Hi, On Fri, Oct 28, 2011 at 06:18:55PM +0300, Felipe Balbi wrote: > 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(); Actually it needs to two situations: a) SCSI command doesn't have FUA set b) Ignore FUA module parameter is set On the above cases we need to sync, so something like: if (!scsi_cmd->fua || ignore_fua) fsync(); -- balbi
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