VFS_LOCK_GIANT(9) MidnightBSD Kernel Developer’s Manual 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/mount.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, returning a flag indicating whether Giant was set, which may later be passed to VFS_UNLOCK_GIANT(). The value of mp will typically be derived 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 argument will be derived from the return values of VFS_LOCK_GIANT() 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.

MidnightBSD 0.3 September 21, 2005 MidnightBSD 0.3