file.c

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/*
 * file.c - NILFS regular file handling primitives including fsync().
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Amagai Yoshiji <[email protected]>,
 *            Ryusuke Konishi <[email protected]>
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/writeback.h>
#include "nilfs.h"
#include "segment.h"

int nilfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
    /*
     * Called from fsync() system call
     * This is the only entry point that can catch write and synch
     * timing for both data blocks and intermediate blocks.
     *
     * This function should be implemented when the writeback function
     * will be implemented.
     */
    struct the_nilfs *nilfs;
    struct inode *inode = file->f_mapping->host;
    int err;

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

    if (nilfs_inode_dirty(inode)) {
        if (datasync)
            err = nilfs_construct_dsync_segment(inode->i_sb, inode,
                                0, LLONG_MAX);
        else
            err = nilfs_construct_segment(inode->i_sb);
    }
    mutex_unlock(&inode->i_mutex);

    nilfs = inode->i_sb->s_fs_info;
    if (!err && nilfs_test_opt(nilfs, BARRIER)) {
        err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
        if (err != -EIO)
            err = 0;
    }
    return err;
}

static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
    struct page *page = vmf->page;
    struct inode *inode = vma->vm_file->f_dentry->d_inode;
    struct nilfs_transaction_info ti;
    int ret = 0;

    if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
        return VM_FAULT_SIGBUS; /* -ENOSPC */

    sb_start_pagefault(inode->i_sb);
    lock_page(page);
    if (page->mapping != inode->i_mapping ||
        page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
        unlock_page(page);
        ret = -EFAULT;  /* make the VM retry the fault */
        goto out;
    }

    /*
     * check to see if the page is mapped already (no holes)
     */
    if (PageMappedToDisk(page))
        goto mapped;

    if (page_has_buffers(page)) {
        struct buffer_head *bh, *head;
        int fully_mapped = 1;

        bh = head = page_buffers(page);
        do {
            if (!buffer_mapped(bh)) {
                fully_mapped = 0;
                break;
            }
        } while (bh = bh->b_this_page, bh != head);

        if (fully_mapped) {
            SetPageMappedToDisk(page);
            goto mapped;
        }
    }
    unlock_page(page);

    /*
     * fill hole blocks
     */
    ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
    /* never returns -ENOMEM, but may return -ENOSPC */
    if (unlikely(ret))
        goto out;

    file_update_time(vma->vm_file);
    ret = __block_page_mkwrite(vma, vmf, nilfs_get_block);
    if (ret) {
        nilfs_transaction_abort(inode->i_sb);
        goto out;
    }
    nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
    nilfs_transaction_commit(inode->i_sb);

 mapped:
    wait_on_page_writeback(page);
 out:
    sb_end_pagefault(inode->i_sb);
    return block_page_mkwrite_return(ret);
}

static const struct vm_operations_struct nilfs_file_vm_ops = {
    .fault      = filemap_fault,
    .page_mkwrite   = nilfs_page_mkwrite,
    .remap_pages    = generic_file_remap_pages,
};

static int nilfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
    file_accessed(file);
    vma->vm_ops = &nilfs_file_vm_ops;
    return 0;
}

/*
 * We have mostly NULL's here: the current defaults are ok for
 * the nilfs filesystem.
 */
const struct file_operations nilfs_file_operations = {
    .llseek     = generic_file_llseek,
    .read       = do_sync_read,
    .write      = do_sync_write,
    .aio_read   = generic_file_aio_read,
    .aio_write  = generic_file_aio_write,
    .unlocked_ioctl = nilfs_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = nilfs_compat_ioctl,
#endif  /* CONFIG_COMPAT */
    .mmap       = nilfs_file_mmap,
    .open       = generic_file_open,
    /* .release = nilfs_release_file, */
    .fsync      = nilfs_sync_file,
    .splice_read    = generic_file_splice_read,
};

const struct inode_operations nilfs_file_inode_operations = {
    .truncate   = nilfs_truncate,
    .setattr    = nilfs_setattr,
    .permission     = nilfs_permission,
    .fiemap     = nilfs_fiemap,
};

/* end of file */