vn_isdisk(9) [freebsd man page]

VN_ISDISK(9)						   BSD Kernel Developer's Manual					      VN_ISDISK(9)

NAME

     vn_isdisk -- checks if a vnode represents a disk

SYNOPSIS

     #include <sys/param.h>
     #include <sys/vnode.h>

     int
     vn_isdisk(struct vnode *vp, int *errp);

DESCRIPTION

     The vn_isdisk() function checks to see if vp represents a disk.  In order for vp to be a disk, it must be a character device, v_rdev must be
     valid, and the cdevsw entry's flags must have D_DISK set.

     Its arguments are:

     vp    The vnode to check.

     errp  An integer pointer to store the error number in if the call fails.

RETURN VALUES

     If the vnode represents a disk, 1 is returned; otherwise, 0 is returned and errp will contain the error number.

AUTHORS

     This manual page was written by Chad David <davidc@acns.ab.ca>.

BSD
								   July 9, 2001 							       BSD

VRELE(9)						   BSD Kernel Developer's Manual						  VRELE(9)

NAME

     vput, vrele, vunref -- decrement the use count for a vnode

SYNOPSIS

     #include <sys/param.h>
     #include <sys/vnode.h>

     void
     vput(struct vnode *vp);

     void
     vrele(struct vnode *vp);

     void
     vunref(struct vnode *vp);

DESCRIPTION

     Decrement the v_usecount field of a vnode.

     vp  the vnode to decrement

     The vrele() function takes an unlocked vnode and returns with the vnode unlocked.

     The vput() function should be given a locked vnode as argument, the vnode is unlocked after the function returned.  The vput() is opera-
     tionally equivalent to calling VOP_UNLOCK(9) followed by vrele(9), with less overhead.

     The vunref() function takes a locked vnode as argument, and returns with the vnode locked.

     Any code in the system which signified its use of a vnode by usecount should call one of the listed function to decrement use counter.  If
     the v_usecount field of the non-doomed vnode reaches zero, then it will be inactivated and placed on the free list.  Since the functions
     might need to call VOPs for the vnode, the Giant mutex should be conditionally locked around the call.

     The hold count for the vnode is always greater or equal to the usecount.  Non-forced unmount fails when mount point owns a vnode that has
     non-zero usecount, see vflush(9).

SEE ALSO

     vget(9), vnode(9), vref(9), vrefcnt(9)

AUTHORS

     This manual page was written by Doug Rabson and
     Konstantin Belousov.

BSD
								 November 20, 2010							       BSD