dm snapshot: allow chunk size to be less than page size

Allow the snapshot chunk size to be smaller than the page size
The code is now capable of handling this due to some previous
fixes and enhancements.

As the page size varies between computers, prior to this patch,
the chunk size of a snapshot dictated which machines could read it:
Snapshots created on one machine might not be readable on another.

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>

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 932d1b123143ea87bc1c0d2ff6217b86764dfff8..7dbe652efb5aabe8b42bbae0847ab9d062197495 100644 (file)
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -138,16 +138,6 @@ int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
 }
 EXPORT_SYMBOL(dm_exception_store_type_unregister);
 
-/*
- * Round a number up to the nearest 'size' boundary.  size must
- * be a power of 2.
- */
-static ulong round_up(ulong n, ulong size)
-{
-       size--;
-       return (n + size) & ~size;
-}
-
 static int set_chunk_size(struct dm_exception_store *store,
                          const char *chunk_size_arg, char **error)
 {
@@ -166,12 +156,6 @@ static int set_chunk_size(struct dm_exception_store *store,
                return 0;
        }
 
-       /*
-        * Chunk size must be multiple of page size.  Silently
-        * round up if it's not.
-        */
-       chunk_size_ulong = round_up(chunk_size_ulong, PAGE_SIZE >> 9);
-
        return dm_exception_store_set_chunk_size(store,
                                                 (unsigned) chunk_size_ulong,
                                                 error);