ocfs2: teach ocfs2_file_aio_write() about sparse files

[safe/jmp/linux-2.6] / fs / ocfs2 / file.c

/* -*- 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/pipe_fs_i.h>
#include <linux/mount.h>
#include <linux/writeback.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 "mmap.h"
#include "suballoc.h"
#include "super.h"

#include "buffer_head_io.h"

static int ocfs2_sync_inode(struct inode *inode)
{
        filemap_fdatawrite(inode->i_mapping);
        return sync_mapping_buffers(inode->i_mapping);
}

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);

        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 = 0;
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);

        mlog_exit(0);

        return 0;
}

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

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

        err = ocfs2_sync_inode(dentry->d_inode);
        if (err)
                goto bail;

        journal = osb->journal->j_journal;
        err = 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;

        mlog_entry_void();

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

        inode->i_atime = CURRENT_TIME;
        ret = ocfs2_mark_inode_dirty(handle, inode, bh);
        if (ret < 0)
                mlog_errno(ret);

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

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_align_bytes_to_sectors(new_i_size);
        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;
}

static 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 (handle == NULL) {
                ret = -ENOMEM;
                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_orphan_for_truncate(struct ocfs2_super *osb,
                                     struct inode *inode,
                                     struct buffer_head *fe_bh,
                                     u64 new_i_size)
{
        int status;
        handle_t *handle;

        mlog_entry_void();

        /* 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_set_inode_size(handle, inode, fe_bh, new_i_size);
        if (status < 0)
                mlog_errno(status);

        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);
        struct ocfs2_truncate_context *tc = NULL;

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

        truncate_inode_pages(inode->i_mapping, new_i_size);

        fe = (struct ocfs2_dinode *) di_bh->b_data;
        if (!OCFS2_IS_VALID_DINODE(fe)) {
                OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
                status = -EIO;
                goto bail;
        }

        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;

        /* This forces other nodes to sync and drop their pages. Do
         * this 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.  */
        status = ocfs2_data_lock(inode, 1);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }
        ocfs2_data_unlock(inode, 1);

        /* 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;
        }

        status = ocfs2_prepare_truncate(osb, inode, di_bh, &tc);
        if (status < 0) {
                mlog_errno(status);
                goto bail;
        }

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

        /* TODO: orphan dir cleanup here. */
bail:

        mlog_exit(status);
        return status;
}

/*
 * extend 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_do_extend_allocation(struct ocfs2_super *osb,
                               struct inode *inode,
                               u32 *logical_offset,
                               u32 clusters_to_add,
                               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 status = 0;
        int free_extents;
        struct ocfs2_dinode *fe = (struct ocfs2_dinode *) fe_bh->b_data;
        enum ocfs2_alloc_restarted reason = RESTART_NONE;
        u32 bit_off, num_bits;
        u64 block;

        BUG_ON(!clusters_to_add);

        free_extents = ocfs2_num_free_extents(osb, inode, fe);
        if (free_extents < 0) {
                status = free_extents;
                mlog_errno(status);
                goto leave;
        }

        /* there are two cases which could cause us to EAGAIN in the
         * we-need-more-metadata case:
         * 1) we haven't reserved *any*
         * 2) we are so fragmented, we've needed to add metadata too
         *    many times. */
        if (!free_extents && !meta_ac) {
                mlog(0, "we haven't reserved any metadata!\n");
                status = -EAGAIN;
                reason = RESTART_META;
                goto leave;
        } else if ((!free_extents)
                   && (ocfs2_alloc_context_bits_left(meta_ac)
                       < ocfs2_extend_meta_needed(fe))) {
                mlog(0, "filesystem is really fragmented...\n");
                status = -EAGAIN;
                reason = RESTART_META;
                goto leave;
        }

        status = ocfs2_claim_clusters(osb, handle, data_ac, 1,
                                      &bit_off, &num_bits);
        if (status < 0) {
                if (status != -ENOSPC)
                        mlog_errno(status);
                goto leave;
        }

        BUG_ON(num_bits > clusters_to_add);

        /* reserve our write early -- insert_extent may update the inode */
        status = ocfs2_journal_access(handle, inode, fe_bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        block = ocfs2_clusters_to_blocks(osb->sb, bit_off);
        mlog(0, "Allocating %u clusters at block %u for inode %llu\n",
             num_bits, bit_off, (unsigned long long)OCFS2_I(inode)->ip_blkno);
        status = ocfs2_insert_extent(osb, handle, inode, fe_bh,
                                     *logical_offset, block, num_bits,
                                     meta_ac);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        status = ocfs2_journal_dirty(handle, fe_bh);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        clusters_to_add -= num_bits;
        *logical_offset += num_bits;

        if (clusters_to_add) {
                mlog(0, "need to alloc once more, clusters = %u, wanted = "
                     "%u\n", fe->i_clusters, clusters_to_add);
                status = -EAGAIN;
                reason = RESTART_TRANS;
        }

leave:
        mlog_exit(status);
        if (reason_ret)
                *reason_ret = reason;
        return status;
}

/*
 * For a given allocation, determine which allocators will need to be
 * accessed, and lock them, reserving the appropriate number of bits.
 *
 * Called from ocfs2_extend_allocation() for file systems which don't
 * support holes, and from ocfs2_write() for file systems which
 * understand sparse inodes.
 */
int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_dinode *di,
                          u32 clusters_to_add,
                          struct ocfs2_alloc_context **data_ac,
                          struct ocfs2_alloc_context **meta_ac)
{
        int ret, num_free_extents;
        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);

        *meta_ac = NULL;
        *data_ac = NULL;

        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, i_size_read(inode),
             le32_to_cpu(di->i_clusters), clusters_to_add);

        num_free_extents = ocfs2_num_free_extents(osb, inode, di);
        if (num_free_extents < 0) {
                ret = num_free_extents;
                mlog_errno(ret);
                goto out;
        }

        /*
         * Sparse allocation file systems need to be more conservative
         * with reserving room for expansion - the actual allocation
         * happens while we've got a journal handle open so re-taking
         * a cluster lock (because we ran out of room for another
         * extent) will violate ordering rules.
         *
         * Most of the time we'll only be seeing this 1 cluster at a time
         * anyway.
         */
        if (!num_free_extents ||
            (ocfs2_sparse_alloc(osb) && num_free_extents < clusters_to_add)) {
                ret = ocfs2_reserve_new_metadata(osb, di, meta_ac);
                if (ret < 0) {
                        if (ret != -ENOSPC)
                                mlog_errno(ret);
                        goto out;
                }
        }

        ret = ocfs2_reserve_clusters(osb, clusters_to_add, data_ac);
        if (ret < 0) {
                if (ret != -ENOSPC)
                        mlog_errno(ret);
                goto out;
        }

out:
        if (ret) {
                if (*meta_ac) {
                        ocfs2_free_alloc_context(*meta_ac);
                        *meta_ac = NULL;
                }

                /*
                 * We cannot have an error and a non null *data_ac.
                 */
        }

        return ret;
}

static int ocfs2_extend_allocation(struct inode *inode,
                                   u32 clusters_to_add)
{
        int status = 0;
        int restart_func = 0;
        int drop_alloc_sem = 0;
        int credits;
        u32 prev_clusters, logical_start;
        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);

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

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

        status = ocfs2_read_block(osb, OCFS2_I(inode)->ip_blkno, &bh,
                                  OCFS2_BH_CACHED, inode);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        fe = (struct ocfs2_dinode *) bh->b_data;
        if (!OCFS2_IS_VALID_DINODE(fe)) {
                OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, fe);
                status = -EIO;
                goto leave;
        }

        logical_start = OCFS2_I(inode)->ip_clusters;

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

        /* blocks peope 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. Ordering wrt
         * start_trans is important here -- always do it before! */
        down_write(&OCFS2_I(inode)->ip_alloc_sem);
        drop_alloc_sem = 1;

        status = ocfs2_lock_allocators(inode, fe, clusters_to_add, &data_ac,
                                       &meta_ac);
        if (status) {
                mlog_errno(status);
                goto leave;
        }

        credits = ocfs2_calc_extend_credits(osb->sb, fe, 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:
        /* 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(handle, inode, bh,
                                      OCFS2_JOURNAL_ACCESS_WRITE);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        prev_clusters = OCFS2_I(inode)->ip_clusters;

        status = ocfs2_do_extend_allocation(osb,
                                            inode,
                                            &logical_start,
                                            clusters_to_add,
                                            bh,
                                            handle,
                                            data_ac,
                                            meta_ac,
                                            &why);
        if ((status < 0) && (status != -EAGAIN)) {
                if (status != -ENOSPC)
                        mlog_errno(status);
                goto leave;
        }

        status = ocfs2_journal_dirty(handle, bh);
        if (status < 0) {
                mlog_errno(status);
                goto leave;
        }

        spin_lock(&OCFS2_I(inode)->ip_lock);
        clusters_to_add -= (OCFS2_I(inode)->ip_clusters - prev_clusters);
        spin_unlock(&OCFS2_I(inode)->ip_lock);

        if (why != RESTART_NONE && clusters_to_add) {
                if (why == RESTART_META) {
                        mlog(0, "restarting function.\n");
                        restart_func = 1;
                } 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,
                                                            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",
             fe->i_clusters, (unsigned long long)fe->i_size);
        mlog(0, "inode: ip_clusters=%u, i_size=%lld\n",
             OCFS2_I(inode)->ip_clusters, i_size_read(inode));

leave:
        if (drop_alloc_sem) {
                up_write(&OCFS2_I(inode)->ip_alloc_sem);
                drop_alloc_sem = 0;
        }
        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;
        }
        if (bh) {
                brelse(bh);
                bh = NULL;
        }

        mlog_exit(status);
        return status;
}

/* 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 ->prepare_write() and
 * ->commit_write(). */
static int ocfs2_write_zero_page(struct inode *inode,
                                 u64 size)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        unsigned long index;
        unsigned int offset;
        handle_t *handle = NULL;
        int ret;

        offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */
        /* ugh.  in prepare/commit_write, if from==to==start of block, we 
        ** skip the prepare.  make sure we never send an offset for the start
        ** of a block
        */
        if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
                offset++;
        }
        index = size >> PAGE_CACHE_SHIFT;

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

        ret = ocfs2_prepare_write_nolock(inode, page, offset, offset);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_unlock;
        }

        if (ocfs2_should_order_data(inode)) {
                handle = ocfs2_start_walk_page_trans(inode, page, offset,
                                                     offset);
                if (IS_ERR(handle)) {
                        ret = PTR_ERR(handle);
                        handle = NULL;
                        goto out_unlock;
                }
        }

        /* must not update i_size! */
        ret = block_commit_write(page, offset, offset);
        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;
}

static int ocfs2_zero_extend(struct inode *inode,
                             u64 zero_to_size)
{
        int ret = 0;
        u64 start_off;
        struct super_block *sb = inode->i_sb;

        start_off = ocfs2_align_bytes_to_blocks(sb, i_size_read(inode));
        while (start_off < zero_to_size) {
                ret = ocfs2_write_zero_page(inode, start_off);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out;
                }

                start_off += sb->s_blocksize;

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

out:
        return ret;
}

/* 
 * A tail_to_skip value > 0 indicates that we're being called from
 * ocfs2_file_aio_write(). This has the following implications:
 *
 * - we don't want to update i_size
 * - di_bh will be NULL, which is fine because it's only used in the
 *   case where we want to update i_size.
 * - ocfs2_zero_extend() will then only be filling the hole created
 *   between i_size and the start of the write.
 */
static int ocfs2_extend_file(struct inode *inode,
                             struct buffer_head *di_bh,
                             u64 new_i_size,
                             size_t tail_to_skip)
{
        int ret = 0;
        u32 clusters_to_add = 0;

        BUG_ON(!tail_to_skip && !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));

        if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
                BUG_ON(tail_to_skip != 0);
                goto out_update_size;
        }

        clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size) - 
                OCFS2_I(inode)->ip_clusters;

        /* 
         * protect the pages that ocfs2_zero_extend is going to be
         * pulling into the page cache.. we do this before the
         * metadata extend so that we don't get into the situation
         * where we've extended the metadata but can't get the data
         * lock to zero.
         */
        ret = ocfs2_data_lock(inode, 1);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        if (clusters_to_add) {
                ret = ocfs2_extend_allocation(inode, clusters_to_add);
                if (ret < 0) {
                        mlog_errno(ret);
                        goto out_unlock;
                }
        }

        /*
         * 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, (u64)new_i_size - tail_to_skip);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_unlock;
        }

out_update_size:
        if (!tail_to_skip) {
                /* We're being called from ocfs2_setattr() which wants
                 * us to update i_size */
                ret = ocfs2_simple_size_update(inode, di_bh, new_i_size);
                if (ret < 0)
                        mlog_errno(ret);
        }

out_unlock:
        if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
                ocfs2_data_unlock(inode, 1);

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;

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

        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;

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

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

        status = inode_setattr(inode, attr);
        if (status < 0) {
                mlog_errno(status);
                goto bail_commit;
        }

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

bail_commit:
        ocfs2_commit_trans(osb, handle);
bail_unlock:
        ocfs2_meta_unlock(inode, 1);
bail_unlock_rw:
        if (size_change)
                ocfs2_rw_unlock(inode, 1);
bail:
        if (bh)
                brelse(bh);

        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, struct nameidata *nd)
{
        int ret;

        mlog_entry_void();

        ret = ocfs2_meta_lock(inode, NULL, 0);
        if (ret) {
                if (ret != -ENOENT)
                        mlog_errno(ret);
                goto out;
        }

        ret = generic_permission(inode, mask, NULL);

        ocfs2_meta_unlock(inode, 0);
out:
        mlog_exit(ret);
        return ret;
}

static int ocfs2_write_remove_suid(struct inode *inode)
{
        int ret;
        struct buffer_head *bh = NULL;
        struct ocfs2_inode_info *oi = OCFS2_I(inode);
        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)oi->ip_blkno, inode->i_mode);

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

        ret = ocfs2_read_block(osb, oi->ip_blkno, &bh, OCFS2_BH_CACHED, inode);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_trans;
        }

        ret = ocfs2_journal_access(handle, inode, bh,
                                   OCFS2_JOURNAL_ACCESS_WRITE);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_bh;
        }

        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);

        ret = ocfs2_journal_dirty(handle, bh);
        if (ret < 0)
                mlog_errno(ret);
out_bh:
        brelse(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_prepare_inode_for_write(struct dentry *dentry,
                                         loff_t *ppos,
                                         size_t count,
                                         int appending,
                                         int *direct_io)
{
        int ret = 0, meta_level = appending;
        struct inode *inode = dentry->d_inode;
        u32 clusters;
        loff_t newsize, saved_pos;

        /* 
         * We sample i_size under a read level meta lock to see if our write
         * is extending the file, if it is we back off and get a write level
         * meta lock.
         */
        for(;;) {
                ret = ocfs2_meta_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_meta_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;
                }

                if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
                        loff_t end = saved_pos + count;

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

                /*
                 * The rest of this loop is concerned with legacy file
                 * systems which don't support sparse files.
                 */

                newsize = count + saved_pos;

                mlog(0, "pos=%lld newsize=%lld cursize=%lld\n",
                     (long long) saved_pos, (long long) newsize,
                     (long long) i_size_read(inode));

                /* No need for a higher level metadata lock if we're
                 * never going past i_size. */
                if (newsize <= i_size_read(inode))
                        break;

                if (meta_level == 0) {
                        ocfs2_meta_unlock(inode, meta_level);
                        meta_level = 1;
                        continue;
                }

                spin_lock(&OCFS2_I(inode)->ip_lock);
                clusters = ocfs2_clusters_for_bytes(inode->i_sb, newsize) -
                        OCFS2_I(inode)->ip_clusters;
                spin_unlock(&OCFS2_I(inode)->ip_lock);

                mlog(0, "Writing at EOF, may need more allocation: "
                     "i_size = %lld, newsize = %lld, need %u clusters\n",
                     (long long) i_size_read(inode), (long long) newsize,
                     clusters);

                /* We only want to continue the rest of this loop if
                 * our extend will actually require more
                 * allocation. */
                if (!clusters)
                        break;

                ret = ocfs2_extend_file(inode, NULL, newsize, count);
                if (ret < 0) {
                        if (ret != -ENOSPC)
                                mlog_errno(ret);
                        goto out_unlock;
                }
                break;
        }

        if (appending)
                *ppos = saved_pos;

out_unlock:
        ocfs2_meta_unlock(inode, meta_level);

out:
        return ret;
}

static inline void
ocfs2_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
{
        const struct iovec *iov = *iovp;
        size_t base = *basep;

        do {
                int copy = min(bytes, iov->iov_len - base);

                bytes -= copy;
                base += copy;
                if (iov->iov_len == base) {
                        iov++;
                        base = 0;
                }
        } while (bytes);
        *iovp = iov;
        *basep = base;
}

static struct page * ocfs2_get_write_source(struct ocfs2_buffered_write_priv *bp,
                                            const struct iovec *cur_iov,
                                            size_t iov_offset)
{
        int ret;
        char *buf;
        struct page *src_page = NULL;

        buf = cur_iov->iov_base + iov_offset;

        if (!segment_eq(get_fs(), KERNEL_DS)) {
                /*
                 * Pull in the user page. We want to do this outside
                 * of the meta data locks in order to preserve locking
                 * order in case of page fault.
                 */
                ret = get_user_pages(current, current->mm,
                                     (unsigned long)buf & PAGE_CACHE_MASK, 1,
                                     0, 0, &src_page, NULL);
                if (ret == 1)
                        bp->b_src_buf = kmap(src_page);
                else
                        src_page = ERR_PTR(-EFAULT);
        } else {
                bp->b_src_buf = buf;
        }

        return src_page;
}

static void ocfs2_put_write_source(struct ocfs2_buffered_write_priv *bp,
                                   struct page *page)
{
        if (page) {
                kunmap(page);
                page_cache_release(page);
        }
}

static ssize_t ocfs2_file_buffered_write(struct file *file, loff_t *ppos,
                                         const struct iovec *iov,
                                         unsigned long nr_segs,
                                         size_t count,
                                         ssize_t o_direct_written)
{
        int ret = 0;
        ssize_t copied, total = 0;
        size_t iov_offset = 0;
        const struct iovec *cur_iov = iov;
        struct ocfs2_buffered_write_priv bp;
        struct page *page;

        /*
         * handle partial DIO write.  Adjust cur_iov if needed.
         */
        ocfs2_set_next_iovec(&cur_iov, &iov_offset, o_direct_written);

        do {
                bp.b_cur_off = iov_offset;
                bp.b_cur_iov = cur_iov;

                page = ocfs2_get_write_source(&bp, cur_iov, iov_offset);
                if (IS_ERR(page)) {
                        ret = PTR_ERR(page);
                        goto out;
                }

                copied = ocfs2_buffered_write_cluster(file, *ppos, count,
                                                      ocfs2_map_and_write_user_data,
                                                      &bp);

                ocfs2_put_write_source(&bp, page);

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

                total += copied;
                *ppos = *ppos + copied;
                count -= copied;

                ocfs2_set_next_iovec(&cur_iov, &iov_offset, copied);
        } while(count);

out:
        return total ? total : ret;
}

static int ocfs2_check_iovec(const struct iovec *iov, size_t *counted,
                             unsigned long *nr_segs)
{
        size_t ocount;          /* original count */
        unsigned long seg;

        ocount = 0;
        for (seg = 0; seg < *nr_segs; seg++) {
                const struct iovec *iv = &iov[seg];

                /*
                 * If any segment has a negative length, or the cumulative
                 * length ever wraps negative then return -EINVAL.
                 */
                ocount += iv->iov_len;
                if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
                        return -EINVAL;
                if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
                        continue;
                if (seg == 0)
                        return -EFAULT;
                *nr_segs = seg;
                ocount -= iv->iov_len;  /* This segment is no good */
                break;
        }

        *counted = ocount;
        return 0;
}

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, sync = 0;
        ssize_t written = 0;
        size_t ocount;          /* original count */
        size_t count;           /* after file limit checks */
        loff_t *ppos = &iocb->ki_pos;
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_path.dentry->d_inode;

        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;

        ret = ocfs2_check_iovec(iov, &ocount, &nr_segs);
        if (ret)
                return ret;

        count = ocount;

        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);

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;
        }

        /* concurrent O_DIRECT writes are allowed */
        rw_level = !direct_io;
        ret = ocfs2_rw_lock(inode, rw_level);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_sems;
        }

        can_do_direct = direct_io;
        ret = ocfs2_prepare_inode_for_write(file->f_path.dentry, ppos,
                                            iocb->ki_left, appending,
                                            &can_do_direct);
        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;
                sync = 1;
                goto relock;
        }

        if (!sync && ((file->f_flags & O_SYNC) || IS_SYNC(inode)))
                sync = 1;

        /*
         * XXX: Is it ok to execute these checks a second time?
         */
        ret = generic_write_checks(file, ppos, &count, S_ISBLK(inode->i_mode));
        if (ret)
                goto out;

        /*
         * Set pos so that sync_page_range_nolock() below understands
         * where to start from. We might've moved it around via the
         * calls above. The range we want to actually sync starts from
         * *ppos here.
         *
         */
        pos = *ppos;

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

        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 {
                written = ocfs2_file_buffered_write(file, ppos, iov, nr_segs,
                                                    count, written);
                if (written < 0) {
                        ret = written;
                        if (ret != -EFAULT || ret != -ENOSPC)
                                mlog_errno(ret);
                        goto out;
                }
        }

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

        /* 
         * 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);

        if (written > 0 && sync) {
                ssize_t err;

                err = sync_page_range_nolock(inode, file->f_mapping, pos, count);
                if (err < 0)
                        written = err;
        }

        mutex_unlock(&inode->i_mutex);

        mlog_exit(ret);
        return written ? written : ret;
}

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 inode *inode = out->f_path.dentry->d_inode;

        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);

        inode_double_lock(inode, pipe->inode);

        ret = ocfs2_rw_lock(inode, 1);
        if (ret < 0) {
                mlog_errno(ret);
                goto out;
        }

        ret = ocfs2_prepare_inode_for_write(out->f_path.dentry, ppos, len, 0,
                                            NULL);
        if (ret < 0) {
                mlog_errno(ret);
                goto out_unlock;
        }

        /* ok, we're done with i_size and alloc work */
        ret = generic_file_splice_write_nolock(pipe, out, ppos, len, flags);

out_unlock:
        ocfs2_rw_unlock(inode, 1);
out:
        inode_double_unlock(inode, pipe->inode);

        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;
        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_meta_lock(inode, NULL, 0);
        if (ret < 0) {
                mlog_errno(ret);
                goto bail;
        }
        ocfs2_meta_unlock(inode, 0);

        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;
        }

        /* 
         * 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;

                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);
        }

        /*
         * 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_meta_lock_atime(inode, filp->f_vfsmnt, &lock_level);
        if (ret < 0) {
                mlog_errno(ret);
                goto bail;
        }
        ocfs2_meta_unlock(inode, lock_level);

        ret = generic_file_aio_read(iocb, iov, nr_segs, iocb->ki_pos);
        if (ret == -EINVAL)
                mlog(ML_ERROR, "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);
        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,
};

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

const struct file_operations ocfs2_fops = {
        .read           = do_sync_read,
        .write          = do_sync_write,
        .sendfile       = generic_file_sendfile,
        .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,
        .ioctl          = ocfs2_ioctl,
        .splice_read    = ocfs2_file_splice_read,
        .splice_write   = ocfs2_file_splice_write,
};

const struct file_operations ocfs2_dops = {
        .read           = generic_read_dir,
        .readdir        = ocfs2_readdir,
        .fsync          = ocfs2_sync_file,
        .ioctl          = ocfs2_ioctl,
};