vfs_lock_giant(9)

NAME

VFS_LOCK_GIANT, VFS_UNLOCK_GIANT - Conditionally lock and

unlock Giant
around entry into VFS

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
int
VFS_LOCK_GIANT(struct mount *mp);
void
VFS_UNLOCK_GIANT(int vfslocked);

DESCRIPTION

VFS_LOCK_GIANT() will conditionally acquire the Giant lock

if the file
system referenced by mp is marked as MPSAFE or not, return

ing a flag
indicating whether Giant was set, which may later be passed

to
VFS_UNLOCK_GIANT(). The value of mp will typically be de

rived from the
mount pointer in a vnode on which a VFS operation will be

performed.

VFS_UNLOCK_GIANT() conditionally releases the Giant lock if

the passed
vfslocked argument is non-zero. It is expected that the ar

gument will be
derived from the return values of or NDHASGIANT(9).

RETURN VALUES

VFS_LOCK_GIANT() returns a boolean indicating whether or not

Giant was
acquired.

SEE ALSO

mutex(9), NDHASGIANT(9), vnode(9)

AUTHORS

MPSAFE VFS support for FreeBSD was implemented by Jeff

Roberson.

This manual page was written by
Robert Watson.

BUGS

Non-MPSAFE file systems exist, requiring callers conditional

locking and
unlocking of Giant.

BSD September 21, 2005

BSD