On Fri, Feb 10 2017, Chris Siebenmann wrote: > I was recently reading this manual page as part of exploring running > an NFS server on Ubuntu 16.04 (with Ubuntu's kernel '4.4.0') and found > two inaccuracies with the current state of the kernel (or at least how > it looks to me based on both experimentation and code). > > First, there is no /proc/net/rpc/auth.domain directory and cache any > more. This was removed from the kernel in 2006 (in commit efc36aa5608f), > so I think it should be safe to remove from current versions of the > manpage. I agree. > > Second, the manpage says about the 'flush' files to be found in eg > /proc/net/rpc/auth.unix.ip: > > When a number of seconds since epoch (1 Jan 1970) is written to > this file, all entries in the cache that were last updated before > that file become invalidated and will be flushed out. Writing > 1 will flush everything. [...] > > The bit about 'writing 1 will flush everything' does not appear to be > accurate. I was never accurate. I vaguely remember writing it. I must have been confused. Would you be able to create a patch which fixes these issues, and post it, with a signed-off-by ? Thanks, NeilBrown > Experimentally, writing 1 does not work (it flushes nothing), > and in the current kernel code there is no special handling for a write of > '1' to the "flush" files in net/sunrpc/cache.c's write_flush() function, > which I believe is where this is implemented. Based on the implementation, > the only way to flush everything is to write a time in the future to > "flush". > > Based on looking at the kernel logs and code diffs, this may have > changed in commit 778620364ef5, 'sunrpc/cache: make cache flushing more > reliable', which gitk tells me came between v4.3-rc3 and v4.4-rc1 (it > was made in October 2015). The commit description definitely talks about > changing how cache expiry works, and it touches write_flush() et al in > various ways. This may call for a kernel change to make it work again, > but even if so I would suggest that the manpage be updated to reflect > that writing 1 doesn't work in a range of kernel versions (some of which > will be in the field for years to come, eg Ubuntu 16.04 LTS). > > - cks > -- > 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
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