Provided by: freebsd-manpages_8.2-1_all
VFS_LOCK_GIANT, VFS_UNLOCK_GIANT — conditionally lock and unlock Giant around entry into VFS
#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);
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).
VFS_LOCK_GIANT() returns a boolean indicating whether or not Giant was acquired.
mutex(9), NDHASGIANT(9), vnode(9)
MPSAFE VFS support for FreeBSD was implemented by Jeff Roberson. This manual page was written by Robert Watson.
Non-MPSAFE file systems exist, requiring callers conditional locking and unlocking of Giant.