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dm bio prison: pass cell memory in

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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>
This commit is contained in:
Joe Thornber
2013-03-01 22:45:50 +00:00
committed by Alasdair G Kergon
parent 4e7f1f9089
commit 6beca5eb6e
3 changed files with 178 additions and 103 deletions
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33
drivers/md/dm-bio-prison.h
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@@ -35,17 +35,36 @@ struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
void dm_bio_prison_destroy(struct dm_bio_prison *prison);
/*
* This may block if a new cell needs allocating. You must ensure that
* cells will be unlocked even if the calling thread is blocked.
* These two functions just wrap a mempool. This is a transitory step:
* Eventually all bio prison clients should manage their own cell memory.
*
* Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
* in interrupt context or passed GFP_NOWAIT.
*/
struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,
gfp_t gfp);
void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell);
/*
* An atomic op that combines retrieving a cell, and adding a bio to it.
*
* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
*/
int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
struct bio *inmate, struct dm_bio_prison_cell **ref);
int dm_bio_detain(struct dm_bio_prison *prison,
struct dm_cell_key *key,
struct bio *inmate,
struct dm_bio_prison_cell *cell_prealloc,
struct dm_bio_prison_cell **cell_result);
void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
void dm_cell_error(struct dm_bio_prison_cell *cell);
void dm_cell_release(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *bios);
void dm_cell_release_no_holder(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell,
struct bio_list *inmates);
void dm_cell_error(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell);
/*----------------------------------------------------------------*/