Messages in this thread | | | Date | Tue, 12 May 2009 11:53:01 -0400 | From | Christoph Hellwig <> | Subject | Re: mmap vs mtime in 2.6.26 and up |
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On Tue, May 12, 2009 at 08:37:43AM -0700, Ray Lee wrote: > > I've noticed that the last modification times of our RRD files got > > stuck after upgrading from 2.6.24 to 2.6.26 (Debian Etch -> Lenny; I > > also tested with 2.6.30-rc5, they are still stuck). ??It has some > > literature, most notably kernel bug #2645, but that's closed long ago > > and the resulting patch http://lkml.org/lkml/2008/1/22/370 is present > > in my kernels. ??Still, the test program (version 3 from the bug report) > > gives failures:
The problem is pretty simple. do_wp_page and __do_fault use file_update_time to update ctime and mtime. But this function is only a helper for simply filesystems that have a binary inode dirty/non dirty state and keep the m/ctime purely in the Linux inode. It must not be called from generic code as more complex filesystems need a notification through ->setattr to update the timestamps. This will also affect other filesystems like ubifs. I'm not entirely sure why it ever worked before, we must have picked up those c/mtime updates by accident somehow.
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