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241835 Make sure that we always zero unitialized data before
making it accessible to the user.  We were failing to do so
in the case where when we mapped an extent it was delalloc,
but when xfs_strat_read() got the buffer for it it had been
allocated.  Thus we read it from disk but it had not yet been
initialized.  Now we track where the holes are when we map
out a region in xfs_strat_write() and use that list to know
which blocks must be unitialized in xfs_strat_read().

#ifndef	_XFS_RW_H
#define	_XFS_RW_H


/*
 * This is a structure used to hold the local variables used
 * in xfs_strat_write().  We dynamically allocate this to reduce
 * the amount of stack space we use.  This is here in the public
 * header file since it is exported to xfs_init() so it can
 * initialize the zone allocator.
 */
typedef struct xfs_strat_write_locals {
	xfs_fileoff_t	offset_fsb;
	xfs_fileoff_t   map_start_fsb;
	xfs_fileoff_t	imap_offset;
	xfs_fsblock_t	first_block;
	xfs_fsize_t	real_size;
	xfs_extlen_t	count_fsb;
	xfs_extlen_t	imap_blocks;
	off_t		last_rbp_offset;
	xfs_extlen_t	last_rbp_bcount;
	daddr_t		last_rbp_blkno;
	int		rbp_count;
	int		x;
	caddr_t		datap;
	buf_t		*rbp;
	xfs_mount_t	*mp;
	xfs_inode_t	*ip;
	xfs_trans_t	*tp;
	int		error;
	xfs_bmap_free_t	free_list;
	xfs_bmbt_irec_t	*imapp;
	int		rbp_offset;
	int		rbp_len;
	int		set_lead;
	int		s;
	int		loops;
	int		imap_index;
	int		nimaps;
	xfs_bmbt_irec_t	imap[XFS_BMAP_MAX_NMAP];
} xfs_strat_write_locals_t;

/*
 * This structure is used to communicate which extents of a file
 * were holes when a write started from xfs_write_file() to
 * xfs_strat_read().  This is necessary so that we can know which
 * blocks need to be zeroed when they are read in in xfs_strat_read()
 * if they weren\'t allocated when the buffer given to xfs_strat_read()
 * was mapped.
 *
 * We keep a list of these attached to the inode.  The list is
 * protected by the inode lock and the fact that the io lock is
 * held exclusively by writers.
 */
typedef struct xfs_gap {
	struct xfs_gap	*xg_next;
	xfs_fileoff_t	xg_offset_fsb;
	xfs_extlen_t	xg_count_fsb;
} xfs_gap_t;

/*
 * Count of bmaps allocated in one call to the xfs_bmap_zone
 * allocator.
 */
#define	XFS_ZONE_NBMAPS	4

/*
 * Maximum size of a buffer that we\'ll map.  Making this
 * too big will degrade performance due to the number of
 * pages which need to be gathered.  Making it too small
 * will prevent us from doing large I/O\'s to hardware that
 * needs it.
 *
 * This is currently set to 512 KB.
 */
#define	XFS_MAX_BMAP_LEN_BB	1024
#define	XFS_MAX_BMAP_LEN_BYTES	524288

/*
 * Defines for the trace mechanisms in xfs_rw.c.
 */
#define	XFS_RW_KTRACE_SIZE	64
#define	XFS_STRAT_KTRACE_SIZE	64
#define	XFS_STRAT_GTRACE_SIZE	512

#define	XFS_READ_ENTER		1
#define	XFS_WRITE_ENTER		2
#define XFS_IOMAP_READ_ENTER	3
#define	XFS_IOMAP_WRITE_ENTER	4
#define	XFS_IOMAP_READ_MAP	5
#define	XFS_IOMAP_WRITE_MAP	6
#define	XFS_IOMAP_WRITE_NOSPACE	7

#define	XFS_STRAT_ENTER		1
#define	XFS_STRAT_FAST		2
#define	XFS_STRAT_SUB		3

/*
 * Prototypes for functions in xfs_rw.c.
 */
int
xfs_read(vnode_t	*vp,
	 uio_t		*uiop,
	 int		ioflag,
	 cred_t		*credp);

int
xfs_write(vnode_t	*vp,
	  uio_t		*uiop,
	  int		ioflag,
	  cred_t	*credp);

void
xfs_strategy(vnode_t	*vp,
	     buf_t	*bp);

int
xfs_bmap(vnode_t	*vp,
	 off_t		offset,
	 ssize_t	count,
	 int		flags,
	 cred_t		*credp,
	 struct bmapval	*bmapp,
	 int		*nbmaps);

void
xfs_zero_eof(xfs_inode_t	*ip,
	     off_t		offset,
	     xfs_fsize_t	isize,
	     cred_t		*credp);



#endif /* _XFS_RW_H */