From: "J. Bruce Fields" <bfields@xxxxxxxxxx> NFSv4 delegations are currently implemented as leases. However, leases don't have quite the same semantics, which means that delegations are currently enforced correctly only for conflicts between NFSv4 clients. I previously attempted to address this by "fixing" the existing lease behavior, assuming it was a bug--but from further investigation it looks like that would be the wrong thing to do for Samba. So instead I'm defining a new FL_DELEG flag to mark NFSv4 delegations, and varying behavior based on that. Delegations aren't meant to be available to userspace for now--nfsd is the only user. In theory this code allows both read and write delegations, but I'm only using read delegations for now--write delegations are a project for another day. (At which point write leases will probably need some fixing while we're at it.) Still to do: if OPEN(dirfd, name) returns a delegation to the client, then the client should be guaranteed that the opened file is still linked as (dirfd, name). But the current nfsd code allows a rename or unlink to intervene between the lookup and the request for a delegation. --b. J. Bruce Fields (6): locks: introduce new FL_DELEG lock flag. locks: give break_lease its own flags locks: break delegations on unlink locks: break delegations on rename locks: break delegations on any attribute modification locks: break delegations on link Documentation/filesystems/directory-locking | 11 +++--- fs/attr.c | 3 ++ fs/locks.c | 51 +++++++++++++++++++------- fs/namei.c | 27 ++++++++++++-- fs/nfsd/nfs4state.c | 2 +- fs/nfsd/vfs.c | 6 ++-- fs/open.c | 4 +- include/linux/fs.h | 50 ++++++++++++++++++++++++-- 8 files changed, 122 insertions(+), 32 deletions(-) -- 1.7.5.4 -- 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
