/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * file.c
 *
 * File open, close, extend, truncate
 *
 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * 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/capability.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/sched.h>
#include <linux/splice.h>
#include <linux/mount.h>
#include <linux/writeback.h>
#include <linux/falloc.h>
#include <linux/quotaops.h>
#include <linux/blkdev.h>

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

#include "ocfs2.h"

#include "alloc.h"
#include "aops.h"
#include "dir.h"
#include "dlmglue.h"
#include "extent_map.h"
#include "file.h"
#include "sysfile.h"
#include "inode.h"
#include "ioctl.h"
#include "journal.h"
#include "locks.h"
#include "mmap.h"
#include "suballoc.h"
#include "super.h"
#include "xattr.h"
#include "acl.h"
#include "quota.h"
#include "refcounttree.h"

#include "buffer_head_io.h"

static int ocfs2_init_file_private(struct inode *inode, struct file *file)
{
        struct ocfs2_file_private *fp;

        fp = kzalloc(sizeof(struct ocfs2_file_private), GFP_KERNEL);
        if (!fp)
                return -ENOMEM;

        fp->fp_file = file;
        mutex_init(&fp->fp_mutex);
        ocfs2_file_lock_res_init(&fp->fp_flock, fp);
        file->private_data = fp;

        return 0;
}

static void ocfs2_free_file_private(struct inode *inode, struct file *file)
{
        struct ocfs2_file_private *fp = file->private_data;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

        if (fp) {
                ocfs2_simple_drop_lockres(osb, &fp->fp_flock);
                ocfs2_lock_res_free(&fp->fp_flock);
                kfree(fp);
                file->private_data = NULL;
        }
}

static int ocfs2_file_open(struct inode *inode, struct file *file)
{
        int status;
        int mode = file->f_flags;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);

        mlog_entry("(0x%p, 0x%p, '%.*s')\n", inode, file,
                   file->f_path.dentry->d_name.len, file->f_path.dentry->d_name.name);

        if (file->f_mode & FMODE_WRITE)
                dquot_initialize(inode);

        spin_lock(&oi->ip_lock);

        /* Check that the inode hasn't been wiped from disk by another
         * node. If it hasn't then we're safe as long as we hold the
         * spin lock until our increment of open count. */
        if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
                spin_unlock(&oi->ip_lock);

                status = -ENOENT;
                goto leave;
        }

        if (mode & O_DIRECT)
                oi->ip_flags |= OCFS2_INODE_OPEN_DIRECT;

        oi->ip_open_count++;
        spin_unlock(&oi->ip_lock);

        status = ocfs2_init_file_private(inode, file);
        if (status) {
                /*
                 * We want to set open count back if we're failing the
                 * open.
                 */
                spin_lock(&oi->ip_lock);
                oi->ip_open_count--;
                spin_unlock(&oi->ip_lock);
        }

leave:
        mlog_exit(status);
        return status;
}

static int ocfs2_file_release(struct inode *inode, struct file *file)
{
        struct ocfs2_inode_info *oi = OCFS2_I(inode);

        mlog_entry("(0x%p, 0x%p, '%.*s')\n", inode, file,
                       file->f_path.dentry->d_name.len,
                       file->f_path.dentry->d_name.name);

        spin_lock(&oi->ip_lock);
        if (!--oi->ip_open_count)
                oi->ip_flags &= ~OCFS2_INODE_OPEN_DIRECT;
        spin_unlock(&oi->ip_lock);

        ocfs2_free_file_private(inode, file);

        mlog_exit(0);

        return 0;
}

static int ocfs2_dir_open(struct inode *inode, struct file *file)
{
        return ocfs2_init_file_private(inode, file);
}

static int ocfs2_dir_release(struct inode *inode, struct file *file)
{
        ocfs2_free_file_private(inode, file);
        return 0;
}

static int ocfs2_sync_file(struct file *file, int datasync)
{
        int err = 0;
        journal_t *journal;
        struct inode *inode = file->f_mapping->host;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

        mlog_entry("(0x%p, %d, 0x%p, '%.*s')\n", file, datasync,
                   file->f_path.dentry, file->f_path.dentry->d_name.len,
                   file->f_path.dentry->d_name.name);

        if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) {
                /*
                 * We still have to flush drive's caches to get data to the
                 * platter
                 */
                if (osb->s_mount_opt & OCFS2_MOUNT_BARRIER)
                        blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
                goto bail;
        }

        journal = osb->journal->j_journal;
        err = jbd2_journal_force_commit(journal);

bail:
        mlog_exit(err);

        return (err < 0) ? -EIO : 0;
}

int ocfs2_should_update_atime(struct inode *inode,
                              struct vfsmount *vfsmnt)
{
        struct timespec now;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

        if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
                return 0;

        if ((inode->i_flags & S_NOATIME) ||
            ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode)))
                return 0;

        /*
         * We can be called with no vfsmnt structure - NFSD will
         * sometimes do this.
         *
         * Note that our action here is different than touch_atime() -
         * if we can't tell whether this is a noatime mount, then we
         * don't know whether to trust the value of s_atime_quantum.
         */
        if (vfsmnt == NULL)
                return 0;

        if ((vfsmnt->mnt_flags & MNT_NOATIME) ||
            ((vfsmnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
                return 0;

        if (vfsmnt->mnt_flags & MNT_RELATIME) {
                if ((timespec_compare(&inode->i_atime, &inode->i_mtime) <= 0) ||
                    (timespec_compare(&inode->i_atime, &inode->i_ctime) <= 0))
                        return 1;

                return 0;
        }

        now = CURRENT_TIME;
        if ((now.tv_sec - inode->i_atime.tv_sec <= osb->s_atime_quantum))
                return 0;
        else
                return 1;
}

int ocfs2_update_inode_atime(struct inode *inode,
                             struct buffer_head *bh)
{
        int ret;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        handle_t *handle;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *) bh->b_data;

        mlog_entry_void();

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret) {
                mlog_errno(ret);
                goto out_commit;
        }

        /*
         * Don't use ocfs2_mark_inode_dirty() here as we don't always
         * have i_mutex to guard against concurrent changes to other
         * inode fields.
         */
        inode->i_atime = CURRENT_TIME;
        di->i_atime = cpu_to_le64(inode->i_atime.tv_sec);
        di->i_atime_nsec = cpu_to_le32(inode->i_atime.tv_nsec);
        ocfs2_journal_dirty(handle, bh);

out_commit:
        ocfs2_commit_trans(OCFS2_SB(inode->i_sb), handle);
out:
        mlog_exit(ret);
        return ret;
}

static int ocfs2_set_inode_size(handle_t *handle,
                                struct inode *inode,
                                struct buffer_head *fe_bh,
                                u64 new_i_size)
{
        int status;

        mlog_entry_void();
        i_size_write(inode, new_i_size);
        inode->i_blocks = ocfs2_inode_sector_count(inode);
        inode->i_ctime = inode->i_mtime = CURRENT_TIME;

        status = ocfs2_mark_inode_dirty(handle, inode, fe_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

bail:
        mlog_exit(status);
        return status;
}

int ocfs2_simple_size_update(struct inode *inode,
                             struct buffer_head *di_bh,
                             u64 new_i_size)
{
        int ret;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        handle_t *handle = NULL;

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_set_inode_size(handle, inode, di_bh,
                                   new_i_size);
        if (ret < 0)
                mlog_errno(ret);

        ocfs2_commit_trans(osb, handle);
out:
        return ret;
}

static int ocfs2_cow_file_pos(struct inode *inode,
                              struct buffer_head *fe_bh,
                              u64 offset)
{
        int status;
        u32 phys, cpos = offset >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
        unsigned int num_clusters = 0;
        unsigned int ext_flags = 0;

        /*
         * If the new offset is aligned to the range of the cluster, there is
         * no space for ocfs2_zero_range_for_truncate to fill, so no need to
         * CoW either.
         */
        if ((offset & (OCFS2_SB(inode->i_sb)->s_clustersize - 1)) == 0)
                return 0;

        status = ocfs2_get_clusters(inode, cpos, &phys,
                                    &num_clusters, &ext_flags);
        if (status) {
                mlog_errno(status);
                goto out;
        }

        if (!(ext_flags & OCFS2_EXT_REFCOUNTED))
                goto out;

        return ocfs2_refcount_cow(inode, NULL, fe_bh, cpos, 1, cpos+1);

out:
        return status;
}

static int ocfs2_orphan_for_truncate(struct ocfs2_super *osb,
                                     struct inode *inode,
                                     struct buffer_head *fe_bh,
                                     u64 new_i_size)
{
        int status;
        handle_t *handle;
        struct ocfs2_dinode *di;
        u64 cluster_bytes;

        mlog_entry_void();

        /*
         * We need to CoW the cluster contains the offset if it is reflinked
         * since we will call ocfs2_zero_range_for_truncate later which will
         * write "0" from offset to the end of the cluster.
         */
        status = ocfs2_cow_file_pos(inode, fe_bh, new_i_size);
        if (status) {
                mlog_errno(status);
                return status;
        }

        /* TODO: This needs to actually orphan the inode in this
         * transaction. */

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out;
        }

        status = ocfs2_journal_access_di(handle, INODE_CACHE(inode), fe_bh,
                                         OCFS2_JOURNAL_ACCESS_WRITE);
        if (status < 0) {
                mlog_errno(status);
                goto out_commit;
        }

        /*
         * Do this before setting i_size.
         */
        cluster_bytes = ocfs2_align_bytes_to_clusters(inode->i_sb, new_i_size);
        status = ocfs2_zero_range_for_truncate(inode, handle, new_i_size,
                                               cluster_bytes);
        if (status) {
                mlog_errno(status);
                goto out_commit;
        }

        i_size_write(inode, new_i_size);
        inode->i_ctime = inode->i_mtime = CURRENT_TIME;

        di = (struct ocfs2_dinode *) fe_bh->b_data;
        di->i_size = cpu_to_le64(new_i_size);
        di->i_ctime = di->i_mtime = cpu_to_le64(inode->i_ctime.tv_sec);
        di->i_ctime_nsec = di->i_mtime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);

        ocfs2_journal_dirty(handle, fe_bh);

out_commit:
        ocfs2_commit_trans(osb, handle);
out:

        mlog_exit(status);
        return status;
}

static int ocfs2_truncate_file(struct inode *inode,
                               struct buffer_head *di_bh,
                               u64 new_i_size)
{
        int status = 0;
        struct ocfs2_dinode *fe = NULL;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

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

        /* We trust di_bh because it comes from ocfs2_inode_lock(), which
         * already validated it */
        fe = (struct ocfs2_dinode *) di_bh->b_data;

        mlog_bug_on_msg(le64_to_cpu(fe->i_size) != i_size_read(inode),
                        "Inode %llu, inode i_size = %lld != di "
                        "i_size = %llu, i_flags = 0x%x\n",
                        (unsigned long long)OCFS2_I(inode)->ip_blkno,
                        i_size_read(inode),
                        (unsigned long long)le64_to_cpu(fe->i_size),
                        le32_to_cpu(fe->i_flags));

        if (new_i_size > le64_to_cpu(fe->i_size)) {
                mlog(0, "asked to truncate file with size (%llu) to size (%llu)!\n",
                     (unsigned long long)le64_to_cpu(fe->i_size),
                     (unsigned long long)new_i_size);
                status = -EINVAL;
                mlog_errno(status);
                goto bail;
        }

        mlog(0, "inode %llu, i_size = %llu, new_i_size = %llu\n",
             (unsigned long long)le64_to_cpu(fe->i_blkno),
             (unsigned long long)le64_to_cpu(fe->i_size),
             (unsigned long long)new_i_size);

        /* lets handle the simple truncate cases before doing any more
         * cluster locking. */
        if (new_i_size == le64_to_cpu(fe->i_size))
                goto bail;

        down_write(&OCFS2_I(inode)->ip_alloc_sem);

        ocfs2_resv_discard(&osb->osb_la_resmap,
                           &OCFS2_I(inode)->ip_la_data_resv);

        /*
         * The inode lock forced other nodes to sync and drop their
         * pages, which (correctly) happens even if we have a truncate
         * without allocation change - ocfs2 cluster sizes can be much
         * greater than page size, so we have to truncate them
         * anyway.
         */
        unmap_mapping_range(inode->i_mapping, new_i_size + PAGE_SIZE - 1, 0, 1);
        truncate_inode_pages(inode->i_mapping, new_i_size);

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                status = ocfs2_truncate_inline(inode, di_bh, new_i_size,
                                               i_size_read(inode), 1);
                if (status)
                        mlog_errno(status);

                goto bail_unlock_sem;
        }

        /* alright, we're going to need to do a full blown alloc size
         * change. Orphan the inode so that recovery can complete the
         * truncate if necessary. This does the task of marking
         * i_size. */
        status = ocfs2_orphan_for_truncate(osb, inode, di_bh, new_i_size);
        if (status < 0) {
                mlog_errno(status);
                goto bail_unlock_sem;
        }

        status = ocfs2_commit_truncate(osb, inode, di_bh);
        if (status < 0) {
                mlog_errno(status);
                goto bail_unlock_sem;
        }

        /* TODO: orphan dir cleanup here. */
bail_unlock_sem:
        up_write(&OCFS2_I(inode)->ip_alloc_sem);

bail:
        if (!status && OCFS2_I(inode)->ip_clusters == 0)
                status = ocfs2_try_remove_refcount_tree(inode, di_bh);

        mlog_exit(status);
        return status;
}

/*
 * extend file allocation only here.
 * we'll update all the disk stuff, and oip->alloc_size
 *
 * expect stuff to be locked, a transaction started and enough data /
 * metadata reservations in the contexts.
 *
 * Will return -EAGAIN, and a reason if a restart is needed.
 * If passed in, *reason will always be set, even in error.
 */
int ocfs2_add_inode_data(struct ocfs2_super *osb,
                         struct inode *inode,
                         u32 *logical_offset,
                         u32 clusters_to_add,
                         int mark_unwritten,
                         struct buffer_head *fe_bh,
                         handle_t *handle,
                         struct ocfs2_alloc_context *data_ac,
                         struct ocfs2_alloc_context *meta_ac,
                         enum ocfs2_alloc_restarted *reason_ret)
{
        int ret;
        struct ocfs2_extent_tree et;

        ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), fe_bh);
        ret = ocfs2_add_clusters_in_btree(handle, &et, logical_offset,
                                          clusters_to_add, mark_unwritten,
                                          data_ac, meta_ac, reason_ret);

        return ret;
}

static int __ocfs2_extend_allocation(struct inode *inode, u32 logical_start,
                                     u32 clusters_to_add, int mark_unwritten)
{
        int status = 0;
        int restart_func = 0;
        int credits;
        u32 prev_clusters;
        struct buffer_head *bh = NULL;
        struct ocfs2_dinode *fe = NULL;
        handle_t *handle = NULL;
        struct ocfs2_alloc_context *data_ac = NULL;
        struct ocfs2_alloc_context *meta_ac = NULL;
        enum ocfs2_alloc_restarted why;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_extent_tree et;
        int did_quota = 0;

        mlog_entry("(clusters_to_add = %u)\n", clusters_to_add);

        /*
         * This function only exists for file systems which don't
         * support holes.
         */
        BUG_ON(mark_unwritten && !ocfs2_sparse_alloc(osb));

        status = ocfs2_read_inode_block(inode, &bh);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }
        fe = (struct ocfs2_dinode *) bh->b_data;

restart_all:
        BUG_ON(le32_to_cpu(fe->i_clusters) != OCFS2_I(inode)->ip_clusters);

        mlog(0, "extend inode %llu, i_size = %lld, di->i_clusters = %u, "
             "clusters_to_add = %u\n",
             (unsigned long long)OCFS2_I(inode)->ip_blkno,
             (long long)i_size_read(inode), le32_to_cpu(fe->i_clusters),
             clusters_to_add);
        ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), bh);
        status = ocfs2_lock_allocators(inode, &et, clusters_to_add, 0,
                                       &data_ac, &meta_ac);
        if (status) {
                mlog_errno(status);
                goto leave;
        }

        credits = ocfs2_calc_extend_credits(osb->sb, &fe->id2.i_list,
                                            clusters_to_add);
        handle = ocfs2_start_trans(osb, credits);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                handle = NULL;
                mlog_errno(status);
                goto leave;
        }

restarted_transaction:
        status = dquot_alloc_space_nodirty(inode,
                        ocfs2_clusters_to_bytes(osb->sb, clusters_to_add));
        if (status)
                goto leave;
        did_quota = 1;

        /* reserve a write to the file entry early on - that we if we
         * run out of credits in the allocation path, we can still
         * update i_size. */
        status = ocfs2_journal_access_di(handle, INODE_CACHE(inode), bh,
                                         OCFS2_JOURNAL_ACCESS_WRITE);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        prev_clusters = OCFS2_I(inode)->ip_clusters;

        status = ocfs2_add_inode_data(osb,
                                      inode,
                                      &logical_start,
                                      clusters_to_add,
                                      mark_unwritten,
                                      bh,
                                      handle,
                                      data_ac,
                                      meta_ac,
                                      &why);
        if ((status < 0) && (status != -EAGAIN)) {
                if (status != -ENOSPC)
                        mlog_errno(status);
                goto leave;
        }

        ocfs2_journal_dirty(handle, bh);

        spin_lock(&OCFS2_I(inode)->ip_lock);
        clusters_to_add -= (OCFS2_I(inode)->ip_clusters - prev_clusters);
        spin_unlock(&OCFS2_I(inode)->ip_lock);
        /* Release unused quota reservation */
        dquot_free_space(inode,
                        ocfs2_clusters_to_bytes(osb->sb, clusters_to_add));
        did_quota = 0;

        if (why != RESTART_NONE && clusters_to_add) {
                if (why == RESTART_META) {
                        mlog(0, "restarting function.\n");
                        restart_func = 1;
                        status = 0;
                } else {
                        BUG_ON(why != RESTART_TRANS);

                        mlog(0, "restarting transaction.\n");
                        /* TODO: This can be more intelligent. */
                        credits = ocfs2_calc_extend_credits(osb->sb,
                                                            &fe->id2.i_list,
                                                            clusters_to_add);
                        status = ocfs2_extend_trans(handle, credits);
                        if (status < 0) {
                                /* handle still has to be committed at
                                 * this point. */
                                status = -ENOMEM;
                                mlog_errno(status);
                                goto leave;
                        }
                        goto restarted_transaction;
                }
        }

        mlog(0, "fe: i_clusters = %u, i_size=%llu\n",
             le32_to_cpu(fe->i_clusters),
             (unsigned long long)le64_to_cpu(fe->i_size));
        mlog(0, "inode: ip_clusters=%u, i_size=%lld\n",
             OCFS2_I(inode)->ip_clusters, (long long)i_size_read(inode));

leave:
        if (status < 0 && did_quota)
                dquot_free_space(inode,
                        ocfs2_clusters_to_bytes(osb->sb, clusters_to_add));
        if (handle) {
                ocfs2_commit_trans(osb, handle);
                handle = NULL;
        }
        if (data_ac) {
                ocfs2_free_alloc_context(data_ac);
                data_ac = NULL;
        }
        if (meta_ac) {
                ocfs2_free_alloc_context(meta_ac);
                meta_ac = NULL;
        }
        if ((!status) && restart_func) {
                restart_func = 0;
                goto restart_all;
        }
        brelse(bh);
        bh = NULL;

        mlog_exit(status);
        return status;
}

/*
 * While a write will already be ordering the data, a truncate will not.
 * Thus, we need to explicitly order the zeroed pages.
 */
static handle_t *ocfs2_zero_start_ordered_transaction(struct inode *inode)
{
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        handle_t *handle = NULL;
        int ret = 0;

        if (!ocfs2_should_order_data(inode))
                goto out;

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_jbd2_file_inode(handle, inode);
        if (ret < 0)
                mlog_errno(ret);

out:
        if (ret) {
                if (!IS_ERR(handle))
                        ocfs2_commit_trans(osb, handle);
                handle = ERR_PTR(ret);
        }
        return handle;
}

/* Some parts of this taken from generic_cont_expand, which turned out
 * to be too fragile to do exactly what we need without us having to
 * worry about recursive locking in ->write_begin() and ->write_end(). */
static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
                                 u64 abs_to)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        unsigned long index = abs_from >> PAGE_CACHE_SHIFT;
        handle_t *handle = NULL;
        int ret = 0;
        unsigned zero_from, zero_to, block_start, block_end;

        BUG_ON(abs_from >= abs_to);
        BUG_ON(abs_to > (((u64)index + 1) << PAGE_CACHE_SHIFT));
        BUG_ON(abs_from & (inode->i_blkbits - 1));

        page = find_or_create_page(mapping, index, GFP_NOFS);
        if (!page) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out;
        }

        /* Get the offsets within the page that we want to zero */
        zero_from = abs_from & (PAGE_CACHE_SIZE - 1);
        zero_to = abs_to & (PAGE_CACHE_SIZE - 1);
        if (!zero_to)
                zero_to = PAGE_CACHE_SIZE;

        mlog(0,
             "abs_from = %llu, abs_to = %llu, index = %lu, zero_from = %u, zero_to = %u\n",
             (unsigned long long)abs_from, (unsigned long long)abs_to,
             index, zero_from, zero_to);

        /* We know that zero_from is block aligned */
        for (block_start = zero_from; block_start < zero_to;
             block_start = block_end) {
                block_end = block_start + (1 << inode->i_blkbits);

                /*
                 * block_start is block-aligned.  Bump it by one to force
                 * __block_write_begin and block_commit_write to zero the
                 * whole block.
                 */
                ret = __block_write_begin(page, block_start + 1, 0,
                                          ocfs2_get_block);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_unlock;
                }

                if (!handle) {
                        handle = ocfs2_zero_start_ordered_transaction(inode);
                        if (IS_ERR(handle)) {
                                ret = PTR_ERR(handle);
                                handle = NULL;
                                break;
                        }
                }

                /* must not update i_size! */
                ret = block_commit_write(page, block_start + 1,
                                         block_start + 1);
                if (ret < 0)
                        mlog_errno(ret);
                else
                        ret = 0;
        }

        if (handle)
                ocfs2_commit_trans(OCFS2_SB(inode->i_sb), handle);

out_unlock:
        unlock_page(page);
        page_cache_release(page);
out:
        return ret;
}

/*
 * Find the next range to zero.  We do this in terms of bytes because
 * that's what ocfs2_zero_extend() wants, and it is dealing with the
 * pagecache.  We may return multiple extents.
 *
 * zero_start and zero_end are ocfs2_zero_extend()s current idea of what
 * needs to be zeroed.  range_start and range_end return the next zeroing
 * range.  A subsequent call should pass the previous range_end as its
 * zero_start.  If range_end is 0, there's nothing to do.
 *
 * Unwritten extents are skipped over.  Refcounted extents are CoWd.
 */
static int ocfs2_zero_extend_get_range(struct inode *inode,
                                       struct buffer_head *di_bh,
                                       u64 zero_start, u64 zero_end,
                                       u64 *range_start, u64 *range_end)
{
        int rc = 0, needs_cow = 0;
        u32 p_cpos, zero_clusters = 0;
        u32 zero_cpos =
                zero_start >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
        u32 last_cpos = ocfs2_clusters_for_bytes(inode->i_sb, zero_end);
        unsigned int num_clusters = 0;
        unsigned int ext_flags = 0;

        while (zero_cpos < last_cpos) {
                rc = ocfs2_get_clusters(inode, zero_cpos, &p_cpos,
                                        &num_clusters, &ext_flags);
                if (rc) {
                        mlog_errno(rc);
                        goto out;
                }

                if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
                        zero_clusters = num_clusters;
                        if (ext_flags & OCFS2_EXT_REFCOUNTED)
                                needs_cow = 1;
                        break;
                }

                zero_cpos += num_clusters;
        }
        if (!zero_clusters) {
                *range_end = 0;
                goto out;
        }

        while ((zero_cpos + zero_clusters) < last_cpos) {
                rc = ocfs2_get_clusters(inode, zero_cpos + zero_clusters,
                                        &p_cpos, &num_clusters,
                                        &ext_flags);
                if (rc) {
                        mlog_errno(rc);
                        goto out;
                }

                if (!p_cpos || (ext_flags & OCFS2_EXT_UNWRITTEN))
                        break;
                if (ext_flags & OCFS2_EXT_REFCOUNTED)
                        needs_cow = 1;
                zero_clusters += num_clusters;
        }
        if ((zero_cpos + zero_clusters) > last_cpos)
                zero_clusters = last_cpos - zero_cpos;

        if (needs_cow) {
                rc = ocfs2_refcount_cow(inode, NULL, di_bh, zero_cpos,
                                        zero_clusters, UINT_MAX);
                if (rc) {
                        mlog_errno(rc);
                        goto out;
                }
        }

        *range_start = ocfs2_clusters_to_bytes(inode->i_sb, zero_cpos);
        *range_end = ocfs2_clusters_to_bytes(inode->i_sb,
                                             zero_cpos + zero_clusters);

out:
        return rc;
}

/*
 * Zero one range returned from ocfs2_zero_extend_get_range().  The caller
 * has made sure that the entire range needs zeroing.
 */
static int ocfs2_zero_extend_range(struct inode *inode, u64 range_start,
                                   u64 range_end)
{
        int rc = 0;
        u64 next_pos;
        u64 zero_pos = range_start;

        mlog(0, "range_start = %llu, range_end = %llu\n",
             (unsigned long long)range_start,
             (unsigned long long)range_end);
        BUG_ON(range_start >= range_end);

        while (zero_pos < range_end) {
                next_pos = (zero_pos & PAGE_CACHE_MASK) + PAGE_CACHE_SIZE;
                if (next_pos > range_end)
                        next_pos = range_end;
                rc = ocfs2_write_zero_page(inode, zero_pos, next_pos);
                if (rc < 0) {
                        mlog_errno(rc);
                        break;
                }
                zero_pos = next_pos;

                /*
                 * Very large extends have the potential to lock up
                 * the cpu for extended periods of time.
                 */
                cond_resched();
        }

        return rc;
}

int ocfs2_zero_extend(struct inode *inode, struct buffer_head *di_bh,
                      loff_t zero_to_size)
{
        int ret = 0;
        u64 zero_start, range_start = 0, range_end = 0;
        struct super_block *sb = inode->i_sb;

        zero_start = ocfs2_align_bytes_to_blocks(sb, i_size_read(inode));
        mlog(0, "zero_start %llu for i_size %llu\n",
             (unsigned long long)zero_start,
             (unsigned long long)i_size_read(inode));
        while (zero_start < zero_to_size) {
                ret = ocfs2_zero_extend_get_range(inode, di_bh, zero_start,
                                                  zero_to_size,
                                                  &range_start,
                                                  &range_end);
                if (ret) {
                        mlog_errno(ret);
                        break;
                }
                if (!range_end)
                        break;
                /* Trim the ends */
                if (range_start < zero_start)
                        range_start = zero_start;
                if (range_end > zero_to_size)
                        range_end = zero_to_size;

                ret = ocfs2_zero_extend_range(inode, range_start,
                                              range_end);
                if (ret) {
                        mlog_errno(ret);
                        break;
                }
                zero_start = range_end;
        }

        return ret;
}

int ocfs2_extend_no_holes(struct inode *inode, struct buffer_head *di_bh,
                          u64 new_i_size, u64 zero_to)
{
        int ret;

        u32 clusters_to_add;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);

        /*
         * Only quota files call this without a bh, and they can't be
         * refcounted.
         */
        BUG_ON(!di_bh && (oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
        BUG_ON(!di_bh && !(oi->ip_flags & OCFS2_INODE_SYSTEM_FILE));

        clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size);
        if (clusters_to_add < oi->ip_clusters)
                clusters_to_add = 0;
        else
                clusters_to_add -= oi->ip_clusters;

        if (clusters_to_add) {
                ret = __ocfs2_extend_allocation(inode, oi->ip_clusters,
                                                clusters_to_add, 0);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
        }

        /*
         * Call this even if we don't add any clusters to the tree. We
         * still need to zero the area between the old i_size and the
         * new i_size.
         */
        ret = ocfs2_zero_extend(inode, di_bh, zero_to);
        if (ret < 0)
                mlog_errno(ret);

out:
        return ret;
}

static int ocfs2_extend_file(struct inode *inode,
                             struct buffer_head *di_bh,
                             u64 new_i_size)
{
        int ret = 0;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);

        BUG_ON(!di_bh);

        /* setattr sometimes calls us like this. */
        if (new_i_size == 0)
                goto out;

        if (i_size_read(inode) == new_i_size)
                goto out;
        BUG_ON(new_i_size < i_size_read(inode));

        /*
         * The alloc sem blocks people in read/write from reading our
         * allocation until we're done changing it. We depend on
         * i_mutex to block other extend/truncate calls while we're
         * here.  We even have to hold it for sparse files because there
         * might be some tail zeroing.
         */
        down_write(&oi->ip_alloc_sem);

        if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                /*
                 * We can optimize small extends by keeping the inodes
                 * inline data.
                 */
                if (ocfs2_size_fits_inline_data(di_bh, new_i_size)) {
                        up_write(&oi->ip_alloc_sem);
                        goto out_update_size;
                }

                ret = ocfs2_convert_inline_data_to_extents(inode, di_bh);
                if (ret) {
                        up_write(&oi->ip_alloc_sem);
                        mlog_errno(ret);
                        goto out;
                }
        }

        if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
                ret = ocfs2_zero_extend(inode, di_bh, new_i_size);
        else
                ret = ocfs2_extend_no_holes(inode, di_bh, new_i_size,
                                            new_i_size);

        up_write(&oi->ip_alloc_sem);

        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

out_update_size:
        ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
        if (ret < 0)
                mlog_errno(ret);

out:
        return ret;
}

int ocfs2_setattr(struct dentry *dentry, struct iattr *attr)
{
        int status = 0, size_change;
        struct inode *inode = dentry->d_inode;
        struct super_block *sb = inode->i_sb;
        struct ocfs2_super *osb = OCFS2_SB(sb);
        struct buffer_head *bh = NULL;
        handle_t *handle = NULL;
        struct dquot *transfer_to[MAXQUOTAS] = { };
        int qtype;

        mlog_entry("(0x%p, '%.*s')\n", dentry,
                   dentry->d_name.len, dentry->d_name.name);

        /* ensuring we don't even attempt to truncate a symlink */
        if (S_ISLNK(inode->i_mode))
                attr->ia_valid &= ~ATTR_SIZE;

        if (attr->ia_valid & ATTR_MODE)
                mlog(0, "mode change: %d\n", attr->ia_mode);
        if (attr->ia_valid & ATTR_UID)
                mlog(0, "uid change: %d\n", attr->ia_uid);
        if (attr->ia_valid & ATTR_GID)
                mlog(0, "gid change: %d\n", attr->ia_gid);
        if (attr->ia_valid & ATTR_SIZE)
                mlog(0, "size change...\n");
        if (attr->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_CTIME))
                mlog(0, "time change...\n");

#define OCFS2_VALID_ATTRS (ATTR_ATIME | ATTR_MTIME | ATTR_CTIME | ATTR_SIZE \
                           | ATTR_GID | ATTR_UID | ATTR_MODE)
        if (!(attr->ia_valid & OCFS2_VALID_ATTRS)) {
                mlog(0, "can't handle attrs: 0x%x\n", attr->ia_valid);
                return 0;
        }

        status = inode_change_ok(inode, attr);
        if (status)
                return status;

        if (is_quota_modification(inode, attr))
                dquot_initialize(inode);
        size_change = S_ISREG(inode->i_mode) && attr->ia_valid & ATTR_SIZE;
        if (size_change) {
                status = ocfs2_rw_lock(inode, 1);
                if (status < 0) {
                        mlog_errno(status);
                        goto bail;
                }
        }

        status = ocfs2_inode_lock(inode, &bh, 1);
        if (status < 0) {
                if (status != -ENOENT)
                        mlog_errno(status);
                goto bail_unlock_rw;
        }

        if (size_change && attr->ia_size != i_size_read(inode)) {
                status = inode_newsize_ok(inode, attr->ia_size);
                if (status)
                        goto bail_unlock;

                if (i_size_read(inode) > attr->ia_size) {
                        if (ocfs2_should_order_data(inode)) {
                                status = ocfs2_begin_ordered_truncate(inode,
                                                                      attr->ia_size);
                                if (status)
                                        goto bail_unlock;
                        }
                        status = ocfs2_truncate_file(inode, bh, attr->ia_size);
                } else
                        status = ocfs2_extend_file(inode, bh, attr->ia_size);
                if (status < 0) {
                        if (status != -ENOSPC)
                                mlog_errno(status);
                        status = -ENOSPC;
                        goto bail_unlock;
                }
        }

        if ((attr->ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
            (attr->ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
                /*
                 * Gather pointers to quota structures so that allocation /
                 * freeing of quota structures happens here and not inside
                 * dquot_transfer() where we have problems with lock ordering
                 */
                if (attr->ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid
                    && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
                    OCFS2_FEATURE_RO_COMPAT_USRQUOTA)) {
                        transfer_to[USRQUOTA] = dqget(sb, attr->ia_uid,
                                                      USRQUOTA);
                        if (!transfer_to[USRQUOTA]) {
                                status = -ESRCH;
                                goto bail_unlock;
                        }
                }
                if (attr->ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid
                    && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
                    OCFS2_FEATURE_RO_COMPAT_GRPQUOTA)) {
                        transfer_to[GRPQUOTA] = dqget(sb, attr->ia_gid,
                                                      GRPQUOTA);
                        if (!transfer_to[GRPQUOTA]) {
                                status = -ESRCH;
                                goto bail_unlock;
                        }
                }
                handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS +
                                           2 * ocfs2_quota_trans_credits(sb));
                if (IS_ERR(handle)) {
                        status = PTR_ERR(handle);
                        mlog_errno(status);
                        goto bail_unlock;
                }
                status = __dquot_transfer(inode, transfer_to);
                if (status < 0)
                        goto bail_commit;
        } else {
                handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
                if (IS_ERR(handle)) {
                        status = PTR_ERR(handle);
                        mlog_errno(status);
                        goto bail_unlock;
                }
        }

        /*
         * This will intentionally not wind up calling truncate_setsize(),
         * since all the work for a size change has been done above.
         * Otherwise, we could get into problems with truncate as
         * ip_alloc_sem is used there to protect against i_size
         * changes.
         *
         * XXX: this means the conditional below can probably be removed.
         */
        if ((attr->ia_valid & ATTR_SIZE) &&
            attr->ia_size != i_size_read(inode)) {
                status = vmtruncate(inode, attr->ia_size);
                if (status) {
                        mlog_errno(status);
                        goto bail_commit;
                }
        }

        setattr_copy(inode, attr);
        mark_inode_dirty(inode);

        status = ocfs2_mark_inode_dirty(handle, inode, bh);
        if (status < 0)
                mlog_errno(status);

bail_commit:
        ocfs2_commit_trans(osb, handle);
bail_unlock:
        ocfs2_inode_unlock(inode, 1);
bail_unlock_rw:
        if (size_change)
                ocfs2_rw_unlock(inode, 1);
bail:
        brelse(bh);

        /* Release quota pointers in case we acquired them */
        for (qtype = 0; qtype < MAXQUOTAS; qtype++)
                dqput(transfer_to[qtype]);

        if (!status && attr->ia_valid & ATTR_MODE) {
                status = ocfs2_acl_chmod(inode);
                if (status < 0)
                        mlog_errno(status);
        }

        mlog_exit(status);
        return status;
}

int ocfs2_getattr(struct vfsmount *mnt,
                  struct dentry *dentry,
                  struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        struct super_block *sb = dentry->d_inode->i_sb;
        struct ocfs2_super *osb = sb->s_fs_info;
        int err;

        mlog_entry_void();

        err = ocfs2_inode_revalidate(dentry);
        if (err) {
                if (err != -ENOENT)
                        mlog_errno(err);
                goto bail;
        }

        generic_fillattr(inode, stat);

        /* We set the blksize from the cluster size for performance */
        stat->blksize = osb->s_clustersize;

bail:
        mlog_exit(err);

        return err;
}

int ocfs2_permission(struct inode *inode, int mask, unsigned int flags)
{
        int ret;

        if (flags & IPERM_FLAG_RCU)
                return -ECHILD;

        mlog_entry_void();

        ret = ocfs2_inode_lock(inode, NULL, 0);
        if (ret) {
                if (ret != -ENOENT)
                        mlog_errno(ret);
                goto out;
        }

        ret = generic_permission(inode, mask, flags, ocfs2_check_acl);

        ocfs2_inode_unlock(inode, 0);
out:
        mlog_exit(ret);
        return ret;
}

static int __ocfs2_write_remove_suid(struct inode *inode,
                                     struct buffer_head *bh)
{
        int ret;
        handle_t *handle;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_dinode *di;

        mlog_entry("(Inode %llu, mode 0%o)\n",
                   (unsigned long long)OCFS2_I(inode)->ip_blkno, inode->i_mode);

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_trans;
        }

        inode->i_mode &= ~S_ISUID;
        if ((inode->i_mode & S_ISGID) && (inode->i_mode & S_IXGRP))
                inode->i_mode &= ~S_ISGID;

        di = (struct ocfs2_dinode *) bh->b_data;
        di->i_mode = cpu_to_le16(inode->i_mode);

        ocfs2_journal_dirty(handle, bh);

out_trans:
        ocfs2_commit_trans(osb, handle);
out:
        mlog_exit(ret);
        return ret;
}

/*
 * Will look for holes and unwritten extents in the range starting at
 * pos for count bytes (inclusive).
 */
static int ocfs2_check_range_for_holes(struct inode *inode, loff_t pos,
                                       size_t count)
{
        int ret = 0;
        unsigned int extent_flags;
        u32 cpos, clusters, extent_len, phys_cpos;
        struct super_block *sb = inode->i_sb;

        cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
        clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;

        while (clusters) {
                ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
                                         &extent_flags);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out;
                }

                if (phys_cpos == 0 || (extent_flags & OCFS2_EXT_UNWRITTEN)) {
                        ret = 1;
                        break;
                }

                if (extent_len > clusters)
                        extent_len = clusters;

                clusters -= extent_len;
                cpos += extent_len;
        }
out:
        return ret;
}

static int ocfs2_write_remove_suid(struct inode *inode)
{
        int ret;
        struct buffer_head *bh = NULL;

        ret = ocfs2_read_inode_block(inode, &bh);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        ret =  __ocfs2_write_remove_suid(inode, bh);
out:
        brelse(bh);
        return ret;
}

/*
 * Allocate enough extents to cover the region starting at byte offset
 * start for len bytes. Existing extents are skipped, any extents
 * added are marked as "unwritten".
 */
static int ocfs2_allocate_unwritten_extents(struct inode *inode,
                                            u64 start, u64 len)
{
        int ret;
        u32 cpos, phys_cpos, clusters, alloc_size;
        u64 end = start + len;
        struct buffer_head *di_bh = NULL;

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                ret = ocfs2_read_inode_block(inode, &di_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                /*
                 * Nothing to do if the requested reservation range
                 * fits within the inode.
                 */
                if (ocfs2_size_fits_inline_data(di_bh, end))
                        goto out;

                ret = ocfs2_convert_inline_data_to_extents(inode, di_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
        }

        /*
         * We consider both start and len to be inclusive.
         */
        cpos = start >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
        clusters = ocfs2_clusters_for_bytes(inode->i_sb, start + len);
        clusters -= cpos;

        while (clusters) {
                ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
                                         &alloc_size, NULL);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                /*
                 * Hole or existing extent len can be arbitrary, so
                 * cap it to our own allocation request.
                 */
                if (alloc_size > clusters)
                        alloc_size = clusters;

                if (phys_cpos) {
                        /*
                         * We already have an allocation at this
                         * region so we can safely skip it.
                         */
                        goto next;
                }

                ret = __ocfs2_extend_allocation(inode, cpos, alloc_size, 1);
                if (ret) {
                        if (ret != -ENOSPC)
                                mlog_errno(ret);
                        goto out;
                }

next:
                cpos += alloc_size;
                clusters -= alloc_size;
        }

        ret = 0;
out:

        brelse(di_bh);
        return ret;
}

/*
 * Truncate a byte range, avoiding pages within partial clusters. This
 * preserves those pages for the zeroing code to write to.
 */
static void ocfs2_truncate_cluster_pages(struct inode *inode, u64 byte_start,
                                         u64 byte_len)
{
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        loff_t start, end;
        struct address_space *mapping = inode->i_mapping;

        start = (loff_t)ocfs2_align_bytes_to_clusters(inode->i_sb, byte_start);
        end = byte_start + byte_len;
        end = end & ~(osb->s_clustersize - 1);

        if (start < end) {
                unmap_mapping_range(mapping, start, end - start, 0);
                truncate_inode_pages_range(mapping, start, end - 1);
        }
}

static int ocfs2_zero_partial_clusters(struct inode *inode,
                                       u64 start, u64 len)
{
        int ret = 0;
        u64 tmpend, end = start + len;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        unsigned int csize = osb->s_clustersize;
        handle_t *handle;

        /*
         * The "start" and "end" values are NOT necessarily part of
         * the range whose allocation is being deleted. Rather, this
         * is what the user passed in with the request. We must zero
         * partial clusters here. There's no need to worry about
         * physical allocation - the zeroing code knows to skip holes.
         */
        mlog(0, "byte start: %llu, end: %llu\n",
             (unsigned long long)start, (unsigned long long)end);

        /*
         * If both edges are on a cluster boundary then there's no
         * zeroing required as the region is part of the allocation to
         * be truncated.
         */
        if ((start & (csize - 1)) == 0 && (end & (csize - 1)) == 0)
                goto out;

        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out;
        }

        /*
         * We want to get the byte offset of the end of the 1st cluster.
         */
        tmpend = (u64)osb->s_clustersize + (start & ~(osb->s_clustersize - 1));
        if (tmpend > end)
                tmpend = end;

        mlog(0, "1st range: start: %llu, tmpend: %llu\n",
             (unsigned long long)start, (unsigned long long)tmpend);

        ret = ocfs2_zero_range_for_truncate(inode, handle, start, tmpend);
        if (ret)
                mlog_errno(ret);

        if (tmpend < end) {
                /*
                 * This may make start and end equal, but the zeroing
                 * code will skip any work in that case so there's no
                 * need to catch it up here.
                 */
                start = end & ~(osb->s_clustersize - 1);

                mlog(0, "2nd range: start: %llu, end: %llu\n",
                     (unsigned long long)start, (unsigned long long)end);

                ret = ocfs2_zero_range_for_truncate(inode, handle, start, end);
                if (ret)
                        mlog_errno(ret);
        }

        ocfs2_commit_trans(osb, handle);
out:
        return ret;
}

static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
{
        int i;
        struct ocfs2_extent_rec *rec = NULL;

        for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {

                rec = &el->l_recs[i];

                if (le32_to_cpu(rec->e_cpos) < pos)
                        break;
        }

        return i;
}

/*
 * Helper to calculate the punching pos and length in one run, we handle the
 * following three cases in order:
 *
 * - remove the entire record
 * - remove a partial record
 * - no record needs to be removed (hole-punching completed)
*/
static void ocfs2_calc_trunc_pos(struct inode *inode,
                                 struct ocfs2_extent_list *el,
                                 struct ocfs2_extent_rec *rec,
                                 u32 trunc_start, u32 *trunc_cpos,
                                 u32 *trunc_len, u32 *trunc_end,
                                 u64 *blkno, int *done)
{
        int ret = 0;
        u32 coff, range;

        range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);

        if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
                *trunc_cpos = le32_to_cpu(rec->e_cpos);
                /*
                 * Skip holes if any.
                 */
                if (range < *trunc_end)
                        *trunc_end = range;
                *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
                *blkno = le64_to_cpu(rec->e_blkno);
                *trunc_end = le32_to_cpu(rec->e_cpos);
        } else if (range > trunc_start) {
                *trunc_cpos = trunc_start;
                *trunc_len = *trunc_end - trunc_start;
                coff = trunc_start - le32_to_cpu(rec->e_cpos);
                *blkno = le64_to_cpu(rec->e_blkno) +
                                ocfs2_clusters_to_blocks(inode->i_sb, coff);
                *trunc_end = trunc_start;
        } else {
                /*
                 * It may have two following possibilities:
                 *
                 * - last record has been removed
                 * - trunc_start was within a hole
                 *
                 * both two cases mean the completion of hole punching.
                 */
                ret = 1;
        }

        *done = ret;
}

static int ocfs2_remove_inode_range(struct inode *inode,
                                    struct buffer_head *di_bh, u64 byte_start,
                                    u64 byte_len)
{
        int ret = 0, flags = 0, done = 0, i;
        u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
        u32 cluster_in_el;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_cached_dealloc_ctxt dealloc;
        struct address_space *mapping = inode->i_mapping;
        struct ocfs2_extent_tree et;
        struct ocfs2_path *path = NULL;
        struct ocfs2_extent_list *el = NULL;
        struct ocfs2_extent_rec *rec = NULL;
        struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
        u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);

        ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
        ocfs2_init_dealloc_ctxt(&dealloc);

        if (byte_len == 0)
                return 0;

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                ret = ocfs2_truncate_inline(inode, di_bh, byte_start,
                                            byte_start + byte_len, 0);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
                /*
                 * There's no need to get fancy with the page cache
                 * truncate of an inline-data inode. We're talking
                 * about less than a page here, which will be cached
                 * in the dinode buffer anyway.
                 */
                unmap_mapping_range(mapping, 0, 0, 0);
                truncate_inode_pages(mapping, 0);
                goto out;
        }

        /*
         * For reflinks, we may need to CoW 2 clusters which might be
         * partially zero'd later, if hole's start and end offset were
         * within one cluster(means is not exactly aligned to clustersize).
         */

        if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL) {

                ret = ocfs2_cow_file_pos(inode, di_bh, byte_start);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                ret = ocfs2_cow_file_pos(inode, di_bh, byte_start + byte_len);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }
        }

        trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
        trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
        cluster_in_el = trunc_end;

        mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: %u\n",
             (unsigned long long)OCFS2_I(inode)->ip_blkno,
             (unsigned long long)byte_start,
             (unsigned long long)byte_len, trunc_start, trunc_end);

        ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        path = ocfs2_new_path_from_et(&et);
        if (!path) {
                ret = -ENOMEM;
                mlog_errno(ret);
                goto out;
        }

        while (trunc_end > trunc_start) {

                ret = ocfs2_find_path(INODE_CACHE(inode), path,
                                      cluster_in_el);
                if (ret) {
                        mlog_errno(ret);
                        goto out;
                }

                el = path_leaf_el(path);

                i = ocfs2_find_rec(el, trunc_end);
                /*
                 * Need to go to previous extent block.
                 */
                if (i < 0) {
                        if (path->p_tree_depth == 0)
                                break;

                        ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
                                                            path,
                                                            &cluster_in_el);
                        if (ret) {
                                mlog_errno(ret);
                                goto out;
                        }

                        /*
                         * We've reached the leftmost extent block,
                         * it's safe to leave.
                         */
                        if (cluster_in_el == 0)
                                break;

                        /*
                         * The 'pos' searched for previous extent block is
                         * always one cluster less than actual trunc_end.
                         */
                        trunc_end = cluster_in_el + 1;

                        ocfs2_reinit_path(path, 1);

                        continue;

                } else
                        rec = &el->l_recs[i];

                ocfs2_calc_trunc_pos(inode, el, rec, trunc_start, &trunc_cpos,
                                     &trunc_len, &trunc_end, &blkno, &done);
                if (done)
                        break;

                flags = rec->e_flags;
                phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);

                ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
                                               phys_cpos, trunc_len, flags,
                                               &dealloc, refcount_loc);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out;
                }

                cluster_in_el = trunc_end;

                ocfs2_reinit_path(path, 1);
        }

        ocfs2_truncate_cluster_pages(inode, byte_start, byte_len);

out:
        ocfs2_schedule_truncate_log_flush(osb, 1);
        ocfs2_run_deallocs(osb, &dealloc);

        return ret;
}

/*
 * Parts of this function taken from xfs_change_file_space()
 */
static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
                                     loff_t f_pos, unsigned int cmd,
                                     struct ocfs2_space_resv *sr,
                                     int change_size)
{
        int ret;
        s64 llen;
        loff_t size;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct buffer_head *di_bh = NULL;
        handle_t *handle;
        unsigned long long max_off = inode->i_sb->s_maxbytes;

        if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
                return -EROFS;

        mutex_lock(&inode->i_mutex);

        /*
         * This prevents concurrent writes on other nodes
         */
        ret = ocfs2_rw_lock(inode, 1);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_inode_lock(inode, &di_bh, 1);
        if (ret) {
                mlog_errno(ret);
                goto out_rw_unlock;
        }

        if (inode->i_flags & (S_IMMUTABLE|S_APPEND)) {
                ret = -EPERM;
                goto out_inode_unlock;
        }

        switch (sr->l_whence) {
        case 0: /*SEEK_SET*/
                break;
        case 1: /*SEEK_CUR*/
                sr->l_start += f_pos;
                break;
        case 2: /*SEEK_END*/
                sr->l_start += i_size_read(inode);
                break;
        default:
                ret = -EINVAL;
                goto out_inode_unlock;
        }
        sr->l_whence = 0;

        llen = sr->l_len > 0 ? sr->l_len - 1 : sr->l_len;

        if (sr->l_start < 0
            || sr->l_start > max_off
            || (sr->l_start + llen) < 0
            || (sr->l_start + llen) > max_off) {
                ret = -EINVAL;
                goto out_inode_unlock;
        }
        size = sr->l_start + sr->l_len;

        if (cmd == OCFS2_IOC_RESVSP || cmd == OCFS2_IOC_RESVSP64) {
                if (sr->l_len <= 0) {
                        ret = -EINVAL;
                        goto out_inode_unlock;
                }
        }

        if (file && should_remove_suid(file->f_path.dentry)) {
                ret = __ocfs2_write_remove_suid(inode, di_bh);
                if (ret) {
                        mlog_errno(ret);
                        goto out_inode_unlock;
                }
        }

        down_write(&OCFS2_I(inode)->ip_alloc_sem);
        switch (cmd) {
        case OCFS2_IOC_RESVSP:
        case OCFS2_IOC_RESVSP64:
                /*
                 * This takes unsigned offsets, but the signed ones we
                 * pass have been checked against overflow above.
                 */
                ret = ocfs2_allocate_unwritten_extents(inode, sr->l_start,
                                                       sr->l_len);
                break;
        case OCFS2_IOC_UNRESVSP:
        case OCFS2_IOC_UNRESVSP64:
                ret = ocfs2_remove_inode_range(inode, di_bh, sr->l_start,
                                               sr->l_len);
                break;
        default:
                ret = -EINVAL;
        }
        up_write(&OCFS2_I(inode)->ip_alloc_sem);
        if (ret) {
                mlog_errno(ret);
                goto out_inode_unlock;
        }

        /*
         * We update c/mtime for these changes
         */
        handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                mlog_errno(ret);
                goto out_inode_unlock;
        }

        if (change_size && i_size_read(inode) < size)
                i_size_write(inode, size);

        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
        ret = ocfs2_mark_inode_dirty(handle, inode, di_bh);
        if (ret < 0)
                mlog_errno(ret);

        ocfs2_commit_trans(osb, handle);

out_inode_unlock:
        brelse(di_bh);
        ocfs2_inode_unlock(inode, 1);
out_rw_unlock:
        ocfs2_rw_unlock(inode, 1);

out:
        mutex_unlock(&inode->i_mutex);
        return ret;
}

int ocfs2_change_file_space(struct file *file, unsigned int cmd,
                            struct ocfs2_space_resv *sr)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

        if ((cmd == OCFS2_IOC_RESVSP || cmd == OCFS2_IOC_RESVSP64) &&
            !ocfs2_writes_unwritten_extents(osb))
                return -ENOTTY;
        else if ((cmd == OCFS2_IOC_UNRESVSP || cmd == OCFS2_IOC_UNRESVSP64) &&
                 !ocfs2_sparse_alloc(osb))
                return -ENOTTY;

        if (!S_ISREG(inode->i_mode))
                return -EINVAL;

        if (!(file->f_mode & FMODE_WRITE))
                return -EBADF;

        return __ocfs2_change_file_space(file, inode, file->f_pos, cmd, sr, 0);
}

static long ocfs2_fallocate(struct file *file, int mode, loff_t offset,
                            loff_t len)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        struct ocfs2_space_resv sr;
        int change_size = 1;
        int cmd = OCFS2_IOC_RESVSP64;

        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
                return -EOPNOTSUPP;
        if (!ocfs2_writes_unwritten_extents(osb))
                return -EOPNOTSUPP;

        if (mode & FALLOC_FL_KEEP_SIZE)
                change_size = 0;

        if (mode & FALLOC_FL_PUNCH_HOLE)
                cmd = OCFS2_IOC_UNRESVSP64;

        sr.l_whence = 0;
        sr.l_start = (s64)offset;
        sr.l_len = (s64)len;

        return __ocfs2_change_file_space(NULL, inode, offset, cmd, &sr,
                                         change_size);
}

int ocfs2_check_range_for_refcount(struct inode *inode, loff_t pos,
                                   size_t count)
{
        int ret = 0;
        unsigned int extent_flags;
        u32 cpos, clusters, extent_len, phys_cpos;
        struct super_block *sb = inode->i_sb;

        if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)) ||
            !(OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL) ||
            OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                return 0;

        cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
        clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;

        while (clusters) {
                ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
                                         &extent_flags);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out;
                }

                if (phys_cpos && (extent_flags & OCFS2_EXT_REFCOUNTED)) {
                        ret = 1;
                        break;
                }

                if (extent_len > clusters)
                        extent_len = clusters;

                clusters -= extent_len;
                cpos += extent_len;
        }
out:
        return ret;
}

static int ocfs2_prepare_inode_for_refcount(struct inode *inode,
                                            struct file *file,
                                            loff_t pos, size_t count,
                                            int *meta_level)
{
        int ret;
        struct buffer_head *di_bh = NULL;
        u32 cpos = pos >> OCFS2_SB(inode->i_sb)->s_clustersize_bits;
        u32 clusters =
                ocfs2_clusters_for_bytes(inode->i_sb, pos + count) - cpos;

        ret = ocfs2_inode_lock(inode, &di_bh, 1);
        if (ret) {
                mlog_errno(ret);
                goto out;
        }

        *meta_level = 1;

        ret = ocfs2_refcount_cow(inode, file, di_bh, cpos, clusters, UINT_MAX);
        if (ret)
                mlog_errno(ret);
out:
        brelse(di_bh);
        return ret;
}

static int ocfs2_prepare_inode_for_write(struct file *file,
                                         loff_t *ppos,
                                         size_t count,
                                         int appending,
                                         int *direct_io,
                                         int *has_refcount)
{
        int ret = 0, meta_level = 0;
        struct dentry *dentry = file->f_path.dentry;
        struct inode *inode = dentry->d_inode;
        loff_t saved_pos, end;

        /*
         * We start with a read level meta lock and only jump to an ex
         * if we need to make modifications here.
         */
        for(;;) {
                ret = ocfs2_inode_lock(inode, NULL, meta_level);
                if (ret < 0) {
                        meta_level = -1;
                        mlog_errno(ret);
                        goto out;
                }

                /* Clear suid / sgid if necessary. We do this here
                 * instead of later in the write path because
                 * remove_suid() calls ->setattr without any hint that
                 * we may have already done our cluster locking. Since
                 * ocfs2_setattr() *must* take cluster locks to
                 * proceeed, this will lead us to recursively lock the
                 * inode. There's also the dinode i_size state which
                 * can be lost via setattr during extending writes (we
                 * set inode->i_size at the end of a write. */
                if (should_remove_suid(dentry)) {
                        if (meta_level == 0) {
                                ocfs2_inode_unlock(inode, meta_level);
                                meta_level = 1;
                                continue;
                        }

                        ret = ocfs2_write_remove_suid(inode);
                        if (ret < 0) {
                                mlog_errno(ret);
                                goto out_unlock;
                        }
                }

                /* work on a copy of ppos until we're sure that we won't have
                 * to recalculate it due to relocking. */
                if (appending) {
                        saved_pos = i_size_read(inode);
                        mlog(0, "O_APPEND: inode->i_size=%llu\n", saved_pos);
                } else {
                        saved_pos = *ppos;
                }

                end = saved_pos + count;

                ret = ocfs2_check_range_for_refcount(inode, saved_pos, count);
                if (ret == 1) {
                        ocfs2_inode_unlock(inode, meta_level);
                        meta_level = -1;

                        ret = ocfs2_prepare_inode_for_refcount(inode,
                                                               file,
                                                               saved_pos,
                                                               count,
                                                               &meta_level);
                        if (has_refcount)
                                *has_refcount = 1;
                        if (direct_io)
                                *direct_io = 0;
                }

                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_unlock;
                }

                /*
                 * Skip the O_DIRECT checks if we don't need
                 * them.
                 */
                if (!direct_io || !(*direct_io))
                        break;

                /*
                 * There's no sane way to do direct writes to an inode
                 * with inline data.
                 */
                if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                        *direct_io = 0;
                        break;
                }

                /*
                 * Allowing concurrent direct writes means
                 * i_size changes wouldn't be synchronized, so
                 * one node could wind up truncating another
                 * nodes writes.
                 */
                if (end > i_size_read(inode)) {
                        *direct_io = 0;
                        break;
                }

                /*
                 * We don't fill holes during direct io, so
                 * check for them here. If any are found, the
                 * caller will have to retake some cluster
                 * locks and initiate the io as buffered.
                 */
                ret = ocfs2_check_range_for_holes(inode, saved_pos, count);
                if (ret == 1) {
                        *direct_io = 0;
                        ret = 0;
                } else if (ret < 0)
                        mlog_errno(ret);
                break;
        }

        if (appending)
                *ppos = saved_pos;

out_unlock:
        if (meta_level >= 0)
                ocfs2_inode_unlock(inode, meta_level);

out:
        return ret;
}

static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
                                    const struct iovec *iov,
                                    unsigned long nr_segs,
                                    loff_t pos)
{
        int ret, direct_io, appending, rw_level, have_alloc_sem  = 0;
        int can_do_direct, has_refcount = 0;
        ssize_t written = 0;
        size_t ocount;          /* original count */
        size_t count;           /* after file limit checks */
        loff_t old_size, *ppos = &iocb->ki_pos;
        u32 old_clusters;
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_path.dentry->d_inode;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
        int full_coherency = !(osb->s_mount_opt &
                               OCFS2_MOUNT_COHERENCY_BUFFERED);

        mlog_entry("(0x%p, %u, '%.*s')\n", file,
                   (unsigned int)nr_segs,
                   file->f_path.dentry->d_name.len,
                   file->f_path.dentry->d_name.name);

        if (iocb->ki_left == 0)
                return 0;

        vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);

        appending = file->f_flags & O_APPEND ? 1 : 0;
        direct_io = file->f_flags & O_DIRECT ? 1 : 0;

        mutex_lock(&inode->i_mutex);

        ocfs2_iocb_clear_sem_locked(iocb);

relock:
        /* to match setattr's i_mutex -> i_alloc_sem -> rw_lock ordering */
        if (direct_io) {
                down_read(&inode->i_alloc_sem);
                have_alloc_sem = 1;
                /* communicate with ocfs2_dio_end_io */
                ocfs2_iocb_set_sem_locked(iocb);
        }

        /*
         * Concurrent O_DIRECT writes are allowed with
         * mount_option "coherency=buffered".
         */
        rw_level = (!direct_io || full_coherency);

        ret = ocfs2_rw_lock(inode, rw_level);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_sems;
        }

        /*
         * O_DIRECT writes with "coherency=full" need to take EX cluster
         * inode_lock to guarantee coherency.
         */
        if (direct_io && full_coherency) {
                /*
                 * We need to take and drop the inode lock to force
                 * other nodes to drop their caches.  Buffered I/O
                 * already does this in write_begin().
                 */
                ret = ocfs2_inode_lock(inode, NULL, 1);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_sems;
                }

                ocfs2_inode_unlock(inode, 1);
        }

        can_do_direct = direct_io;
        ret = ocfs2_prepare_inode_for_write(file, ppos,
                                            iocb->ki_left, appending,
                                            &can_do_direct, &has_refcount);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        /*
         * We can't complete the direct I/O as requested, fall back to
         * buffered I/O.
         */
        if (direct_io && !can_do_direct) {
                ocfs2_rw_unlock(inode, rw_level);
                up_read(&inode->i_alloc_sem);

                have_alloc_sem = 0;
                rw_level = -1;

                direct_io = 0;
                goto relock;
        }

        /*
         * To later detect whether a journal commit for sync writes is
         * necessary, we sample i_size, and cluster count here.
         */
        old_size = i_size_read(inode);
        old_clusters = OCFS2_I(inode)->ip_clusters;

        /* communicate with ocfs2_dio_end_io */
        ocfs2_iocb_set_rw_locked(iocb, rw_level);

        ret = generic_segment_checks(iov, &nr_segs, &ocount,
                                     VERIFY_READ);
        if (ret)
                goto out_dio;

        count = ocount;
        ret = generic_write_checks(file, ppos, &count,
                                   S_ISBLK(inode->i_mode));
        if (ret)
                goto out_dio;

        if (direct_io) {
                written = generic_file_direct_write(iocb, iov, &nr_segs, *ppos,
                                                    ppos, count, ocount);
                if (written < 0) {
                        ret = written;
                        goto out_dio;
                }
        } else {
                current->backing_dev_info = file->f_mapping->backing_dev_info;
                written = generic_file_buffered_write(iocb, iov, nr_segs, *ppos,
                                                      ppos, count, 0);
                current->backing_dev_info = NULL;
        }

out_dio:
        /* buffered aio wouldn't have proper lock coverage today */
        BUG_ON(ret == -EIOCBQUEUED && !(file->f_flags & O_DIRECT));

        if (((file->f_flags & O_DSYNC) && !direct_io) || IS_SYNC(inode) ||
            ((file->f_flags & O_DIRECT) && !direct_io)) {
                ret = filemap_fdatawrite_range(file->f_mapping, pos,
                                               pos + count - 1);
                if (ret < 0)
                        written = ret;

                if (!ret && ((old_size != i_size_read(inode)) ||
                             (old_clusters != OCFS2_I(inode)->ip_clusters) ||
                             has_refcount)) {
                        ret = jbd2_journal_force_commit(osb->journal->j_journal);
                        if (ret < 0)
                                written = ret;
                }

                if (!ret)
                        ret = filemap_fdatawait_range(file->f_mapping, pos,
                                                      pos + count - 1);
        }

        /*
         * deep in g_f_a_w_n()->ocfs2_direct_IO we pass in a ocfs2_dio_end_io
         * function pointer which is called when o_direct io completes so that
         * it can unlock our rw lock.  (it's the clustered equivalent of
         * i_alloc_sem; protects truncate from racing with pending ios).
         * Unfortunately there are error cases which call end_io and others
         * that don't.  so we don't have to unlock the rw_lock if either an
         * async dio is going to do it in the future or an end_io after an
         * error has already done it.
         */
        if ((ret == -EIOCBQUEUED) || (!ocfs2_iocb_is_rw_locked(iocb))) {
                rw_level = -1;
                have_alloc_sem = 0;
        }

out:
        if (rw_level != -1)
                ocfs2_rw_unlock(inode, rw_level);

out_sems:
        if (have_alloc_sem) {
                up_read(&inode->i_alloc_sem);
                ocfs2_iocb_clear_sem_locked(iocb);
        }

        mutex_unlock(&inode->i_mutex);

        if (written)
                ret = written;
        mlog_exit(ret);
        return ret;
}

static int ocfs2_splice_to_file(struct pipe_inode_info *pipe,
                                struct file *out,
                                struct splice_desc *sd)
{
        int ret;

        ret = ocfs2_prepare_inode_for_write(out, &sd->pos,
                                            sd->total_len, 0, NULL, NULL);
        if (ret < 0) {
                mlog_errno(ret);
                return ret;
        }

        return splice_from_pipe_feed(pipe, sd, pipe_to_file);
}

static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
                                       struct file *out,
                                       loff_t *ppos,
                                       size_t len,
                                       unsigned int flags)
{
        int ret;
        struct address_space *mapping = out->f_mapping;
        struct inode *inode = mapping->host;
        struct splice_desc sd = {
                .total_len = len,
                .flags = flags,
                .pos = *ppos,
                .u.file = out,
        };

        mlog_entry("(0x%p, 0x%p, %u, '%.*s')\n", out, pipe,
                   (unsigned int)len,
                   out->f_path.dentry->d_name.len,
                   out->f_path.dentry->d_name.name);

        if (pipe->inode)
                mutex_lock_nested(&pipe->inode->i_mutex, I_MUTEX_PARENT);

        splice_from_pipe_begin(&sd);
        do {
                ret = splice_from_pipe_next(pipe, &sd);
                if (ret <= 0)
                        break;

                mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
                ret = ocfs2_rw_lock(inode, 1);
                if (ret < 0)
                        mlog_errno(ret);
                else {
                        ret = ocfs2_splice_to_file(pipe, out, &sd);
                        ocfs2_rw_unlock(inode, 1);
                }
                mutex_unlock(&inode->i_mutex);
        } while (ret > 0);
        splice_from_pipe_end(pipe, &sd);

        if (pipe->inode)
                mutex_unlock(&pipe->inode->i_mutex);

        if (sd.num_spliced)
                ret = sd.num_spliced;

        if (ret > 0) {
                unsigned long nr_pages;
                int err;

                nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

                err = generic_write_sync(out, *ppos, ret);
                if (err)
                        ret = err;
                else
                        *ppos += ret;

                balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
        }

        mlog_exit(ret);
        return ret;
}

static ssize_t ocfs2_file_splice_read(struct file *in,
                                      loff_t *ppos,
                                      struct pipe_inode_info *pipe,
                                      size_t len,
                                      unsigned int flags)
{
        int ret = 0, lock_level = 0;
        struct inode *inode = in->f_path.dentry->d_inode;

        mlog_entry("(0x%p, 0x%p, %u, '%.*s')\n", in, pipe,
                   (unsigned int)len,
                   in->f_path.dentry->d_name.len,
                   in->f_path.dentry->d_name.name);

        /*
         * See the comment in ocfs2_file_aio_read()
         */
        ret = ocfs2_inode_lock_atime(inode, in->f_vfsmnt, &lock_level);
        if (ret < 0) {
                mlog_errno(ret);
                goto bail;
        }
        ocfs2_inode_unlock(inode, lock_level);

        ret = generic_file_splice_read(in, ppos, pipe, len, flags);

bail:
        mlog_exit(ret);
        return ret;
}

static ssize_t ocfs2_file_aio_read(struct kiocb *iocb,
                                   const struct iovec *iov,
                                   unsigned long nr_segs,
                                   loff_t pos)
{
        int ret = 0, rw_level = -1, have_alloc_sem = 0, lock_level = 0;
        struct file *filp = iocb->ki_filp;
        struct inode *inode = filp->f_path.dentry->d_inode;

        mlog_entry("(0x%p, %u, '%.*s')\n", filp,
                   (unsigned int)nr_segs,
                   filp->f_path.dentry->d_name.len,
                   filp->f_path.dentry->d_name.name);

        if (!inode) {
                ret = -EINVAL;
                mlog_errno(ret);
                goto bail;
        }

        ocfs2_iocb_clear_sem_locked(iocb);

        /*
         * buffered reads protect themselves in ->readpage().  O_DIRECT reads
         * need locks to protect pending reads from racing with truncate.
         */
        if (filp->f_flags & O_DIRECT) {
                down_read(&inode->i_alloc_sem);
                have_alloc_sem = 1;
                ocfs2_iocb_set_sem_locked(iocb);

                ret = ocfs2_rw_lock(inode, 0);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto bail;
                }
                rw_level = 0;
                /* communicate with ocfs2_dio_end_io */
                ocfs2_iocb_set_rw_locked(iocb, rw_level);
        }

        /*
         * We're fine letting folks race truncates and extending
         * writes with read across the cluster, just like they can
         * locally. Hence no rw_lock during read.
         *
         * Take and drop the meta data lock to update inode fields
         * like i_size. This allows the checks down below
         * generic_file_aio_read() a chance of actually working.
         */
        ret = ocfs2_inode_lock_atime(inode, filp->f_vfsmnt, &lock_level);
        if (ret < 0) {
                mlog_errno(ret);
                goto bail;
        }
        ocfs2_inode_unlock(inode, lock_level);

        ret = generic_file_aio_read(iocb, iov, nr_segs, iocb->ki_pos);
        if (ret == -EINVAL)
                mlog(0, "generic_file_aio_read returned -EINVAL\n");

        /* buffered aio wouldn't have proper lock coverage today */
        BUG_ON(ret == -EIOCBQUEUED && !(filp->f_flags & O_DIRECT));

        /* see ocfs2_file_aio_write */
        if (ret == -EIOCBQUEUED || !ocfs2_iocb_is_rw_locked(iocb)) {
                rw_level = -1;
                have_alloc_sem = 0;
        }

bail:
        if (have_alloc_sem) {
                up_read(&inode->i_alloc_sem);
                ocfs2_iocb_clear_sem_locked(iocb);
        }
        if (rw_level != -1)
                ocfs2_rw_unlock(inode, rw_level);
        mlog_exit(ret);

        return ret;
}

const struct inode_operations ocfs2_file_iops = {
        .setattr        = ocfs2_setattr,
        .getattr        = ocfs2_getattr,
        .permission     = ocfs2_permission,
        .setxattr       = generic_setxattr,
        .getxattr       = generic_getxattr,
        .listxattr      = ocfs2_listxattr,
        .removexattr    = generic_removexattr,
        .fiemap         = ocfs2_fiemap,
};

const struct inode_operations ocfs2_special_file_iops = {
        .setattr        = ocfs2_setattr,
        .getattr        = ocfs2_getattr,
        .permission     = ocfs2_permission,
};

/*
 * Other than ->lock, keep ocfs2_fops and ocfs2_dops in sync with
 * ocfs2_fops_no_plocks and ocfs2_dops_no_plocks!
 */
const struct file_operations ocfs2_fops = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
        .mmap           = ocfs2_mmap,
        .fsync          = ocfs2_sync_file,
        .release        = ocfs2_file_release,
        .open           = ocfs2_file_open,
        .aio_read       = ocfs2_file_aio_read,
        .aio_write      = ocfs2_file_aio_write,
        .unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ocfs2_compat_ioctl,
#endif
        .lock           = ocfs2_lock,
        .flock          = ocfs2_flock,
        .splice_read    = ocfs2_file_splice_read,
        .splice_write   = ocfs2_file_splice_write,
        .fallocate      = ocfs2_fallocate,
};

const struct file_operations ocfs2_dops = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .readdir        = ocfs2_readdir,
        .fsync          = ocfs2_sync_file,
        .release        = ocfs2_dir_release,
        .open           = ocfs2_dir_open,
        .unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ocfs2_compat_ioctl,
#endif
        .lock           = ocfs2_lock,
        .flock          = ocfs2_flock,
};

/*
 * POSIX-lockless variants of our file_operations.
 *
 * These will be used if the underlying cluster stack does not support
 * posix file locking, if the user passes the "localflocks" mount
 * option, or if we have a local-only fs.
 *
 * ocfs2_flock is in here because all stacks handle UNIX file locks,
 * so we still want it in the case of no stack support for
 * plocks. Internally, it will do the right thing when asked to ignore
 * the cluster.
 */
const struct file_operations ocfs2_fops_no_plocks = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
        .mmap           = ocfs2_mmap,
        .fsync          = ocfs2_sync_file,
        .release        = ocfs2_file_release,
        .open           = ocfs2_file_open,
        .aio_read       = ocfs2_file_aio_read,
        .aio_write      = ocfs2_file_aio_write,
        .unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ocfs2_compat_ioctl,
#endif
        .flock          = ocfs2_flock,
        .splice_read    = ocfs2_file_splice_read,
        .splice_write   = ocfs2_file_splice_write,
};

const struct file_operations ocfs2_dops_no_plocks = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .readdir        = ocfs2_readdir,
        .fsync          = ocfs2_sync_file,
        .release        = ocfs2_dir_release,
        .open           = ocfs2_dir_open,
        .unlocked_ioctl = ocfs2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ocfs2_compat_ioctl,
#endif
        .flock          = ocfs2_flock,
};