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| author | Mike Snitzer <snitzer@redhat.com> | 2009-12-11 00:52:24 +0100 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2009-12-11 00:52:24 +0100 |
| commit | c1f0c183f6acc6d32c5a1d0249ec68bf783af7b1 (patch) | |
| tree | f8e8e88e5403a9dbbebff14dc4afd6d475d1c03a /drivers/md/dm.c | |
| parent | dm: keep old table until after resume succeeded (diff) | |
| download | linux-c1f0c183f6acc6d32c5a1d0249ec68bf783af7b1.tar.xz linux-c1f0c183f6acc6d32c5a1d0249ec68bf783af7b1.zip | |
dm snapshot: allow live exception store handover between tables
Permit in-use snapshot exception data to be 'handed over' from one
snapshot instance to another. This is a pre-requisite for patches
that allow the changes made in a snapshot device to be merged back into
its origin device and also allows device resizing.
The basic call sequence is:
dmsetup load new_snapshot (referencing the existing in-use cow device)
- the ctr code detects that the cow is already in use and allows the
two snapshot target instances to be linked together
dmsetup suspend original_snapshot
dmsetup resume new_snapshot
- the new_snapshot becomes live, and if anything now tries to access
the original one it will receive -EIO
dmsetup remove original_snapshot
(There can only be two snapshot targets referencing the same cow device
simultaneously.)
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm.c')
0 files changed, 0 insertions, 0 deletions