Provided by: freebsd-manpages_8.2-1_all bug

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.