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VOP_FSYNC (9)

>> VOP_FSYNC (9) ( FreeBSD man: Ядро )

BSD mandoc

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:

Fa vp

The vnode of the file.

Fa 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.

Fa td

The calling thread.

The argument Fa 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) {
        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);
}