Messages in this thread | | | Date | Sat, 17 Mar 2007 12:53:37 +0200 | From | "Pekka Enberg" <> | Subject | Re: forced umount? |
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On 3/17/07, Mike Snitzer <snitzer@gmail.com> wrote: > Thanks for the heads up; its good to see that Pekka Enberg's work has > continued. I actually stumbled onto that line of work earlier while > searching for more info on Tigran Aivazian's forced unmount (badfs) > patches: > http://lwn.net/Articles/192632/
FYI, the revoke implementation have since been changed to follow the badfs-style approach of the forced unmount patches. However, there are some problems with the forced unmount patches that are now fixed in the revoke implementation:
- You can't use munmap() to take down shared memory mappings because the application can accidentally remap something completely different to that region. - The ->f_light bits slow down other fget_light() users and there's a race between fcheck_files() and set_f_light(). - The operation can live-lock if a malicious process keeps forking. The revoke implementation solves this by revoking in two passes: (1) take down the descriptors and (2) take down the actual inodes.
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