Manual Pages  — VN_DEALLOCATE

vn_deallocate – zero and/or deallocate storage from a file

SYNOPSIS DESCRIPTION RETURN VALUES SEE ALSO AUTHORS

#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);

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 zeroed before the end-of-file.

Upon successful completion, the value 0 is returned; otherwise the appropriate error is returned.

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