md/bitmap: prepare for storing write-intent-bitmap via dm-dirty-log.

This allows md/raid5 to fully work as a dm target.

Normally md uses a 'filemap' which contains a list of pages of bits
each of which may be written separately.
dm-log uses and all-or-nothing approach to writing the log, so
when using a dm-log, ->filemap is NULL and the flags normally stored
in filemap_attr are stored in ->logattrs instead.



Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 3797dea4723a..a7a11134268d 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -222,6 +222,10 @@ struct bitmap {
         unsigned long file_pages; /* number of pages in the file */
         int last_page_size; /* bytes in the last page */
 
+        unsigned long logattrs; /* used when filemap_attr doesn't exist
+                                 * because we are working with a dirty_log
+                                 */
+
         unsigned long flags;
 
         int allclean;
@@ -243,6 +247,7 @@ struct bitmap {
         wait_queue_head_t behind_wait;
 
         struct sysfs_dirent *sysfs_can_clear;
+
 };
 
 /* the bitmap API */