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Re: VOP_GETATTR: locking protocol change proposal
> yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi) wrote:
>> > <...>
>> > With the attached diff the locking protocol requests at least a shared
>> > lock and all calls to VOP_GETATTR() outside of file systems respect it.
>> > <...>
>> postgresql assumes instant lseek(SEEK_END) to get the size of
>> their heap files.
>> as fsync etc keeps the vnode lock during i/o, it might cause severe
>> performance regression.
> I wonder if it is worth having a separate VOP for that, which would
> retrieve a subset of vattr without lock held. There are potentially
> more uses in the tree.
while it's good to have VOP_GETATTR take a mask to specify a set of
requested attributes, i don't think it's worth to have a serparete VOP
for this. (PR/30250 is related)
IMO we should make unlocked VOP calls safe (against revoke and umount -f)
and put VOP_GETATTR locking back into filesystem internal.
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