2013/3/5 Simo <simo@xxxxxxxxx>: > On 03/05/2013 01:13 PM, J. Bruce Fields wrote: >> >> On Mon, Mar 04, 2013 at 05:49:46PM -0500, Simo wrote: >>> >>> On 03/04/2013 04:19 PM, J. Bruce Fields wrote: >>>> I'm a little more worried: these are mandatory locks, and applications >>>> that use them are used to the locks being enforced correctly. Are we >>>> sure that an application that opens a file O_DENYWRITE won't crash if it >>>> sees the file data change while it holds the open? >>> >>> The redirector may simply assume it has full control of that part of >>> the file and not read nor send data until the lock is released too, >>> so you get conflicting views of the file contents between different >>> clients if you let a mandatory lock not be mandatory. >>> >>>> In general the idea of making a mandatory lock opt-in makes me nervous. >>>> I'd prefer something like a mount option, so that we know that everyone >>>> on that one filesystem is playing by the same rules, but we can still >>>> mount filesystems like / without the option. >>> >>> +1 >>> >>>> But I'll admit I'm definitely not an expert on Windows locking and may >>>> be missing something about how these locks are meant to work. >>> >>> Mandatory locks really are mandatory in Windows. >>> That may not be nice to a Unix system but what can you do ? >> >> I wonder if we could repurpose the existing -omand mount option? >> >> That would be a problem for anyone that wants to allow mandatory fcntl >> locks without allowing share locks. I doubt anyone sane actually uses >> mandatory fcntl locks, but still I suppose it would probably be better >> to play it safe and use a new mount option. > > > Maybe we should have a -o win_semantics option :-) > > /me runs > (CC'ing Al Viro, since these patches should go through his tree) I don't mind to introduce a new mount option for turning this feature on/off - something like '-o denylock' to make it mathing names of new flags would be ok. Al, what do you think about this feature overall? -- Best regards, Pavel Shilovsky. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
