root/fs/ext4/file.c

DEFINITIONS

1. ext4_release_file
2. ext4_file_write
3. ext4_file_mmap

/*
 *  linux/fs/ext4/file.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/file.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext4 fs regular file handling primitives
 *
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *      (jj@sunsite.ms.mff.cuni.cz)
 */

#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd2.h>
#include "ext4.h"
#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"

/*
 * Called when an inode is released. Note that this is different
 * from ext4_file_open: open gets called at every open, but release
 * gets called only when /all/ the files are closed.
 */
static int ext4_release_file(struct inode *inode, struct file *filp)
{
        /* if we are the last writer on the inode, drop the block reservation */
        if ((filp->f_mode & FMODE_WRITE) &&
                        (atomic_read(&inode->i_writecount) == 1))
        {
                down_write(&EXT4_I(inode)->i_data_sem);
                ext4_discard_preallocations(inode);
                up_write(&EXT4_I(inode)->i_data_sem);
        }
        if (is_dx(inode) && filp->private_data)
                ext4_htree_free_dir_info(filp->private_data);

        return 0;
}

static ssize_t
ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
                unsigned long nr_segs, loff_t pos)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_path.dentry->d_inode;
        ssize_t ret;
        int err;

        /*
         * If we have encountered a bitmap-format file, the size limit
         * is smaller than s_maxbytes, which is for extent-mapped files.
         */

        if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
                struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
                size_t length = iov_length(iov, nr_segs);

                if (pos > sbi->s_bitmap_maxbytes)
                        return -EFBIG;

                if (pos + length > sbi->s_bitmap_maxbytes) {
                        nr_segs = iov_shorten((struct iovec *)iov, nr_segs,
                                              sbi->s_bitmap_maxbytes - pos);
                }
        }

        ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
        /*
         * Skip flushing if there was an error, or if nothing was written.
         */
        if (ret <= 0)
                return ret;

        /*
         * If the inode is IS_SYNC, or is O_SYNC and we are doing data
         * journalling then we need to make sure that we force the transaction
         * to disk to keep all metadata uptodate synchronously.
         */
        if (file->f_flags & O_SYNC) {
                /*
                 * If we are non-data-journaled, then the dirty data has
                 * already been flushed to backing store by generic_osync_inode,
                 * and the inode has been flushed too if there have been any
                 * modifications other than mere timestamp updates.
                 *
                 * Open question --- do we care about flushing timestamps too
                 * if the inode is IS_SYNC?
                 */
                if (!ext4_should_journal_data(inode))
                        return ret;

                goto force_commit;
        }

        /*
         * So we know that there has been no forced data flush.  If the inode
         * is marked IS_SYNC, we need to force one ourselves.
         */
        if (!IS_SYNC(inode))
                return ret;

        /*
         * Open question #2 --- should we force data to disk here too?  If we
         * don't, the only impact is that data=writeback filesystems won't
         * flush data to disk automatically on IS_SYNC, only metadata (but
         * historically, that is what ext2 has done.)
         */

force_commit:
        err = ext4_force_commit(inode->i_sb);
        if (err)
                return err;
        return ret;
}

static struct vm_operations_struct ext4_file_vm_ops = {
        .fault          = filemap_fault,
        .page_mkwrite   = ext4_page_mkwrite,
};

static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct address_space *mapping = file->f_mapping;

        if (!mapping->a_ops->readpage)
                return -ENOEXEC;
        file_accessed(file);
        vma->vm_ops = &ext4_file_vm_ops;
        vma->vm_flags |= VM_CAN_NONLINEAR;
        return 0;
}

extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                __u64 start, __u64 len);

const struct file_operations ext4_file_operations = {
        .llseek         = generic_file_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
        .aio_read       = generic_file_aio_read,
        .aio_write      = ext4_file_write,
        .unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ext4_compat_ioctl,
#endif
        .mmap           = ext4_file_mmap,
        .open           = generic_file_open,
        .release        = ext4_release_file,
        .fsync          = ext4_sync_file,
        .splice_read    = generic_file_splice_read,
        .splice_write   = generic_file_splice_write,
};

const struct inode_operations ext4_file_inode_operations = {
        .truncate       = ext4_truncate,
        .setattr        = ext4_setattr,
        .getattr        = ext4_getattr,
#ifdef CONFIG_EXT4_FS_XATTR
        .setxattr       = generic_setxattr,
        .getxattr       = generic_getxattr,
        .listxattr      = ext4_listxattr,
        .removexattr    = generic_removexattr,
#endif
        .permission     = ext4_permission,
        .fallocate      = ext4_fallocate,
        .fiemap         = ext4_fiemap,
};