NAME    [Toc]    [Back]

     VOP_FSYNC -- flush file system buffers for a file

SYNOPSIS    [Toc]    [Back]

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

     int
     VOP_FSYNC(struct vnode *vp, struct ucred *cred, int waitfor,
	 struct thread *td);

DESCRIPTION    [Toc]    [Back]

     This call flushes any dirty file system buffers for the file.  It is used
     to implement the sync(2) and fsync(2) system calls.

     Its arguments are:

     vp       the vnode of the file

     cred     the caller's credentials

     waitfor  whether the function should wait for I/O to complete.  Possible
	      values are:

	      MNT_WAIT	  synchronously wait for I/O to complete

	      MNT_NOWAIT  start all I/O, but do not wait for it

	      MNT_LAZY	  push data not written by file system syncer

     td       the calling thread

     The argument waitfor is either MNT_WAIT or MNT_NOWAIT and specifies
     whether or not the function should wait for the writes to finish before
     returning.

LOCKS    [Toc]    [Back]

     The file should be locked on entry.

RETURN VALUES    [Toc]    [Back]

     Zero is returned if the call is successful, otherwise an appropriate
     error code is returned.

PSEUDOCODE    [Toc]    [Back]

     int
     vop_fsync(struct vnode *vp, struct ucred *cred, int waitfor, struct thread *td)
     {
	 struct buf *bp;
	 struct buf *nbp;
	 struct timeval tv;
	 int s;

     loop:
	 s = splbio();
	 for (bp = vp->v_dirtyblkhd.lh_first; bp; bp = nbp) {
	     nbp = bp->b_vnbufs.le_next;

	     /*
	      * Ignore buffers which are already being written.
	      */
	     if (bp->b_flags & B_BUSY)
		 continue;

	     /*
	      * Make sure the buffer is dirty.
	      */
	     if ((bp->b_flags & B_DELWRI) == 0)
		 panic("vop_fsync: not dirty");

	     vfs_bio_awrite(bp);
	     splx(s);
	     goto loop;
	 }
	 splx(s);

	 if (waitfor == MNT_WAIT) {
	     s = splbio();
	     while (vp->v_numoutput) {
		 vp->v_flag |= VBWAIT;
		 tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "vopfsn");
	     }
	     splx(s);
     #ifdef DIAGNOSTIC
	     if (vp->v_dirtyblkhd.lh_first) {
		 vprint("vop_fsync: dirty", vp);
		 goto loop;
	     }
     #endif
	 }

	 /*
	  * Write out the on-disc version of the vnode.
	  */
	 tv = time;
	 return VOP_UPDATE(vp, &tv, &tv, waitfor == MNT_WAIT);
     }

ERRORS    [Toc]    [Back]

     [ENOSPC]		The file system is full.

     [EDQUOT]		Quota exceeded.

SEE ALSO    [Toc]    [Back]

     vnode(9)

AUTHORS    [Toc]    [Back]

     This man page was written by Doug Rabson.


FreeBSD 5.2.1			 July 24, 1996			 FreeBSD 5.2.1