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VOP_BMAP(9)		 BSD Kernel Developer's	Manual		   VOP_BMAP(9)

NAME
     VOP_BMAP -- Logical to physical block number conversion

SYNOPSIS
     #include <sys/param.h>
     #include <sys/vnode.h>

     int
     VOP_BMAP(struct vnode *vp,	daddr_t	bn, struct bufobj **bop, daddr_t *bnp,
	 int *runp, int	*runb);

DESCRIPTION
     This vnode	call is	used to	lookup the physical block number of the	file
     system's underlying device	where a	given logical block of a file is
     stored.  Its arguments are:

     vp	   The vnode of	the file.

     bn	   Logical block number	within the file	identified by vp.

     bop   Return storage for the buffer object	associated with	the file sys-
	   tem's underlying device.

     bnp   Return storage for the physical block number.

     runp  Return storage for the number of succeeding logical blocks that may
	   be efficiently read at the same time	as the requested block.	 This
	   will	usually	be the number of logical blocks	whose physical blocks
	   are contiguously allocated.	However	a file system is free to de-
	   fine	"efficient" as it see fit.

     runb  Like	runp but for preceding rather than succeeding blocks.

     Any of the	return arguments may be	NULL to	indicate that the caller does
     not care about that information.

LOCKS
     The vnode will be locked on entry and should remain locked	on return.

RETURN VALUES
     Zero is returned on success, otherwise an error code is returned.

SEE ALSO
     vnode(9),

HISTORY
     A bmap() function first appeared in 4.2BSD.

AUTHORS
     This manual page was written by Alan Somers.

BSD				 June 19, 2019				   BSD

NAME | SYNOPSIS | DESCRIPTION | LOCKS | RETURN VALUES | SEE ALSO | HISTORY | AUTHORS

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