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path: root/drivers/md/dm-bio-prison.h
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2013-03-02dm: add cache targetJoe Thornber1-0/+11
Add a target that allows a fast device such as an SSD to be used as a cache for a slower device such as a disk. A plug-in architecture was chosen so that the decisions about which data to migrate and when are delegated to interchangeable tunable policy modules. The first general purpose module we have developed, called "mq" (multiqueue), follows in the next patch. Other modules are under development. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Heinz Mauelshagen <mauelshagen@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2013-03-02dm thin: remove cells from stackJoe Thornber1-1/+11
This patch takes advantage of the new bio-prison interface where the memory is now passed in rather than using a mempool in bio-prison. This allows the map function to avoid performing potentially-blocking allocations that could lead to deadlocks: We want to avoid the cell allocation that is done in bio_detain. (The potential for mempool deadlocks still remains in other functions that use bio_detain.) Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2013-03-02dm bio prison: pass cell memory inJoe Thornber1-8/+27
Change the dm_bio_prison interface so that instead of allocating memory internally, dm_bio_detain is supplied with a pre-allocated cell each time it is called. This enables a subsequent patch to move the allocation of the struct dm_bio_prison_cell outside the thin target's mapping function so it can no longer block there. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-12-22dm thin: replace dm_cell_release_singleton with cell_defer_exceptJoe Thornber1-1/+0
Change existing users of the function dm_cell_release_singleton to share cell_defer_except instead, and then remove the now-unused function. Everywhere that calls dm_cell_release_singleton, the bio in question is the holder of the cell. If there are no non-holder entries in the cell then cell_defer_except behaves exactly like dm_cell_release_singleton. Conversely, if there *are* non-holder entries then dm_cell_release_singleton must not be used because those entries would need to be deferred. Consequently, it is safe to replace use of dm_cell_release_singleton with cell_defer_except. This patch is a pre-requisite for "dm thin: fix race between simultaneous io and discards to same block". Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-10-13dm thin: move bio_prison code to separate moduleMike Snitzer1-0/+72
The bio prison code will be useful to other future DM targets so move it to a separate module. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>