NAME
VOP_FSYNC – flush file system buffers for a file
SYNOPSIS
#include <sys/param.h>
#include <sys/vnode.h>
int
VOP_FSYNC(struct vnode *vp, struct ucred *cred, int waitfor, struct thread *td);
DESCRIPTION
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
The file should be locked on entry.
RETURN VALUES
Zero is returned if the call is successful, otherwise an appropriate error code is returned.
PSEUDOCODE
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
- [ENOSPC]
-
The file system is full.
- [EDQUOT]
-
Quota exceeded.
SEE ALSO
AUTHORS
This manual page was written by Doug Rabson.