Re: usb-storage: fsync() take too much time when handing ALLOW_MEDIUM_REMOVAL

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On Fri, Oct 28, 2011 at 10:50:04AM -0400, Alan Stern wrote:
> On Fri, 28 Oct 2011, Felipe Balbi wrote:
> 
> > > I'm pretty sure Windows assumes that once a write to a removable device
> > > completes, the data is safe. Most Windows users don't bother to "safely
> > > eject" a thumb drive, they just yank it once the transfer is shown as
> > > complete.
> > 
> > That's configurable. You can optimize for performance - which will do
> > asynchronous writes - or you can optimize for removal - which will all
> > SCSI Writes to be synchronous.
> > 
> > Commit a93917d39fc388c4761d2530af82513e2d3bf9f6 added a module parameter
> > to ignore the FUA bit.
> > 
> > The point is, if FUA is set and all writes are synchronous already, do
> > we need to fsync() again ?
> 
> No, we shouldn't need to.  But turn it around.  If we are ignoring FUA, 
> can we afford not to fsync?

the fact is that we're not ignoring by default, right ? That's a module
parameter. Which means that we could:

if (ignore_fua)
	fsync();

would that work ?

-- 
balbi

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