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Command: VOP_ADVISE | Section: 9 | Source: FreeBSD | File: VOP_ADVISE.9.gz
VOP_ADVISE(9) FreeBSD Kernel Developer's Manual VOP_ADVISE(9)
NAME
VOP_ADVISE - apply advice about use of file data
SYNOPSIS
#include <sys/param.h>
#include <sys/vnode.h>
int
VOP_ADVISE(struct vnode *vp, off_t start, off_t end, int advice);
DESCRIPTION
This call applies advice for a range of a file's data. It is used to
implement the posix_fadvise(2) system call.
Its arguments are:
vp The vnode of the file.
start The start of the range of file data.
end The end of the range of file data. A value of OFF_MAX indicates
that the advice is to be applied up to the end of the file.
advice The type of operation to apply to the file data. Possible values
are:
POSIX_FADV_WILLNEED Initiate an asynchronous read of the file
data if it is not already resident.
POSIX_FADV_DONTNEED Decrease the in-memory priority of clean
file data or discard clean file data.
If the start and end offsets are both zero, then the operation should be
applied to the entire file. Note that this call is advisory only and may
perform the requested operation on a subset of the requested range
(including not performing it at all) and still return success.
LOCKS
The file should be unlocked on entry.
RETURN VALUES
Zero is returned if the call is successful, otherwise an appropriate
error code is returned.
ERRORS
[EINVAL] An invalid value was given for advice.
SEE ALSO
vnode(9)
FreeBSD 14.1-RELEASE-p8 September 26, 2015 FreeBSD 14.1-RELEASE-p8