name, namelen,
                                          block << sb->s_blocksize_bits,
                                          bh->b_data, sb->s_blocksize,
                                          res_dir);
                if (i == 1) {
                        OCFS2_I(dir)->ip_dir_start_lookup = block;
                        ret = bh;
                        goto cleanup_and_exit;
                } else {
                        brelse(bh);
                        if (i < 0)
                                goto cleanup_and_exit;
                }
        next:
                if (++block >= nblocks)
                        block = 0;
        } while (block != start);

        /*
         * If the directory has grown while we were searching, then
         * search the last part of the directory before giving up.
         */
        block = nblocks;
        nblocks = i_size_read(dir) >> sb->s_blocksize_bits;
        if (block < nblocks) {
                start = 0;
                goto restart;
        }

cleanup_and_exit:
        /* Clean up the read-ahead blocks */
        for (; ra_ptr < ra_max; ra_ptr++)
                brelse(bh_use[ra_ptr]);

        mlog_exit_ptr(ret);
        return ret;
}

/*
 * Try to find an entry of the provided name within 'dir'.
 *
 * If nothing was found, NULL is returned. Otherwise, a buffer_head
 * and pointer to the dir entry are passed back.
 *
 * Caller can NOT assume anything about the contents of the
 * buffer_head - it is passed back only so that it can be passed into
 * any one of the manipulation functions (add entry, delete entry,
 * etc). As an example, bh in the extent directory case is a data
 * block, in the inline-data case it actually points to an inode.
 */
struct buffer_head *ocfs2_find_entry(const char *name, int namelen,
                                     struct inode *dir,
                                     struct ocfs2_dir_entry **res_dir)
{
        *res_dir = NULL;

        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                return ocfs2_find_entry_id(name, namelen, dir, res_dir);

        return ocfs2_find_entry_el(name, namelen, dir, res_dir);
}

/*
 * Update inode number and type of a previously found directory entry.
 */
int ocfs2_update_entry(struct inode *dir, handle_t *handle,
                       struct buffer_head *de_bh, struct ocfs2_dir_entry *de,
                       struct inode *new_entry_inode)
{
        int ret;

        /*
         * The same code works fine for both inline-data and extent
         * based directories, so no need to split this up.
         */

        ret = ocfs2_journal_access(handle, dir, de_bh,
                                   OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        de->inode = cpu_to_le64(OCFS2_I(new_entry_inode)->ip_blkno);
        ocfs2_set_de_type(de, new_entry_inode->i_mode);

        ocfs2_journal_dirty(handle, de_bh);

out:
        return ret;
}

static int __ocfs2_delete_entry(handle_t *handle, struct inode *dir,
                                struct ocfs2_dir_entry *de_del,
                                struct buffer_head *bh, char *first_de,
                                unsigned int bytes)
{
        struct ocfs2_dir_entry *de, *pde;
        int i, status = -ENOENT;

        mlog_entry("(0x%p, 0x%p, 0x%p, 0x%p)\n", handle, dir, de_del, bh);

        i = 0;
        pde = NULL;
        de = (struct ocfs2_dir_entry *) first_de;
        while (i < bytes) {
                if (!ocfs2_check_dir_entry(dir, de, bh, i)) {
                        status = -EIO;
                        mlog_errno(status);
                        goto bail;
                }
                if (de == de_del)  {
                        status = ocfs2_journal_access(handle, dir, bh,
                                                      OCFS2_JOURNAL_ACCESS_WRITE);
                        if (status < 0) {
                                status = -EIO;
                                mlog_errno(status);
                                goto bail;
                        }
                        if (pde)
                                pde->rec_len =
                                        cpu_to_le16(le16_to_cpu(pde->rec_len) +
                                                    le16_to_cpu(de->rec_len));
                        else
                                de->inode = 0;
                        dir->i_version++;
                        status = ocfs2_journal_dirty(handle, bh);
                        goto bail;
                }
                i += le16_to_cpu(de->rec_len);
                pde = de;
                de = (struct ocfs2_dir_entry *)((char *)de + le16_to_cpu(de->rec_len));
        }
bail:
        mlog_exit(status);
        return status;
}

static inline int ocfs2_delete_entry_id(handle_t *handle,
                                        struct inode *dir,
                                        struct ocfs2_dir_entry *de_del,
                                        struct buffer_head *bh)
{
        int ret;
        struct buffer_head *di_bh = NULL;
        struct ocfs2_dinode *di;
        struct ocfs2_inline_data *data;

        ret = ocfs2_read_block(OCFS2_SB(dir->i_sb), OCFS2_I(dir)->ip_blkno,
                               &di_bh, OCFS2_BH_CACHED, dir);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        di = (struct ocfs2_dinode *)di_bh->b_data;
        data = &di->id2.i_data;

        ret = __ocfs2_delete_entry(handle, dir, de_del, bh, data->id_data,
                                   i_size_read(dir));

        brelse(di_bh);
out:
        return ret;
}

static inline int ocfs2_delete_entry_el(handle_t *handle,
                                        struct inode *dir,
                                        struct ocfs2_dir_entry *de_del,
                                        struct buffer_head *bh)
{
        return __ocfs2_delete_entry(handle, dir, de_del, bh, bh->b_data,
                                    bh->b_size);
}

/*
 * ocfs2_delete_entry deletes a directory entry by merging it with the
 * previous entry
 */
int ocfs2_delete_entry(handle_t *handle,
                       struct inode *dir,
                       struct ocfs2_dir_entry *de_del,
                       struct buffer_head *bh)
{
        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                return ocfs2_delete_entry_id(handle, dir, de_del, bh);

        return ocfs2_delete_entry_el(handle, dir, de_del, bh);
}

/*
 * Check whether 'de' has enough room to hold an entry of
 * 'new_rec_len' bytes.
 */
static inline int ocfs2_dirent_would_fit(struct ocfs2_dir_entry *de,
                                         unsigned int new_rec_len)
{
        unsigned int de_really_used;

        /* Check whether this is an empty record with enough space */
        if (le64_to_cpu(de->inode) == 0 &&
            le16_to_cpu(de->rec_len) >= new_rec_len)
                return 1;

        /*
         * Record might have free space at the end which we can
         * use.
         */
        de_really_used = OCFS2_DIR_REC_LEN(de->name_len);
        if (le16_to_cpu(de->rec_len) >= (de_really_used + new_rec_len))
            return 1;

        return 0;
}

/* we don't always have a dentry for what we want to add, so people
 * like orphan dir can call this instead.
 *
 * If you pass me insert_bh, I'll skip the search of the other dir
 * blocks and put the record in there.
 */
int __ocfs2_add_entry(handle_t *handle,
                      struct inode *dir,
                      const char *name, int namelen,
                      struct inode *inode, u64 blkno,
                      struct buffer_head *parent_fe_bh,
                      struct buffer_head *insert_bh)
{
        unsigned long offset;
        unsigned short rec_len;
        struct ocfs2_dir_entry *de, *de1;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)parent_fe_bh->b_data;
        struct super_block *sb = dir->i_sb;
        int retval, status;
        unsigned int size = sb->s_blocksize;
        char *data_start = insert_bh->b_data;

        mlog_entry_void();

        if (!namelen)
                return -EINVAL;

        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                data_start = di->id2.i_data.id_data;
                size = i_size_read(dir);

                BUG_ON(insert_bh != parent_fe_bh);
        }

        rec_len = OCFS2_DIR_REC_LEN(namelen);
        offset = 0;
        de = (struct ocfs2_dir_entry *) data_start;
        while (1) {
                BUG_ON((char *)de >= (size + data_start));

                /* These checks should've already been passed by the
                 * prepare function, but I guess we can leave them
                 * here anyway. */
                if (!ocfs2_check_dir_entry(dir, de, insert_bh, offset)) {
                        retval = -ENOENT;
                        goto bail;
                }
                if (ocfs2_match(namelen, name, de)) {
                        retval = -EEXIST;
                        goto bail;
                }

                if (ocfs2_dirent_would_fit(de, rec_len)) {
                        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
                        retval = ocfs2_mark_inode_dirty(handle, dir, parent_fe_bh);
                        if (retval < 0) {
                                mlog_errno(retval);
                                goto bail;
                        }

                        status = ocfs2_journal_access(handle, dir, insert_bh,
                                                      OCFS2_JOURNAL_ACCESS_WRITE);
                        /* By now the buffer is marked for journaling */
                        offset += le16_to_cpu(de->rec_len);
                        if (le64_to_cpu(de->inode)) {
                                de1 = (struct ocfs2_dir_entry *)((char *) de +
                                        OCFS2_DIR_REC_LEN(de->name_len));
                                de1->rec_len =
                                        cpu_to_le16(le16_to_cpu(de->rec_len) -
                                        OCFS2_DIR_REC_LEN(de->name_len));
                                de->rec_len = cpu_to_le16(OCFS2_DIR_REC_LEN(de->name_len));
                                de = de1;
                        }
                        de->file_type = OCFS2_FT_UNKNOWN;
                        if (blkno) {
                                de->inode = cpu_to_le64(blkno);
                                ocfs2_set_de_type(de, inode->i_mode);
                        } else
                                de->inode = 0;
                        de->name_len = namelen;
                        memcpy(de->name, name, namelen);

                        dir->i_version++;
                        status = ocfs2_journal_dirty(handle, insert_bh);
                        retval = 0;
                        goto bail;
                }
                offset += le16_to_cpu(de->rec_len);
                de = (struct ocfs2_dir_entry *) ((char *) de + le16_to_cpu(de->rec_len));
        }

        /* when you think about it, the assert above should prevent us
         * from ever getting here. */
        retval = -ENOSPC;
bail:

        mlog_exit(retval);
        return retval;
}

static int ocfs2_dir_foreach_blk_id(struct inode *inode,
                                    u64 *f_version,
                                    loff_t *f_pos, void *priv,
                                    filldir_t filldir, int *filldir_err)
{
        int ret, i, filldir_ret;
        unsigned long offset = *f_pos;
        struct buffer_head *di_bh = NULL;
        struct ocfs2_dinode *di;
        struct ocfs2_inline_data *data;
        struct ocfs2_dir_entry *de;

        ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
                               &di_bh, OCFS2_BH_CACHED, inode);
        if (ret) {
                mlog(ML_ERROR, "Unable to read inode block for dir %llu\n",
                     (unsigned long long)OCFS2_I(inode)->ip_blkno);
                goto out;
        }

        di = (struct ocfs2_dinode *)di_bh->b_data;
        data = &di->id2.i_data;

        while (*f_pos < i_size_read(inode)) {
revalidate:
                /* If the dir block has changed since the last call to
                 * readdir(2), then we might be pointing to an invalid
                 * dirent right now.  Scan from the start of the block
                 * to make sure. */
                if (*f_version != inode->i_version) {
                        for (i = 0; i < i_size_read(inode) && i < offset; ) {
                                de = (struct ocfs2_dir_entry *)
                                        (data->id_data + i);
                                /* It's too expensive to do a full
                                 * dirent test each time round this
                                 * loop, but we do have to test at
                                 * least that it is non-zero.  A
                                 * failure will be detected in the
                                 * dirent test below. */
                                if (le16_to_cpu(de->rec_len) <
                                    OCFS2_DIR_REC_LEN(1))
                                        break;
                                i += le16_to_cpu(de->rec_len);
                        }
                        *f_pos = offset = i;
                        *f_version = inode->i_version;
                }

                de = (struct ocfs2_dir_entry *) (data->id_data + *f_pos);
                if (!ocfs2_check_dir_entry(inode, de, di_bh, *f_pos)) {
                        /* On error, skip the f_pos to the end. */
                        *f_pos = i_size_read(inode);
                        goto out;
                }
                offset += le16_to_cpu(de->rec_len);
                if (le64_to_cpu(de->inode)) {
                        /* We might block in the next section
                         * if the data destination is
                         * currently swapped out.  So, use a
                         * version stamp to detect whether or
                         * not the directory has been modified
                         * during the copy operation.
                         */
                        u64 version = *f_version;
                        unsigned char d_type = DT_UNKNOWN;

                        if (de->file_type < OCFS2_FT_MAX)
                                d_type = ocfs2_filetype_table[de->file_type];

                        filldir_ret = filldir(priv, de->name,
                                              de->name_len,
                                              *f_pos,
                                              le64_to_cpu(de->inode),
                                              d_type);
                        if (filldir_ret) {
                                if (filldir_err)
                                        *filldir_err = filldir_ret;
                                break;
                        }
                        if (version != *f_version)
                                goto revalidate;
                }
                *f_pos += le16_to_cpu(de->rec_len);
        }

out:
        brelse(di_bh);

        return 0;
}

static int ocfs2_dir_foreach_blk_el(struct inode *inode,
                                    u64 *f_version,
                                    loff_t *f_pos, void *priv,
                                    filldir_t filldir, int *filldir_err)
{
        int error = 0;
        unsigned long offset, blk, last_ra_blk = 0;
        int i, stored;
        struct buffer_head * bh, * tmp;
        struct ocfs2_dir_entry * de;
        int err;
        struct super_block * sb = inode->i_sb;
        unsigned int ra_sectors = 16;

        stored = 0;
        bh = NULL;

        offset = (*f_pos) & (sb->s_blocksize - 1);

        while (!error && !stored && *f_pos < i_size_read(inode)) {
                blk = (*f_pos) >> sb->s_blocksize_bits;
                bh = ocfs2_bread(inode, blk, &err, 0);
                if (!bh) {
                        mlog(ML_ERROR,
                             "directory #%llu contains a hole at offset %lld\n",
                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
                             *f_pos);
                        *f_pos += sb->s_blocksize - offset;
                        continue;
                }

                /* The idea here is to begin with 8k read-ahead and to stay
                 * 4k ahead of our current position.
                 *
                 * TODO: Use the pagecache for this. We just need to
                 * make sure it's cluster-safe... */
                if (!last_ra_blk
                    || (((last_ra_blk - blk) << 9) <= (ra_sectors / 2))) {
                        for (i = ra_sectors >> (sb->s_blocksize_bits - 9);
                             i > 0; i--) {
                                tmp = ocfs2_bread(inode, ++blk, &err, 1);
                                if (tmp)
                                        brelse(tmp);
                        }
                        last_ra_blk = blk;
                        ra_sectors = 8;
                }

revalidate:
                /* If the dir block has changed since the last call to
                 * readdir(2), then we might be pointing to an invalid
                 * dirent right now.  Scan from the start of the block
                 * to make sure. */
                if (*f_version != inode->i_version) {
                        for (i = 0; i < sb->s_blocksize && i < offset; ) {
                                de = (struct ocfs2_dir_entry *) (bh->b_data + i);
                                /* It's too expensive to do a full
                                 * dirent test each time round this
                                 * loop, but we do have to test at
                                 * least that it is non-zero.  A
                                 * failure will be detected in the
                                 * dirent test below. */
                                if (le16_to_cpu(de->rec_len) <
                                    OCFS2_DIR_REC_LEN(1))
                                        break;
                                i += le16_to_cpu(de->rec_len);
                        }
                        offset = i;
                        *f_pos = ((*f_pos) & ~(sb->s_blocksize - 1))
                                | offset;
                        *f_version = inode->i_version;
                }

                while (!error && *f_pos < i_size_read(inode)
                       && offset < sb->s_blocksize) {
                        de = (struct ocfs2_dir_entry *) (bh->b_data + offset);
                        if (!ocfs2_check_dir_entry(inode, de, bh, offset)) {
                                /* On error, skip the f_pos to the
                                   next block. */
                                *f_pos = ((*f_pos) | (sb->s_blocksize - 1)) + 1;
                                brelse(bh);
                                goto out;
                        }
                        offset += le16_to_cpu(de->rec_len);
                        if (le64_to_cpu(de->inode)) {
                                /* We might block in the next section
                                 * if the data destination is
                                 * currently swapped out.  So, use a
                                 * version stamp to detect whether or
                                 * not the directory has been modified
                                 * during the copy operation.
                                 */
                                unsigned long version = *f_version;
                                unsigned char d_type = DT_UNKNOWN;

                                if (de->file_type < OCFS2_FT_MAX)
                                        d_type = ocfs2_filetype_table[de->file_type];
                                error = filldir(priv, de->name,
                                                de->name_len,
                                                *f_pos,
                                                le64_to_cpu(de->inode),
                                                d_type);
                                if (error) {
                                        if (filldir_err)
                                                *filldir_err = error;
                                        break;
                                }
                                if (version != *f_version)
                                        goto revalidate;
                                stored ++;
                        }
                        *f_pos += le16_to_cpu(de->rec_len);
                }
                offset = 0;
                brelse(bh);
        }

        stored = 0;
out:
        return stored;
}

static int ocfs2_dir_foreach_blk(struct inode *inode, u64 *f_version,
                                 loff_t *f_pos, void *priv, filldir_t filldir,
                                 int *filldir_err)
{
        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                return ocfs2_dir_foreach_blk_id(inode, f_version, f_pos, priv,
                                                filldir, filldir_err);

        return ocfs2_dir_foreach_blk_el(inode, f_version, f_pos, priv, filldir,
                                        filldir_err);
}

/*
 * This is intended to be called from inside other kernel functions,
 * so we fake some arguments.
 */
int ocfs2_dir_foreach(struct inode *inode, loff_t *f_pos, void *priv,
                      filldir_t filldir)
{
        int ret = 0, filldir_err = 0;
        u64 version = inode->i_version;

        while (*f_pos < i_size_read(inode)) {
                ret = ocfs2_dir_foreach_blk(inode, &version, f_pos, priv,
                                            filldir, &filldir_err);
                if (ret || filldir_err)
                        break;
        }

        if (ret > 0)
                ret = -EIO;

        return 0;
}

/*
 * ocfs2_readdir()
 *
 */
int ocfs2_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
        int error = 0;
        struct inode *inode = filp->f_path.dentry->d_inode;
        int lock_level = 0;

        mlog_entry("dirino=%llu\n",
                   (unsigned long long)OCFS2_I(inode)->ip_blkno);

        error = ocfs2_meta_lock_atime(inode, filp->f_vfsmnt, &lock_level);
        if (lock_level && error >= 0) {
                /* We release EX lock which used to update atime
                 * and get PR lock again to reduce contention
                 * on commonly accessed directories. */
                ocfs2_meta_unlock(inode, 1);
                lock_level = 0;
                error = ocfs2_meta_lock(inode, NULL, 0);
        }
        if (error < 0) {
                if (error != -ENOENT)
                        mlog_errno(error);
                /* we haven't got any yet, so propagate the error. */
                goto bail_nolock;
        }

        error = ocfs2_dir_foreach_blk(inode, &filp->f_version, &filp->f_pos,
                                      dirent, filldir, NULL);

        ocfs2_meta_unlock(inode, lock_level);

bail_nolock:
        mlog_exit(error);

        return error;
}

/*
 * NOTE: this should always be called with parent dir i_mutex taken.
 */
int ocfs2_find_files_on_disk(const char *name,
                             int namelen,
                             u64 *blkno,
                             struct inode *inode,
                             struct buffer_head **dirent_bh,
                             struct ocfs2_dir_entry **dirent)
{
        int status = -ENOENT;

        mlog_entry("(name=%.*s, blkno=%p, inode=%p, dirent_bh=%p, dirent=%p)\n",
                   namelen, name, blkno, inode, dirent_bh, dirent);

        *dirent_bh = ocfs2_find_entry(name, namelen, inode, dirent);
        if (!*dirent_bh || !*dirent) {
                status = -ENOENT;
                goto leave;
        }

        *blkno = le64_to_cpu((*dirent)->inode);

        status = 0;
leave:
        if (status < 0) {
                *dirent = NULL;
                if (*dirent_bh) {
                        brelse(*dirent_bh);
                        *dirent_bh = NULL;
                }
        }

        mlog_exit(status);
        return status;
}

/*
 * Convenience function for callers which just want the block number
 * mapped to a name and don't require the full dirent info, etc.
 */
int ocfs2_lookup_ino_from_name(struct inode *dir, const char *name,
                               int namelen, u64 *blkno)
{
        int ret;
        struct buffer_head *bh = NULL;
        struct ocfs2_dir_entry *dirent = NULL;

        ret = ocfs2_find_files_on_disk(name, namelen, blkno, dir, &bh, &dirent);
        brelse(bh);

        return ret;
}

/* Check for a name within a directory.
 *
 * Return 0 if the name does not exist
 * Return -EEXIST if the directory contains the name
 *
 * Callers should have i_mutex + a cluster lock on dir
 */
int ocfs2_check_dir_for_entry(struct inode *dir,
                              const char *name,
                              int namelen)
{
        int ret;
        struct buffer_head *dirent_bh = NULL;
        struct ocfs2_dir_entry *dirent = NULL;

        mlog_entry("dir %llu, name '%.*s'\n",
                   (unsigned long long)OCFS2_I(dir)->ip_blkno, namelen, name);

        ret = -EEXIST;
        dirent_bh = ocfs2_find_entry(name, namelen, dir, &dirent);
        if (dirent_bh)
                goto bail;

        ret = 0;
bail:
        if (dirent_bh)
                brelse(dirent_bh);

        mlog_exit(ret);
        return ret;
}

struct ocfs2_empty_dir_priv {
        unsigned seen_dot;
        unsigned seen_dot_dot;
        unsigned seen_other;
};
static int ocfs2_empty_dir_filldir(void *priv, const char *name, int name_len,
                                   loff_t pos, u64 ino, unsigned type)
{
        struct ocfs2_empty_dir_priv *p = priv;

        /*
         * Check the positions of "." and ".." records to be sure
         * they're in the correct place.
         */
        if (name_len == 1 && !strncmp(".", name, 1) && pos == 0) {
                p->seen_dot = 1;
                return 0;
        }

        if (name_len == 2 && !strncmp("..", name, 2) &&
            pos == OCFS2_DIR_REC_LEN(1)) {
                p->seen_dot_dot = 1;
                return 0;
        }

        p->seen_other = 1;
        return 1;
}
/*
 * routine to check that the specified directory is empty (for rmdir)
 *
 * Returns 1 if dir is empty, zero otherwise.
 */
int ocfs2_empty_dir(struct inode *inode)
{
        int ret;
        loff_t start = 0;
        struct ocfs2_empty_dir_priv priv;

        memset(&priv, 0, sizeof(priv));

        ret = ocfs2_dir_foreach(inode, &start, &priv, ocfs2_empty_dir_filldir);
        if (ret)
                mlog_errno(ret);

        if (!priv.seen_dot || !priv.seen_dot_dot) {
                mlog(ML_ERROR, "bad directory (dir #%llu) - no `.' or `..'\n",
                     (unsigned long long)OCFS2_I(inode)->ip_blkno);
                /*
                 * XXX: Is it really safe to allow an unlink to continue?
                 */
                return 1;
        }

        return !priv.seen_other;
}

static void ocfs2_fill_initial_dirents(struct inode *inode,
                                       struct inode *parent,
                                       char *start, unsigned int size)
{
        struct ocfs2_dir_entry *de = (struct ocfs2_dir_entry *)start;

        de->inode = cpu_to_le64(OCFS2_I(inode)->ip_blkno);
        de->name_len = 1;
        de->rec_len =
                cpu_to_le16(OCFS2_DIR_REC_LEN(de->name_len));
        strcpy(de->name, ".");
        ocfs2_set_de_type(de, S_IFDIR);

        de = (struct ocfs2_dir_entry *) ((char *)de + le16_to_cpu(de->rec_len));
        de->inode = cpu_to_le64(OCFS2_I(parent)->ip_blkno);
        de->rec_len = cpu_to_le16(size - OCFS2_DIR_REC_LEN(1));
        de->name_len = 2;
        strcpy(de->name, "..");
        ocfs2_set_de_type(de, S_IFDIR);
}

/*
 * This works together with code in ocfs2_mknod_locked() which sets
 * the inline-data flag and initializes the inline-data section.
 */
static int ocfs2_fill_new_dir_id(struct ocfs2_super *osb,
                                 handle_t *handle,
                                 struct inode *parent,
                                 struct inode *inode,
                                 struct buffer_head *di_bh)
{
        int ret;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        struct ocfs2_inline_data *data = &di->id2.i_data;
        unsigned int size = le16_to_cpu(data->id_count);

        ret = ocfs2_journal_access(handle, inode, di_bh,
                                   OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ocfs2_fill_initial_dirents(inode, parent, data->id_data, size);

        ocfs2_journal_dirty(handle, di_bh);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        i_size_write(inode, size);
        inode->i_nlink = 2;
        inode->i_blocks = ocfs2_inode_sector_count(inode);

        ret = ocfs2_mark_inode_dirty(handle, inode, di_bh);
        if (ret < 0)
                mlog_errno(ret);

out:
        return ret;
}

static int ocfs2_fill_new_dir_el(struct ocfs2_super *osb,
                                 handle_t *handle,
                                 struct inode *parent,
                                 struct inode *inode,
                                 struct buffer_head *fe_bh,
                                 struct ocfs2_alloc_context *data_ac)
{
        int status;
        struct buffer_head *new_bh = NULL;

        mlog_entry_void();

        status = ocfs2_do_extend_dir(osb->sb, handle, inode, fe_bh,
                                     data_ac, NULL, &new_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        ocfs2_set_new_buffer_uptodate(inode, new_bh);

        status = ocfs2_journal_access(handle, inode, new_bh,
                                      OCFS2_JOURNAL_ACCESS_CREATE);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }
        memset(new_bh->b_data, 0, osb->sb->s_blocksize);

        ocfs2_fill_initial_dirents(inode, parent, new_bh->b_data,
                                   osb->sb->s_blocksize);

        status = ocfs2_journal_dirty(handle, new_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        i_size_write(inode, inode->i_sb->s_blocksize);
        inode->i_nlink = 2;
        inode->i_blocks = ocfs2_inode_sector_count(inode);
        status = ocfs2_mark_inode_dirty(handle, inode, fe_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        status = 0;
bail:
        if (new_bh)
                brelse(new_bh);

        mlog_exit(status);
        return status;
}

int ocfs2_fill_new_dir(struct ocfs2_super *osb,
                       handle_t *handle,
                       struct inode *parent,
                       struct inode *inode,
                       struct buffer_head *fe_bh,
                       struct ocfs2_alloc_context *data_ac)
{
        BUG_ON(!ocfs2_supports_inline_data(osb) && data_ac == NULL);

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                return ocfs2_fill_new_dir_id(osb, handle, parent, inode, fe_bh);

        return ocfs2_fill_new_dir_el(osb, handle, parent, inode, fe_bh,
                                     data_ac);
}

static void ocfs2_expand_last_dirent(char *start, unsigned int old_size,
                                     unsigned int new_size)
{
        struct ocfs2_dir_entry *de;
        struct ocfs2_dir_entry *prev_de;
        char *de_buf, *limit;
        unsigned int bytes = new_size - old_size;

        limit = start + old_size;
        de_buf = start;
        de = (struct ocfs2_dir_entry *)de_buf;
        do {
                prev_de = de;
                de_buf += le16_to_cpu(de->rec_len);
                de = (struct ocfs2_dir_entry *)de_buf;
        } while (de_buf < limit);

        le16_add_cpu(&prev_de->rec_len, bytes);
}

/*
 * We allocate enough clusters to fulfill "blocks_wanted", but set
 * i_size to exactly one block. Ocfs2_extend_dir() will handle the
 * rest automatically for us.
 *
 * *first_block_bh is a pointer to the 1st data block allocated to the
 *  directory.
 */
static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
                                   unsigned int blocks_wanted,
                                   struct buffer_head **first_block_bh)
{
        int ret, credits = OCFS2_INLINE_TO_EXTENTS_CREDITS;
        u32 alloc, bit_off, len;
        struct super_block *sb = dir->i_sb;
        u64 blkno, bytes = blocks_wanted << sb->s_blocksize_bits;
        struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
        struct ocfs2_inode_info *oi = OCFS2_I(dir);
        struct ocfs2_alloc_context *data_ac;
        struct buffer_head *dirdata_bh = NULL;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        handle_t *handle;

        alloc = ocfs2_clusters_for_bytes(sb, bytes);

        /*
         * We should never need more than 2 clusters for this -
         * maximum dirent size is far less than one block. In fact,
         * the only time we'd need more than one cluster is if
         * blocksize == clustersize and the dirent won't fit in the
         * extra space that the expansion to a single block gives. As
         * of today, that only happens on 4k/4k file systems.
         */
        BUG_ON(alloc > 2);

        ret = ocfs2_reserve_clusters(osb, alloc, &data_ac);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        down_write(&oi->ip_alloc_sem);

        /*
         * Prepare for worst case allocation scenario of two seperate
         * extents.
         */
        if (alloc == 2)
                credits += OCFS2_SUBALLOC_ALLOC;

        handle = ocfs2_start_trans(osb, credits);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out_sem;
        }

        /*
         * Try to claim as many clusters as the bitmap can give though
         * if we only get one now, that's enough to continue. The rest
         * will be claimed after the conversion to extents.
         */
        ret = ocfs2_claim_clusters(osb, handle, data_ac, 1, &bit_off, &len);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        /*
         * Operations are carefully ordered so that we set up the new
         * data block first. The conversion from inline data to
         * extents follows.
         */
        blkno = ocfs2_clusters_to_blocks(dir->i_sb, bit_off);
        dirdata_bh = sb_getblk(sb, blkno);
        if (!dirdata_bh) {
                ret = -EIO;
                mlog_errno(ret);
                goto out_commit;
        }

        ocfs2_set_new_buffer_uptodate(dir, dirdata_bh);

        ret = ocfs2_journal_access(handle, dir, dirdata_bh,
                                   OCFS2_JOURNAL_ACCESS_CREATE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        memcpy(dirdata_bh->b_data, di->id2.i_data.id_data, i_size_read(dir));
        memset(dirdata_bh->b_data + i_size_read(dir), 0,
               sb->s_blocksize - i_size_read(dir));
        ocfs2_expand_last_dirent(dirdata_bh->b_data, i_size_read(dir),
                                 sb->s_blocksize);

        ret = ocfs2_journal_dirty(handle, dirdata_bh);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        /*
         * Set extent, i_size, etc on the directory. After this, the
         * inode should contain the same exact dirents as before and
         * be fully accessible from system calls.
         *
         * We let the later dirent insert modify c/mtime - to the user
         * the data hasn't changed.
         */
        ret = ocfs2_journal_access(handle, dir, di_bh,
                                   OCFS2_JOURNAL_ACCESS_CREATE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        spin_lock(&oi->ip_lock);
        oi->ip_dyn_features &= ~OCFS2_INLINE_DATA_FL;
        di->i_dyn_features = cpu_to_le16(oi->ip_dyn_features);
        spin_unlock(&oi->ip_lock);

        ocfs2_dinode_new_extent_list(dir, di);

        i_size_write(dir, sb->s_blocksize);
        dir->i_mtime = dir->i_ctime = CURRENT_TIME;

        di->i_size = cpu_to_le64(sb->s_blocksize);
        di->i_ctime = di->i_mtime = cpu_to_le64(dir->i_ctime.tv_sec);
        di->i_ctime_nsec = di->i_mtime_nsec = cpu_to_le32(dir->i_ctime.tv_nsec);
        dir->i_blocks = ocfs2_inode_sector_count(dir);

        /*
         * This should never fail as our extent list is empty and all
         * related blocks have been journaled already.
         */
        ret = ocfs2_insert_extent(osb, handle, dir, di_bh, 0, blkno, len, 0,
                                  NULL);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_dirty(handle, di_bh);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        /*
         * We asked for two clusters, but only got one in the 1st
         * pass. Claim the 2nd cluster as a separate extent.
         */
        if (alloc > len) {
                ret = ocfs2_claim_clusters(osb, handle, data_ac, 1, &bit_off,
                                           &len);
                if (ret) {
                        mlog_errno(ret);
                        goto out_commit;
                }
                blkno = ocfs2_clusters_to_blocks(dir->i_sb, bit_off);

                ret = ocfs2_insert_extent(osb, handle, dir, di_bh, 1, blkno,
                                          len, 0, NULL);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
        }

        *first_block_bh = dirdata_bh;
        dirdata_bh = NULL;

out_commit:
        ocfs2_commit_trans(osb, handle);

out_sem:
        up_write(&oi->ip_alloc_sem);

out:
        if (data_ac)
                ocfs2_free_alloc_context(data_ac);

        brelse(dirdata_bh);

        return ret;
}

/* returns a bh of the 1st new block in the allocation. */
static int ocfs2_do_extend_dir(struct super_block *sb,
                               handle_t *handle,
                               struct inode *dir,
                               struct buffer_head *parent_fe_bh,
                               struct ocfs2_alloc_context *data_ac,
                               struct ocfs2_alloc_context *meta_ac,
                               struct buffer_head **new_bh)
{
        int status;
        int extend;
        u64 p_blkno, v_blkno;

        spin_lock(&OCFS2_I(dir)->ip_lock);
        extend = (i_size_read(dir) == ocfs2_clusters_to_bytes(sb, OCFS2_I(dir)->ip_clusters));
        spin_unlock(&OCFS2_I(dir)->ip_lock);

        if (extend) {
                u32 offset = OCFS2_I(dir)->ip_clusters;

                status = ocfs2_do_extend_allocation(OCFS2_SB(sb), dir, &offset,
                                                    1, 0, parent_fe_bh, handle,
                                                    data_ac, meta_ac, NULL);
                BUG_ON(status == -EAGAIN);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }
        }

        v_blkno = ocfs2_blocks_for_bytes(sb, i_size_read(dir));
        status = ocfs2_extent_map_get_blocks(dir, v_blkno, &p_blkno, NULL, NULL);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        *new_bh = sb_getblk(sb, p_blkno);
        if (!*new_bh) {
                status = -EIO;
                mlog_errno(status);
                goto bail;
        }
        status = 0;
bail:
        mlog_exit(status);
        return status;
}

/*
 * Assumes you already have a cluster lock on the directory.
 *
 * 'blocks_wanted' is only used if we have an inline directory which
 * is to be turned into an extent based one. The size of the dirent to
 * insert might be larger than the space gained by growing to just one
 * block, so we may have to grow the inode by two blocks in that case.
 */
static int ocfs2_extend_dir(struct ocfs2_super *osb,
                            struct inode *dir,
                            struct buffer_head *parent_fe_bh,
                            unsigned int blocks_wanted,
                            struct buffer_head **new_de_bh)
{
        int status = 0;
        int credits, num_free_extents, drop_alloc_sem = 0;
        loff_t dir_i_size;
        struct ocfs2_dinode *fe = (struct ocfs2_dinode *) parent_fe_bh->b_data;
        struct ocfs2_alloc_context *data_ac = NULL;
        struct ocfs2_alloc_context *meta_ac = NULL;
        handle_t *handle = NULL;
        struct buffer_head *new_bh = NULL;
        struct ocfs2_dir_entry * de;
        struct super_block *sb = osb->sb;

        mlog_entry_void();

        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                status = ocfs2_expand_inline_dir(dir, parent_fe_bh,
                                                 blocks_wanted, &new_bh);
                if (status) {
                        mlog_errno(status);
                        goto bail;
                }

                if (blocks_wanted == 1) {
                        /*
                         * If the new dirent will fit inside the space
                         * created by pushing out to one block, then
                         * we can complete the operation
                         * here. Otherwise we have to expand i_size
                         * and format the 2nd block below.
                         */
                        BUG_ON(new_bh == NULL);
                        goto bail_bh;
                }

                /*
                 * Get rid of 'new_bh' - we want to format the 2nd
                 * data block and return that instead.
                 */
                brelse(new_bh);
                new_bh = NULL;

                dir_i_size = i_size_read(dir);
                credits = OCFS2_SIMPLE_DIR_EXTEND_CREDITS;
                goto do_extend;
        }

        dir_i_size = i_size_read(dir);
        mlog(0, "extending dir %llu (i_size = %lld)\n",
             (unsigned long long)OCFS2_I(dir)->ip_blkno, dir_i_size);

        /* dir->i_size is always block aligned. */
        spin_lock(&OCFS2_I(dir)->ip_lock);
        if (dir_i_size == ocfs2_clusters_to_bytes(sb, OCFS2_I(dir)->ip_clusters)) {
                spin_unlock(&OCFS2_I(dir)->ip_lock);
                num_free_extents = ocfs2_num_free_extents(osb, dir, fe);
                if (num_free_extents < 0) {
                        status = num_free_extents;
                        mlog_errno(status);
                        goto bail;
                }

                if (!num_free_extents) {
                        status = ocfs2_reserve_new_metadata(osb, fe, &meta_ac);
                        if (status < 0) {
                                if (status != -ENOSPC)
                                        mlog_errno(status);
                                goto bail;
                        }
                }

                status = ocfs2_reserve_clusters(osb, 1, &data_ac);
                if (status < 0) {
                        if (status != -ENOSPC)
                                mlog_errno(status);
                        goto bail;
                }

                credits = ocfs2_calc_extend_credits(sb, fe, 1);
        } else {
                spin_unlock(&OCFS2_I(dir)->ip_lock);
                credits = OCFS2_SIMPLE_DIR_EXTEND_CREDITS;
        }

do_extend:
        down_write(&OCFS2_I(dir)->ip_alloc_sem);
        drop_alloc_sem = 1;

        handle = ocfs2_start_trans(osb, credits);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                handle = NULL;
                mlog_errno(status);
                goto bail;
        }

        status = ocfs2_do_extend_dir(osb->sb, handle, dir, parent_fe_bh,
                                     data_ac, meta_ac, &new_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        ocfs2_set_new_buffer_uptodate(dir, new_bh);

        status = ocfs2_journal_access(handle, dir, new_bh,
                                      OCFS2_JOURNAL_ACCESS_CREATE);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }
        memset(new_bh->b_data, 0, sb->s_blocksize);
        de = (struct ocfs2_dir_entry *) new_bh->b_data;
        de->inode = 0;
        de->rec_len = cpu_to_le16(sb->s_blocksize);
        status = ocfs2_journal_dirty(handle, new_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

        dir_i_size += dir->i_sb->s_blocksize;
        i_size_write(dir, dir_i_size);
        dir->i_blocks = ocfs2_inode_sector_count(dir);
        status = ocfs2_mark_inode_dirty(handle, dir, parent_fe_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

bail_bh:
        *new_de_bh = new_bh;
        get_bh(*new_de_bh);
bail:
        if (drop_alloc_sem)
                up_write(&OCFS2_I(dir)->ip_alloc_sem);
        if (handle)
                ocfs2_commit_trans(osb, handle);

        if (data_ac)
                ocfs2_free_alloc_context(data_ac);
        if (meta_ac)
                ocfs2_free_alloc_context(meta_ac);

        if (new_bh)
                brelse(new_bh);

        mlog_exit(status);
        return status;
}

static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
                                   const char *name, int namelen,
                                   struct buffer_head **ret_de_bh,
                                   unsigned int *blocks_wanted)
{
        int ret;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        struct ocfs2_dir_entry *de, *last_de = NULL;
        char *de_buf, *limit;
        unsigned long offset = 0;
        unsigned int rec_len, new_rec_len;

        de_buf = di->id2.i_data.id_data;
        limit = de_buf + i_size_read(dir);
        rec_len = OCFS2_DIR_REC_LEN(namelen);

        while (de_buf < limit) {
                de = (struct ocfs2_dir_entry *)de_buf;

                if (!ocfs2_check_dir_entry(dir, de, di_bh, offset)) {
                        ret = -ENOENT;
                        goto out;
                }
                if (ocfs2_match(namelen, name, de)) {
                        ret = -EEXIST;
                        goto out;
                }
                if (ocfs2_dirent_would_fit(de, rec_len)) {
                        /* Ok, we found a spot. Return this bh and let
                         * the caller actually fill it in. */
                        *ret_de_bh = di_bh;
                        get_bh(*ret_de_bh);
                        ret = 0;
                        goto out;
                }

                last_de = de;
                de_buf += le16_to_cpu(de->rec_len);
                offset += le16_to_cpu(de->rec_len);
        }

        /*
         * We're going to require expansion of the directory - figure
         * out how many blocks we'll need so that a place for the
         * dirent can be found.
         */
        *blocks_wanted = 1;
        new_rec_len = le16_to_cpu(last_de->rec_len) + (dir->i_sb->s_blocksize - i_size_read(dir));
        if (new_rec_len < (rec_len + OCFS2_DIR_REC_LEN(last_de->name_len)))
                *blocks_wanted = 2;

        ret = -ENOSPC;
out:
        return ret;
}

static int ocfs2_find_dir_space_el(struct inode *dir, const char *name,
                                   int namelen, struct buffer_head **ret_de_bh)
{
        unsigned long offset;
        struct buffer_head *bh = NULL;
        unsigned short rec_len;
        struct ocfs2_dir_entry *de;
        struct super_block *sb = dir->i_sb;
        int status;

        bh = ocfs2_bread(dir, 0, &status, 0);
        if (!bh) {
                mlog_errno(status);
                goto bail;
        }

        rec_len = OCFS2_DIR_REC_LEN(namelen);
        offset = 0;
        de = (struct ocfs2_dir_entry *) bh->b_data;
        while (1) {
                if ((char *)de >= sb->s_blocksize + bh->b_data) {
                        brelse(bh);
                        bh = NULL;

                        if (i_size_read(dir) <= offset) {
                                /*
                                 * Caller will have to expand this
                                 * directory.
                                 */
                                status = -ENOSPC;
                                goto bail;
                        }
                        bh = ocfs2_bread(dir,
                                         offset >> sb->s_blocksize_bits,
                                         &status,
                                         0);
                        if (!bh) {
                                mlog_errno(status);
                                goto bail;
                        }
                        /* move to next block */
                        de = (struct ocfs2_dir_entry *) bh->b_data;
                }
                if (!ocfs2_check_dir_entry(dir, de, bh, offset)) {
                        status = -ENOENT;
                        goto bail;
                }
                if (ocfs2_match(namelen, name, de)) {
                        status = -EEXIST;
                        goto bail;
                }
                if (ocfs2_dirent_would_fit(de, rec_len)) {
                        /* Ok, we found a spot. Return this bh and let
                         * the caller actually fill it in. */
                        *ret_de_bh = bh;
                        get_bh(*ret_de_bh);
                        status = 0;
                        goto bail;
                }
                offset += le16_to_cpu(de->rec_len);
                de = (struct ocfs2_dir_entry *)((char *) de + le16_to_cpu(de->rec_len));
        }

        status = 0;
bail:
        if (bh)
                brelse(bh);

        mlog_exit(status);
        return status;
}

int ocfs2_prepare_dir_for_insert(struct ocfs2_super *osb,
                                 struct inode *dir,
                                 struct buffer_head *parent_fe_bh,
                                 const char *name,
                                 int namelen,
                                 struct buffer_head **ret_de_bh)
{
        int ret;
        unsigned int blocks_wanted = 1;
        struct buffer_head *bh = NULL;

        mlog(0, "getting ready to insert namelen %d into dir %llu\n",
             namelen, (unsigned long long)OCFS2_I(dir)->ip_blkno);

        *ret_de_bh = NULL;

        if (!namelen) {
                ret = -EINVAL;
                mlog_errno(ret);
                goto out;
        }

        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                ret = ocfs2_find_dir_space_id(dir, parent_fe_bh, name,
                                              namelen, &bh, &blocks_wanted);
        } else
                ret = ocfs2_find_dir_space_el(dir, name, namelen, &bh);

        if (ret && ret != -ENOSPC) {
                mlog_errno(ret);
                goto out;
        }

        if (ret == -ENOSPC) {
                /*
                 * We have to expand the directory to add this name.
                 */
                BUG_ON(bh);

                ret = ocfs2_extend_dir(osb, dir, parent_fe_bh, blocks_wanted,
                                       &bh);
                if (ret) {
                        if (ret != -ENOSPC)
                                mlog_errno(ret);
                        goto out;
                }

                BUG_ON(!bh);
        }

        *ret_de_bh = bh;
        bh = NULL;
out:
        if (bh)
                brelse(bh);
        return ret;
}