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dm snapshot: abstract minimum_chunk_size fn

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The origin needs to find minimum chunksize of all snapshots.  This logic is
moved to a separate function because it will be used at another place in
the snapshot merge patches.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mikulas Patocka
2009-12-10 23:52:08 +00:00
committed by Alasdair G Kergon
parent 102c6ddb1d
commit 7e201b3513
1 changed files with 22 additions and 12 deletions
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34
drivers/md/dm-snap.c
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@@ -523,6 +523,25 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new)
return 0; return 0;
} }
#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
/*
* Return a minimum chunk size of all snapshots that have the specified origin.
* Return zero if the origin has no snapshots.
*/
static sector_t __minimum_chunk_size(struct origin *o)
{
struct dm_snapshot *snap;
unsigned chunk_size = 0;
if (o)
list_for_each_entry(snap, &o->snapshots, list)
chunk_size = min_not_zero(chunk_size,
snap->store->chunk_size);
return chunk_size;
}
/* /*
* Hard coded magic. * Hard coded magic.
*/ */
@@ -1395,8 +1414,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
} }
#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
/* /*
* Set the target "split_io" field to the minimum of all the snapshots' * Set the target "split_io" field to the minimum of all the snapshots'
* chunk sizes. * chunk sizes.
@@ -1404,19 +1421,12 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
static void origin_resume(struct dm_target *ti) static void origin_resume(struct dm_target *ti)
{ {
struct dm_dev *dev = ti->private; struct dm_dev *dev = ti->private;
struct dm_snapshot *snap;
struct origin *o;
unsigned chunk_size = 0;
down_read(&_origins_lock); down_read(&_origins_lock);
o = __lookup_origin(dev->bdev);
if (o)
list_for_each_entry (snap, &o->snapshots, list)
chunk_size = min_not_zero(chunk_size,
snap->store->chunk_size);
up_read(&_origins_lock);
ti->split_io = chunk_size; ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev));
up_read(&_origins_lock);
} }
static int origin_status(struct dm_target *ti, status_type_t type, char *result, static int origin_status(struct dm_target *ti, status_type_t type, char *result,