Re: vfs: Add MS_FLUSHONFSYNC mount flag

[Jeff Garzik]

Eric Sandeen wrote:
> Fernando Luis Vázquez Cao wrote:
> > This mount flag will be used to determine whether the block device's write
> > cache should be flush or not on fsync()/fdatasync().
> >
> > Signed-off-by: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
> > ---
>
> Again, apologies for chiming in late.
>
> But wouldn't it be better to make this a block device property rather
> than a new filesystem mount option?
>
> That way the filesystem can always do "the right thing" and call the
> blkdev flush on fsync.
>
> The block device *could* choose to ignore this in hardware if it knows
> it's built with a nonvolatile write cache or if it has no write cache.

That would certainly be my preference -- turn this ON by default, and 
them if a layer NEEDS to ignore it, it can.

	Jeff




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