dm snapshot: abstract minimum_chunk_size fn
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>
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@ -523,6 +523,25 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new)
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return 0;
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}
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#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
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/*
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* Return a minimum chunk size of all snapshots that have the specified origin.
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* Return zero if the origin has no snapshots.
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*/
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static sector_t __minimum_chunk_size(struct origin *o)
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{
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struct dm_snapshot *snap;
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unsigned chunk_size = 0;
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if (o)
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list_for_each_entry(snap, &o->snapshots, list)
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chunk_size = min_not_zero(chunk_size,
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snap->store->chunk_size);
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return chunk_size;
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}
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/*
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* Hard coded magic.
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*/
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@ -1395,8 +1414,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
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return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
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}
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#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
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/*
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* Set the target "split_io" field to the minimum of all the snapshots'
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* chunk sizes.
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@ -1404,19 +1421,12 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
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static void origin_resume(struct dm_target *ti)
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{
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struct dm_dev *dev = ti->private;
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struct dm_snapshot *snap;
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struct origin *o;
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unsigned chunk_size = 0;
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down_read(&_origins_lock);
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o = __lookup_origin(dev->bdev);
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if (o)
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list_for_each_entry (snap, &o->snapshots, list)
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chunk_size = min_not_zero(chunk_size,
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snap->store->chunk_size);
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up_read(&_origins_lock);
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ti->split_io = chunk_size;
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ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev));
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up_read(&_origins_lock);
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}
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static int origin_status(struct dm_target *ti, status_type_t type, char *result,
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