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VOP_FSYNC(9)          DragonFly Kernel Developer's Manual         VOP_FSYNC(9)


NAME

     VOP_FDATASYNC, VOP_FSYNC - flush filesystem buffers for a file


SYNOPSIS

     #include <sys/param.h>
     #include <sys/vnode.h>

     int
     VOP_FDATASYNC(struct vnode *vp, int waitfor, int flags);

     int
     VOP_FSYNC(struct vnode *vp, int waitfor, int flags);


DESCRIPTION

     This call flushes any dirty filesystem 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 do data, meta-data updates or be
              full-synchronous.

     flags    are additional flags to be passed to the filesystem specific
              fsync(2) function.

     The argument waitfor can use the following flags:

     MNT_NOWAIT      is for an asynchronous data pass and a meta-data pass as
                     well.

     MNT_LAZY        means a limited amount of data from dirty buffers and a
                     full meta-data synchronization pass.

     MNT_WAIT        will make syncer(4) try to do a full synchronization
                     pass.  That is, a meta-data pass and multiple data
                     passes.

     The argument flags is to specify additional flags passed to the
     filesystem specific fsync(2) call.  The only supported flag at the moment
     is VOP_FSYNC_SYSCALL which indicates the file synchronization was
     requested from userland.

     VOP_FDATASYNC() is similar, but it does not require that all of the
     file's metadata be flushed.  It only requires that the file's data be
     recoverable after a crash.  That implies that the data itself must be
     flushed to disk, as well as some metadata such as the file's size but not
     necessarily its attributes.  VOP_FDATASYNC() should always wait for I/O
     to complete, as if called with MNT_WAIT.  VOP_FDATASYNC() is used to
     implement fdatasync(2).


RETURN VALUES

     Zero is returned if the call is successful, otherwise an appropriate
     error code is returned.


ERRORS

     [ENOSPC]           The filesystem is full.

     [EDQUOT]           Quota exceeded.


SEE ALSO

     syncer(4), vnode(9)


AUTHORS

     This man page was written by Doug Rabson.

DragonFly 6.1-DEVELOPMENT     September 14, 2021     DragonFly 6.1-DEVELOPMENT

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