file.c

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/* -*- 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>

#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 "ocfs2_trace.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);

    trace_ocfs2_file_open(inode, file, file->f_path.dentry,
                  (unsigned long long)OCFS2_I(inode)->ip_blkno,
                  file->f_path.dentry->d_name.len,
                  file->f_path.dentry->d_name.name, mode);

    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:
    return status;
}

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

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

    trace_ocfs2_file_release(inode, file, file->f_path.dentry,
                 oi->ip_blkno,
                 file->f_path.dentry->d_name.len,
                 file->f_path.dentry->d_name.name,
                 oi->ip_open_count);
    spin_unlock(&oi->ip_lock);

    ocfs2_free_file_private(inode, file);

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

    trace_ocfs2_sync_file(inode, file, file->f_path.dentry,
                  OCFS2_I(inode)->ip_blkno,
                  file->f_path.dentry->d_name.len,
                  file->f_path.dentry->d_name.name,
                  (unsigned long long)datasync);

    err = filemap_write_and_wait_range(inode->i_mapping, start, end);
    if (err)
        return err;

    /*
     * Probably don't need the i_mutex at all in here, just putting it here
     * to be consistent with how fsync used to be called, someone more
     * familiar with the fs could possibly remove it.
     */
    mutex_lock(&inode->i_mutex);
    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:
    if (err)
        mlog_errno(err);
    mutex_unlock(&inode->i_mutex);

    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;

    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:
    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;

    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:
    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;

    /*
     * 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:
    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);

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

    trace_ocfs2_truncate_file((unsigned long long)OCFS2_I(inode)->ip_blkno,
                  (unsigned long long)le64_to_cpu(fe->i_size),
                  (unsigned long long)new_i_size);

    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)) {
        trace_ocfs2_truncate_file_error(
            (unsigned long long)le64_to_cpu(fe->i_size),
            (unsigned long long)new_i_size);
        status = -EINVAL;
        mlog_errno(status);
        goto bail;
    }

    /* 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);

    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;

    /*
     * 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);

    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:
    trace_ocfs2_extend_allocation(
        (unsigned long long)OCFS2_I(inode)->ip_blkno,
        (unsigned long long)i_size_read(inode),
        le32_to_cpu(fe->i_clusters), clusters_to_add,
        why, restart_func);

    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) {
            restart_func = 1;
            status = 0;
        } else {
            BUG_ON(why != RESTART_TRANS);

            /* 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;
        }
    }

    trace_ocfs2_extend_allocation_end(OCFS2_I(inode)->ip_blkno,
         le32_to_cpu(fe->i_clusters),
         (unsigned long long)le64_to_cpu(fe->i_size),
         OCFS2_I(inode)->ip_clusters,
         (unsigned 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;

    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;

    trace_ocfs2_write_zero_page(
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            (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;

    trace_ocfs2_zero_extend_range(
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            (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));
    trace_ocfs2_zero_extend((unsigned long long)OCFS2_I(inode)->ip_blkno,
                (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;

    trace_ocfs2_setattr(inode, dentry,
                (unsigned long long)OCFS2_I(inode)->ip_blkno,
                dentry->d_name.len, dentry->d_name.name,
                attr->ia_valid, attr->ia_mode,
                attr->ia_uid, attr->ia_gid);

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

#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))
        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;

        inode_dio_wait(inode);

        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, make_kqid_uid(attr->ia_uid));
            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, make_kqid_gid(attr->ia_gid));
            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);
    }

    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;

    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:
    return err;
}

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

    if (mask & MAY_NOT_BLOCK)
        return -ECHILD;

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

    ret = generic_permission(inode, mask);

    ocfs2_inode_unlock(inode, 0);
out:
    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;

    trace_ocfs2_write_remove_suid(
            (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:
    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.
     */
    trace_ocfs2_zero_partial_clusters(
        (unsigned long long)OCFS2_I(inode)->ip_blkno,
        (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;

    trace_ocfs2_zero_partial_clusters_range1((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);

        trace_ocfs2_zero_partial_clusters_range2(
            (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) {
        /*
         * remove an entire extent record.
         */
        *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) {
        /*
         * remove a partial extent record, which means we're
         * removing the last extent record.
         */
        *trunc_cpos = trunc_start;
        /*
         * skip hole if any.
         */
        if (range < *trunc_end)
            *trunc_end = range;
        *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);

    trace_ocfs2_remove_inode_range(
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            (unsigned long long)byte_start,
            (unsigned long long)byte_len);

    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;

    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);

    if (file && (file->f_flags & O_SYNC))
        handle->h_sync = 1;

    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);
    int ret;

    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;

    ret = mnt_want_write_file(file);
    if (ret)
        return ret;
    ret = __ocfs2_change_file_space(file, inode, file->f_pos, cmd, sr, 0);
    mnt_drop_write_file(file);
    return ret;
}

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 void ocfs2_aiodio_wait(struct inode *inode)
{
    wait_queue_head_t *wq = ocfs2_ioend_wq(inode);

    wait_event(*wq, (atomic_read(&OCFS2_I(inode)->ip_unaligned_aio) == 0));
}

static int ocfs2_is_io_unaligned(struct inode *inode, size_t count, loff_t pos)
{
    int blockmask = inode->i_sb->s_blocksize - 1;
    loff_t final_size = pos + count;

    if ((pos & blockmask) || (final_size & blockmask))
        return 1;
    return 0;
}

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 = 0, 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
         * proceed, 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);
        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:
    trace_ocfs2_prepare_inode_for_write(OCFS2_I(inode)->ip_blkno,
                        saved_pos, appending, count,
                        direct_io, has_refcount);

    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);
    int unaligned_dio = 0;

    trace_ocfs2_file_aio_write(inode, file, file->f_path.dentry,
        (unsigned long long)OCFS2_I(inode)->ip_blkno,
        file->f_path.dentry->d_name.len,
        file->f_path.dentry->d_name.name,
        (unsigned int)nr_segs);

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

    sb_start_write(inode->i_sb);

    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 -> rw_lock ordering */
    if (direct_io) {
        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;
    }

    if (direct_io && !is_sync_kiocb(iocb))
        unaligned_dio = ocfs2_is_io_unaligned(inode, iocb->ki_left,
                              *ppos);

    /*
     * 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);

        have_alloc_sem = 0;
        rw_level = -1;

        direct_io = 0;
        goto relock;
    }

    if (unaligned_dio) {
        /*
         * Wait on previous unaligned aio to complete before
         * proceeding.
         */
        ocfs2_aiodio_wait(inode);

        /* Mark the iocb as needing a decrement in ocfs2_dio_end_io */
        atomic_inc(&OCFS2_I(inode)->ip_unaligned_aio);
        ocfs2_iocb_set_unaligned_aio(iocb);
    }

    /*
     * 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.
     * 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;
        unaligned_dio = 0;
    }

    if (unaligned_dio) {
        ocfs2_iocb_clear_unaligned_aio(iocb);
        atomic_dec(&OCFS2_I(inode)->ip_unaligned_aio);
    }

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

out_sems:
    if (have_alloc_sem)
        ocfs2_iocb_clear_sem_locked(iocb);

    mutex_unlock(&inode->i_mutex);
    sb_end_write(inode->i_sb);

    if (written)
        ret = written;
    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,
    };


    trace_ocfs2_file_splice_write(inode, out, out->f_path.dentry,
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            out->f_path.dentry->d_name.len,
            out->f_path.dentry->d_name.name, len);

    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);
    }

    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;

    trace_ocfs2_file_splice_read(inode, in, in->f_path.dentry,
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            in->f_path.dentry->d_name.len,
            in->f_path.dentry->d_name.name, len);

    /*
     * 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:
    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;

    trace_ocfs2_file_aio_read(inode, filp, filp->f_path.dentry,
            (unsigned long long)OCFS2_I(inode)->ip_blkno,
            filp->f_path.dentry->d_name.len,
            filp->f_path.dentry->d_name.name, nr_segs);


    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) {
        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);
    trace_generic_file_aio_read_ret(ret);

    /* 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)
        ocfs2_iocb_clear_sem_locked(iocb);

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

    return ret;
}

/* Refer generic_file_llseek_unlocked() */
static loff_t ocfs2_file_llseek(struct file *file, loff_t offset, int origin)
{
    struct inode *inode = file->f_mapping->host;
    int ret = 0;

    mutex_lock(&inode->i_mutex);

    switch (origin) {
    case SEEK_SET:
        break;
    case SEEK_END:
        offset += inode->i_size;
        break;
    case SEEK_CUR:
        if (offset == 0) {
            offset = file->f_pos;
            goto out;
        }
        offset += file->f_pos;
        break;
    case SEEK_DATA:
    case SEEK_HOLE:
        ret = ocfs2_seek_data_hole_offset(file, &offset, origin);
        if (ret)
            goto out;
        break;
    default:
        ret = -EINVAL;
        goto out;
    }

    if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
        ret = -EINVAL;
    if (!ret && offset > inode->i_sb->s_maxbytes)
        ret = -EINVAL;
    if (ret)
        goto out;

    if (offset != file->f_pos) {
        file->f_pos = offset;
        file->f_version = 0;
    }

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

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,
    .get_acl    = ocfs2_iop_get_acl,
};

const struct inode_operations ocfs2_special_file_iops = {
    .setattr    = ocfs2_setattr,
    .getattr    = ocfs2_getattr,
    .permission = ocfs2_permission,
    .get_acl    = ocfs2_iop_get_acl,
};

/*
 * 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     = ocfs2_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     = ocfs2_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,
    .fallocate  = ocfs2_fallocate,
};

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,
};