[NFS-Ganesha-Devel] Re: fsal_close old and new API

> On 07/11/2018 04:44 AM, ntvietvn(a)gmail.com wrote: >> Hello, >> >> While reading the fsal_remove function, it seems that there may be a >> missing check before calling fsal_close(), if the FSAL supports new >> API or not >> >> /* Make sure the to_remove_obj is closed since unlink of an >> * open file results in 'silly rename' on certain platforms. >> */ >> status = fsal_close(to_remove_obj); >> >> So even if the FSAL tells the SAL that support_ex = true, it still needs to > implement the op->close function which is a little bit strange. >> >> Can you shed some light on this point? >> >> Thank you >> _______________________________________________ >> Devel mailing list -- devel(a)lists.nfs-ganesha.org To unsubscribe send >> an email to devel-leave(a)lists.nfs-ganesha.org >> > > > fsal_close() and the close() API are still used to close the global file descriptor. > I'm not sure if this has been explained before, so if you've heard it, just skip to > the end. > > In NFS, there are two types of operations that operate on an FD: > anonymous, and explicit open. NFSv4 added an explicit open to the protocol, > which allows the client to get a special state ID that corresponds to an open file. > This allows things like exclusive open modes, and allows the client to better > reclaim open state on a restart or failover. Supporting this necessitated a new > API in Ganesha, the > support_ex() API. It added open2()/close2(), which can take a state_t argument > for the explicit-open cases. It also added new APIs for each file op that works > on an FD, so that they can take an optional state_t to represent the FD to > operate on. > > However, NFSv3 doesn't have explicit-open, and NFSv4 allows anonymous I/O > without an open, if the client so desires, so FSALs still need to have a concept of > a global FD that can be used as a catch-all for cases where explicit-open isn't > used. To simplify the code a bit, the close() call was kept, to handle closing the > global FD, since this is a complicated case, and is used in lots of code. > > TL;DR, a FSAL still needs both close2() for explicit-open, and close() for global > FD. It's not well advertised, but there is some documentation here: https://docs.google.com/document/d/1pOpN7Ea3zK4Yf5aIK-rTVxVC91Y7HdjGpECqA... Someone should link this from our wiki :-) Since that document may not cover every little subtlety we have found, I welcome folks to request access to comment or even edit.