VOP_FSYNC(9) MidnightBSD Kernel Developer’s Manual VOP_FSYNC(9)
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, 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.
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, 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) {
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nbp = bp->b_vnbufs.le_next; |
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/* |
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* Ignore buffers which are already being written. |
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*/ |
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if (bp->b_flags & B_BUSY) |
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continue; |
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/* |
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* Make sure the buffer is dirty. |
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*/ |
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if ((bp->b_flags & B_DELWRI) == 0) |
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panic("vop_fsync: not dirty"); |
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vfs_bio_awrite(bp); |
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splx(s); |
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goto loop; |
}
splx(s);
if (waitfor == MNT_WAIT) {
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s = splbio(); |
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while (vp->v_numoutput) { |
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vp->v_flag |= VBWAIT; |
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tsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "vopfsn"); |
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} |
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splx(s); |
#ifdef DIAGNOSTIC
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if (vp->v_dirtyblkhd.lh_first) { |
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vprint("vop_fsync: dirty", vp); |
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goto loop; |
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} |
#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
vnode(9)
AUTHORS
This manual page was written by Doug Rabson.
MidnightBSD 0.3 July 24, 1996 MidnightBSD 0.3