path: root/fs/gfs2/ops_file.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/blkdev.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/gfs2_ioctl.h>
#include <linux/fs.h>
#include <asm/semaphore.h>
#include <asm/uaccess.h>

#include "gfs2.h"
#include "bmap.h"
#include "dir.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "lm.h"
#include "log.h"
#include "meta_io.h"
#include "ops_file.h"
#include "ops_vm.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"

/* "bad" is for NFS support */
struct filldir_bad_entry {
	char *fbe_name;
	unsigned int fbe_length;
	uint64_t fbe_offset;
	struct gfs2_inum fbe_inum;
	unsigned int fbe_type;
};

struct filldir_bad {
	struct gfs2_sbd *fdb_sbd;

	struct filldir_bad_entry *fdb_entry;
	unsigned int fdb_entry_num;
	unsigned int fdb_entry_off;

	char *fdb_name;
	unsigned int fdb_name_size;
	unsigned int fdb_name_off;
};

/* For regular, non-NFS */
struct filldir_reg {
	struct gfs2_sbd *fdr_sbd;
	int fdr_prefetch;

	filldir_t fdr_filldir;
	void *fdr_opaque;
};

static int gfs2_read_actor(read_descriptor_t *desc, struct page *page,
			   unsigned long offset, unsigned long size)
{
	char *kaddr;
	unsigned long count = desc->count;

	if (size > count)
		size = count;

	kaddr = kmap(page);
	memcpy(desc->arg.buf, kaddr + offset, size);
        kunmap(page);

        desc->count = count - size;
        desc->written += size;
        desc->arg.buf += size;
        return size;
}

int gfs2_internal_read(struct gfs2_inode *ip, struct file_ra_state *ra_state,
		       char *buf, loff_t *pos, unsigned size)
{
	struct inode *inode = ip->i_vnode;
	read_descriptor_t desc;
	desc.written = 0;
	desc.arg.buf = buf;
	desc.count = size;
	desc.error = 0;
	do_generic_mapping_read(inode->i_mapping, ra_state, NULL, pos, &desc, gfs2_read_actor);
	return desc.written ? desc.written : desc.error;
}

/**
 * gfs2_llseek - seek to a location in a file
 * @file: the file
 * @offset: the offset
 * @origin: Where to seek from (SEEK_SET, SEEK_CUR, or SEEK_END)
 *
 * SEEK_END requires the glock for the file because it references the
 * file's size.
 *
 * Returns: The new offset, or errno
 */

static loff_t gfs2_llseek(struct file *file, loff_t offset, int origin)
{
	struct gfs2_inode *ip = get_v2ip(file->f_mapping->host);
	struct gfs2_holder i_gh;
	loff_t error;

	atomic_inc(&ip->i_sbd->sd_ops_file);

	if (origin == 2) {
		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY,
					   &i_gh);
		if (!error) {
			error = remote_llseek(file, offset, origin);
			gfs2_glock_dq_uninit(&i_gh);
		}
	} else
		error = remote_llseek(file, offset, origin);

	return error;
}


static ssize_t gfs2_direct_IO_read(struct kiocb *iocb, const struct iovec *iov,
				   loff_t offset, unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct address_space *mapping = file->f_mapping;
	ssize_t retval;

	retval = filemap_write_and_wait(mapping);
	if (retval == 0) {
		retval = mapping->a_ops->direct_IO(READ, iocb, iov, offset,
						   nr_segs);
	}
	return retval;
}

/**
 * __gfs2_file_aio_read - The main GFS2 read function
 * 
 * N.B. This is almost, but not quite the same as __generic_file_aio_read()
 * the important subtle different being that inode->i_size isn't valid
 * unless we are holding a lock, and we do this _only_ on the O_DIRECT
 * path since otherwise locking is done entirely at the page cache
 * layer.
 */
static ssize_t __gfs2_file_aio_read(struct kiocb *iocb,
				    const struct iovec *iov,
				    unsigned long nr_segs, loff_t *ppos)
{
	struct file *filp = iocb->ki_filp;
	struct gfs2_inode *ip = get_v2ip(filp->f_mapping->host);
	struct gfs2_holder gh;
	ssize_t retval;
	unsigned long seg;