tree 65d4af8d6cf36ac4bcc8c226f8be891740d343ee
parent 515ad66cc4c82f210d726340349c8f7c1ec6b125
author Mikulas Patocka <mpatocka@redhat.com> 1260489151 +0000
committer Alasdair G Kergon <agk@redhat.com> 1260489151 +0000

dm snapshot: avoid allocating exceptions in merge

The snapshot-merge target should not allocate new exceptions because the
intent is to merge all of its exceptions as quickly and safely as
possible.

This patch introduces the snapshot-merge mapping function and updates
__origin_write() so that it doesn't allocate exceptions on any snapshots
that are being merged.

If a write request to a merging snapshot device is to be dispatched
directly to the origin (because the chunk is not remapped or was already
merged), snapshot_merge_map() must make exceptions in other snapshots so
calls do_origin().

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>