Is this revoke system supported for the filesystem as a whole? I
thought it was just to force specific files closed, not the whole
filesystem. What if the filesystem itself has pending IO to say, update
inodes or block bitmaps? Can these be aborted?
Pekka Enberg wrote:
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.
Pekka
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