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VN_DEALLOCATE(9)	   Kernel Developer's Manual	      VN_DEALLOCATE(9)

NAME
       vn_deallocate --	zero and/or deallocate storage from a file

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

       int
       vn_deallocate(struct vnode *vp,	    off_t *offset,	off_t *length,
	   int flags,	       int ioflag,	    struct ucred *active_cred,
	   struct ucred	*file_cred);

DESCRIPTION
       The  vn_deallocate()  function zeros and/or deallocates backing storage
       space from a file.  This	function only works on vnodes with VREG	type.

       The arguments are:

       vp	    The	vnode of the file.

       offset	    The	starting offset	of the operation range.

       length	    The	length of the operation	range.	This must  be  greater
		    than 0.

       flags	    The	control	flags of the operation.	 This should be	set to
		    0 for now.

       ioflag	    Directives and hints to be given to	the file system.

       active_cred  The	user credentials of the	calling	thread.

       file_cred    The	credentials installed on the file description pointing
		    to the vnode or NOCRED.

       The  ioflag()  argument	gives directives and hints to the file system.
       It may include one or more of the following flags:

       IO_NODELOCKED   The vnode was locked before the call.

       IO_RANGELOCKED  Rangelock was owned around the call.

       IO_NOMACCHECK   Skip MAC	checking in the	call.

       IO_SYNC	       Do I/O synchronously.

       IO_DIRECT       Attempt to bypass buffer	cache.

       *offset and *length are updated to reflect  the	unprocessed  operation
       range  of the call.  For	a successful completion, *length is updated to
       be the value 0, and *offset is incremented by the number	of  bytes  ze-
       roed before the end-of-file.

RETURN VALUES
       Upon  successful	completion, the	value 0	is returned; otherwise the ap-
       propriate error is returned.

SEE ALSO
       vnode(9), VOP_DEALLOCATE(9)

AUTHORS
       vn_deallocate  and  this	 manual	 page  was  written  by	  Ka   Ho   Ng
       <khng@FreeBSD.org> under	sponsorship from the FreeBSD Foundation.

FreeBSD	14.3			August 25, 2021		      VN_DEALLOCATE(9)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=vn_deallocate&sektion=9&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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