2013/1/18 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>: > Hi Pavel, > > On Thu, 17 Jan 2013 20:52:09 +0400 Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote: >> >> This patchset adds support of O_DENY* flags for Linux fs layer. These flags can be used by any application that needs share reservations to organize a file access. VFS already has some sort of this capability - now it's done through flock/LOCK_MAND mechanis, but that approach is non-atomic. This patchset build new capabilities on top of the existing one but doesn't bring any changes into the flock call semantic. > > This has probably been discussed, but is Linux's leases implementation > not sufficient? Just wondering. As I understand it, leases play different role: they allow to cache a data for the particular open and then flush it when a lease break comes. But we need to protect opens from being done if their access/share mode is not suitable for previously done opens. E.g. if we have already opened a file with O_RDONLY | O_DENYWRITE we can't open it again with any of O_WRONLY, O_RDWR and O_DENYREAD flags (of course all these things should only work if O_DENYMAND is specified for the first and the second opens). -- Best regards, Pavel Shilovsky. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
