/*
 *  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
 * 
 *  Removed unnecessary code duplication for little endian machines
 *  and excessive __inline__s. 
 *        Andi Kleen, 1997
 *
 * Major simplications and cleanup - we only need to do the metadata, because
 * we can depend on generic_block_fdatasync() to sync the data blocks.
 */

#include <linux/fs.h>
#include <linux/locks.h>
#include <linux/smp_lock.h>


#define blocksize	(EXT2_BLOCK_SIZE(inode->i_sb))
#define addr_per_block	(EXT2_ADDR_PER_BLOCK(inode->i_sb))

static int sync_indirect(struct inode * inode, u32 * block, int wait)
{
	struct buffer_head * bh;
	
	if (!*block)
		return 0;
	bh = get_hash_table(inode->i_dev, le32_to_cpu(*block), blocksize);
	if (!bh)
		return 0;
	if (wait && buffer_req(bh) && !buffer_uptodate(bh)) {
		/* There can be a parallell read(2) that started read-I/O
		   on the buffer so we can't assume that there's been
		   an I/O error without first waiting I/O completation. */
		wait_on_buffer(bh);
		if (!buffer_uptodate(bh))
		{
			brelse (bh);
			return -1;
		}
	}
	if (wait || !buffer_uptodate(bh) || !buffer_dirty(bh)) {
		if (wait)
			/* when we return from fsync all the blocks
			   must be _just_ stored on disk */
			wait_on_buffer(bh);
		brelse(bh);
		return 0;
	}
	ll_rw_block(WRITE, 1, &bh);
	atomic_dec(&bh->b_count);
	return 0;
}

static int sync_iblock(struct inode * inode, u32 * iblock, 
			struct buffer_head ** bh, int wait) 
{
	int rc, tmp;
	
	*bh = NULL;
	tmp = le32_to_cpu(*iblock);
	if (!tmp)
		return 0;
	rc = sync_indirect(inode, iblock, wait);
	if (rc)
		return rc;
	*bh = bread(inode->i_dev, tmp, blocksize);
	if (!*bh)
		return -1;
	return 0;
}

static 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(inode, ((u32 *) dind_bh->b_data) + i, wait);
		if (rc)
			err = rc;
	}
	brelse(dind_bh);
	return err;
}

static 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(inode, ((u32 *) tind_bh->b_data) + i, wait);
		if (rc)
			err = rc;
	}
	brelse(tind_bh);
	return err;
}

/*
 *	File may be NULL when we are called. Perhaps we shouldn't
 *	even pass file to fsync ?
 */

int ext2_sync_file(struct file * file, struct dentry *dentry)
{
	int wait, err = 0;
	struct inode *inode = dentry->d_inode;

	lock_kernel();
	if (S_ISLNK(inode->i_mode) && !(inode->i_blocks))
		/*
		 * Don't sync fast links!
		 */
		goto skip;

	err = generic_buffer_fdatasync(inode, 0, ~0UL);

	for (wait=0; wait<=1; 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);
	unlock_kernel();
	return err ? -EIO : 0;
}