xref: /freebsd/share/man/man9/VOP_FSYNC.9 (revision 7f3dea244c40159a41ab22da77a434d7c5b5e85a)
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3.\" Copyright (c) 1996 Doug Rabson
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29.\" $FreeBSD$
30.\"
31.Dd July 24, 1996
32.Os
33.Dt VOP_FSYNC 9
34.Sh NAME
35.Nm VOP_FSYNC
36.Nd flush filesystem buffers for a file
37.Sh SYNOPSIS
38.Fd #include <sys/param.h>
39.Fd #include <sys/vnode.h>
40.Ft int
41.Fn VOP_FSYNC "struct vnode *vp" "struct ucred *cred" "int waitfor" "struct proc *p"
42.Sh DESCRIPTION
43This call flushes any dirty filesystem buffers for the file.
44It is used to implement the
45.Xr sync 2
46and
47.Xr fsync 2
48system calls.
49.Pp
50Its arguments are:
51.Bl -tag -width waitfor
52.It Ar vp
53the vnode of the file
54.It Ar cred
55the caller's credentials
56.It Ar waitfor
57whether the function should wait for I/O to complete
58.It Ar p
59the calling process
60.El
61.Pp
62The argument
63.Fa waitfor
64is either
65.Dv MNT_WAIT
66or
67.Dv MNT_NOWAIT
68and specifies whether or not the function should wait for the writes
69to finish before returning.
70.Sh LOCKS
71The file should be locked on entry.
72.Sh RETURN VALUES
73Zero is returned if the call is successful, otherwise an appropriate
74error code is returned.
75.Sh PSEUDOCODE
76.Bd -literal
77int
78vop_fsync(struct vnode *vp, struct ucred *cred, int waitfor, struct proc *p)
79{
80    struct buf *bp;
81    struct buf *nbp;
82    struct timeval tv;
83    int s;
84
85loop:
86    s = splbio();
87    for (bp = vp->v_dirtyblkhd.lh_first; bp; bp = nbp) {
88	nbp = bp->b_vnbufs.le_next;
89
90	/*
91	 * Ignore buffers which are already being written.
92	 */
93	if (bp->b_flags & B_BUSY)
94	    continue;
95
96	/*
97	 * Make sure the buffer is dirty.
98	 */
99	if ((bp->b_flags & B_DELWRI) == 0)
100	    panic("vop_fsync: not dirty");
101
102	vfs_bio_awrite(bp);
103	splx(s);
104	goto loop;
105    }
106    splx(s);
107
108    if (waitfor == MNT_WAIT) {
109	s = splbio();
110	while (vp->v_numoutput) {
111	    vp->v_flag |= VBWAIT;
112	    tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "vopfsn");
113	}
114	splx(s);
115#ifdef DIAGNOSTIC
116	if (vp->v_dirtyblkhd.lh_first) {
117	    vprint("vop_fsync: dirty", vp);
118	    goto loop;
119	}
120#endif
121    }
122
123    /*
124     * Write out the on-disc version of the vnode.
125     */
126    tv = time;
127    return VOP_UPDATE(vp, &tv, &tv, waitfor == MNT_WAIT);
128}
129.Ed
130.Sh ERRORS
131.Bl -tag -width Er
132.It Bq Er ENOSPC
133The filesystem is full.
134.It Bq Er EDQUOT
135Quota exceeded.
136.El
137.Sh SEE ALSO
138.Xr vnode 9
139.Sh AUTHORS
140This man page was written by
141.An Doug Rabson .
142