ops_file.c

linux 内核源代码

/**
 * gfs2_mmap -
 * @file: The file to map
 * @vma: The VMA which described the mapping
 *
 * Returns: 0 or error code
 */

static int gfs2_mmap(struct file *file, struct vm_area_struct *vma)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_holder i_gh;
	int error;

	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &i_gh);
	error = gfs2_glock_nq_atime(&i_gh);
	if (error) {
		gfs2_holder_uninit(&i_gh);
		return error;
	}

	/* This is VM_MAYWRITE instead of VM_WRITE because a call
	   to mprotect() can turn on VM_WRITE later. */

	if ((vma->vm_flags & (VM_MAYSHARE | VM_MAYWRITE)) ==
	    (VM_MAYSHARE | VM_MAYWRITE))
		vma->vm_ops = &gfs2_vm_ops_sharewrite;
	else
		vma->vm_ops = &gfs2_vm_ops_private;

	gfs2_glock_dq_uninit(&i_gh);

	return error;
}

/**
 * gfs2_open - open a file
 * @inode: the inode to open
 * @file: the struct file for this opening
 *
 * Returns: errno
 */

static int gfs2_open(struct inode *inode, struct file *file)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_holder i_gh;
	struct gfs2_file *fp;
	int error;

	fp = kzalloc(sizeof(struct gfs2_file), GFP_KERNEL);
	if (!fp)
		return -ENOMEM;

	mutex_init(&fp->f_fl_mutex);

	gfs2_assert_warn(GFS2_SB(inode), !file->private_data);
	file->private_data = fp;

	if (S_ISREG(ip->i_inode.i_mode)) {
		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
					   &i_gh);
		if (error)
			goto fail;

		if (!(file->f_flags & O_LARGEFILE) &&
		    ip->i_di.di_size > MAX_NON_LFS) {
			error = -EOVERFLOW;
			goto fail_gunlock;
		}

		/* Listen to the Direct I/O flag */

		if (ip->i_di.di_flags & GFS2_DIF_DIRECTIO)
			file->f_flags |= O_DIRECT;

		gfs2_glock_dq_uninit(&i_gh);
	}

	return 0;

fail_gunlock:
	gfs2_glock_dq_uninit(&i_gh);
fail:
	file->private_data = NULL;
	kfree(fp);
	return error;
}

/**
 * gfs2_close - called to close a struct file
 * @inode: the inode the struct file belongs to
 * @file: the struct file being closed
 *
 * Returns: errno
 */

static int gfs2_close(struct inode *inode, struct file *file)
{
	struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
	struct gfs2_file *fp;

	fp = file->private_data;
	file->private_data = NULL;

	if (gfs2_assert_warn(sdp, fp))
		return -EIO;

	kfree(fp);

	return 0;
}

/**
 * gfs2_fsync - sync the dirty data for a file (across the cluster)
 * @file: the file that points to the dentry (we ignore this)
 * @dentry: the dentry that points to the inode to sync
 *
 * The VFS will flush "normal" data for us. We only need to worry
 * about metadata here. For journaled data, we just do a log flush
 * as we can't avoid it. Otherwise we can just bale out if datasync
 * is set. For stuffed inodes we must flush the log in order to
 * ensure that all data is on disk.
 *
 * The call to write_inode_now() is there to write back metadata and
 * the inode itself. It does also try and write the data, but thats
 * (hopefully) a no-op due to the VFS having already called filemap_fdatawrite()
 * for us.
 *
 * Returns: errno
 */

static int gfs2_fsync(struct file *file, struct dentry *dentry, int datasync)
{
	struct inode *inode = dentry->d_inode;
	int sync_state = inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC);
	int ret = 0;

	if (gfs2_is_jdata(GFS2_I(inode))) {
		gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl);
		return 0;
	}

	if (sync_state != 0) {
		if (!datasync)
			ret = write_inode_now(inode, 0);

		if (gfs2_is_stuffed(GFS2_I(inode)))
			gfs2_log_flush(GFS2_SB(inode), GFS2_I(inode)->i_gl);
	}

	return ret;
}

/**
 * gfs2_setlease - acquire/release a file lease
 * @file: the file pointer
 * @arg: lease type
 * @fl: file lock
 *
 * Returns: errno
 */

static int gfs2_setlease(struct file *file, long arg, struct file_lock **fl)
{
	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);

	/*
	 * We don't currently have a way to enforce a lease across the whole
	 * cluster; until we do, disable leases (by just returning -EINVAL),
	 * unless the administrator has requested purely local locking.
	 */
	if (!sdp->sd_args.ar_localflocks)
		return -EINVAL;
	return generic_setlease(file, arg, fl);
}

/**
 * gfs2_lock - acquire/release a posix lock on a file
 * @file: the file pointer
 * @cmd: either modify or retrieve lock state, possibly wait
 * @fl: type and range of lock
 *
 * Returns: errno
 */

static int gfs2_lock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);
	struct lm_lockname name =
		{ .ln_number = ip->i_no_addr,
		  .ln_type = LM_TYPE_PLOCK };

	if (!(fl->fl_flags & FL_POSIX))
		return -ENOLCK;
	if (__mandatory_lock(&ip->i_inode))
		return -ENOLCK;

	if (sdp->sd_args.ar_localflocks) {
		if (IS_GETLK(cmd)) {
			posix_test_lock(file, fl);
			return 0;
		} else {
			return posix_lock_file_wait(file, fl);
		}
	}

	if (cmd == F_CANCELLK) {
		/* Hack: */
		cmd = F_SETLK;
		fl->fl_type = F_UNLCK;
	}
	if (IS_GETLK(cmd))
		return gfs2_lm_plock_get(sdp, &name, file, fl);
	else if (fl->fl_type == F_UNLCK)
		return gfs2_lm_punlock(sdp, &name, file, fl);
	else
		return gfs2_lm_plock(sdp, &name, file, cmd, fl);
}

static int do_flock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_file *fp = file->private_data;
	struct gfs2_holder *fl_gh = &fp->f_fl_gh;
	struct gfs2_inode *ip = GFS2_I(file->f_path.dentry->d_inode);
	struct gfs2_glock *gl;
	unsigned int state;
	int flags;
	int error = 0;

	state = (fl->fl_type == F_WRLCK) ? LM_ST_EXCLUSIVE : LM_ST_SHARED;
	flags = (IS_SETLKW(cmd) ? 0 : LM_FLAG_TRY) | GL_EXACT | GL_NOCACHE 
		| GL_FLOCK;

	mutex_lock(&fp->f_fl_mutex);

	gl = fl_gh->gh_gl;
	if (gl) {
		if (fl_gh->gh_state == state)
			goto out;
		flock_lock_file_wait(file,
				     &(struct file_lock){.fl_type = F_UNLCK});
		gfs2_glock_dq_wait(fl_gh);
		gfs2_holder_reinit(state, flags, fl_gh);
	} else {
		error = gfs2_glock_get(GFS2_SB(&ip->i_inode),
				      ip->i_no_addr, &gfs2_flock_glops,
				      CREATE, &gl);
		if (error)
			goto out;
		gfs2_holder_init(gl, state, flags, fl_gh);
		gfs2_glock_put(gl);
	}
	error = gfs2_glock_nq(fl_gh);
	if (error) {
		gfs2_holder_uninit(fl_gh);
		if (error == GLR_TRYFAILED)
			error = -EAGAIN;
	} else {
		error = flock_lock_file_wait(file, fl);
		gfs2_assert_warn(GFS2_SB(&ip->i_inode), !error);
	}

out:
	mutex_unlock(&fp->f_fl_mutex);
	return error;
}

static void do_unflock(struct file *file, struct file_lock *fl)
{
	struct gfs2_file *fp = file->private_data;
	struct gfs2_holder *fl_gh = &fp->f_fl_gh;

	mutex_lock(&fp->f_fl_mutex);
	flock_lock_file_wait(file, fl);
	if (fl_gh->gh_gl)
		gfs2_glock_dq_uninit(fl_gh);
	mutex_unlock(&fp->f_fl_mutex);
}

/**
 * gfs2_flock - acquire/release a flock lock on a file
 * @file: the file pointer
 * @cmd: either modify or retrieve lock state, possibly wait
 * @fl: type and range of lock
 *
 * Returns: errno
 */

static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
{
	struct gfs2_inode *ip = GFS2_I(file->f_mapping->host);
	struct gfs2_sbd *sdp = GFS2_SB(file->f_mapping->host);

	if (!(fl->fl_flags & FL_FLOCK))
		return -ENOLCK;
	if (__mandatory_lock(&ip->i_inode))
		return -ENOLCK;

	if (sdp->sd_args.ar_localflocks)
		return flock_lock_file_wait(file, fl);

	if (fl->fl_type == F_UNLCK) {
		do_unflock(file, fl);
		return 0;
	} else {
		return do_flock(file, cmd, fl);
	}
}

const struct file_operations gfs2_file_fops = {
	.llseek		= gfs2_llseek,
	.read		= do_sync_read,
	.aio_read	= generic_file_aio_read,
	.write		= do_sync_write,
	.aio_write	= generic_file_aio_write,
	.unlocked_ioctl	= gfs2_ioctl,
	.mmap		= gfs2_mmap,
	.open		= gfs2_open,
	.release	= gfs2_close,
	.fsync		= gfs2_fsync,
	.lock		= gfs2_lock,
	.flock		= gfs2_flock,
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
	.setlease	= gfs2_setlease,
};

const struct file_operations gfs2_dir_fops = {
	.readdir	= gfs2_readdir,
	.unlocked_ioctl	= gfs2_ioctl,
	.open		= gfs2_open,
	.release	= gfs2_close,
	.fsync		= gfs2_fsync,
	.lock		= gfs2_lock,
	.flock		= gfs2_flock,
};