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dm bio prison: introduce support for locking ranges of blocks

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Ranges will be placed in the same cell if they overlap.

Range locking is a prerequisite for more efficient multi-block discard
support in both the cache and thin-provisioning targets.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-09-17 10:17:39 +01:00 committed by Mike Snitzer
parent f1afb36a61
commit 5f274d8865
4 changed files with 16 additions and 9 deletions
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4
drivers/md/dm-bio-prison.c
View File

@ -95,10 +95,10 @@ static int cmp_keys(struct dm_cell_key *lhs,
if (lhs->dev > rhs->dev)
return 1;
if (lhs->block < rhs->block)
if (lhs->block_end <= rhs->block_begin)
return -1;
if (lhs->block > rhs->block)
if (lhs->block_begin >= rhs->block_end)
return 1;
return 0;

12
drivers/md/dm-bio-prison.h
View File

@ -23,11 +23,14 @@
*/
struct dm_bio_prison;
/* FIXME: this needs to be more abstract */
/*
* Keys define a range of blocks within either a virtual or physical
* device.
*/
struct dm_cell_key {
int virtual;
dm_thin_id dev;
dm_block_t block;
dm_block_t block_begin, block_end;
};
/*
@ -59,7 +62,7 @@ void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
struct dm_bio_prison_cell *cell);
/*
* Creates, or retrieves a cell for the given key.
* Creates, or retrieves a cell that overlaps the given key.
*
* Returns 1 if pre-existing cell returned, zero if new cell created using
* @cell_prealloc.
@ -70,7 +73,8 @@ int dm_get_cell(struct dm_bio_prison *prison,
struct dm_bio_prison_cell **cell_result);
/*
* An atomic op that combines retrieving a cell, and adding a bio to it.
* An atomic op that combines retrieving or creating a cell, and adding a
* bio to it.
*
* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
*/

3
drivers/md/dm-cache-target.c
View File

@ -436,7 +436,8 @@ static void build_key(dm_oblock_t oblock, struct dm_cell_key *key)
{
key->virtual = 0;
key->dev = 0;
key->block = from_oblock(oblock);
key->block_begin = from_oblock(oblock);
key->block_end = key->block_begin + 1ULL;
}
/*

6
drivers/md/dm-thin.c
View File

@ -115,7 +115,8 @@ static void build_data_key(struct dm_thin_device *td,
{
key->virtual = 0;
key->dev = dm_thin_dev_id(td);
key->block = b;
key->block_begin = b;
key->block_end = b + 1ULL;
}
static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
@ -123,7 +124,8 @@ static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
{
key->virtual = 1;
key->dev = dm_thin_dev_id(td);
key->block = b;
key->block_begin = b;
key->block_end = b + 1ULL;
}
/*----------------------------------------------------------------*/