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Use the right offset when ensuring a delayed allocate conversion has covered the offset originally requested.  Can cause data corruption when multiple processes are performing writeout on different areas of the same file.  Quite difficult to hit though.
Merge of xfs-linux-melb:xfs-kern:22377a by kenmcd.

/*
 * Copyright (c) 2003,2004 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */
#ifndef __XFS_IOMAP_H__
#define __XFS_IOMAP_H__

#define IOMAP_DADDR_NULL ((xfs_daddr_t) (-1LL))


typedef enum {				/* iomap_flags values */
	IOMAP_EOF =		0x01,	/* mapping contains EOF   */
	IOMAP_HOLE =		0x02,	/* mapping covers a hole  */
	IOMAP_DELAY =		0x04,	/* mapping covers delalloc region  */
	IOMAP_REALTIME =	0x10,	/* mapping on the realtime device  */
	IOMAP_UNWRITTEN =	0x20,	/* mapping covers allocated */
					/* but uninitialized file data  */
	IOMAP_NEW =		0x40	/* just allocate */
} iomap_flags_t;

typedef enum {
	/* base extent manipulation calls */
	BMAPI_READ = (1 << 0),		/* read extents */
	BMAPI_WRITE = (1 << 1),		/* create extents */
	BMAPI_ALLOCATE = (1 << 2),	/* delayed allocate to real extents */
	BMAPI_UNWRITTEN  = (1 << 3),	/* unwritten extents to real extents */
	/* modifiers */
	BMAPI_IGNSTATE = (1 << 4),	/* ignore unwritten state on read */
	BMAPI_DIRECT = (1 << 5),	/* direct instead of buffered write */
	BMAPI_MMAP = (1 << 6),		/* allocate for mmap write */
	BMAPI_SYNC = (1 << 7),		/* sync write to flush delalloc space */
	BMAPI_TRYLOCK = (1 << 8),	/* non-blocking request */
	BMAPI_DEVICE = (1 << 9),	/* we only want to know the device */
} bmapi_flags_t;


/*
 * xfs_iomap_t:  File system I/O map
 *
 * The iomap_bn field is expressed in 512-byte blocks, and is where the 
 * mapping starts on disk.
 *
 * The iomap_offset, iomap_bsize and iomap_delta fields are in bytes.
 * iomap_offset is the offset of the mapping in the file itself.
 * iomap_bsize is the size of the mapping,  iomap_delta is the 
 * desired data's offset into the mapping, given the offset supplied 
 * to the file I/O map routine.
 *
 * When a request is made to read beyond the logical end of the object,
 * iomap_size may be set to 0, but iomap_offset and iomap_length should be set
 * to the actual amount of underlying storage that has been allocated, if any.
 */

typedef struct xfs_iomap {
	xfs_daddr_t		iomap_bn;	/* first 512b blk of mapping */
	xfs_buftarg_t		*iomap_target;
	loff_t			iomap_offset;	/* offset of mapping, bytes */
	loff_t			iomap_bsize;	/* size of mapping, bytes */
	size_t			iomap_delta;	/* offset into mapping, bytes */
	iomap_flags_t		iomap_flags;
} xfs_iomap_t;

struct xfs_iocore;
struct xfs_inode;
struct xfs_bmbt_irec;

extern int xfs_iomap(struct xfs_iocore *, xfs_off_t, ssize_t, int,
		     struct xfs_iomap *, int *);
extern int xfs_iomap_write_direct(struct xfs_inode *, loff_t, size_t,
				  int, struct xfs_bmbt_irec *, int *, int);
extern int xfs_iomap_write_delay(struct xfs_inode *, loff_t, size_t, int,
				 struct xfs_bmbt_irec *, int *);
extern int xfs_iomap_write_allocate(struct xfs_inode *, loff_t, size_t,
				struct xfs_bmbt_irec *, int *);
extern int xfs_iomap_write_unwritten(struct xfs_inode *, loff_t, size_t);

#endif /* __XFS_IOMAP_H__*/