xref: /dragonfly/share/man/man9/VOP_FSYNC.9 (revision 606a6e92)
1.\" Copyright (c) 1996 Doug Rabson
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27.\" $FreeBSD: src/share/man/man9/VOP_FSYNC.9,v 1.6.2.2 2001/12/17 11:30:18 ru Exp $
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29.\"
30.Dd July 24, 1996
31.Os
32.Dt VOP_FSYNC 9
33.Sh NAME
34.Nm VOP_FSYNC
35.Nd flush filesystem buffers for a file
36.Sh SYNOPSIS
37.In sys/param.h
38.In sys/vnode.h
39.Ft int
40.Fn VOP_FSYNC "struct vnode *vp" "struct ucred *cred" "int waitfor" "struct proc *p"
41.Sh DESCRIPTION
42This call flushes any dirty filesystem buffers for the file.
43It is used to implement the
44.Xr sync 2
45and
46.Xr fsync 2
47system calls.
48.Pp
49Its arguments are:
50.Bl -tag -width waitfor
51.It Ar vp
52the vnode of the file
53.It Ar cred
54the caller's credentials
55.It Ar waitfor
56whether the function should wait for I/O to complete
57.It Ar p
58the calling process
59.El
60.Pp
61The argument
62.Fa waitfor
63is either
64.Dv MNT_WAIT
65or
66.Dv MNT_NOWAIT
67and specifies whether or not the function should wait for the writes
68to finish before returning.
69.Sh LOCKS
70The file should be locked on entry.
71.Sh RETURN VALUES
72Zero is returned if the call is successful, otherwise an appropriate
73error code is returned.
74.Sh PSEUDOCODE
75.Bd -literal
76int
77vop_fsync(struct vnode *vp, struct ucred *cred, int waitfor, struct proc *p)
78{
79    struct buf *bp;
80    struct buf *nbp;
81    struct timeval tv;
82    int s;
83
84loop:
85    s = splbio();
86    for (bp = vp->v_dirtyblkhd.lh_first; bp; bp = nbp) {
87	nbp = bp->b_vnbufs.le_next;
88
89	/*
90	 * Ignore buffers which are already being written.
91	 */
92	if (bp->b_flags & B_BUSY)
93	    continue;
94
95	/*
96	 * Make sure the buffer is dirty.
97	 */
98	if ((bp->b_flags & B_DELWRI) == 0)
99	    panic("vop_fsync: not dirty");
100
101	vfs_bio_awrite(bp);
102	splx(s);
103	goto loop;
104    }
105    splx(s);
106
107    if (waitfor == MNT_WAIT) {
108	s = splbio();
109	while (vp->v_numoutput) {
110	    vp->v_flag |= VBWAIT;
111	    tsleep((caddr_t)&vp->v_numoutput, 0, "vopfsn");
112	}
113	splx(s);
114#ifdef DIAGNOSTIC
115	if (vp->v_dirtyblkhd.lh_first) {
116	    vprint("vop_fsync: dirty", vp);
117	    goto loop;
118	}
119#endif
120    }
121
122    /*
123     * Write out the on-disc version of the vnode.
124     */
125    tv = time;
126    return VOP_UPDATE(vp, &tv, &tv, waitfor == MNT_WAIT);
127}
128.Ed
129.Sh ERRORS
130.Bl -tag -width Er
131.It Bq Er ENOSPC
132The filesystem is full.
133.It Bq Er EDQUOT
134Quota exceeded.
135.El
136.Sh SEE ALSO
137.Xr vnode 9
138.Sh AUTHORS
139This man page was written by
140.An Doug Rabson .
141