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/*
 *  linux/fs/ext2/fsync.c
 *
 *  Copyright (C) 1993  Stephen Tweedie (sct@dcs.ed.ac.uk)
 *  from
 *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
 *                      Laboratoire MASI - Institut Blaise Pascal
 *                      Universite Pierre et Marie Curie (Paris VI)
 *  from
 *  linux/fs/minix/truncate.c   Copyright (C) 1991, 1992  Linus Torvalds
 * 
 *  ext2fs fsync primitive
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 *  Fast 'fsync' on large files (Scott Laird <laird@pacificrim.net>)
 */
 
#include <asm/segment.h>
#include <asm/system.h>
 
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ext2_fs.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/stat.h>
#include <linux/locks.h>
 
 
#define blocksize (EXT2_BLOCK_SIZE(inode->i_sb))
#define addr_per_block (EXT2_ADDR_PER_BLOCK(inode->i_sb))
 
static __inline__ int sync_block (struct inode * inode, u32 * block, int wait)
{
	struct buffer_head * bh;
	int tmp;
 
	if (!*block)
		return 0;
	tmp = *block;
	bh = get_hash_table (inode->i_dev, *block, blocksize);
	if (!bh)
		return 0;
	if (*block != tmp) {
		brelse (bh);
		return 1;
	}
	if (wait && buffer_req(bh) && !buffer_uptodate(bh)) {
		brelse (bh);
		return -1;
	}
	if (wait || !buffer_uptodate(bh) || !buffer_dirty(bh)) {
		brelse (bh);
		return 0;
	}
	ll_rw_block (WRITE, 1, &bh);
	bh->b_count--;
	return 0;
}
 
static __inline__ int sync_block_swab32 (struct inode * inode, u32 * block, int wait)
{
	struct buffer_head * bh;
	int tmp;
 
	if (!swab32(*block))
		return 0;
	tmp = swab32(*block);
	bh = get_hash_table (inode->i_dev, swab32(*block), blocksize);
	if (!bh)
		return 0;
	if (swab32(*block) != tmp) {
		brelse (bh);
		return 1;
	}
	if (wait && buffer_req(bh) && !buffer_uptodate(bh)) {
		brelse (bh);
		return -1;
	}
	if (wait || !buffer_uptodate(bh) || !buffer_dirty(bh)) {
		brelse (bh);
		return 0;
	}
	ll_rw_block (WRITE, 1, &bh);
	bh->b_count--;
	return 0;
}
 
static __inline__ int sync_iblock (struct inode * inode, u32 * iblock, 
			struct buffer_head ** bh, int wait) 
{
	int rc, tmp;
 
	*bh = NULL;
	tmp = *iblock;
	if (!tmp)
		return 0;
	rc = sync_block (inode, iblock, wait);
	if (rc)
		return rc;
	*bh = bread (inode->i_dev, tmp, blocksize);
	if (tmp != *iblock) {
		brelse (*bh);
		*bh = NULL;
		return 1;
	}
	if (!*bh)
		return -1;
	return 0;
}
 
static __inline__ int sync_iblock_swab32 (struct inode * inode, u32 * iblock, 
			       struct buffer_head ** bh, int wait) 
{
	int rc, tmp;
 
	*bh = NULL;
	tmp = swab32(*iblock);
	if (!tmp)
		return 0;
	rc = sync_block_swab32 (inode, iblock, wait);
	if (rc)
		return rc;
	*bh = bread (inode->i_dev, tmp, blocksize);
	if (tmp != swab32(*iblock)) {
		brelse (*bh);
		*bh = NULL;
		return 1;
	}
	if (!*bh)
		return -1;
	return 0;
}
 
 
static __inline__ int sync_direct (struct inode * inode, int wait)
{
	int i;
	int rc, err = 0;
 
	for (i = 0; i < EXT2_NDIR_BLOCKS; i++) {
		rc = sync_block (inode, inode->u.ext2_i.i_data + i, wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	return err;
}
 
static __inline__ int sync_indirect (struct inode * inode, u32 * iblock, int wait)
{
	int i;
	struct buffer_head * ind_bh;
	int rc, err = 0;
 
	rc = sync_iblock (inode, iblock, &ind_bh, wait);
	if (rc || !ind_bh)
		return rc;
 
	for (i = 0; i < addr_per_block; i++) {
		rc = sync_block_swab32 (inode, 
					((u32 *) ind_bh->b_data) + i,
					wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	brelse (ind_bh);
	return err;
}
 
static __inline__ int sync_indirect_swab32 (struct inode * inode, u32 * iblock, int wait)
{
	int i;
	struct buffer_head * ind_bh;
	int rc, err = 0;
 
	rc = sync_iblock_swab32 (inode, iblock, &ind_bh, wait);
	if (rc || !ind_bh)
		return rc;
 
	for (i = 0; i < addr_per_block; i++) {
		rc = sync_block_swab32 (inode, 
					((u32 *) ind_bh->b_data) + i,
					wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	brelse (ind_bh);
	return err;
}
 
static __inline__ int sync_dindirect (struct inode * inode, u32 * diblock, int wait)
{
	int i;
	struct buffer_head * dind_bh;
	int rc, err = 0;
 
	rc = sync_iblock (inode, diblock, &dind_bh, wait);
	if (rc || !dind_bh)
		return rc;
 
	for (i = 0; i < addr_per_block; i++) {
		rc = sync_indirect_swab32 (inode,
					   ((u32 *) dind_bh->b_data) + i,
					   wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	brelse (dind_bh);
	return err;
}
 
static __inline__ int sync_dindirect_swab32 (struct inode * inode, u32 * diblock, int wait)
{
	int i;
	struct buffer_head * dind_bh;
	int rc, err = 0;
 
	rc = sync_iblock_swab32 (inode, diblock, &dind_bh, wait);
	if (rc || !dind_bh)
		return rc;
 
	for (i = 0; i < addr_per_block; i++) {
		rc = sync_indirect_swab32 (inode,
					   ((u32 *) dind_bh->b_data) + i,
					   wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	brelse (dind_bh);
	return err;
}
 
static __inline__ int sync_tindirect (struct inode * inode, u32 * tiblock, int wait)
{
	int i;
	struct buffer_head * tind_bh;
	int rc, err = 0;
 
	rc = sync_iblock (inode, tiblock, &tind_bh, wait);
	if (rc || !tind_bh)
		return rc;
 
	for (i = 0; i < addr_per_block; i++) {
		rc = sync_dindirect_swab32 (inode,
					    ((u32 *) tind_bh->b_data) + i,
					    wait);
		if (rc > 0)
			break;
		if (rc)
			err = rc;
	}
	brelse (tind_bh);
	return err;
}
 
int ext2_sync_file (struct inode * inode, struct file * file)
{
	int wait, err = 0;
 
	if (S_ISLNK(inode->i_mode) && !(inode->i_blocks))
		/*
		 * Don't sync fast links!
		 */
		goto skip;
 
	/* fsync on large files is *slow*, so fall back to sync() if
	 * the file's over 10M */
	if (inode->i_size>10000000) {
		file_fsync(inode,file);
		goto skip;
	}
 
	for (wait=0; wait<=1; wait++)
	{
		err |= sync_direct (inode, wait);
		err |= sync_indirect (inode,
				      inode->u.ext2_i.i_data+EXT2_IND_BLOCK,
				      wait);
		err |= sync_dindirect (inode,
				       inode->u.ext2_i.i_data+EXT2_DIND_BLOCK, 
				       wait);
		err |= sync_tindirect (inode, 
				       inode->u.ext2_i.i_data+EXT2_TIND_BLOCK, 
				       wait);
	}
skip:
	err |= ext2_sync_inode (inode);
	return (err < 0) ? -EIO : 0;
}