On Fri, Apr 24, 2015 at 8:16 AM, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 2015-04-24 at 02:14 +0000, Kweh, Hock Leong wrote: >> > -----Original Message----- >> > From: James Bottomley [mailto:James.Bottomley@xxxxxxxxxxxxxxxxxxxxx] >> > Sent: Thursday, April 23, 2015 10:10 PM >> > >> > On Thu, 2015-04-23 at 08:30 +0000, Kweh, Hock Leong wrote: >> > > > -----Original Message----- >> > > > From: James Bottomley >> > [mailto:James.Bottomley@xxxxxxxxxxxxxxxxxxxxx] >> > > > Sent: Wednesday, April 22, 2015 11:19 PM >> > > > >> > > > >> > > > Yes, I think we've all agreed we can do it ... it's now a question of whether >> > we >> > > > can stomach the ick factor of actually initiating a transaction in close ... I'm >> > still >> > > > feeling queasy. >> > > >> > > The file "close" here can I understand that the file system will call the >> > "release" >> > > function at the file_operations struct? >> > > http://lxr.free-electrons.com/source/include/linux/fs.h#L1538 >> > > >> > > So, James you are meaning that we could initiating the update transaction >> > > inside the f_ops->release() and return the error code if update failed in this >> > > function? >> > >> > Well, that's what I was thinking. However the return value of ->release >> > doesn't get propagated in sys_close (or indeed anywhere ... no idea why >> > it returns an int) thanks to the task work additions, so we'd actually >> > have to use the operation whose value is propagated in sys_close() which >> > turns out to be flush. >> > >> > James >> > >> >> Okay, I think I got you. Just to double check for in case: you are meaning >> to implement it at f_ops->flush() instead of f_ops->release(). > > Well, what I'm saying is that the only way to propagate an error to > close is by returning one from the flush file_operation. > > Let's cc fsdevel to see if they have any brighter ideas. > > The problem is we need to update firmware (several megabytes of it) via > standard system tools. We're thinking cat to a device. The problem is > that we need an error code back once the update goes through (which it > can't until we've fed all the firmware data into the system). To use > standard unix tools, we have to trigger off the standard system calls > cat uses and since write() will happen in chunks, the only way to commit > the transaction is in close(). > > We initially through of initiating the transaction in f_ops->release and > returning the error code there, but that doesn't work because its value > isn't actually propagated, so we're now thinking of initiating the > transaction in f_ops->flush instead (this is a device, not a file, so it > won't get any other flushers). Are there any other ways for us to > propagate error on close? > I think we may end up wanting to support both UpdateCapsule and QueryCapsuleCapabilities, in which case this gets awkward. Maybe we really should do a misc device + ioctl. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
