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VN_LOCK(9)            DragonFly Kernel Developer's Manual           VN_LOCK(9)

NAME
     vn_lock, vn_unlock, vn_islocked -- serialize access to a vnode

SYNOPSIS
     #include <sys/vnode.h>

     int
     vn_lock(struct vnode *vp, int flags);

     void
     vn_unlock(struct vnode *vp);

     int
     vn_islocked(struct vnode *vp);

DESCRIPTION
     These calls are used to serialize access to the filesystem, such as to
     prevent two writes to the same file from happening at the same time.

     The arguments are:

     vp     the vnode being locked or unlocked

     flags  One of the lock request types:

                  LK_RETRY          Automatically retry on timeout
                  LK_FAILRECLAIM    Fail if the vnode is being reclaimed

     The vn_lock() function will require either LK_EXCLUSIVE or LK_SHARED to
     be or'ed with the request flags described above in order to specify the
     type of lock to be used.

     The vn_unlock() function uses LK_RELEASE internally to release a
     previously held lock.

     Please note all these functions rely on lockmgr(9) to perform their
     operations.

RETURN VALUES
     The vn_lock() function returns zero on success and non-zero on failure.

     The vn_islocked() function has identical return values as lockstatus(9).

SEE ALSO
     lockmgr(9), vnode(9)

AUTHORS
     This man page was written by Doug Rabson.

DragonFly 4.1                  November 17, 2014                 DragonFly 4.1