Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 12 Dec 2021 22:32:54 +0100 (CET) | From | Richard Weinberger <> | Subject | Re: [RFC PATCH] NFS: Save 4 bytes when re-exporting |
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----- Ursprüngliche Mail ----- > Von: "Trond Myklebust" <trondmy@hammerspace.com> > On Sun, 2021-12-12 at 22:00 +0100, Richard Weinberger wrote: >> When re-exporting, the whole struct nfs_fh is embedded in the new >> fhandle. >> But we need only nfs_fh->data[], nfs_fh->size is not needed. >> So skip fs_fh->size and save a full word (4 bytes). >> The downside is the extra memcpy() in nfs_fh_to_dentry(). >> >> Signed-off-by: Richard Weinberger <richard@nod.at> >> --- >> While investigating into improving NFS re-export I noticed that >> we can already save 4 bytes of overhead. >> I don't think we need to embedd the full struct nfs_fh and >> can skip ->size. >> > > NACK. This will break existing running clients. Any code to change the > filehandle format must be accompanied with code to detect and service > filehandles that are presented in the old format.
One possible way to distinguish between old and new formats is looking at the length of the data. 2 * XDR_UNIT = new format (without ->size). 3 * XDR_UNIT = old format.
What do you think?
Thanks, //richard
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