>>>>> " " == Jamie Lokier <firstname.lastname@example.org> writes:
> Do you know how good other clients are about taking into
> account the microsecond/nanosecond field? Is Linux the only
> cacheing NFS client with this problem, so I can otherwise rely
> on using microseconds?
I couldn't tell you for sure, but I'd imagine all sane clients use the
full 64-bit value (32-bit seconds + 32-bit mu/nano-seconds) as a
cookie for cache invalidation. NFSv4 takes this a step further and
formalizes it it the draft specs.
I first implemented this in the NFSv3 patches for 2.2.x, so it is
already available for the stable kernel too...
> The race I'm thinking of is
> Task1 Task2
> allocate a page send readlink request wait_on_page
> allocate a page -- same
> symlink so
> find the one
> allocated by Task1
> response arrives
> see Task1's symlink value see Task1's symlink value
> Possibly the page cache won't do this (I've not studied it) but
> your comment "we wait on page" doesn't sound like enough to
> avoid this situation.
It's quite safe: __find_get_page() waits on the page, then releases
it, and looks up the page cache again. If the first page was dropped
from the page cache, then the new lookup will fail.
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This archive was generated by hypermail 2b29 : Mon May 15 2000 - 21:00:11 EST