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				.Dd May 11, 2021
				.Dt VOP_DEALLOCATE 9
				.Os
				.Sh NAME
				.Nm VOP_DEALLOCATE
				.Nd zero and/or deallocate storage from a file
				.Sh SYNOPSIS
				.In sys/param.h
				.In sys/vnode.h
				.Ft int
				.Fo VOP_DEALLOCATE
				.Fa "struct vnode *vp"
				kibUnsubmitted Done Inline Actions It is better to use .Fo/.Fc for long prototypes kib: It is better to use .Fo/.Fc for long prototypes
				.Fa "off_t *offset"
				.Fa "off_t *len"
				.Fa "int flags"
				.Fa "struct ucred *cred"
				.Fc
				.Sh DESCRIPTION
				This VOP call zeroes/deallocates storage for an offset range in a file.
				It is used to implement the
				.Xr fspacectl 2
				system call.
				.Pp
				Its arguments are:
				.Bl -tag -width offset
				.It Fa vp
				The vnode of the file.
				kibUnsubmitted Done Inline Actions Where is the list of the accepted flags and its meaning? kib: Where is the list of the accepted flags and its meaning?
				khngAuthorUnsubmitted Done Inline Actions For this commit it has to be 0. khng: For this commit it has to be 0.
				.It Fa offset
				The start of the range to deallocate storage in the file.
				.It Fa len
				The length of the range to deallocate storage in the file.
				kibUnsubmitted Done Inline Actions What is this? kib: What is this?
				.It Fa flags
				The flags of this call.
				This should be set to 0 for now.
				.It Fa cred
				The credentials of the caller.
				.El
				.Pp
				.Fa *offset
				and
				.Fa *len
				kibUnsubmitted Done Inline Actions What does this sentence mean? I cannot understand it in context of the previous text. kib: What does this sentence mean? I cannot understand it in context of the previous text.
				khngAuthorUnsubmitted Done Inline Actions It was a leftover line when I was also trying to implement preallocation. Will clean this up. khng: It was a leftover line when I was also trying to implement preallocation. Will clean this up.
				are updated to reflect the portion of the range that
				still needs to be zeroed/deallocated on return.
				kibUnsubmitted Not Done Inline Actions What it means 'file should be locked' ? kib: What it means 'file should be locked' ?
				khngAuthorUnsubmitted Done Inline Actions vnode lock has to be acquired (either shared or exclusively) before calling this function. khng: vnode lock has to be acquired (either shared or exclusively) before calling this function.
				khngAuthorUnsubmitted Done Inline Actions The line was actually the same as the one in LOCKS section in VOP_READ/VOP_WRITE/VOP_RDWR. khng: The line was actually the same as the one in LOCKS section in VOP_READ/VOP_WRITE/VOP_RDWR.
				Partial result is considered a successful operation.
				kibUnsubmitted Done Inline Actions I think this should be The .Fa offset and .Fa len variables are updated ... kib: I think this should be ``` The .Fa offset and .Fa len variables are updated ... ```
				.Sh LOCKS
				The vnode should be locked on entry and will still be locked on exit.
				.Sh RETURN VALUES
				Zero is returned if the call is successful, otherwise an appropriate
				error code is returned.
				.Sh ERRORS
				.Bl -tag -width Er
				.It Bq Er EINVAL
				Invalid
				.Fa offset , len
				or
				.Fa flags
				parameters are passed into this VOP call.
				.It Bq Er ENODEV
				The vnode type is not supported by this VOP call.
				.It Bq Er ENOSPC
				The file system is full.
				.It Bq Er EPERM
				An append-only flag is set on the file, but the caller is attempting to
				zero before the current end of file.
				.El
				.Sh SEE ALSO
				kibUnsubmitted Done Inline Actions I do not think that caller tries to write. At best, he tries to zero. kib: I do not think that caller tries to write. At best, he tries to zero.
				.Xr vnode 9
				.Sh AUTHORS
				.Nm
				and this manual page were developed by
				.An Ka Ho Ng Aq Mt khng@FreeBSD.org
				under sponsorship from the FreeBSD Foundation.